NASA Fact Sheet

ATLAS-1: The First Atmospheric Laboratory for Applications and Science
 
 
Earth is the launching pad for space missions of all types. It is our home port, but is it a safe haven? Today we face a number of environmental problems on the home front: the destruction of forests, depletion of the ozone layer and air pollution, to name only a few.

If we hope to preserve our fragile environment, we must first understand our planet's major components -- the land, oceans and atmosphere -- how they interact with one another and how other forces such as the sun and Earth's magnetic field interact with them. A series of NASA Space Shuttle missions assisted this effort through detailed studies of one part of the complex system that supports life on Earth: the atmosphere. The series, called Atmospheric Laboratory for Applications and Science (ATLAS for short), uses Spacelab, a Shuttle-based research laboratory.

ATLAS missions were part of Phase I of NASA's Mission to Planet Earth, a large-scale, unified study of planet Earth as a single, dynamic system. Throughout the ATLAS series, scientists gathered new information to gain a better understanding of how the atmosphere reacts to natural and human-induced atmospheric changes. That knowledge helped us identify measures to keep our planet suitable for life for future generations.

Mission Overview

ATLAS-1 flew aboard Space Shuttle Atlantis on mission STS-45 in spring 1992. It was the first of up to nine ATLAS missions that were undertaken throughout one solar cycle, which lasted 11 years. During that period solar flares, sunspots and other magnetic activity in the sun changes from one extreme to the other and back.

The mission carried 14 experiments to investigate the interactions of the Earth's atmosphere and the sun. The experiments studied the chemistry, physics and movement of the middle and upper atmosphere by measuring the sun's energy. They also observed the links between magnetic fields and electrified gases, called plasma, that lie between the sun and Earth. By studying these factors throughout a solar cycle, scientists formed a more detailed picture of Earth's atmosphere and its response to changes in the sun. Also, an astronomical telescope examined sources of ultraviolet radiation in the Milky Way and other galaxies learned more about the stages in the life of a star.

The Space Shuttle Atlantis carried the ATLAS-1 Spacelab on an eight-day flight, during which its crew gathered information used by scientists on the ground. The European Space Agency provided the reusable Spacelab platform in 1981 as its contribution to the Space Shuttle program. The versatile Spacelab facility comprised pressurized modules that provided laboratory work space and open U-shaped platforms, called pallets, that held instruments requiring direct exposure to space, such as telescopes. On missions such as ATLAS, which use open pallets alone, the instruments' power supply, command-and data-handling system, and the temperature control system are housed in a pressurized container, called an igloo.

Spacelab elements are arranged in the Space Shuttle cargo bay to meet the unique needs of each flight. For the ATLAS-1 mission, the scientific instruments were mounted on two Spacelab pallets in the Shuttle cargo bay. Most of the instruments flew on earlier Spacelab missions, reducing the cost of this space-based research. Reuse of these facilities allowed scientists to expand their base of knowledge to provide a more accurate, long-term picture of our planet and its environment. From Atlantis's 183-mile-high orbit, these instruments were exposed directly to space when the Shuttle bay doors were open. During the mission, the orbiter's position was changed frequently to point the scientific instruments toward their targets: the sun, the Earth and space.

NASA's Office of Space Science and Applications, Washington, D.C., sponsors the ATLAS-1 mission. Marshall Space Flight Center, Huntsville, Ala., trained the science crew and the ground-based science team. During the flight, NASA's Spacelab Mission Operations Control facility at Marshall controlled science activities.

Kennedy Space Center in Florida prepared the Spacelab and launched it aboard Atlantis. Johnson Space Center in Houston, Texas, trained the flight crew and provided Shuttle orbiter flight control.

Belgium, France, Germany, Japan, the Netherlands, Switzerland and the United Kingdom participated in experiments on the ATLAS-1 payload. The European Space Agency provided operational support for the European investigations.

Unraveling the mysteries of the atmosphere requires dedication and patience. Each Shuttle mission is the culmination of long years of hard work, which continues after the Shuttle returns to Earth. Scientists will spend years poring over the data collected during the mission. This information was organized at a special data-processing facility at NASA's Goddard Space Flight Center, Greenbelt, Md., where it was made available to other researchers studying global change, and formed the foundation for the remaining missions in the 11-year ATLAS series.

Scientific Investigations

Without the atmosphere, life as we know it could not survive. Proper atmospheric pressure, temperature and oxygen levels are critical to maintaining life. Energy is absorbed and cycled when radiation from the sun interacts with atmospheric chemicals -- mainly nitrogen and oxygen, with traces of carbon dioxide, water vapor and other gases. Additionally, energy is absorbed and cycled when charged particles (ions and electrons) interact with the magnetic field generated by the Earth's core.

