STS-66 (66)

Atlantis (13)

Pad 39-B (31)

66th Shuttle Mission

13th Flight OV-104

EAFB Landing (43)

Crew:

Donald R. McMonagle (3), Commander

Curtis L. Brown Jr. (2), Pilot

Ellen Ochoa (2), Payload Commander

Scott E. Parazynski, M.D. (1), Mission Specialist

Joseph R. Tanner (1), Mission Specialist

Jean-Francois Clervoy (1), Mission Specialist

Milestones:

OPF -- 5/30/94

VAB -- 10/3/94

PAD -- 10/9/94

Payload:

ATLAS-03, SSBUV-7, CRISTA-SPAS, ESCAPE-II, PARE/NIR-R, PCG-TES, PCG-STES,

STL/NIH-C, SAMS, HPP-2

Mission Objectives:

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The Atmospheric Laboratory for Applications and Sciences - 3 (ATLAS-03) is the primary payload aboard STS-66. It will continue the series of Spacelab flights to study the energy of the sun and how it affects the Earth's climate and environment. The ATLAS 3 mission will make the first detailed measurements from the Shuttle of the Northern Hemisphere's middle atmosphere in late fall. The timing of the flight, when the Antarctic ozone hole is diminishing, allows scientists to study possible effects of the ozone hole on mid-latitudes, the way Antarctic air recovers, and how the northern atmosphere changes as the winter season approaches.

In addition to the ATLAS-03 investigations, the mission will include deployment and retrieval of the Cryogenic Infrared Spectrometer Telescopefor Atmosphere, or CRISTA. Mounted on the Shuttle Pallet Satellite, the payload is designed to explore the variability of the atmosphere and provide measurements that will complement those obtained by the Upper Atmosphere Research Satellite launched aboard Discovery in 1991. CRISTA-SPAS is a joint U.S./German experiment.

Other payloads in Atlantis cargo bay include the Shuttle Solar Backscatter Ultraviolet (SSBUV-7) payload and the Experiment on the Sun Complementing ATLAS (ESCAPE-II). Payloads located in the middeck include the Physiological & Anatomical Rodent Experiment (PARE/NIR-R), Protein Crystal Growth-Thermal Enclosure (PCG-TES), Protein Crystal Growth- Single Locker (PCG-STES), Space Tissue Loss/National Institute of Health (STL/NIH-C), Space Acceleration Measurement System (SAMS) and the Heat Pipe Performance-2 Experiment (HPP-2).

Launch:

Launch November 3, 1994. 11:59:43.060am EDT from LC-39B. Launch window was from 11:56am EDT to 12:58pm EDT.Window was 1 hr 02 min. Weather at KSC was excellent but a cold front approaching the Iberian Peninsula caused weather concerns at the Transatlantic Abort Landing (TAL) sites in Spain and Portugal. Weather at Zaragoza, Spain and Moron, Spain was unacceptable for launch but Ben Guerir, Morocco was initially marginal with cross wind in excess of 18 knots. Cross winds were showing a downward trend so the count was resumed at the T-9min mark at 11:47am EDT with a plan to reaccess the weather situation in Morocco at the T-5min mark. The countdown was held for three minutes and 43 seconds at the T-5 minute mark as managers discussed the weather at the transoceanic abort landing sites. At T-5min, cross winds were at 14-15 knots and a go was given for launch.

No significant technical issues were worked throughout the duration of the countdown. Post launch inspections of the pad reveal no unusual damage to the pad surface or the mobile launcher platform. The solid rocket booster retrieval ships have reached the spent boosters. Divers have recovered the parachutes and the ships will begin towing the boosters back to Port Canaveral later today.

Had Atlantis not launched by Monday, it would have been delayed until at least November 14 so that Helium in the Cryogenic Infrared Spectrometers & Telescope (CCRISTA-SPAS) payload could be replenished.

The launch was originally scheduled for October 27 but the the need to refurbish three more engines for Atlantis after the RSLS abort of the initial launch attempt of STS-68 caused a week delay. Earlier during launch processing, on Monday, October 3, 1994 at 10 a.m. CDT, STS-68 MCC Status Report #5 reports that one of Columbia's windows was removed and placed on Atlantis which was found to have a tiny scratch in one of the overhead windows. Other concerns included a check of Atlantis's plumbing after a water leak onboard Endeavour during the landing of STS-68 on October 11, 1994.

Orbit:

Altitude: 164nm

Inclination: 57 degrees

Orbits: 174

Duration: 10 days, 22 hours, 34 minutes, 2 seconds.

Distance: 4,554,791 miles

Hardware:

SRB: BI-069

SRM: 360L/W038

ET : SN-67

MLP: 3

SSME-1: SN-2030

SSME-2: SN-2034

SSME-3: SN-2017

Landing:

11/14/94 at 10:33:45am EST. Edwards Air Force Base Runway 22. Landing was originally scheduled for KSC but was diverted to California due to high winds, rain and clouds caused by Tropical Storm Gordon. Fourth diverted landing in 1994 and third in a row. 43rd landing at Edwards. Main wheel touchdown at 10:33:45 EST, Nose wheel touchdown at 10:33:56 and wheel stop at 10:34:34. Rollout distance 7,657 feet (2,334 meters). Rollout time: 49 seconds.

APU #1 was requested shutdown shortly after landing due to fuel line temperature fluxuations. All other post landing activites were normal. Mission Control requested the Ammonia Boiler B to be activated at 10:38am EST. This is a normal procedure anytime the orbiter avionics need to loose excess heat beyond what can be done by cold soaking before deorbit.

Planned KSC landing on 11/14/94 at 7:31 a.m. EST was passed over due to a tropical storm system off the coast of Florida in the Atlantic. This storm is expected to bring a chance of clouds and thunderstorms into the Kennedy Space Center.for tomorrow's two east coast landing opportunities. The two landing times in Florida are 6:31 a.m. and 8:04 a.m. central time with the deorbit burn occurring about an hour prior to landing. Two landing opportunities available for California's Edwards Air Force Base were at 9:34 a.m. and 11:07 a.m. central time. The weather is expected to be favorable on the west coast tomorrow.

Mission Highlights:

Shortly after launch, on of Atlantis's Reaction Control System (RCS) steering jets on the Left Aft side failed. This is not expected to cause any problems due to the number of redundant RCS jets.

On Thursday, November 3, 1994 at 5pm CDT, STS-66 MCC Status Report # 1 reports: Commander Donald R. McMonagle, Pilot Curtis L. Brown Jr., Payload Commander Ellen Ochoa and Mission Specialists Jean-Francois Clervoy, Scott E. Parazynski, and Joe Tanner immediately began configuring Atlantis and its Atmospheric Laboratory for Applications and Science-3 payload for 11 days of scientific investigations that should provide clues on how the environment is changing and how humans contribute to those changes.

The astronauts were given a "go" for orbit operations at 12:33 p.m. Central, and immediately began activation of the Spacelab pallet and its experiments. Ochoa and Tanner successfully checked out the 50-foot robot arm, and at 3:54 p.m. Central Ochoa reported that she had grappled the German-built Shuttle Pallet Satellite (SPAS) and was beginning to power up its systems.

Using the Canadian-built remote manipulator system, Ochoa will lift SPAS out of the payload bay Friday morning and deploy it for eight days of free-flying observations with its primary instruments -- the Cryogenic Infrared Spectrometers and Telescopes for the Atmosphere and the Middle Atmosphere High Resolution Spectrograph Investigation. The instruments will be measuring a variety of gases in the middle atmosphere and lower thermosphere. Also onboard SPAS will be the Surface Effects Sample Monitor, which will measure the decay of surfaces in the near-Earth environment of space.

The astronauts are split into two teams to provide around-the-clock support for the scientific investigations. The Red Team of McMonagle, Ochoa and Tanner worked the first duty shift, while the Blue Team of Brown, Clervoy and Parazynski began a six-hour sleep shift at 3 p.m. Central that will put the astronauts on a night-shift schedule by Houston standards.

On Thursday, November 3, 1994 at 6 p.m.CST, STS-66 Payload Status Report # 1 reports: The seven atmospheric and solar instruments from the previous ATLAS missions have reinforcements this flight - two new atmospheric experiments mounted on the German space agency's deployable CRISTA-SPAS satellite.

Payload Commander Ellen Ochoa, a veteran of the ATLAS 2 mission, finished activating Spacelab systems at 1:34 p.m. CST. Ground controllers at Spacelab Mission Operations Control in Huntsville, Ala., completed commands to power up the ATLAS payload at 2:30 p.m, three and a half hours after launch.

The first ATLAS 3 experiment operation was a test of the Atmospheric Trace Molecule Spectroscopy (ATMOS) experiment's sun tracker. The experiment, provided by NASA's Jet Propulsion Laboratory, views the atmosphere illuminated by the rising and setting sun to measure the quantity and distribution of 30 to 40 atmospheric gases - more than any other space instrument. The sun tracker's motorized mirrors follow the sun as it moves in relation to the orbiter, reflecting sunlight onto the instrument's detectors. Commander Donald R. McMonagle maneuvered Atlantis so the experiment team in Huntsville could receive real-time video as they commanded the tracker to scan from the middle to the edge of the solar disk. "This is the first time we have been able to compare video of the tracker's actual movements with the commands we sent," said Principal Investigator Dr. Mike Gunson. "We found the instrument is positioned very accurately, and this gives us an important reference point for commanding throughout the mission." ATMOS made its first science observation of an orbital sunrise at 4:30 p.m.

Mission Specialist Joe Tanner used the orbiter's Remote Manipulator System arm to power up the CRISTA-SPAS satellite for a Cryogenic Infrared Spectrometers and Telescopes for the Atmosphere (CRISTA) status test. The experiment, one of two onboard the satellite, is encased in a thermos-bottle-like vacuum container cooled with super-cold helium. This prevents heat given off by the instrument from interfering with its readings of cool, infrared radiation in the atmosphere. After its deployment, the satellite will follow about 24 to 44 miles (40 to 70 kilometers) behind the Shuttle for a week, adding new insights on the distribution of gases which contribute to ozone chemistry in the middle atmosphere.

On Friday, November 4, 1994 at 7:30am CDT, STS-66 MCC Status Report # 2 reports: The CRISTA-SPAS science satellite was released from Atlantis`s payload bay early this morning for an eight-day flight free from the Shuttle to measure the Earth's atmosphere and ozone layer.

After a complete checkout of the Cryogenic Infrared Spectrometers and Telescopes for the Atmosphere (CRISTA) and the Middle Atmosphere High Resolution Spectrograph Investigation, Mission Specialist Jean-Francois Clervoy used the Shuttle's robot arm to gently raise the satellite out of the payload bay and released it at 6:50 a.m. Central. The release took place as Atlantis flew 164 nautical miles above Germany on the 14th orbit of the mission. Payload Commander Ellen Ochoa will use the robot arm again on November 12 to capture the satellite and place it back in the payload bay for the trip home.

Overnight, Curtis L. Brown Jr., Parazynski and Clervoy worked with the Active Cavity Radiometer Irradiance Monitor, one of seven instruments that comprise the Atmospheric Laboratory for Applications and Science-3 payload. The payload complement is designed to study the Earth's atmosphere with particular attention to the ozone layer and will help researchers determine how human activity is affecting the atmosphere.

Brown also took sightings on several stars to calibrate and test Atlantis's heads up display and Course Optical Alignment Site instruments. These instruments are used to backup the Inertial Measurement Units on board the orbiter that keepAtlantis oriented in space.

Mission Commander Donald R. McMonagle, Ochoa and Mission Specialist Joe Tanner began their second day in space at about 4 a.m. today. The other three astronauts are scheduled to go to bed at about 1 p.m. this afternoon

On Friday, November 4, 1994 at 6 a.m. CDT, STS-66 Payload Status Report # 2 reports: At MET 0/19:00, Instruments aboard the third Atmospheric Laboratory for Applications and Science (ATLAS-3) Spacelab mission have been powered up, and two of them took readings of a variety of gases in the middle atmosphere throughout the past twelve hours. Information from the ATLAS experiments, along with that gathered by free-flying satellites, will give scientists increased insight into the complex chemistry of the middle atmosphere which affects global ozone levels.

The mission's atmospheric studies continued as the Millimeter-Wave Atmospheric Sounder (MAS), made its first set of measurements and employed its improved scan mode to continuously observe Earth's far horizon and look for traces of water vapor, ozone and chlorine monoxide at different altitudes. The instrument, mounted on the Spacelab pallet, uses a dish-shaped antenna to study the chemistry of ozone, and also to measure temperature and pressure, in Earth's middle atmosphere. Using its new chlorine monoxide receiver, that is twice as sensitive as the one that flew on the ATLAS 1 (STS-45) and ATLAS 2 (STS-56) missions, MAS can take better measurements of chlorine monoxide, an important compound involved in ozone depletion, over both hemispheres.

