The first Extended Duration Orbiter flight of 1994 will carry a diversified collection of experiments that could yield advances in both spaceflight and Earth-based technologies. During the 14-day flight of Mission STS-62, five veteran astronauts will both monitor and conduct numerous experiments located on the middeck and in the payload bay of the Space Shuttle Columbia.

Columbia will lift off from Launch Pad 39B at a 39 degree-inclination to the equator into a 160-nautical mile(185 statute mile/298 kilometer) orbit.

Leading the crew as commander is two-time space traveler John H. Casper (Col., USAF). Pilot Andrew M. Allen (Maj., USMC)is making his second trip into space. The three mission specialists, Charles D. 'Sam" Gemar (Lt. Col., USA), Marsha S. lvins and Pierre J. Thuot (Cdr., USN), have all flown twice before on the Shuttle.

The 61st Space Shuttle mission is scheduled to conclude with a landing at Kennedy Space Center's Shuttle Landing Facility.

The two primary payloads of Mission STS-62 are clusters of experiments grouped as the Office of Aeronautics and Space Technology-2 (USMP-2) and the U.S. Microgravity Payload-2 (USMP-2),'both making a second flight aboard the Shuttle.

USMP-2 capitalizes on the near weightless environment of space to carry out scientific experiments which could improve technology on Earth. The USMP is sponsored by NASA's Office of Life and Microgravity Sciences and Applications, and managed by the Marshall Space Flight Center (MSFC), Huntsville, Ala. USMP-1 flew on Mission STS-52 in 1992. The USMP missions are designed for Shuttle microgravity experiments which do not require crew interaction, and consist of two spacelab-related Multipurpose

Equipment Support Structures (MPESS) which hold the experiments and are located in the payload bay. After activation by the crew, the experiments will be monitored and controlled from the Spacelab Mission 0perations Control Center at MSFC.

Two of the USMP-2 experiments focus on directional solidification, a well-known industrial process for making semiconductors and metals. On Earth, gravitational influences can affect directional solidification and consequently the quality of the metal or semiconductor being produced. The goal of the Advanced Automated Directional Solidification Furnace (AADSF) is to exploit the gravity-free environment of space to gain understanding of the effects of gravitational forces on the material properties of semiconductors. The sample material, mercury cadmium telluride, is used in infrared detectors for applications such as remote sensing and astronomy. It will be grown very slowly, at only 0.028 inches (0.7 mm) per hour. The result should be a crystal of mercury cadmium telluride that tests theories about the uniformity and properties of materials.

The other directional solidification experiment, Materials for the Study of Interesting Phenomena of Solidification on Earth and in Orbit (MEPHISTO), flew on the first USMP as well. MEPHISTO is a cooperative program between NASA and the French space agency, CNES, which also built the payload. MEPHISTO focuses on the process of directional solidification rather than an end product. When a sample of material is melted and then solidified from one end, there will be a front or interface where solid meets liquid. What happens at this interface influences the final composition, structure and properties of the solid. MEPHISTO will study the location and shape of the interface, building on data collected on the first flight.

The Isothermal Dendritic Growth Experiment (IDGE) also studies solidification of materials, but on a very different scale. Dendrites are tiny crystalline forms that develop as materials solidify under certain conditions. Their Christmas tree-like shape gave rise to their name, 'dendrite," from the Greek word meaning tree. Many of the metal products that we rely on in our daily lives, such as automobiles and jet engine blades, are formed under conditions that yield dendrites. On STS-62, a single dendrite will be grown and photographed under several different sets of experimental parameters, with the growth process repeated 35 to 4O times. The photos of the space-grown dendrites can be compared with ones grown on Earth under similar conditions, testing theoretical explanations of how a dendrite forms. Greater understanding of the physics could lead to improved industrial production techniques.

The Critical Fluid Light Scattering Experiment/Zeno (CFLSE/Zeno)studies fluid behavior, specifically of a material in a state called the critical point where portions of the substance are simultaneously a gas and a liquid. Studying the critical point on Earth is difficult due to the effects of gravity. In the near weightlessness of space, the critical point zone should be widened and researchers may be able to gain a 100 times more accurate estimate of the behavior of the fluid near the temperature at which the critical point occurs. The substance being studied is xenon gas, chosen not only because R is inert, but also because it develops telltale patches of milky iridescence as it approaches the critical point.

The fifth USMP-2 payload is the Space Acceleration Measurement System (SAMS), which has flown previously. SAMS is designed to provide information about the acceleration environment in which the other four USMP experiments are being conducted.