Human activities, including agriculture and industry, affect these complex processes. For example, the chlorofluorocarbons (CFCs) used in air conditioning and other industries rise to the stratosphere, where they are reduced to reactive chlorine that depletes the ozone layer, which protects the Earth's surface from harmful solar radiation. Halons, which contain bromine and are commonly used as fire inhibitors, behave similarly. Naturally occurring chemicals such as methane and nitrous oxide can lead to ozone depletion or inhibit chlorine-induced ozone depletion. Atmospheric concentrations of all these gases are increasing, as is the concentration of carbon dioxide, which is produced by fossil fuel combustion. These changes are likely to result in increased stratospheric ozone depletion and changes in atmospheric temperatures. The ATLAS mission will help scientists validate and refine their models of the effects of chemical change in the stratosphere.

Earth's atmosphere comprises five layers: troposphere, stratosphere, mesosphere, thermosphere and exosphere. These are classified by temperature, pressure and chemical composition.

Imbedded in the mesosphere and thermosphere is an electrically charged area called the ionosphere. Beyond the ionosphere is the magnetosphere, which separates Earth's magnetic field from interplanetary space. The solar wind -- a high-speed stream of charged particles (electrons and protons) from the sun -- gives the magnetosphere a comet-like shape with a tail extending for vast distances from the night side of the planet.

The boundaries of these layers are not exact; they interact and form a chain from Earth's surface to interplanetary space. Since they are interconnected, what happens at levels above the clouds affects us on the ground below.

The instruments aboard ATLAS-1 collected information about the composition of Earth's atmosphere, investigate how Earth's electric and magnetic fields and atmosphere influence one another, examine sources of ultraviolet light in the universe, and measure the energy contained in sunlight and how that energy varies during the mission. The ATLAS-1 investigations were divided into four broad areas: atmospheric science, solar science, space plasma physics and astronomy.

A master timeline schedule was programmed into a computer aboard the Spacelab to orchestrate many mission experiment sequences automatically. Although this timeline was revised when necessary, computer coordination contributed to the smooth operation of complex scientific instruments and tasks.

Most of the atmospheric and solar instruments and the astronomical telescope were computer operated; the instrument data was sent directly to scientists at the Spacelab Mission Operations Control facility on the ground. The crew ran the space plasma physics instruments manually. For example, the crew reported to their counterparts on the ground on visual effects observed from the firing of a beam of charged particles (electrons) into the surrounding plasma.

ATLAS-1 instrument controls were located in the aft flight deck of the Shuttle orbiter. The crew ensured that automatically controlled instruments function properly and entered observational sequences for manually controlled equipment. They also fine-tuned and aligned video cameras and television monitors, and selected camera filters, among other tasks.

Atmospheric Science

Six atmospheric science investigations on ATLAS-1 studied the middle and upper atmosphere with a variety of instruments that helped correlate atmospheric composition, temperature and pressure with altitude, latitude, longitude and changes in solar radiation. The types of environmental phenomena examined included global distribution of atmospheric components and temperatures, as well as atmospheric reaction to external influences such as solar input and geomagnetic storms. The high-altitude effects of terrestrial environmental episodes -- volcanic eruptions, forest fires, massive oil fires in Kuwait -- were examined. Data collection helped scientists to monitor short- and long-term changes, the goal of the series of ATLAS flights.

Gases in the upper atmosphere and ionosphere undergo constant changes triggered by variations in ultraviolet sunlight, by reactions between layers and by air motions. Many of the photochemical reactions -- the effect of light or other radiant energy in producing chemical action -- cause atoms and molecules to emit light of very specific wavelengths. These light signatures are called spectral features.

The Imaging Spectrometric Observatory (ISO) measured spectral features to determine the composition of the atmosphere, down to trace amounts of chemicals measured in parts-per-trillion. This investigation, which previously flew on Spacelab 1, added to data about the varied reactions and energy transfer processes that occur in Earth's environment.

The Atmospheric Trace Molecule Spectroscopy (ATMOS) and the Grille Spectrometer (Grille) experiments mapped trace molecules, including carbon dioxide and ozone, in the middle atmosphere. This mapping was accomplished at orbital sunrise and sunset by measuring the infrared radiation that these molecules absorb. An orbital "day," with a sunrise and sunset, occurs approximately every 90 minutes during flight. These data was compared with information gathered during other missions to note worldwide, seasonal and long-term atmospheric changes. Both instruments flew previously, ATMOS on Spacelab 3 in 1985 and Grille on Spacelab 1 in 1983.

The Atmospheric Lyman-Alpha Emissions (ALAE) experiment measured the abundance of two forms of hydrogen: common hydrogen and deuterium, or heavy hydrogen. ALAE observed ultraviolet light, called Lyman-alpha, which hydrogen and deuterium radiate at slightly different wavelengths. Deuterium's relative abundance compared to hydrogen at the altitudes ALAE studied is an indication of atmospheric turbulence. After determining the hydrogen/deuterium ratio, scientists can better study the rate of water evolution in Earth's atmosphere.