Also, the Atmospheric Trace Molecule Spectroscopy (ATMOS) instrument continued to operate nominally, making its observations of orbital sunrises and sunsets and measuring the concentrations of more than 30 gases in the middle atmosphere. The device uses a technique called limb sounding, which involves viewing the infrared portion of sunlight as it shines through the Earth's horizon, or 'limb.' Because trace gases absorb at very specific infrared wavelengths, the science team can determine what gases are present, in what concentrations, and at what altitudes. A more thorough knowledge of which gases are present, and of how their concentrations change over time, can help scientists determine the extent of man-made and natural changes.

Mission Specialist Ellen Ochoa activated the Shuttle Solar Backscatter Ultraviolet (SSBUV) experiment, which will be used to verify the accuracy of atmospheric ozone and solar ultraviolet irradiance data obtained by instruments on free-flying National Oceanic and Atmospheric Administration and NASA satellites. Its door was opened to expose the instrument to the space environment, and a period of "outgassing" followed, during which the device cooled until 5:30 a.m. CST. SSBUV will take its first atmospheric readings after the first period of solar observations.

The Cryogenic Infrared Spectrometers and Telescopes for the Atmosphere (CRISTA) experiment began its checkout and pre-deploy activities in preparation for its release aboard the ASTRO-SPAS retrievable satellite at 6:50 a.m. CST. This instrument will gather the first global information about medium and small scale disturbances in trace gases of the middle atmosphere. These measurements will be taken in three dimensions simultaneously and will provide information about disturbances caused by winds, waves, turbulence and other processes. A pressure increase observed earlier in CRISTA's liquid helium container has since leveled off and should not affect the scheduled deployment of the satellite. Also aboard the ASTRO-SPAS carrier, the Middle Atmosphere High Resolution Spectrograph Investigation (MAHRSI) will measure amounts of hydroxyl and nitric oxide in the middle atmosphere and lower thermosphere, from 24 to 72 miles (40 to about 120 km) high.

The solar instruments have been activated and calibrated for the first period of solar observations. SOLSPEC and SUSIM are operating nominally. ACRIM successfully completed its shutter test and is undergoing further testing. During the next twelve hours, solar observations will begin after the deployment of ASTRO-SPAS as ATLAS 3 starts its second day in orbit. All Spacelab systems are working well at this time.

On Friday, November 4, 1994 at 5pm CDT, STS-66 MCC Status Report # 3 reports: The Cryogenic Infrared Spectrometers and Telescopes for the Atmosphere-Shuttle Pallet Satellite (CRISTA-SPAS), released from Atlantis this morning to fly free and study the sun for eight days, is now trailing Atlantis by about 22 nautical miles, separating from the orbiter at a rate of about three miles per orbit. During the afternoon, controllers for the satellite prepared CRISTA-SPAS for the hands-off operations over the next several days. Controllers refined the satellite's navigation via ground commands to solve a brief problem with its precise pointing ability, but CRISTA-SPAS is now working well as it aims the scientific instruments at their planned targets.

Ochoa took two brief breaks from her work today first to explain the Measurement of Solar Constant Experiment, or SOLCON, to ground controllers and then to answer questions about her research from high school honor students during an interview with WRC-TV in Washington, D.C.

The crew reported a minor problem with the resistance settings on an exercise bicycle carried on board Atlantis, however the problem was solved by manually setting the bike's tension for each astronaut. Exercise is a constant feature of all shuttle missions for both ongoing medical studies and as a method of counteracting the effects of weightlessness on the body.

On Friday, November 4, 1994 at 6 p.m. CST, STS-66 Payload Status Report # 3 reports: (MET 1/7:00) With the STS-66 mission well into its second day in orbit, six additional instruments are at work to decipher the complex chemistry of Earth's atmosphere.

The flight is part of NASA's Mission to Planet Earth, a coordinated research effort to comprehensively study the planet's environment. The mission's first solar observation period, which began around noon today, will measure the sun's energy during daylight portions of eight orbits. All four solar instruments are veterans of both previous ATLAS (STS-45, STS-56) flights, plus either Spacelab 1 (STS-9 or Spacelab 2 (51-F) in the mid-1980s.

The Jet Propulsion Laboratory's Active Cavity Radiometer Irradiance Monitor (ACRIM) and Belgium's Measurement of the Solar Constant (SOLCON) experiment detect the total amount of radiation from the sun, to within 0.1 percent accuracy. The Solar Spectrum Measurement (SOLSPEC) experiment from France breaks sunlight down into ultraviolet, visible and infrared wavelengths, while the Naval Research Laboratory's Solar Ultraviolet Spectral Irradiance Monitor (SUSIM) concentrates on ultraviolet radiation.

Sunlight, particularly ultraviolet radiation, provides energy for the chemical reactions that create atmospheric changes. Before scientists can predict accurately how human activity will affect the atmosphere, they must thoroughly understand the natural forces driving it. Even small fluctuations in solar radiation are important parts of that equation. For instance, variations of one percent or less in total solar radiation could cause droughts or lengthy periods of unseasonal cooling.

Two new atmospheric instruments are in operation for the first time in space - the Cryogenic Infrared Spectrometers and Telescopes for the Atmosphere (CRISTA) experiment and the Middle Atmosphere High Resolution Spectrograph Investigation (MAHRSI). Both are aboard the autonomous CRISTA-SPAS satellite, which the crew deployed at 6:50 CST this morning. After receiving several hours of start-up commands from the operations team at Kennedy Space Center. the instruments made their first observations shortly before noon.

CRISTA, provided by the University of Wuppertal in Germany, is gathering data to give scientists their first three-dimensional global "maps" of the middle atmosphere. The instrument uses three infrared telescopes looking in different directions to locate small-scale structures of various gases, thought to be distributed in the atmosphere by winds, wave interactions, turbulence and other disturbances. Global measurements of these gases and their changes will help scientists create more precise models of the chemistry and dynamics of the stratosphere - the region of the atmosphere 10 to 30 miles above the Earth which contains the ozone layer - and give them a better understanding of Earth's energy balance.

Science operations for CRISTA were interrupted when the satellite's guidance system lost sight of its reference stars this afternoon, but they resumed when ground commands successfully reoriented the satellite a few hours later.

MAHRSI is making ultraviolet measurements of nitric oxide and hydroxyl in an area parallel to that of CRISTA's center telescope. Comparing results from CRISTA and MAHRSI will provide important insights into the chemistry and the heating and cooling of the middle atmosphere. Both hydroxyl and nitric oxide are natural chemicals that react with ozone and other gases to affect the chemical balance of the ozone layer. This is the first time hydroxyl has been measured from space so low in the atmosphere. Principal Investigator Dr. Robert Conway, of the Naval Research Laboratory in Washington, D.C., reports that the first data received from MAHRSI is remarkably close to their predictions, based on expected hydroxyl amounts and instrument properties.

While the CRISTA/SPAS instruments were being activated, the Atmospheric Trace Molecule Spectroscopy (ATMOS) experiment got two bonus observations of orbital sunsets, measuring the distribution of trace gases in the atmosphere over northern Europe.

This morning, the Goddard Space Flight Center. s Shuttle Solar Backscatter Ultraviolet (SSBUV) experiment completed internal calibration exercises to ensure it is operating properly. The experiment team is completing preparations for SSBUV to take its first science data - measurements of ultraviolet radiation from the sun - on the last two solar orbits tonight.

This afternoon, Payload Commander Ellen Ochoa restarted the ATLAS 3 Global Positioning System (GPS), and it locked onto four of the positioning satellites in orbit. An earlier attempt had only locked onto two of the necessary four satellites. This will give ATLAS 3 experiment teams an extra means for verifying the precise locations where their instruments take data. Primary position information comes from the Shuttle's inertial measurement units.

ATLAS 3 payload controllers and the Millimeter Wave Atmospheric Sounder (MAS) team in Huntsville are investigating a loss of science data transmission from the MAS instrument, which occurred after its successful observations last night. Thus far, they have not determined the source of the problem. The next MAS operations are scheduled for early tomorrow morning.

After solar observations conclude just before midnight, the crew will point the Shuttle toward the CRISTA-SPAS satellite to receive a sample of science data to be relayed to the ground. Then the atmospheric instruments will begin another set of measurements, and SSUBV will make its first ATLAS 3 readings of global ozone.

On Saturday, November 5, 1994 at 9am CST, STS-66 MCC Status Report # 4 reports: The rate at which the CRISTA-SPAS separates from the orbiter has been smaller than expected, but the distance between the two spacecraft is well within safe limits for Atlantis' scheduled maneuvering engine firings. In fact, one of those periodic engine firings that had been scheduled for this morning was not needed as the satellite and shuttle continued to separate at a sufficient rate, a deletion that resulted in fuel savings for the orbiter.

The Blue Team of astronauts -- Pilot Curt Brown and Mission Specialists Jean-Francois Clervoy and Scott Parazynski -- began their day about nine last night. Parazynski worked with a student-designed payload, Experiment of the Sun for Complementing the ATLAS Payload and for Education (ESCAPE). ESCAPE is conducting research in extreme ultraviolet wavelengths, a field in which little research has been done over the last 20 years.

On Saturday, November 5, 1994 at 6 a.m. CST, STS-66 Payload Status Report # 4 reports: Solar instruments aboard the third Atmospheric Laboratory for Applications and Science (ATLAS 3) completed their first eight orbits of observations last night, and the mission's second session of atmospheric observations is currently in progress. Scientists need both types of data to view the "big picture" of factors which influence this planet's atmospheric life-support system, especially its protective ozone layer.

The period of solar observations concluded around midnight CST, and the crew pointed the Shuttle toward the Cryogenic Infrared Spectrometers and Telescopes for the Atmosphere-Shuttle Pallet Satellite (CRISTA-SPAS) to receive a sample of science data to be relayed to the ground. Science teams for the four solar instruments at Spacelab Mission Operations Control in Huntsville report their observations went very smoothly, and the quality of the data collected looks good.

At around 6:45 p.m. CST, Commander Donald R. McMonagle, aided by Mission Specialist Ellen Ochoa, maneuvered the Orbiter Atlantis to perform a special calibration of the Solar Ultraviolet Spectral Irradiance Monitor (SUSIM). This planned procedure allowed the SUSIM device to scan across the sun, pointing at the sun's center and at four off-center points to verify the alignment of the instrument on the center of the sun. Changes in ultraviolet radiation output bring about changes in Earth's atmospheric conditions, such as the amount of ozone in the middle atmosphere. A better record of the sun's ultraviolet output will help scientists distinguish between atmospheric changes caused by variations in ultraviolet radiation and those brought about by human activity.

The Active Cavity Radiometer Irradiance Monitor (ACRIM), from NASA's Jet Propulsion Laboratory, and Belgium's Solar Constant experiment (SOLCON) each made extremely precise, independent measurements of the total solar irradiance, or total energy from the sun received by the planet Earth. Computer models suggest that even small variations in this total solar irradiance could have significant impacts on climate. Therefore, these instruments measure this quantity to a long-term accuracy of plus or minus 0.1 percent or better. SOLCON commands were sent from their remote control facility in Brussels.

France's Solar Spectrum (SOLSPEC) experiment concentrates on measuring solar radiation as a function of wavelength in the ultraviolet, visible and infrared. The device is monitored by scientists at the Spacelab Mission Operations Control center in Huntsville, Ala., but most calibrations and observations for this instrument are controlled through the onboard equipment computer. Some commands are sent from the remote center in Brussels.

The Shuttle Solar Backscatter Ultraviolet (SSBUV) instrument, from NASA's Goddard Space Flight Center. completed a cooling period and then made its first observations of the mission during the last two orbits of the solar observation period. Scientists will compare those measurements with readings of ultraviolet radiation scattered back from the Earth's atmosphere, to be obtained by SSBUV in the atmospheric observation periods of the ATLAS 3 mission. Ozone absorbs different wavelengths of ultraviolet light at different altitudes, so comparisons of the incoming ultraviolet radiation with backscattered radiation give scientists a highly accurate picture of the total amount of ozone in the atmosphere, as well as its distribution by altitude.

Atmospheric observations resumed at around 1 a.m. CST, with remote-sensing operations by the Jet Propulsion Laboratory's Atmospheric Trace Molecule Spectroscopy (ATMOS). The instrument is observing orbital sunrises around the South Pole to study the Antarctic ozone hole and compare ozone amounts inside and outside the edge of the swirling mass of cold air known as the "polar vortex." This vortex acts as a container for chemical reactions that cause ozone depletion.