OAST-2 is sponsored by NASA's Office of Advanced Concepts and Technology, and managed by Goddard Space Flight Center (GSFC), Greenbelt, Md. The OAST series of payloads are designed to advance spaceflight technology. The first OAST payload flew on STS 41 -D in 1984; additional flights are planned. The six OAST-2 experiments are located on a Hitchhiker cross-bay carrier (also managed by GSFC) spanning Columbia's payload bay:

• Experimental Investigation of Spacecraft Glow (EISG)/ Spacecraft Kinetic Infrared Test (SKIRT) consists of two complementary experiment assemblies. Both are designed to measure spacecraft glow, which occurs when the rapidly moving orbiter rams into atoms of oxygen and molecules of nitrogen in low Earth orbit, causing them to give off light. When the orbiter passes in and out of darkness and light as ft circles the Earth, its surface temperature changes, thus affecting the illumination range of the atomic particles. The EISG and SKIRT sensors will measure spacecraft glow as a function of temperature.

• The Emulsion Chamber Technology (ECT) experiment will collect data on radiation in space using photographic plates rather than sensors. ECT is made up of highly sensitive film interleaved with sheets of lead. When exposed to the space environment, radiation particles will pass through the film, leaving tracks that can later be measured and counted with a microscope. NASA hopes that by studying the pattern of radiation particles, ft can better understand requirements for shielding humans and spacecraft in space.

• The Solar Array Module Plasma Interaction Experiment (SAMPIE) will examine a different interaction which can occur between a spacecraft and the widely scattered oxygen and nitrogen atoms found in low Earth orbit. These atoms, called plasma, can harmfully interact with the higher operating voltages present in satellites and launch vehicles.

• SAMPIE contains six individual experiments; each will test a different spacecraft material, including space station materials, for potential electrical interaction with plasma. SAMPlE also includes two electrical probes which will monitor different aspects of the plasma. By collecting information about the arcing and power loss that may occur in these experiments, researchers can improve new solar cell technology and new materials for high voltage space power applications.

• The Thermal Energy Storage (TES) experiment, which simulates a solar dynamic receiver, is contained in two Get Away Special canisters. Inside will be two different thermal storage salts, lithium fluoride and fluoride eutectic. As the salt absorbs heat, ft melts and expands in volume, then cools and solidifies, leading to shrinkage and the subsequent formation of voids or pockets in the salt. This void formation affects the heat absorption rate of the salt. By repeating the cycle of melting and freezing, data can be collected which will allow better understanding of thermal storage salts in microgravity. The results could lead to improved designs for solar dynamic heat receivers.

• Dissipating heat, not collecting R, is the purpose of the Cryogenic Two-Phase(CRYOTP) experiment. The advanced sensors and electronics common in today's spacecraft and vehicles can generate large Quantities of heat. Two different methods will be tested for dissipating this heat, one featuring a heat pipe containing supercold liquid nitrogen, and the other a cryogenic thermal storage unit called Brilliant Eyes Thermal Storage Unit (BETSU).

OAST-2 experiments, with the exception of TES, send and receive commands through the Hitchhiker avionics unit. The avionics are powered by the orbiter, and turned on and off by the crew. The experiments can then be operated by a control center at Goddard. TES will use a laptop computer that is operated by a crew member.

Several other payloads also will be flying in Columbia's payload bay: the Dexterous End Effector (DEE); Shuttle Solar Backscatter Ultraviolet/A (SSBUV/A) experiment; Limited Duration Space Environment Candidate Material Exposure (LDCE) experiment; Orbital Acceleration Research Experiment (OARE); and Inter Mars Tissue Equivalent Proportional Counter (ITEPC).

In the orbiter middeck, the crew will be working with or monitoring a number of payloads: Advanced Protein Crystal Growth (APCG); Physiological Systems Experiment (PSE); Commercial Protein Crystal Growth (CPCG); Commercial Generic Bioprocessing Apparatus (CGBA); Middeck 0-Gravity Dynamics Experiment (MODE): Bioreactor Demonstration System (BDS); and the Auroral Photography Experiment (APE-B). The Air Force Maui Optical Site (AMOS) calibration test requires no onboard hardware.

Columbia is the oldest orbiter in the Shuttle fleet and was the first to fly into space. OV-102 also was the first orbiter to be outfitted for extended spaceflight, and its most recent mission, STS-58, was the longest Shuttle flight to date. STS-62 will be Columbia's 16th trip into space.

Preparations for STS-62 began after Columbia was returned to Orbiter Processing Facility high bay 2. Some payloads were installed while Columbia was in the OPF. The vehicle was then rolled over to the Vehicle Assembly Building on Feb. 3 for mating with the external tank/twin solid rocket booster assembly, and on Feb. 10 transferred to Launch Pad 39B, where the two primary payloads were installed in the vehicle.