The Millimeter-Wave Atmospheric Sounder (MAS) measured the strength of millimeter waves radiating at the specific frequencies of water vapor, chlorine monoxide and ozone. Observations of these gases enabled scientists to better understand their distribution through the upper atmosphere. MAS data was particularly valuable because they should be unaffected by the presence of aerosols, the concentrations of which have increased by the eruption of Mount Pinatubo in June 1991.

The Shuttle Solar Backscatter Ultraviolet Spectrometer (SSBUV) was a calibrating experiment. Its measurements were compared to those from ozone-observing instruments aboard the National Oceanic and Atmospheric Administration's NOAA-9 and NOAA-11 satellites and NASA's NIMBUS-7 satellite. The SSBUV assessed instrument performance by directly comparing data from identical instruments aboard the NOAA spacecraft and NIMBUS-7 as the Shuttle and satellite passed over the same Earth location within an hour. SSBUV data also can be compared to data obtained by the Upper Atmosphere Research Satellite, which was launched in September 1991 to study the processes that lead to ozone depletion. The ATLAS-1 mission was the fourth flight of SSBUV.

Solar Physics

Four solar physics investigations measured the sun's energy output to determine its variations. Such information was important for understanding the effect of solar radiation on the composition of the Earth's atmosphere and ionosphere. Scientists studying our climate and the physical processes of the sun also use the information.

Because the sun is Earth's major source of heat, it drives atmospheric circulation and affects the weather. A change of only a few degrees in the temperature of Earth's atmosphere might cause dramatic changes in the ocean levels, ice caps and climate. There is evidence that the solar constant, the amount of heat normally received at the outer layer of our atmosphere,fluctuates. Therefore, it is important to determine its range and variability.

The Active Cavity Radiometer (ACR) and the Measurement of Solar Constant (SOLCON) experiments measured the total amount of light and energy emitted by the sun, which is especially important in climate studies. The Solar Spectrum Measurement (SOLSPEC), the Solar Ultraviolet Spectral Irradiance Monitor (SUSIM) and SSBUV investigations added to our understanding of how variations in the sun's energy output affect the chemistry of the atmosphere. Spectral information is needed to study atmospheric reactions because different atmospheric components at different altitudes absorb different wavelength ranges.

Space Plasma Physics

Two space plasma physics instruments, the Atmospheric Emissions Photometric Imaging (AEPI) and Space Experiments with Particle Accelerators (SEPAC), studied the charged particle and plasma environment. A third investigation, Energetic Neutral Atom Precipitation (ENAP), was conducted using data from the ISO instrument. Active and passive probing techniques will investigate key cause-and-effect relationships that link the Earth's magnetosphere, ionosphere and upper atmosphere. Electron and plasma beams was injected into the surrounding space plasma to study phenomena such as aurora -- visible signatures of magnetic storms that can disrupt telecommunications, power transmissions and spacecraft electronics -- and spacecraft glow.

Spacecraft glow is a recently discovered phenomenon. On Shuttle missions, surfaces facing the direction of travel were covered with a faintly glowing, thin orange layer. Understanding spacecraft glow is very important because of its impact on experiments in the cargo bay and on other satellites. This emission of light could interfere with sensitive data-collecting instruments.

The space plasma investigations also helped us understand the effects of solar energy on our weather, communications and spacecraft technologies.

Astronomy

The Far Ultraviolet Space Telescope (FAUST), which flew on Spacelab 1, studied astronomical sources of radiation at ultraviolet wavelengths that are inaccessible to observers on Earth. Much remains to be learned about the stages of the rate of star formation in other galaxies. Young stars reach very high temperatures and emit intense ultraviolet radiation, which cannot be detected by ground-based astronomers. However, this radiation can be detected by an ultraviolet sensor, such as the FAUST, placed outside Earth's atmosphere. Better knowledge of ultraviolet emission sources will lead to improved understanding of the life cycle of stars and galaxies throughout the universe.

The Atlas Program

ATLAS-1, the first of the ATLAS series of Shuttle flights, was an important part of the long-term, coordinated research that made up NASA's Mission to Planet Earth. The ATLAS-1 solar science instruments and several of the atmospheric science instruments (MAS, ATMOS and SSBUV) flew on future ATLAS missions. Beyond its own science mission, a key goal of the ATLAS series was to provide calibration for NASA's Upper Atmosphere Research Satellite (UARS), launched from the Space Shuttle in September 1991. Two ATLAS-1 instruments, ACR and SUSIM, have direct counterparts aboard UARS, while other instruments aboard each mission were closely related. Repeated flights of the ATLAS instruments, which can be carefully calibrated before and after each flight, will allow for long-term calibration of UARS instruments.