The Cryogenic Infrared Spectrometers and Telescopes for the Atmosphere (CRISTA) and the Middle Atmosphere High Resolution Spectrograph Investigation (MAHRSI), two new atmospheric instruments aboard the retrievable CRISTA-SPAS satellite, continue to make observations of the middle atmosphere's chemistry. CRISTA measures a variety of gases in the middle atmosphere, and MAHRSI detects the amounts of nitric oxide and hydroxyl in the middle atmosphere and lower thermosphere. With its fast scanning technique, CRISTA recorded several hundred thousand spectra of trace gases in Earth's atmosphere. Currently, all systems aboard the CRISTA-SPAS satellite are working nominally.

The ground control team for the Millimeter-Wave Atmospheric Sounder (MAS) instrument is currently working with ATLAS 3 payload controllers to determine the nature of a problem which is preventing the reception of scientific data from the instrument. It is suspected that the problem is internal, possibly a malfunction in the instrument's microprocessor. Until the source of the problem is determined, its potential impact on MAS's science remains uncertain.

On Saturday, November 5, 1994 at 5pm CDT, STS-66 MCC Status Report # 5 reports: The astronauts on board Atlantis gathered spectacular views of a late season hurricane in the Atlantic Ocean as they continued supporting scientific observations being made with the Atmospheric Laboratory for Applications and Science. Mission commander Donald R. McMonagle shared images of Hurricane Florence during an interview this morning with The Weather Channel.

Throughout the day, McMonagle and his crew mates on the Red Team -- Payload Commander Ellen Ochoa and Mission Specialist Joe Tanner -- tended to a variety of middeck experiments on board Atlantis and continued supporting both the ATLAS-3 and CRISTA-SPAS payloads. The CRISTA-SPAS satellite currently is trailing Atlantis by about 42 miles, and the distance between the two spacecraft is increasing by about 2 miles each orbit.

On Saturday, November 5, 1994 at 6 p.m. CST, STS-66 Payload Status Report # 5 reports: (MET 2/7:00) ATLAS 3 experiments aboard the Shuttle Atlantis are in the midst of an atmospheric observation period which began early this morning and will continue until Sunday night. The two instruments aboard the autonomous CRISTA-SPAS satellite are in their second day of collecting additional information about the composition of the atmosphere.

"The ATLAS 3 mission is the most complete global health check on the atmosphere that has ever been done, measuring more trace gases that are important in ozone chemistry than any previous research effort," said Mission Scientist Dr. Tim Miller. Scientists will add the mission's atmospheric and solar studies to those of satellite instruments to help determine what creates ozone variations over different parts of the globe at different times of the year.

The Shuttle Solar Backscatter Ultraviolet (SSBUV), from NASA's Goddard Space Flight Center, is measuring the total amount of ozone under the orbiter's path and how it is distributed by altitude. SSBUV's primary purpose is to verify ozone readings made by its sister instrument aboard the NOAA-9 meteorological satellite and NASA's Total Ozone Mapping Spectrometer on the Russian Meteor 3 satellite. Satellite instruments can be degraded by extended exposure to ultraviolet radiation and particles such as atomic oxygen. SSBUV undergoes rigorous calibration before and after flight. By comparing its measurements with those made by the satellites over the same Earth location within the hour, scientists can make corrections for any drift in the satellite instruments. ATLAS 3 is SSBUV's seventh flight.

The Atmospheric Trace Molecule Spectroscopy (ATMOS) instrument made spectral measurements of the atmosphere during orbital sunsets over Northern Hemisphere sites from Eastern Europe to the middle portion of North America. Orbital sunrises illuminated the atmosphere for ATMOS observations as far south as the Antarctic coast. The ATMOS team at Spacelab Control in Huntsville relays data to their lab at NASA's Jet Propulsion Laboratory in California, where it is translated to show the amounts and distribution of 30 to 40 trace gases which influence ozone chemistry in the middle atmosphere.

This morning, Commander Donald R. McMonagle pointed the orbiter's cargo bay toward the CRISTA-SPAS satellite for three hours of communications with the instruments onboard -- the Cryogenic Infrared Spectrometers and Telescopes for the Atmosphere (CRISTA) and the Middle Atmosphere High Resolution Spectrograph Investigation (MAHRSI). The Shuttle relayed sample data that had been recorded onboard to scientists at Huntsville and the Payload Operations Center in Florida.

Preliminary data analysis indicates that MAHRSI science operations are going very well, according to instrument scientist Jeff Morrill of the U.S. Naval Research Laboratory. "We feel confident that we will be able to determine distributions of hydroxyl in the middle atmosphere." Hydroxyl is a hydrogen compound that plays a part in the natural destruction of ozone. Measurements of nitric oxide, another catalyst in ozone chemistry, will take place later in the mission.

CRISTA Principal Investigator Dr. Dirk Offermann said he is "very satisfied" with his data, reporting the instrument had measured more than two million spectra in 22 hours of operation. The instrument is making a three-dimensional map of how a variety of gases are distributed in the middle atmosphere. CRISTA's space observations are supported by an ambitious ground-based campaign. Sounding rockets are launched twice a day when the Shuttle and CRISTA-SPAS pass over the Wallops Flight Facility in Virginia. On both daily passes over the Hohenpeissenberg station in Germany, high-precision ozone-measuring balloons are launched. Coordinated readings also are being made by airplane flights west of Scotland over the Atlantic. Data from these instruments will provide extra calibration for the CRISTA measurements.

Throughout the morning, the Millimeter Wave Atmospheric Sounder (MAS) team worked with ATLAS 3 payload controllers to revive their instrument. The onboard computer still is not responding. Though they will continue these efforts the remainder of the flight, the MAS team feels they have very little chance of obtaining more science data from ATLAS 3.

According to Principal Investigator Dr. Gerd Hartmann, MAS experienced an apparent malfunction of its onboard computer system at 6:56 CST Friday morning, resulting in loss of science data transmission to the ground and an inability to communicate with the computer. The problem was discovered when communications were reestablished with the ATLAS 3 payload after the CRISTA-SPAS deployment. Indications are that a sudden input current surge in MAS data control electronics may have burned out some electrical components. The cause of the current surge and the actual components which failed probably will not be firmly established until the instrument is examined after landing, .

Prior to the malfunction, MAS worked flawlessly for 12 hours, with ten hours of data obtained on water vapor and ozone distribution over America, Africa and Europe. Some useful information on chlorine monoxide also was gathered.

Atmospheric observations will continue throughout the night, with an hour-long interruption around midnight to relay science data from instruments on the CRISTA-SPAS satellite through Atlantis to the ground.

On Sunday, November 6, 1994 at 9am CST, STS-66 MCC Status Report # 6 reports: With the Atmospheric Laboratory for Applications and Science operating in Atlantis' payload bay, the six astronauts are continuing round-the-clock studies of the Earth's atmosphere and ozone layer. The Blue Team -- Pilot Curt Brown and Mission Specialists Jean-Francois Clervoy and Scott Parazynski -- began its fourth day on orbit about 8 p.m. CST Saturday. Throughout their shift, the three astronauts have worked with the instruments comprising the ATLAS-3 payload.

Atlantis is station-keeping in front of the CRISTA-SPAS science satellite at a distance of about 48 nautical miles. The Cryogenic Infrared Spectrometers and Telescopes for the Atmosphere satellite was deployed Friday and will be retrieved Saturday following eight days of atmospheric data gathering.

Clervoy devoted most of his work day with the Heat Pipe Performance experiment designed to evaluate fluid transfer through various types of pipes for possible use on future spacecraft.

Today the Red Team -- Mission Commander Donald R. McMonagle, Mission Specialist Joe Tanner and Ochoa -- will support a number of secondary experiments housed in Atlantis' middeck. McMonagle will work with the Heat Pipe Performance experiment. Each of the Red Team astronauts will exercise on the Shuttle's bicycle ergometer during their workday.

On Sunday, November 6, 1994 at 6 a.m. CST, STS-66 Payload Status Report # 6 reports: (MET 2/19:00) Atmospheric instruments of the ATLAS-3 Spacelab continue to use a variety of remote-sensing techniques to define the chemical composition of Earth's atmosphere. The chemistry of the middle atmosphere is very complex, involving many gases. Accurate measurements of a large number of trace molecules are needed to verify computer models of how that chemistry works, so atmospheric changes which occur naturally can be distinguished from those that are induced by human activity.

The Atmospheric Trace Molecule Spectroscopy (ATMOS) instrument continued to view the sun's infrared radiation through the Earth's atmospheric limb during orbital sunrises and sunsets, making global measurements of the composition of the troposphere, stratosphere and mesosphere. Already, the device has provided additional data on atmospheric trace gases in near real-time.

For the first time, scientists here at the Marshall Space Flight Center in Huntsville have been completing analysis of ATMOS' observations within 24 hours of acquisition and comparing their results with those obtained by the Total Ozone Mapping Spectrometer (TOMS) aboard the Russian Meteor 3 satellite. Such rapid data reduction represents a remarkable improvement over the previous flights of the ATMOS instrument. According to ATMOS team member Mark Abrams, "by building automated data processing systems, we've been able to reduce the data processing time by more than a factor of a hundred....from months to hours." ATLAS 3 marks the fourth flight of ATMOS aboard the Shuttle.

The Shuttle Solar Backscatter Ultraviolet Spectrometer (SSBUV) peered through the atmosphere to the Earth's surface to identify both the total amount of ozone present and its distribution by altitude. The SSBUV team has already done preliminary processing of solar data taken by the instrument on Friday to determine how well it compares with data from previous missions. So far, analysis has revealed that these measurements are of high quality and that they agree to within one or two percent with results from ATLAS 1 and 2. This information should help the scientists to distinguish those processes induced by solar activity from those caused by human activities. During the current atmospheric observation period, SSBUV has completed 14 orbits of Earth views and 12 concurrent measurements with its sister instrument aboard the NOAA-9 spacecraft. The primary purpose of SSBUV, now on its seventh flight , is to verify the accuracy of data being gathered by free-flying satellites.

After 30 hours of data collection, the CRISTA instrument had measured more than three million infrared spectra of trace gases in the Earth's atmosphere. The device has completed over 6000 measurements of variations in the distribution of trace gases at heights between 30 and 150 km with a resolution of 1.5 km. CRISTA continues to collect data at a rate of 26 spectra per second, and all parts of the system are working nominally. The second instrument aboard CRISTA- SPAS, the MAHRSI experiment, is measuring hydroxyl spectra in the middle atmosphere, and the observed spectral data shows a clear detection of hydroxyl. Hydroxyl plays a key role in the natural destruction of ozone. Both CRISTA and MAHRSI are very pleased with the quantity and quality of the data they have received.

Atmospheric observations will continue to be the primary focus of activity for the next shift, followed by another period of communication period with the CRISTA-SPAS spacecraft. Then, the mission's second solar pointing period will begin.

On Sunday, November 6, 1994 at 6 p.m. CST, STS-66 Payload Status Report # 7 reports: (MET 2/7:00) The Jet Propulsion Laboratory's ATMOS team reported interesting preliminary results of their observations inside the Antarctic polar vortex, an area of high-speed circulation over the South Pole. The circulation bottles up chemical constituents, making it something of a test tube where the atmosphere can be studied in isolation.

"Our data show very low ozone levels over the Antarctic, as expected for this time of year," said ATMOS Principal Investigator Dr. Mike Gunson. "We also see evidence from certain long-lived gases that the air descended to lower altitudes as it cooled over the preceding winter period. This also was expected, but it is the first time it has actually been observed over such a broad range of altitudes."

A "hole" in the ozone layer forms over the Antarctic around September each year, when increased springtime sunlight strikes air cooled during the Southern Hemisphere winter. The sun's ultraviolet radiation triggers chemical reactions that both create and destroy ozone. In recent years, human activity has introduced high levels of chemicals into the atmosphere which upset its natural balance. For instance, one free atom of chlorine released from chlorofluorocarbons can destroy thousands of ozone molecules.

"By late November, ozone-rich air from the mid-latitudes mixes with the Antarctic air to fill in the lost ozone, and chemicals such as nitrogen oxides - - which act like a sort of atmospheric antacid -- begin to gobble up free chlorine, repairing the ozone loss," explained Gunson. In the winter, nitrogen oxides are frozen as nitric acid in ice crystals in polar stratospheric clouds. ATLAS 3 is flying during an intermediate period, when the ozone hole has begun to recover but before it has dissipated. Today's data indicate that nitrogen oxides are still very low. Chlorine measurements will be available in the next couple of days.

During this morning's communications period with the free-flying CRISTA-SPAS satellite, the Middle Atmosphere High Resolution Spectrograph Investigation (MAHRSI) began taking readings of nitric oxide at high altitudes. The instrument previously had been making global readings of hydroxyl, and it will return to that mode during the next communications period. Both gases are active in the natural cycle of ozone chemistry.