The next ATLAS flight, ATLAS-2, was scheduled for launch in spring 1993. Immediately after ATLAS-1 lands, the science teams for instruments flying on ATLAS-2 began recalibrating and preparing their instruments for reflight, while analyzing and interpreting their ATLAS-1 data.

Crew Profile

The seven-member crew of ATLAS-1 consisted of a commander, a pilot, three mission specialists and two payload specialists. The orbiter crew -- the commander, pilot and one mission specialist -- operated and maneuvered the Shuttle, maintained the Shuttle's subsystems and ensured flight safety. The science crew -- the payload commander, the other mission specialist and the payload specialists -- managed the Spacelab and perform experiments.

The orbiter crew and mission specialists were career NASA astronauts. Payload specialists and alternate payload specialists were members of the science community. These crew members were chosen by an Investigator Working Group, made up of the chief scientists for each mission experiment. To make the best use of their short time in space, the crew was divided into two teams, each working alternate 12-hour shifts.

The commander was U.S. Marine Corps Colonel Charles F. Bolden Jr., an astronaut since 1980. His previous missions included STS-61C, which made a night landing at Dryden Flight Research Facility, and a more recent one, STS-31, which deployed the Hubble Space Telescope.

The pilot was U.S. Air Force Lieutenant Colonel Brian Duffy, who became an astronaut in 1986. He participated in the development of Shuttle computer software and served as Technical Assistant to the Director of Flight Crew Operations. Lieutenant Colonel Duffy represented the Astronaut Office in all matters concerning the ascent phase of flight. ATLAS-1 was his first Shuttle flight.

The orbiter mission specialist was U.S. Navy Captain David C. Leestma, an astronaut since 1980. During Shuttle mission STS-41G, he performed a "spacewalk" to demonstrate the feasibility of satellite refueling. He also flew on STS-28, a Department of Defense mission. Captain Leestma currently was Deputy Director of the Flight Crew Operations Directorate.

Mission Specialist Dr. C. Michael Foale, selected as an astronaut in 1987, holds a doctorate in laboratory astrophysics. He has had responsibility for payload operations for four Shuttle missions. He was involved in the development of the spacewalk, assembly and rescue-operations plans for Space Station Freedom. This was be his first Shuttle flight.

Payload Commander Dr. Kathryn D. Sullivan, an astronaut since 1979, holds a doctorate in geology. Dr. Sullivan was the first U.S. woman to perform a spacewalk when she and Captain Leestma proved the feasibility of satellite refueling during mission STS-41G. She also helped deploy the Hubble Space Telescope during mission STS-31.

Payload Specialist Dr. D. Dirk Frimout of the European Space Agency holds a doctorate in applied physics. He acted as crew coordinator and experiment coordinator for European experiments aboard several Spacelab missions and is a co-investigator on the Grille Spectrometer. This was Dr. Frimout's first flight.

Payload Specialist Dr. Byron K. Lichtenberg holds a doctorate in biomedical engineering. He flew as the first U.S. payload specialist onSpacelab 1. He was a co-investigator on several experiments for other Spacelab missions and has written many articles on biomedical engineering and space flight.

The two alternate payload specialists were Dr. Charles R. Chappell and Dr. Michael L. Lampton. Alternate payload specialists train to back up the primary payload specialists. During the mission, they work with mission managers, principal investigators and the science team at Marshall Center's Spacelab Mission Operations Control facility.

Dr. Chappell, who holds a doctorate in space science, was the mission scientist for Spacelab 1 and currently is the Associate Director for Science at Marshall Center. He also was a co-investigator for the SEPAC instrument. Dr. Lampton holds a doctorate in physics. He served as an alternate payload specialist for the first Spacelab mission. Dr. Lampton, a co-investigator on the FAUST experiment, was a researcher at the Space Sciences Laboratory of the University of California in Berkeley.

Mission Management

Program Manager
    Mr. Earl Montoya
    NASA Headquarters
    Office of Space Science and Applications

Program Scientist
    Dr. Jack Kaye
    NASA Headquarters
    Office of Space Science and Applications

Mission Manager
    Mr. Anthony O'Neil
    Marshall Space Flight Center
    Payload Projects Office

Assistant Mission Managers
    Ms. Teresa Vanhooser
    Mr. Gerald Maxwell
    Marshall Space Flight Center
    Payload Projects Office

Chief Engineer
    Mr. Robert Beaman
    Marshall Space Flight Center
    Payload Projects Office

Mission Scientist
    Dr. Marsha Torr
    Marshall Space Flight Center
    Space Sciences Laboratory

Assistant Mission Scientist
    Mr. Paul D. Craven
    Marshall Space Flight Center
    Space Sciences Laboratory

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