The Cryogenic Infrared Spectrometers and Telescopes for the Atmosphere (CRISTA) continues to scan the atmosphere, making millions of spectra to map global locations and movements of some 15 trace gases. The huge number of observations is necessary because each cubic mile of atmosphere over the Earth is essentially its own separate chemical laboratory. For scientists to thoroughly understand chemical reactions and transport mechanisms like atmospheric winds, they must have extensive samples from as many latitudes, longitudes and altitudes as possible.

The Shuttle Solar Backscatter Ultraviolet (SSBUV) experiment is finishing up its first period of atmospheric viewing, recording ozone levels and distribution for comparison with instruments aboard free-flying ozone-monitoring satellites.

SSBUV is housed in two Get-Away Special (GAS) canisters, mounted in the orbiter's cargo bay just in front of the ATLAS 3 Spacelab pallet. Data from the instrument is being relayed to the Goddard Space Flight Center in Greenbelt, Md., the instrument's home base, for preliminary analysis.

The atmospheric observation period for the Shuttle-mounted instruments will end at about 6:30 p.m. CST. Then the orbiter will maneuver to relay communications between CRISTA-SPAS instruments and ground controllers for one orbit. Eight orbits of solar observations will follow.

On Monday, November 7, 1994 at 8 a.m CST, STS-66 MCC Status Report # 7 reports: The Cryogenic Infrared Spectrometers and Telescopes for the Atmosphere satellite is trailing Atlantis at a distance of about 55 nautical miles. On Sunday, Commander Donald R. McMonagle performed a station-keeping burn to keep the two spacecraft at a relative distance of about 40 n.m. until CRISTA-SPAS is retrieved on Saturday following eight days of atmospheric data gathering.

Throughout the night, the Blue Team -- Pilot Curt Brown and Mission Specialists Jean- Francois Clervoy and Scott Parazynski -- maneuvered Atlantis to allow one of the seven instruments to measure fluctuations in the amount of ultraviolet radiation emitted by the sun. Middeck payload activities included a status check of the protein crystal growth experiment and activation of the student-designed ESCAPE experiment which is studying extreme ultraviolet wavelengths.

After completing his shift, Clervoy discussed the mission and his experiences thus far with French Prime Minister Edouard Balladur, Minister of Defense Francois Leotard, Minister of Transportation and Telecommunications Jose Rossi and European Space Agency Director General Jean-Marie Luton. Crew members also used cameras on board Atlantis to document environmental changes as they orbited at an altitude of approximately 160 n.m.

On Monday, November 7, 1994 at 6 a.m. CST, STS-66 Payload Status Report # 8 reports: (MET 3/19:00) ATLAS 3 had completed a total of 30 orbits of atmospheric observations at the conclusion of the mission's second atmospheric period last night, when Commander Donald R. McMonagle maneuvered Atlantis to relay communications between CRISTA-SPAS instruments and ground controllers for one orbit. During these scheduled communications, the Cryogenic Infrared Spectrometers and Telescopes for the Atmosphere (CRISTA) and Middle Atmosphere High Resolution Spectrograph Investigation (MAHRSI) instruments send their data through the Shuttle Orbiter to scientists on the ground. This enables them to make real-time calibrations and adjustments of these instruments . The CRISTA instrument has now collected about 5 million infrared spectra of trace gases in the Earth's atmosphere. In this communication period, the MAHRSI science team again turned their instrument from nitric oxide measurements at high altitudes to global hydroxyl measurements which will continue into the next shift. Both hydroxyl and nitric oxide participate significantly in the ozone chemistry cycle.

The Active Cavity Radiometer Irradiance Monitor (ACRIM) and the Solar Constant (SOLCON) experiment took "superb" readings of the total solar energy coming to Earth, according to Roger Helizon of the ACRIM team. They made preliminary data comparisons with each other, as well as with observations by the ACRIM 2 instrument aboard the Upper Atmosphere Research Satellite (UARS). Science teams said that the rough comparisons were very good, indicating that instruments measuring total solar irradiance on the satellites had not experienced significant degradation.

ATLAS instruments take very reliable readings of the sun, since they are carefully calibrated against strict laboratory standards before and after each flight. Yet these readings are "snapshots" of only a few days' duration. Long-term conditions are tracked by free-flying satellites, whose instruments may be somewhat degraded by extended exposure in space. By comparing the two measurements, scientists can determine the amount of degradation in free-flying satellite readings. This allows them to make accurate corrections, essential to tracking subtle changes over time in the solar energy influencing atmospheric conditions.

The Solar Spectrum (SOLSPEC) instrument again received good data from solar observations of the infrared, visible and ultraviolet radiation from the sun. The data from these observations is sent to Paris, France for processing, and so far the results of this data analysis are according to expectations. The Naval Research Laboratory's Solar Ultraviolet Spectral Irradiance Monitor (SUSIM) was calibrated successfully, then received good data during the seven solar orbits, permitting comparisons with the SUSIM instrument aboard the UARS satellite. The UARS SUSIM has been decreasing in sensitivity since the satellite was placed in orbit. This is to be expected since ultraviolet light, which SUSIM monitors, has a severe impact on space instruments. Comparison with ATLAS measurements gives scientists an accurate yardstick for evaluating that degradation.

The Shuttle Solar Backscatter Ultraviolet (SSBUV) experiment made solar irradiance measurements during the sixth and seventh solar orbits of this shift. The instrument is operating nominally. The instrument has now completed a total of four solar and 22 Earth orbital views and is making solar ultraviolet data comparisons with SUSIM and SOLSPEC.

The current solar viewing period will continue until around 7:30 am CST this morning. Atmospheric observations will follow, after the next communication between the CRISTA-SPAS instruments and ground controllers.

On Monday, November 7, 1994 at 5 p.m CST, STS-66 MCC Status Report # 8 reports: As the crew worked through its fifth day in space, Mission Commander Don McMonagle spent some time testing heat pipe designs and a special type of cooling radiator that has no moving parts. The tests are part of the Heat Pipe Performance experiment which involves applying specifically-measured amounts of heat to the various heat pipe designs, measuring the cooling capacity of the pipe, and determining the limits of each design's operation. McMonagle found time for additional experiment runs with the heat pipes today beyond those originally planned. The tests will provide designers with insight into how well the pipe designs operate in weightlessness. Heat pipes, because of their efficiency and reliability, already are used on some permanent satellites as cooling devices.

Earlier today, ground controllers noticed performance of one of the channels of Atlantis' Ku-band communication system was degrading. The system is used for high data rate communications with the ground, such as the ATLAS science data. The problem was traced to the connections between one of Atlantis's network signal processors and the Ku- band system. Ground controllers switched to a backup processor aboard Atlantis and full communications capability has been restored. The original network signal processor still works well for all modes of communication except the single Ku-band channel.

Around midday today, Atlantis performed a slight engine firing to maintain its distance from the CRISTA-SPAS satellite. CRISTA-SPAS is now trailing Atlantis at a distance of approximately 47 nautical miles, and is extending that distance by about 1 nautical mile per orbit.

On Monday, November 7, 1994 at 6 p.m. CST, STS-66 Payload Status Report # 9 reports: (MET 4/7:00) Complementary instruments aboard the Shuttle Atlantis and the CRISTA-SPAS satellite are in the fifth day of the STS-66 mission, making a detailed examination of Earth's life support system, the atmosphere.

"Each separate experiment is enhanced by the others, because we can compare similar measurements with other instruments," said Ernest Hilsenrath, principal investigator for the Shuttle Solar Backscatter Ultraviolet (SSBUV) experiment . SSBUV studies both solar radiation and atmospheric gases. It compares the amount of ultraviolet radiation from the sun with that scattered back from the Earth. The difference reveals the amount of ozone in the atmosphere.

Over the past few months, Hilsenrath and his colleagues with the Naval Research Laboratory's Solar Ultraviolet Spectral Irradiance Monitor (SUSIM) and France's Solar Spectrum (SOLSPEC) experiment have been closely comparing their solar ultraviolet measurements from the previous ATLAS flights. They are also comparing the short-term, highly calibrated ATLAS readings with long-term measurements from solar ultraviolet instruments on NASA's Upper Atmosphere Research Satellite (UARS). "We're finding that the agreement among the instruments is ten times better than the agreement which existed between solar instruments that flew before UARS [launched in 1991] and ATLAS [first launched in 1992]," said Hilsenrath.

New computer capabilities and experience from previous flights are speeding up comparisons of the solar observations, Hilsenrath added. "It took us 30 months to compare results from ATLAS 1 and 18 months to compare those from ATLAS 2, but within 36 hours of our first ATLAS 3 observations, we were beginning some preliminary comparisons," he said.

Ultraviolet light is the driver for ozone chemistry. Therefore, for scientists to predict atmospheric changes, they must have a thorough understanding of fluctuations in ultraviolet radiation.

At the end of the flight's second solar observation period this morning, the astronaut crew maneuvered the Shuttle to scan the solar experiments across the disk of the sun. The "criss-cross" scan checks the accuracy of their coalignment and measures how much the instruments' response depends on the sun angle.

A communications period with the CRISTA-SPAS instrument followed. It was extended for about an hour, allowing the Middle Atmosphere High Resolution Spectrograph Investigation (MAHRSI) to refine their pointing by doing extra light-of-sight calibrations with bright guide stars.

Both MAHRSI and the other satellite-mounted instrument, the Cryogenic Infrared Spectrometers and Telescopes for the Atmosphere (CRISTA), will furnish detailed measurements about the global atmosphere that complement those of the ATLAS instruments. MAHRSI zeros in on hydroxyl and nitric oxide, two natural gases important in ozone chemistry. CRISTA is mapping three- dimensional distributions and movements of some 15 trace gases.

After the satellite communication period, SSBUV joined the Atmospheric Trace Molecule Spectroscopy (ATMOS) experiment for the mission's third round of atmospheric observations.

ATMOS principal investigator Dr. Mike Gunson reports that his instrument has already collected the equivalent of some 40,000 floppy disks of data on trace gases in the atmosphere. "To understand the myriad of chemical pathways in the atmosphere and how they relate to each other, we need to collect detailed information on as many gases as possible," Gunson said.

Gunson said preliminary ATMOS data show the Antarctic ozone hole region seems to be very well contained, with marked differences between the atmosphere inside and outside the hole. Thus far, he has seen no signs of intermediate zones.

Though it is too early to interpret readings of Northern Hemisphere ozone, both Hilsenrath and Gunson expect to see it recovering to normal levels after depletion triggered by the Mt. Pinatubo volcano eruption in 1991. "Of course, predictions have been known to be disproved by actual observations," added Hilsenrath.

On Tuesday, November 8, 1994 at 8 a.m CST, STS-66 MCC Status Report # 9 reports: With Atlantis' systems performing without problem, the six astronauts that make up the STS-66 crew took time to discuss the progress of the mission with reporters during the traditional in-flight press conference. Questions from reporters in Texas, Florida and France covered a variety of subjects ranging from the Atmospheric Laboratory for Applications and Science-3 activities to election day. Besides stating that he was pleased with the progress of the mission thus far, Mission Commander Don McMonagle also confirmed that all five U.S. astronauts had the opportunity to vote prior to the flight.

Over night, the Blue Team of Curt Brown, Jean-Francois Clervoy and Scott Parazynski worked supporting the ATLAS-3 instruments and a Heat Pipe Performance unit designed to test various types of cylinders that could provide a more effective and efficient method of dissipating heat on future spacecraft and space stations.

Brown oversaw a small maneuvering engine firing performed just after five this morning to refine Atlantis' orbit in front of the Shuttle Pallet Satellite which was deployed on the second day of the mission. The series of engine firings maintain the proper distance from the satellite prior to its capture and return to the payload bay scheduled for Saturday.

The Red Team of Commander Don McMonagle and Mission Specialists Ellen Ochoa and Joe Tanner took over control of the orbiter and payloads about six o'clock this morning as the crew continues to divide the day into two 12-hour shifts.

On Tuesday, November 8, 1994 at 6 a.m. CST, STS-66 Payload Status Report # 10 reports: (MET 4/19:00) The third mission of the Atmospheric Laboratory for Applications and Science (ATLAS 3) is providing an opportunity for scientists from around the world to gather data about our planet and its atmosphere. Instruments on board Space Shuttle Atlantis operated throughout the night, sending back information about the conditions of the Earth's protective blanket.

The Atlas 3 instruments have completed their second atmospheric and second solar observation periods. The atmospheric instruments continue to gather high-quality data about the atmosphere, and the ATLAS science teams are very pleased with the mission's results so far. Currently, the Shuttle Atlantis' cargo bay is pointed toward the Earth for the flight's third atmospheric period.

Investigators for the Shuttle Solar Backscatter Ultraviolet (SSBUV) experiment have been compiling a precisely calibrated database of global stratospheric ozone measurements. SSBUV, which compares direct solar ultraviolet radiation with the amount of sunlight scattered off the Earth's surface, is using the amount of cloud coverage seen through a payload bay camera in order to determine what produces the backscattering in their field of view. According to SSBUV co-investigator Richard Cebula, "cloud cover helps us understand the reflectivity of the Earth and how that reflectivity affects the retrieval of ozone data."

A primary objective of SSBUV during the ATLAS series of missions is to provide highly accurate ozone measurements that will be used to verify data being obtained by free- flying satellites. SSBUV readings help scientists resolve the problem of calibration drifts in ozone-sensing instruments that are exposed to the environment of space for long periods of time, thus improving the accuracy of the measurements.

The Atmospheric Trace Molecule Spectroscope (ATMOS) continued to observe the atmosphere last night, having completed a total of 110 observations of the sun through the atmosphere during sunrises and sunsets. Scientists want to learn more about the components of the middle atmosphere, how they interact, and how they change over time. Models of stratospheric chemistry are used to predict the future evolution of this atmospheric region, and ATMOS data will help in the evaluation of those models. ATMOS also viewed the Sun with no atmospheric interference to provide calibration of the solar spectral background, solar spectral features, and instrument response to the sun.

The CRISTA-SPAS instrument completed its period of communications with the Orbiter early in the evening, during which the Cryogenic Infrared Spectrometers and Telescopes (CRISTA) made a small, two degree turn from viewing the atmospheric limb to view the Earth directly and verify the instrument's altitude, then turned back to look through the atmosphere. According to CRISTA Principal Investigator Dirk Offermann, this planned special mode of operation "gives us an altitude reference independent of the star tracker." CRISTA has begun a period of observations in the high atmosphere and is acquiring approximately 4,000 height scans of trace gases per day. These measurements have important applications for atmospheric dynamics and chemistry, as well as for the understanding of Earth's energy balance.

The Middle Atmosphere High Resolution Spectrograph Investigation (MAHRSI) experiment continues to accurately measure the concentration of hydroxyl in the middle atmosphere, collecting data that will help scientists more accurately test the current understanding of observed ozone levels in the middle atmosphere and resolve conflicts between satellite ozone observations and ozone amounts predicted by computer models. MAHRSI does this by observing light emitted by hydroxyl molecules after they absorb ultraviolet energy from the Sun. Hydroxyl is an important member of the odd hydrogen family, those gases that contain a single hydrogen atom, and contributes directly to the destruction of ozone in the middle atmosphere. "Things are looking very good for data analysis," said Principal Investigator Robert Conway as MAHRSI continues to work on producing "the first ever global maps of hydroxyl."

On Tuesday, November 8, 1994 at 5 p.m CST, STS-66 MCC Status Report # 10 reports: Throughout the day, the Red Team of Don McMonagle, Ellen Ochoa and Joe Tanner worked with the Atmospheric Laboratory for Applications and Science-3, maneuvering the orbiter to provide the scientific instruments with the best view of the Earth and the Sun. Crew members also spent time with a variety of middeck payloads, including the protein crystal growth experiment and a space tissue loss study designed to validate Earth- based models on how microgravity affects the human body.

This afternoon, McMonagle commanded a small maneuvering engine firing to increase the closing rate between CRISTA- SPAS and Atlantis. The maneuver will keep the relative distance between the two spacecraft at 40 to 60 nautical miles prior to its capture and return to the payload bay scheduled for Saturday morning.

The Blue Team, now in its seventh flight day, is awake and preparing for another busy shift. Pilot Curt Brown, and Mission Specialists Jean- Francois Clervoy and Scott Parazynski will perform routine communications health checks with CRISTA-SPAS and Brown will maneuver Atlantis in support of ATLAS-3 observations of cloud tops and atmospheric gasses.

On Tuesday, November 8, 1994 at 6 p.m. CST, STS-66 Payload Status Report #11 reports: (MET 5/7:00) "As we approach the halfway point in this mission, the management team is very proud of the flawless performance of the Spacelab, and the scientists are very pleased with the data they are getting," said ATLAS 3 Mission Manager Paul Hamby in today's press briefing. Information being collected during the 11-day flight will help scientists understand the chemistry, dynamics and physics of Earth's protective ozone layer.

The German ASTRO-SPAS satellite, with its payloads the Cryogenic Infrared Spectrometers and Telescopes for the Atmosphere (CRISTA) and Middle Atmosphere High Resolution Spectrograph Investigation (MAHRSI), is orbiting the Earth about 65 miles away from Atlantis. ASTRO-SPAS systems are in very good health, and CRISTA and MAHRSI continue gathering large amounts of data. Thus far in the mission, CRISTA has collected more than eight million infrared spectra of trace gases in the atmosphere.

During their communication period with the ground this morning, the two instruments checked alignment of their fields of view with bright targets in the night sky. CRISTA tracked Mars and MAHRSI used Sirius, the brightest star in the sky, as reference points. The coalignment confirmed that both were pointing at the correct altitudes.

The two instruments then began several hours of cooperative observations, taking measurements of nitric oxide in the coldest part of the atmosphere, called the mesopause, about 62 miles (100 kilometers) above the Earth's surface. "In this region, nitric oxide has a fairly long lifetime," explained MAHRSI Principal Investigator Dr. Robert Conway. "By watching its movement as the instruments circle the globe, orbit after orbit, we can see how waves and winds transport the gas."

Nitric oxide collects high in the mesosphere above the winter polar region. Atmospheric circulation then transfers it to lower latitudes above the equator and pushes it down into the upper stratosphere. Though other members of the nitrogen oxide family slow ozone depletion in the lower stratosphere by absorbing chlorine, nitric oxide at higher altitudes participates in the chemical cycle that destroys ozone.

MAHRSI returned to its primary task of measuring hydroxyl in the upper stratosphere during this afternoon's communications linkup between the satellite and the ground.

Dr. Dominique Crommelynck, principal investigator for Belgium's Solar Constant (SOLCON) experiment, and Roger Helizon with the Jet Propulsion Laboratory's Active Cavity Radiometer Irradiance Monitor (ACRIM) say they are pleased with results so far from their measurements of the total radiation from the sun. Both appear to agree with previously obtained values from the Upper Atmosphere Research Satellite's ACRIM-II instrument and the ATLAS 2 mission. Crommelynck said he has been able to adjust measurements from earlier space instruments to assemble a single set of continuous observations since 1978. He stressed, however, that "scientists will need measurements over tens or even hundreds of years to truly understand the influence of solar radiation on Mother Earth."

Principal Investigator Dr. Gerard Thuillier has received the first processed Solar Spectrum (SOLSPEC) data from his home laboratory at the National Center for Scientific Research in Paris, and science teams here in Huntsville are beginning to compare ultraviolet radiation data taken during the mission's initial solar observation period. Thuillier and Dr. Michael VanHoosier, co-investigator for the Solar Ultraviolet Spectral Irradiance Monitor (SUSIM), say data from both of their instruments and Shuttle Solar Backscatter Ultraviolet (SSBUV) experiment show a high level of agreement.

This afternoon, SSBUV completed a series of atmospheric measurements to calibrate their sister ozone-monitoring instrument aboard the NOAA-9 meteorological satellite. Then they adjusted their spectrometers to detect a wavelength range virtually identical to that measured by the Total Ozone Mapping Spectrometer (TOMS). For 11 orbits, SSBUV will make six measurements per second of the total ozone under the Shuttle's orbital path. Results will be used to calibrate the mapping spectrometer, which has been making similar readings from the Russian Meteor-3 satellite since 1991.

On Wednesday, November 9, 1994 at 8 a.m CST, STS-66 MCC Status Report # 11 reports: Overnight, Pilot Curt Brown commanded a maneuvering burn that placed Atlantis in a station keeping orbit 35 miles ahead of the Cryogenic Infrared Spectrometers and Telescopes for the Atmosphere satellite. The satellite will continue to gather data about t he Earth's atmosphere and protective ozone layer until Saturday when Brown and Mission Commander Don McMonagle are scheduled to complete a rendezvous with CRISTA-SPAS.

In the orbiter's payload bay, the Atmospheric Laboratory for Applications and Science continues its observations of the chemical processes that affect the Earth's atmosphere. Throughout the day, both teams of astronauts will continue to monitor the ATLAS -3 investigations with Brown and McMonagle commanding Atlantis into a series of attitudes to enhance the scientific observations.

The Blue Team, consisting of Brown and Mission Specialists Jean-Francois Clervoy and Scott Parazynski, supported the Heat Pipe Performance and Protein Crystal Growth Experiments. Parazynski also demonstrated a new resistive exercise device comprised of a series of tethers which allowed him to use his own body weight for resistance. Data indicate that load-bearing exercise may minimize bone density loss during extended space flights. Parazynski also discussed mission objectives and Tuesday's election results with KCBS television in Los Angeles, Calif., during an interview late last night.

On Wednesday November 9, 1994 at 6 a.m. CST, STS-66 Payload Status Report # 12

reports: (MET 5/19:00) The solar instruments are in standby, as science teams evaluate data from the first two solar observation periods and prepare for the third.

The Atmospheric Trace Molecule Spectroscopy (ATMOS) experiment measured the chemical and physical composition of the middle atmosphere. Since ATMOS first flew on Spacelab 3 in 1985, scientists have retrieved height profiles of over 30 trace gases from ATMOS data, including several chlorofluorocarbons, nitrogen-oxygen compounds, ozone, carbon monoxide, carbon dioxide, water and methane. The instrument measures these gases selectively and can simultaneously observe about ten to fifteen trace gases in one observation.

The ATMOS instrument viewed the stratosphere at orbital sunrise and sunset, gathering information in the infrared portion of the electromagnetic spectrum. Since trace gas molecules absorb solar radiation at different wavelengths, ATMOS determines which wavelengths are being absorbed, giving scientists a more detailed picture of the molecular makeup of the atmosphere. ATMOS data from ATLAS 3 will be compared to information gathered during other missions to examine worldwide, seasonal and long-term atmospheric changes. According to Principal Investigator Mike Gunson, ATMOS has already far exceeded its minimum success requirements for the mission, performing "well beyond expectations" on its "most productive, and certainly most scientifically interesting, flight ever on any Shuttle mission." ATMOS has now filled about 80 percent of its onboard recorder, having completed a total of 166 sunrise and sunset observations.

The Shuttle Solar Backscatter Ultraviolet (SSBUV) experiment continued to perform coincident measurements for NASA's Total Ozone Mapping Spectrometer (TOMS) and with ozone measuring instruments flying on the NOAA 9 satellite as called for by the National Plan for Stratospheric Monitoring. The SSBUV instrument makes its ozone measurements by comparing the amount of solar radiation reaching the top of the Earth's atmosphere to the amount being scattered back from the atmosphere. This information gives scientists a measure of the amount of ozone present in a given area.

At around 3:45 CST this morning, the SSBUV team participated in what Principal Investigator Ernest Hilsenrath called "a spontaneous experiment collaboration" with the Middle Atmosphere High Resolution Spectrograph Investigation (MAHRSI) instrument to test the possibility of using MAHRSI's limb-scanning ability to measure ultraviolet radiation and ozone in the lower stratosphere. Taking advantage of a planned CRISTA-SPAS maneuver in which MAHRSI scanned the ultraviolet portion of the electromagnetic spectrum at heights between 55 and 15 km, the SSBUV team cooperated with the MAHRSI team to demonstrate the feasibility of this ozone limb-scanning technique in preparation for a solar limb- scanning instrument currently under development for possible use on future space missions.

SSBUV measures ozone in the upper stratosphere by looking straight down at the Earth using ultraviolet backscatter observations. MAHRSI, on the other hand, measures hydroxyl and nitric oxide in the stratosphere and mesosphere, using limb-scanning, or edge on viewing above the Earth's horizon. This experiment successfully demonstrated the feasibility of using limb-scanning of the ultraviolet spectrum to obtain ozone measurements in the lower stratosphere. According to MAHRSI Principal Investigator Robert Conway, "there was a question about whether our instrument had enough sensitivity to perform this experiment successfully, but, sure enough, we did. The data look excellent." Analysis of this experiment's results will continue throughout the next shift.

During the second half of the next 12 hour shift, the four solar science instruments for ATLAS 3 will begin their third period of solar observations. The Active Cavity Radiometer Irradiance Monitor, from the Jet Propulsion Laboratory, and Belgium's SOLCON experiment will measure the total solar energy received by the Earth. The SOLSPEC experiment will concentrate on the sun's radiant output in ultraviolet, visible and infrared wavelengths while the U.S. Naval Research Laboratory's Solar Ultraviolet Spectral Irradiance Monitor examines solar output in the ultraviolet wavelengths. SSBUV will also observe the sun during one or two of the solar orbits, and the second Experiment of the Sun for Complementing the Atlas Payload and for Education (ESCAPE-II) will be in operation for all solar orbits.

On Wednesday, November 9, 1994 at 5 p.m CST, STS-66 MCC Status Report #12 reports: The crew told Mission Control that night time passes are becoming shorter as the shuttle's orbit aligns more with the line between night and day, called the terminator. By the last day of the flight, Atlantis' orbit will be almost parallel to the terminator, putting the crew in continual daylight for several orbits.

Payload Commander Ellen Ochoa told controllers the crew can see as many as 13-14 layers in the atmosphere during sunsets, while Commander Don McMonagle said they are collecting photographs of the sunsets with a 300 millimeter telephoto lens to supplement the atmospheric data obtained by cargo bay instruments.

Throughout the day, McMonagle performed a series of maneuvers to position the ATLAS instruments for solar science gathering, rotating the orbiter toward the sun during observations and away from it between observing opportunities. During one maneuver, several "failed jet" messages were observed.

Flight controllers are studying the possibility that one of two hand controllers used to fire the shuttle's large steering jets may have sent spurious firing commands to the shuttle's jets when it was powered on for a maneuver. The jets were turned off at the time and did not fire. The problem does not impact any of the shuttle's current scientific work, since the smaller steering jets, or verniers, are used to point the shuttle for the atmospheric observations. An analysis of the problem, including a possible checkout of the hand controller, is continuing.

On Wednesday November 9, 1994 at 6 p.m. CST, STS-66 Payload Status Report # 13 reports: (MET 6/7:00) ATLAS 3 atmospheric instruments have finished another two days of observations to check the health of the atmosphere, and the four solar instruments are in the midst of their third set of observations.

With the mission less than a day past its mid-point, the Atmospheric Trace Molecule Spectroscopy (ATMOS) instrument has already gathered more data than it did during either ATLAS 1 or ATLAS 2. One of the gases it focused on in the last observing period was hydrogen chloride, which provides a direct measurement of the amount of chlorine available in the atmosphere for ozone chemistry.

Payload Commander Ellen Ochoa explained this morning that ATMOS is unique not only because it measures as many as 30 or 40 trace gases simultaneously, but also because it can detect very small concentrations of those gases -- down to a few parts per billion. "Even though the quantities are small," she observed, "these gases can play a large part in ozone destruction."

The ATMOS team has encouraged the crew to get as many photographs of the atmosphere as possible, and this afternoon Commander Don McMonagle made pictures as a sunrise illuminated Earth's thin protective blanket. Ochoa viewed the sunrise with high-magnification binoculars, and she commented that she could see 13 or 14 atmospheric layers above the clouds.

The Shuttle Solar Backscatter Ultraviolet (SSBUV) experiment completed a series of Earth ozone measurements to calibrate those being made by NASA's Total Ozone Mapping Spectrometer (TOMS) aboard the Russian Meteor-3 satellite.

A six-orbit period of solar observations began at around 1 p.m., with the Solar Constant (SOLCON) experiment and the Active Cavity Irradiance Monitor (ACRIM) making very precise measurements of the total radiation arriving at Earth from the sun. The Solar Spectrum (SOLSPEC) instrument and Solar Ultraviolet Spectral Irradiance Monitor (SUSIM) are looking at the sun's radiation as a function of wavelength.

This morning, principal scientists for SUSIM, SOLSPEC and SSBUV announced that preliminary data for their first set of ultraviolet solar observations agree approximately to five percent of one another. This is the closest agreement ever achieved by three individual solar instruments without post-flight calibration. The correlation is especially significant since each instrument uses different physics to achieve their calibration. The scientists expect to refine the agreement even further during post-flight analysis.

"It is important to obtain very accurate measurements of ultraviolet radiation, because it sets up the chemistry in the atmosphere, triggers catalytic cycles that make and destroy ozone, and drives heating in the atmosphere," said SSBUV Principal Investigator Ernest Hilsenrath. Changes in this ultraviolet output are very subtle, but their impact is of the same order as that of chemicals released into the atmosphere by industrial activity. To distinguish changes due to solar variations from those caused by human activity, both must be closely tracked. "Measurements made by the ATLAS missions and the satellite instruments they calibrate will provide a baseline for the future," said Hilsenrath. "They will be a legacy for environmental investigators in the next century, so they can look back at our data and compare it with changes they may observe in the atmosphere."

While the Shuttle-based experiments concentrate on the sun, the Cryogenic Infrared Spectrometers and Telescopes for the Atmosphere (CRISTA) experiment and the Middle Atmosphere High Resolution Spectrograph Investigation (MAHRSI) are continuing atmospheric observations from aboard Germany's free-flying CRISTA-SPAS satellite.

CRISTA Principal Investigator Dr. Dirk Offermann, of the University of Wuppertal in Germany, reported his instrument has made the first global readings of atomic oxygen in far-infrared wavelengths as low as 62 miles (100 kilometers). "This is important because it will help us understand how atomic oxygen functions as a cooling mechanism in the upper atmosphere," explained Offermann. Though far-infrared readings of atomic oxygen at similar altitudes have been made during brief sounding rocket flights, and by satellite instruments at higher altitudes, they have never before been made so low in the atmosphere on a global scale. Atomic oxygen is produced in the upper stratosphere when solar ultraviolet light strikes molecular oxygen (the form of oxygen people breathe), breaking it down into single oxygen atoms.

The MAHRSI team has processed preliminary data showing global concentrations of hydroxyl. Hydroxyl is very influential in the ozone chemistry of the middle atmosphere.

On Thursday, November 10, 1994 at 8 a.m CST, STS-66 MCC Status Report # 13 reports: After several "failed jet" messages were observed following a maneuver earlier today, ground controllers had the crew check the forward hand controller to verify its operation. Checkout validated performance in all axes and flight controllers continue to study the possibility that contacts in the hand controllers were transiently energized when the flight control power was turned on. The problem does not impact any of the Shuttle's current scientific work, since the smaller steering jets, or verniers, are used to point the shuttle for the atmospheric observations.

Clervoy took time to discuss the science and objectives of the STS-66 mission with European media representatives during an interview overnight.

With the mission past its halfway point, the Red Team -- Mission Commander Don McMonagle, Payload Commander Ellen Ochoa and Mission Specialist Joe Tanner -- are scheduled to take a half day off today and the Blue Team will take a half day off following wakeup late this afternoon. The half day off is a standard practice for Shuttle missions lasting more than 10 days.

On Thursday, November 10, 1994 at 6 a.m. CST, STS-66 Payload Status Report # 14

reports: (MET 6/19:00) The ATLAS 3 solar instruments completed the sixth and final orbit of their solar observation period at around 9:25 p.m. CST, and then last night's scheduled communications with the CRISTA-SPAS satellite started. This was the third of four periods planned during ATLAS 3 for the Shuttle's cargo bay to point at the sun. By accumulating data during multiple observation periods, scientists can make extremely precise measurements of the sun's total energy output and its dispersion. Multiple solar periods also allow them to study short-term solar variations. All the solar instruments collected very high quality data.

Two University of Colorado students participated in science planning meetings in Huntsville during the last three solar observation periods. The students represented a Colorado Space Grant Consortium project, the second Experiment of the Sun for Complementing the ATLAS Payload and for Education (ESCAPE-II), housed in a Get-Away-Special canister in the Shuttle cargo bay.

A secondary payload co-manifested for the ATLAS 3 mission, ESCAPE-II is making observations concurrently with the ATLAS solar instruments, in particular with the Solar Ultraviolet Spectral Irradiance Monitor (SUSIM), which also measures solar ultraviolet radiation in the same wavelength ranges. The experiment was designed, managed and built entirely by 60 undergraduate and graduate students at the University of Colorado in Boulder. ESCAPE II is a follow-on payload to the Extreme Ultraviolet Solar Complex Autonomous Payload Experiment (ESCAPE I), also known as the Solar Ultraviolet Experiment (SUVE), which flew in April 1993 onboard the Space Shuttle Discovery as part of the STS-56/ATLAS 2 mission.

Instruments on ESCAPE II include a Far Ultraviolet Spectrometer (FARUS) and a digital Lyman Alpha Spectrum Imaging Telescope (LASIT), which obtain digital images of the solar disk in extreme ultraviolet, 121.6 nanometer, wavelengths in which little research has been done over the last 20 years. The experiment is expected to shed new light on how the sun's extreme ultraviolet wavelengths affect the upper atmosphere, as well as providing for the ESCAPE II students what instrument Team Leader Kathy Wahl called "a hands-on education that you do not get in any classroom experience."

The Active Cavity Radiometer Irradiance Monitor (ACRIM) monitored solar irradiance in its ongoing effort to determine possible fluctuations in the sun's total output of optical energy. The Upper Atmosphere Research Satellite (UARS) also carries a similar ACRIM instrument, and the two ACRIM's have been making cooperative observations throughout the mission. At the close of the last solar observation period, ACRIM team member Roger Helizon observed, "the sun is very stable this year. This gives us flat data plots, allowing us to do very tight collaborative measurements with UARS."

After the end of the solar period and during the communications between the orbiter and the CRISTA-SPAS instruments, atmospheric observations resumed as the Middle Atmosphere High Resolution Spectrograph Investigation (MAHRSI) switched from measuring hydroxyl to measuring nitric oxide at heights of 60 to 84 miles (100-140 km).

At around 3:30 a.m. CST, the MAHRSI science team at the Marshall Space Flight Center in Huntsville used an Internet connection to research data records of the International Ultraviolet Explorer (IUE), a satellite launched in 1978, to obtain an old ultraviolet spectrum observation of the Moon. In order to compare and validate their spectral measurements of hydroxyl, the MAHRSI team looks for an ultraviolet spectrum, that is free from atmospheric interference, to use as a reference. Ultraviolet spectra of the Moon are ideal for such purposes, and the data records of IUE furnished this reference. "For us, it's a real breakthrough in the analysis of our data," commented MAHRSI Principal Investigator Robert Conway .

Meanwhile, the Cryogenic Infrared Spectrometers and Telescopes for the Atmosphere (CRISTA) instrument continued collecting infrared spectra of trace gases. CRISTA has taken a total of over ten million spectra so far, an amount that would fill more than six thousand computer discs with raw data. Both the CRISTA and MAHRSI instruments continue to perform well, amassing valuable atmospheric data.

The Atmospheric Trace Molecule Spectroscopy (ATMOS) instrument continued observing orbital sunrises and sunsets to identify and measure molecules and their vertical distribution in the atmosphere. ATMOS acquired good spectral data on key atmospheric molecules, especially chlorine-containing gases, that it is intended to measure as part of its science objectives. The ATMOS science team reports that the experiment's onboard data recorder is over eighty-five percent full and that they are trying to take as many of their measurements via live down link in order to conserve the remaining recorder space for the rest of the mission. The Shuttle crew made occasional maneuvers of Atlantis during the night to help facilitate this live down link.

On Thursday, November 10, 1994 at 5 p.m. CST, STS-66 MCC Status Report # 14 report: During space flights lasting more than 10 days, flight controllers schedule a few hours of off-duty time for each crew member. This break from the steady pace of activities helps astronauts maintain their high performance levels throughout the mission. The Red Team - - Mission Commander Don McMonagle, Payload Commander Ellen Ochoa and Mission Specialist Joe Tanner -- had its off-duty time Thursday afternoon while the Blue Team -- Pilot Curt Brown, and Mission Specialists Jean-Francois Clervoy and Scott Parazynski -- has Thursday evening off.

Maneuvers to orient Atlantis to enhance the science gathering efforts of the Atmospheric Laboratory for Applications and Science continued throughout the day. During the first half of its day, the Red Team also worked with a variety of middeck experiments being carried on Atlantis.

On Thursday, November 10, 1994 at 6 p.m. CST, STS-66 Payload Status Report # 15

reports: (MET 7/7:00) The Atmospheric Trace Molecule Spectroscopy (ATMOS) experiment support team, at the Jet Propulsion Laboratory in California, has been working around the clock to convert the instrument's raw data into gas-distribution charts. ATMOS scientists at Spacelab Mission Operations Control in Huntsville say preliminary results seem to provide important pieces in the puzzle of how the Antarctic ozone hole originates and what happens after the ozone is completely destroyed.

"We knew that industrial chlorofluorocarbons have been reaching the stratosphere, where they release free chlorine atoms which then break down Antarctic ozone by the end of winter," said ATMOS Principal Investigator Dr. Mike Gunson. "Today's preliminary results tell a very interesting story about how the chlorine is deactivated in the springtime, as the Antarctic ozone layer begins to return to normal conditions." The data indicated that at altitudes of about 12 miles (20 kilometers), where ozone depletion is greatest, almost all of the chlorine had been chemically bound into hydrogen chloride molecules. At 15 miles (25 kilometers), the atmosphere recovers in a different way. There, the chlorine appeared in both chlorine nitrate and hydrogen chloride compounds.

Gunson added that ATMOS data from ATLAS 3 strongly suggest the ozone hole is a very contained region of the atmosphere. "If the very low water-vapor and nitrogen levels we see in the ozone hole were being spread out to other parts of the atmosphere, that would help explain what causes decreases in ozone levels at mid-latitudes and the tropics," he said. "However, we are not seeing a direct tie between the two areas. If the ozone hole does affect mid-latitudes, it must be in a more indirect fashion."

Sunsets in the Shuttle's orbital path are occurring further south as the mission progresses, so ATMOS observations in the Northern Hemisphere are focusing increasingly on tropical regions.

The Cryogenic Infrared Spectrometers and Telescopes for the Atmosphere (CRISTA) experiment, aboard the free-flying CRISTA-SPAS satellite, has mapped the atmosphere over nearly the entire globe five times since it went into operation Friday. Its three-dimensional records of trace gases in the middle atmosphere will reveal details never measured before.

The CRISTA instrument was built to a large part by students at the University of Wuppertal in Germany and two of their professors. The original idea for the experiment was conceived in 1985. "While the actual instrument was manufactured by industry, students did the calculations, constructed the cryostat, designed the optics, then integrated the equipment with the help of university technicians," said Professor Dirk Offermann. After the mission, the data reduction will be done almost entirely by students. "The instrument is working almost perfectly, and we are very pleased with the results," Offermann added. Offerman is guiding CRISTA science planning at Spacelab Mission Operations Control in Huntsville, and his colleague, Professor Klaus Grossmann, is commanding telescope operations from the Kennedy Space Center in Florida. About 20 students from undergraduate to doctoral levels have been involved in the project over the last nine years.

The Middle Atmosphere High Resolution Spectrograph Investigation (MAHRSI) made measurements of hydroxyl this morning as the CRISTA-SPAS satellite orbited over Southern California. MAHRSI then began a 12-hour set of scans to track distributions of nitric oxide in the middle atmosphere.

At the same time, the Shuttle Solar Backscatter Ultraviolet (SSBUV) experiment started 24 hours of nitric oxide measurements. During last night's solar observations, SSBUV took readings of the sun in nitric oxide wavelengths to furnish comparisons for today's observations. SSBUV controllers first studied nitric oxide during the ATLAS 2 mission, using their instrument's ability to focus on specific wavelengths to pinpoint the gas, then refined the procedure during the STS-62 flight last March. Both nitric oxide and hydroxyl are active in the chain of chemical reactions that destroys ozone in the middle atmosphere.

On Friday, November 11, 1994 at 8 a.m.CST, STS-66 MCC Status Report # 15 reports: The Blue Team -- Pilot Curt Brown, and Mission Specialists Jean-Francois Clervoy and Scott Parazynski -- spent time attempting to fix a hand-held laser device being carried on board Atlantis. The laser is part of a technology demonstration to show that the hand held radar can provide reliable range and range rate information during shuttle rendezvous operations.

Maneuvers to orient Atlantis to enhance the science gathering efforts of the ATLAS-3 payload continue on board, as do operations with several middeck payloads including the Protein Crystal Growth and Space Tissue Loss experiments.

On Friday, November 11, 1994 at 6 a.m. CST, STS-66 Payload Status Report # 16 reports: (MET 7/19:00) Preliminary results, available for the first time during an ATLAS mission, continue to provide scientists and the crew with insights to both the investigations and the processes occurring in the atmosphere. Among the results to date is the detection of increasing amounts of Freon-22 in the stratosphere. This chemical, used as a replacement for Chlorofluorocarbons, is not as great a threat as Chlorofluorocarbons to the ozone layer, but is still a growing source of stratospheric chlorine.

The Atmospheric Trace Molecule Spectroscopy (ATMOS) experiment is viewing sunrises and sunsets through the Earth's atmospheric limb, measuring the trace gases involved in the chemistry of the stratosphere and mesosphere. The ATMOS onboard recorder is nearing capacity, and observations will likely be downlinked live from the orbiter Atlantis throughout the remainder of the mission. The crew will continue to maneuver the Shuttle in ways to best enable the Tracking and Data Relay Satellite System (TDRSS) to provide real-time downlink of ATMOS's observations of sunrises and sunsets.

ATMOS Principal Investigator Dr. Mike Gunson commented that the data are posing a "challenging scientific puzzle" as well as providing a "really interesting story to tell about the ozone hole and the processes leading to its formation." "I'm really happy with the way things have gone," he added. "Enormously successful is almost an understatement at this point."

The Solar Spectrum Measurement (SOLSPEC) instrument, which measures solar radiation in the ultraviolet, visible and near-infrared wavelengths, viewed the Earth during this atmospheric period. Although primarily a solar instrument, SOLSPEC took advantage of the Earth-viewing position of the orbiter to record ultraviolet and visible light as it was scattered back from the atmosphere. This data will be combined with information from SOLSPEC's solar observations to determine concentrations of trace gases in the atmosphere

The Shuttle Solar Backscatter Ultraviolet (SSBUV) instrument continues to obtain measurements of nitric oxide concentrations as the instrument viewed the Earth. These observations are being performed in conjunction with the MAHRSI instrument to produce a more comprehensive understanding of nitric oxide distribution in the atmosphere.

The Middle Atmosphere High Resolution Spectrograph Investigation (MAHRSI) instrument continues to gather nitric oxide data and is working with the SSBUV team to measure global distributions of this compound, which is active in the chain of chemical reactions that destroys ozone in the middle atmosphere.

The Cryogenic Infrared Spectrometers and Telescopes for the Atmosphere (CRISTA) experiment acquired very high resolution data through "oversampling," or making double measurements in specific altitudes to obtain better resolution, during its scans. At this time, CRISTA has taken observations in all of its operating modes, and the science team is very pleased with its performance.

On Friday, November 11, 1994 at 5 p.m. CST, STS-66 MCC Status Report # 16 reports: The ATLAS-3 observations were put on hold for a little more than an hour today due to an electrical problem. A power inverter that converts direct current electricity to alternating current electricity for the ATLAS instruments and their support equipment shut down unexpectedly. Payload Commander Ellen Ochoa aboard Atlantis quickly switched to a backup inverter that repowered the equipment. However, to ensure there was not an electrical problem with the instruments themselves, flight controllers delayed observations for a short while to analyze the situation. Observations with the ATLAS-3 instruments resumed about 4 p.m.

Also, the crew switched the onboard flight control computer being used for systems management to a backup mass memory unit after a connection between the computer and the primary MMU proved faulty. Both the computer, one of five flight control computers on board Atlantis, and the MMU are in excellent condition. The problem was only in the connection between the two devices. To restore full backup capability onboard, flight controllers may eventually ask the crew to switch the Systems Manager function to a different computer and assign another function to the current SM computer.

During the day, Mission Specialist Joe Tanner took a brief break to talk with a Chicago radio station, answering questions about Atlantis's. Commander Don McMonagle took a phone call from Dr. Herman Smith, a retired Marine Corps Captain in Houstan's VA Medical Center, to commemorate Veterans Day and christen a new patient bedside telephone system.

On Friday, November 11, 1994 at 6 a.m. CST, STS-66 Payload Status Report # 17 reports: (MET 7/19:00) Preliminary results, available for the first time during an ATLAS mission, continue to provide scientists and the crew with insights to both the investigations and the processes occurring in the atmosphere. Among the results to date is the detection of increasing amounts of Freon-22 in the stratosphere. This chemical, used as a replacement for Chlorofluorocarbons, is not as great a threat as Chlorofluorocarbons to the ozone layer, but is still a growing source of stratospheric chlorine.

The Atmospheric Trace Molecule Spectroscopy (ATMOS) experiment is viewing sunrises and sunsets through the Earth's atmospheric limb, measuring the trace gases involved in the chemistry of the stratosphere and mesosphere. The ATMOS onboard recorder is nearing capacity, and observations will likely be downlinked live from the orbiter Atlantis throughout the remainder of the mission. The crew will continue to maneuver the Shuttle in ways to best enable the Tracking and Data Relay Satellite System (TDRSS) to provide real-time downlink of ATMOS's observations of sunrises and sunsets.

ATMOS Principal Investigator Dr. Mike Gunson commented that the data are posing a "challenging scientific puzzle" as well as providing a "really interesting story to tell about the ozone hole and the processes leading to its formation." "I'm really happy with the way things have gone," he added. "Enormously successful is almost an understatement at this point."

The Solar Spectrum Measurement (SOLSPEC) instrument, which measures solar radiation in the ultraviolet, visible and near-infrared wavelengths, viewed the Earth during this atmospheric period. Although primarily a solar instrument, SOLSPEC took advantage of the Earth-viewing position of the orbiter to record ultraviolet and visible light as it was scattered back from the atmosphere. This data will be combined with information from SOLSPEC's solar observations to determine concentrations of trace gases in the atmosphere

The Shuttle Solar Backscatter Ultraviolet (SSBUV) instrument continues to obtain measurements of nitric oxide concentrations as the instrument viewed the Earth. These observations are being performed in conjunction with the MAHRSI instrument to produce a more comprehensive understanding of nitric oxide distribution in the atmosphere.

The Middle Atmosphere High Resolution Spectrograph Investigation (MAHRSI) instrument continues to gather nitric oxide data and is working with the SSBUV team to measure global distributions of this compound, which is active in the chain of chemical reactions that destroys ozone in the middle atmosphere.

The Cryogenic Infrared Spectrometers and Telescopes for the Atmosphere (CRISTA) experiment acquired very high resolution data through "oversampling," or making double measurements in specific altitudes to obtain better resolution, during its scans. At this time, CRISTA has taken observations in all of its operating modes, and the science team is very pleased with its performance.

On Saturdy, November 12, 1994 at 5 a.m. CST, STS-66 MCC Status Report # 17 reports: The Cryogenic Infrared Spectrometers and Telescopes for the Atmosphere (CRISTA) satellite ended its eight-day mission this morning when the STS-66 crew retrieved the science satellite and returned it to the orbiter's payload bay for the trip home.

Payload Commander Ellen Ochoa captured the Shuttle Pallet Satellite, with its CRISTA and Middle Atmosphere High Resolution Spectrograph Investigation (MAHRSI) instruments, with the robot arm at 7:05 a.m. Central this morning as Atlantis traveled southeast of New Zealand on Orbit 141. Following additional testing while on the end of the robot arm, the satellite is scheduled to be placed back into the payload bay at about 9:30 a.m. today.

During the rendezvous sequence, Atlantis flew an elliptical pattern in front of the satellite called a MAHRSI Football maneuver to allow the instrument to gather Shuttle glow data. Investigators will use the information to calibrate data obtained from the atmospheric instruments by detecting and measuring the gas hydroxyl in the proximity of the orbiter.

Crew Commander Don McMonagle also tested a new rendezvous technique to demonstrate the approach that will be used on Atlantis' next flight in June 1995 to rendezvous and dock with the Russian Space Station Mir. The technique, which has the orbiter approaching from beneath its target, minimizes thruster jet firings that could "plume" or contaminate the space station systems and solar arrays.

Throughout the night, the Blue Team of astronauts -- Pilot Curt Brown and Mission Specialists Jean-Francois Clervoy and Scott Parazynski -- supported the rendezvous activities, maneuvering Atlantis through a series of burns to place it in the correct position for its rendezvous with CRISTA-SPAS. The Red Team -- McMonagle, Ochoa and Mission Specialist Joe Tanner -- woke up at 2 a.m. to oversee the final stages of the satellite rendezvous and retrieval. Tanner used a hand-held laser device that will be used on the Shuttle/Mir docking missions to gather precise range and range rate data throughout the rendezvous.

On Saturday, November 12, 1994 at 6 a.m. CST, STS-66 Payload Status Report # 18

reports: (MET 8/19:00) Both MAHRSI and the Cryogenic Infrared Spectrometers and Telescopes for the Atmosphere (CRISTA) instrument participated overnight in a cooperative experiment with the Shuttle Solar Ultraviolet Backscatter (SSBUV) instrument. The CRISTA-SPAS satellite, which carries CRISTA and MAHRSI, pointed in an almost completely downward, or nadir, direction to allow these two instruments to operate in an observation mode similar to that of SSBUV, measuring variations in infrared and ultraviolet radiation scattered back from cloud tops and Earth surface areas. Dr. Dirk Offermann, the CRISTA principal investigator, reports that the experiment went very well, and the instruments even passed over one end of the now-elongated Antarctic ozone hole. According to Dr. Offermann, CRISTA verified this fact when it recorded "a clearly visible decrease in our ozone signals" over the tip of South America. CRISTA is the only instrument flying with the STS-66 mission that can use infrared scanning to view the Earth's atmosphere even at night.

At around 12:45 a.m., MAHRSI and CRISTA collaborated on another exploratory observation, simultaneously obtaining spectral measurements of the moon in ultraviolet and infrared wavelengths. This direct look at Earth's satellite will be used as a reference standard for data processing. Robert Conway described the spectrum as superior to the one acquired from the Internet on the previous day, saying, "We needed to know exactly how our instrument looks at these measurements."

The Shuttle Solar Backscatter Ultraviolet (SSBUV) experiment has completed 73 Earth observations periods and, along with the other ATLAS 3 experiments, has temporarily shut down for CRISTA-SPAS retrieval. The instrument team is assessing whether to attempt observations of the moon in conjunction with other instruments and is preparing for further Earth and solar view observations.

The Atmospheric Trace Molecule Spectroscopy (ATMOS) instrument primarily observed sunsets over equatorial latitudes last night. "That's really important to us," said ATMOS Co-Investigator Mark Abrams, who described the equator as a "source region" for ozone mixing over more heavily populated areas of the globe. "Having a good idea about what the source region looks like gives us a good idea about what is going on over the mid-latitudes," he added. ATMOS has made more than 200 solar occultations in this mission, more than the combined occultations of its three previous flights. Many of these measurements will be correlated with observations from instruments on NASA's Upper Atmosphere Research Satellite.

Although ATLAS 3 is flying during what was expected to be the quietest portion of the current solar cycle, information from other observatories obtained via the Internet reveals an unexpected amount of solar activity, including sun spots. The SUSIM instrument has detected higher solar intensities at short wavelengths than expected during its observations, and these data will be critical in characterizing what is occurring and developing a better understanding of solar activity. The instrument team decided to keep the instrument door open and take data during CRISTA-SPAS retrieval. This data will be compared with that obtained with the instrument door closed during deployment.

Preparations are now underway to retrieve the CRISTA-SPAS carrier and secure it in the Shuttle's payload bay. As part of this, the orbiter is in the process of maneuvering around the carrier, in an operation known as the "MAHRSI football" because of the shape of its path, so the MAHRSI instrument can make ultraviolet observations of the Shuttle and the area immediately around it. The measurements of the Shuttle and its attendant "Shuttle glow" will help scientists improve their understanding of this phenomenon and assist with refining data from ATLAS and other missions by allowing interference created by the glow to be predicted.

After the ASTRO-SPAS carrier has been secured at around 7 a.m. this morning, the ATLAS 3 mission will begin its final period of atmospheric and solar observations.

On Saturday, November 12, 1994 at 8 p.m. CST, STS-66 MCC Status Report # 18 reports: Atlantis' crew safely tucked an atmosphere-observing satellite into the shuttle's cargo bay today ending eight days of independent science gathering activities taking measurements of the Earth's atmosphere and sun. The Cryogenic Infrared Spectrometers and Telescopes for the Atmosphere (CRISTA) instrument mounted on its Shuttle Pallet Satellite (SPAS) is now latched securely in Atlantis' payload bay for its return trip to Earth. Observations with the Atmospheric Laboratory for Applications and Science instruments aboard Atlantis continued throughout the day.

With CRISTA securely in place, Ochoa again commanded the shuttle's robot arm to view an icicle that formed on the exterior of the left hand cargo bay door during a routine water dump Friday. The television views showed the door's edges and latches to be free of ice. Flight controllers are considering a variety of options to dislodge the icicle, including using the shuttle's robot arm to break it off of Atlantis' payload bay doors.

On Saturday, November 12, 1994 at 6 p.m. CST, STS-66 Payload Status Report # 19

reports: (MET 9/7:00) Two unique atmospheric instruments concluded almost eight days of very successful operations, as STS-66 Payload Commander Ellen Ochoa retrieved the German Space Agency's reusable CRISTA-SPAS satellite this morning. Its two instruments -- the German Cryogenic Infrared Spectrometers and Telescopes for the Atmosphere (CRISTA), from the University of Wuppertal, and the Middle Atmospheric High Resolution Spectrograph Investigation (MAHRSI), from the U.S. Naval Research Laboratory in Washington, D.C. -- were designed to measure concentrations and distribution of trace gases in Earth's atmosphere on a global scale.

Dr. Dirk Offermann, principal investigator for the CRISTA experiment, reported that his instrument performed almost flawlessly as it gathered unprecedented three-dimensional profiles of the atmosphere. About 100 gigabits of data from 180 hours of CRISTA observing time are stored on magnetic tapes onboard the satellite. "The measurement speed of CRISTA is so high, that conventional satellites would deliver this data set in about half a year," said German Space Agency representative Dr. Wolfgang Frings. CRISTA will be the first instrument to provide such detailed information on the "weather" in the upper atmosphere -- the dynamics of winds, temperature changes and movements which distribute the gases that influence ozone chemistry.

According to Offermann, the CRISTA investigation is not finished yet. A campaign of balloon and rocket experiments will continue for about two weeks, providing additional comparisons on the dynamic atmosphere. Post-flight calibrations at Kennedy Space Center.will check on the accuracy and precision of CRISTA measurements. "This is an important capability only offered by the Space Shuttle, because it brings instruments back to Earth," Offermann said.

"Like CRISTA, we have had a most amazing week," said MAHRSI Principal Investigator Dr. Robert Conway. The instrument accomplished what he termed the "difficult and rather delicate" task of collecting high-resolution, global maps of hydroxyl in the middle atmosphere. It also did almost 30 hours of nitric oxide mapping, much of it in cooperation with the Shuttle Solar Ultraviolet Backscatter (SSBUV) experiment. Both gases are active catalysts in ozone destruction.

Conway compared some early MAHRSI hydroxyl measurements with water vapor data from the Millimeter Wave Atmospheric Sounder (MAS), collected during the mission's first atmospheric research period. "Water vapor is a parent molecule of hydroxyl, because the production of hydroxyl depends on the abundance of water vapor," explained Conway. "By combining the MAS water vapor maps with MAHRSI's maps of hydroxyl abundances, we have two parts of the puzzle for understanding the photochemistry of ozone."

The Atmospheric Trace Molecule Spectroscopy (ATMOS) experiment has completed atmospheric observations for ATLAS 3, after having accumulated the equivalent of 110,000 floppy disks of data -- more than from all three of its previous flights combined.

Today ATMOS viewed the sun directly, rather than using it to illuminate Earth's atmosphere. The current angle of the Shuttle's orbit in relation to the sun would spread atmospheric observations over such a wide area that they would not be useful. "It would be like taking the temperature of Los Angeles and Mexico City at the same time," said ATMOS Assistant Project Manager Gregory Goodson. The unusual illumination conditions of the STS-66 orbit, which changed gradually over the course of the flight, were planned to accommodate the requirements of both ATMOS and CRISTA.

Sensitive infrared measurements of the full sun provide an essential reference for ATMOS scientists because they must remove solar spectra from their atmospheric observations to properly interpret results. Solar scientists will get valuable information about the sun's chemistry and physics from the high-resolution infrared spectra as well.

Spectacular Earth scenes broadcast from Shuttle cameras today supported the Shuttle Solar Backscatter Ultraviolet (SSBUV) experiment's "reflectivity measurements." The video and SSBUV spectra will be compared to determine how various Earth surface features like clouds, oceans, deserts and mountains reflect sunlight back into the atmosphere. Variations in reflectivity affect SSBUV's measurements of the total ozone above the different surface features. "Today's studies give atmospheric scientists a tool for adjusting their ozone models," explained an SSBUV team member.

France's Solar Spectrum (SOLSPEC) experiment is making more readings of solar radiation scattered back from Earth. Though its primary objective is measuring the spectral radiation of the sun, SOLSPEC's Earth views will be compared with its solar results to determine the amount of ozone in the atmosphere. The data also can be compared with that being made by SSBUV, whose primary assignment is to track ozone concentrations by comparing ultraviolet radiation backscattered from the Earth with solar ultraviolet radiation.

On Sunday, November 13, 1994 at 10 a.m. CST, STS-66 MCC Status Report # 19 reports: Today, crew members continued supporting observations of the instruments that make up the third dedicated Atmospheric Laboratory for Applications and Science. They also checked the small thruster jets to ensure their health for tomorrow's landing activities, deactivated several of the middeck secondary experiments and began packing up equipment for the trip home.

Mission managers have decided not to use the robot arm to dislodge an icicle that developed on the left payload bay door and extends to the water dump nozzles on the left side of the orbiter. The decision was made after the camera on the end of the robot arm which would provide ground controllers with insight into the operation malfunctioned overnight. Since the ice is not a safety concern, managers opted to not perform the procedure without the ability to watch it on the ground.

On Sunday, November 13, 1994 at 6 a.m. CST, STS-66 Payload Status Report # 20 reports: (MET 9/19:00) The Atlantis crew maneuvered the orbiter's cargo bay to face the sun last night for the last of four ATLAS 3 solar observation periods. All four solar experiments -- the Active Cavity Radiometer Irradiance Monitor (ACRIM), the Solar Constant (SOLCON) and Solar Spectrum (SOLSPEC) experiments, and the Solar Ultraviolet Spectral Irradiance Monitor (SUSIM) -- are adding nine orbits of observations to the excellent data they acquired during previous solar periods. The Shuttle Solar Backscatter Ultraviolet (SSBUV) instrument is operating in its solar-viewing mode during one of the sun orbits. Solar observations are a vital part of this atmospheric mission, because energy coming from the sun drives the Earth's climate system and the photochemistry of ozone in the stratosphere.

ACRIM Co-Investigator Dr. Roger Helizon, of NASA's Jet Propulsion Laboratory, is especially pleased with comparative sunspot activity measurements his team has made with similar instruments aboard the Upper Atmosphere Research Satellite (UARS). "We learned more about the sensitivity of this device than ever before," he commented, adding that the sun during ATLAS 3 has "just the right amount of sunspot activity" to facilitate sunspot measurements.

SOLCON's unattended monitoring of solar irradiance began at around 11:00 p.m. CST with instrument activation, and the instrument continues to make solar observations. Data from these observations will help determine the total amount of energy reaching Earth from the sun and how this energy changes over time.

The solar constant experiments, designed to take measurements to an accuracy of one-tenth of one percent, are part of a long-term plan during which scientists hope to collect 100 years of data on solar variations. The total energy output of the sun varies only slightly, but variations of just one- half percent over a time scale of decades are thought to be capable of creating major climate changes. Observations of the sun made from space, above the distorting influence of the atmosphere, can be much more precise than ground-based readings. The first observations with this level of accuracy were made by NASA's Solar Maximum Mission in the 1980's.

Before it powered down and entered a deep space cooling period in preparation for its solar observations, SSBUV took measurements in a single wavelength, just short of the visible light wavelengths. This data will help the scientists better understand ultraviolet scattering in the atmosphere, which is important in understanding the accuracy of ozone measurements. After one orbit of pointing at deep space for its cooling period, SSBUV began its solar observations, and is in the process of planning unprecedented lunar observations in conjunction with SUSIM and SOLSPEC to measure the moon's albedo, or the ratio of reflected to incoming sunlight, in various wavelengths. According to SSBUV Principal Investigator Ernest Hilsenrath, this will be the "most accurately calibrated set of instruments ever to look at the moon."

The Atmospheric Trace Molecule Spectroscopy (ATMOS) experiment, having completed all of its atmospheric observations for the mission, is gathering solar spectral data by looking directly at the sun with no atmospheric interference during sunsets. This will provide solar scientists with a high quality solar infrared spectrum. ATMOS has already taken more solar data than on all of its previous missions and is hoping for a solar spectrum with a high ratio of signal to noise, to "capitalize on the opportunity to maximize the amount of data we have," according to Principal Investigator Dr. Mike Gunson.

Following an instrument calibration, SOLSPEC performed three sets of direct Earth measurements in the ultraviolet ranges to assist in the determination of the chemical composition of the atmosphere. The instrument then began unattended solar observations. SOLSPEC is currently gathering data on solar irradiance in the ultraviolet, visible and infrared wavelengths.

After performing a pre-observation calibration to help monitor the instrument's high-resolution performance, SUSIM resumed performing solar observations. The instrument is currently obtaining a complete set of spectral scans to determine the ultraviolet solar irradiance.

Currently, crew members are scheduled to deactivate the payload later this evening. Science teams and payload controllers at Marshall are still awaiting word as to whether the Shuttle landing will be delayed due to weather. ATLAS instruments might have an opportunity for four bonus observations, two atmospheric and two solar, if a decision is made to postpone landing.

After the mission, analysis of these data will begin, producing results which will eventually be publicly archived. "The data belong to everybody," observed NASA Headquarters Program Scientist Dr. Jack Kaye. "Following post-flight data analysis, the data ultimately will be deposited in Earth Observing System Data Information System archives at NASA's Goddard Space Flight Center. where it will be made available to atmospheric scientists around the world."

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