More than two years of the continuous presence of a U.S. astronaut aboard the Russian Mir space station will end during the STS-91 mission when NASA astronaut Andrew S. W. Thomas transfers to the Space Shuttle Orbiter Discovery during docking operations. This final docking mission will also conclude Phase I of the International Space Station (ISS) program. Three other major highlights of this Shuttle flight are the first docking mission for the Space Shuttle Orbiter Discovery, the first on-orbit test of the Alpha Magnetic Spectrometer (AMS), an experiment scheduled to fly aboard the ISS, and the first flight of the new Space Shuttle super lightweight external tank.
The 10-day mission will begin when Discovery lifts off from Launch Pad 39A on its 24th space flight during a 7-to-10-minute window and enters an orbit of 160 miles and an inclination of 51.6 degrees to the Earth's equator. The orbiter will then rendezvous with Mir at an altitude of 213 nautical miles and dock on Flight Day 3. Thomas will board Discovery for the return flight home within hours after the hatches between the two 100-ton spacecraft are opened. The docking operations, which will include the transfer of over a ton of Russian supplies and logistics equipment to Mir from a SPACEHAB Single Module in the orbiter's payload bay and water from its fuel cells, will continue for four days. When docking operations are complete, Discovery will undock and prepare for its return to Earth. Weather permitting, the orbiter will touch down at KSC's Shuttle Landing Facility to conclude the 91st Shuttle mission.
One Russian cosmonaut and six American astronauts will make up the STS-91 crew. Five crew members have previously flown in space.
Mission Commander Charles J. Precourt (Col., USAF) is on his fourth space flight and third trip to Mir, having served as commander on STS-84, pilot on STS-71 and mission specialist on STS-55. His flight experience includes over 6,500 hours in more than 50 types of civil and military aircraft.
Pilot Dominic L. Pudwill Gorie (Cdr., USN) is on his first Shuttle mission. He flew combat missions in Operation Desert Storm and has earned a Distinguished Flying Cross as well as a master's degree in aviation systems.
Mission Specialist Wendy B. Lawrence (Cdr., USN) is on her third Shuttle mission and second trip to Mir. She was a mission specialist on STS-86, the seventh Mir docking flight, and STS-67. She has served as Director of Operations for NASA at the Gagarin Cosmonaut Training Center in Star City, Russia, and has also trained for a Shuttle/Mir flight.
Mission Specialist Franklin R. Chang-Diaz (Ph.D.) is on his sixth space flight. He holds a doctorate in applied plasma physics and is director of the Advanced Space Propulsion Laboratory at the University of Houston.
Mission Specialist Janet Lynn Kavandi (Ph.D.) is on her first Shuttle flight. She was selected as an astronaut candidate in 1994. She holds a doctorate in analytical chemistry and has received two patents.
Mission Specialist and Russian Cosmonaut Valery Victorovitch Ryumin is director of the Russian Shuttle-Mir program and has been flight director for the Salyut-7 and Mir space stations. He is a veteran of three space flights and has logged a total 362 days in space.
Mission Specialist Andrew S. W. Thomas (Ph.D.) began his stay on Mir Jan. 25 during the STS-89 mission. He had flown before as payload commander on STS-77. The Australian-born scientist was selected as an astronaut candidate in 1992. He was previously a Jet Propulsion Laboratory employee who became leader of that center's program for microgravity materials processing in space.
When Thomas leaves Mir during STS-91, he will be ending Phase I of the U.S.-Russian program that has led to significant gains in advanced technology, earth sciences, fundamental biology, human life sciences, microgravity and ISS Risk Mitigation research that began when U.S. astronaut Shannon Lucid boarded the Russian space station on March 24, 1996, during the STS-76 mission. With Thomas' departure, NASA astronauts will have lived and worked with their Russian crewmates continuously for more than 800 days.
The international cooperation and on-going scientific research conducted aboard the Shuttle orbiter and by the U.S. and Mir crew members during the ISS Phase I Program have been considered by both countries to be laying the foundation for the construction and operation of the ISS. Construction of the ISS is scheduled to begin this year. One of the goals of the Shuttle-Mir missions has been to understand more fully how to operate an international space station, providing researchers from all over the world access to laboratory facilities in space.
One of the most perplexing and profound questions yet to be answered about the universe is why it seemingly contains no large amounts of antimatter. Another is where or how the 90 percent or more of its "missing mass" exists. By measuring the amount of antimatter nuclei present in cosmic rays with much higher precision than ever before while looking at the energy spectra of positrons (electron antiparticles) and antiprotons to help determine the nature of dark matter, the AMS will provide data that could provide scientists with solutions for both of these puzzles. The experiment will also measure normal matter cosmic and gamma rays. The 7,050-pound AMS will fly aboard Discovery attached to a 2,150-pound Unique Support Structure (USS) in the orbiter's payload bay. The AMS will employ a unique, 4,200-pound, rare-earth neodymium-iron-boron permanent magnet that will produce a strong uniform magnetic field , along with a state-of-the-art spectrometer, to search for antimatter, dark matter and to understand cosmic ray propagation. The AMS will be the first large magnet experiment ever to be flown in space and could be the first experiment to detect minute quantities of antimatter in cosmic rays coming from outside our galaxy. This antimatter could be an indication of the existence of antimatter galaxies. The AMS is scheduled to operate for 100 hours during the STS-91 mission and will send data to, and be controlled from, the ground. Data will also be recorded on computer hard drives by the crew. This first flight is designed to verify AMS performance under actual space conditions prior to its three-year deployment on the ISS. The AMS is an international collaborative project that involves 37 research institutions in 12 countries and the United States. The U.S. portion of the experiment is sponsored by the Department of Energy. The NASA portion of the AMS program is managed by the agency's Office of Space Science and Office of Life and Microgravity Sciences and Applications. . Mir Supplies and Experiments
The SPACEHAB Single Module in Discovery's payload bay will serve as the means to transport approximately 2,600 pounds of Russian logistics items to the Mir, including storage batteries, food and water containers, clothing, sleeping and personal hygiene articles. More than 1,400 pounds of water will also be supplied from Discovery's fuel cells. Other equipment includes the hardware for four ISS Risk Mitigation Experiments (RMEs) that will be conducted aboard Mir, as well as advanced technology, microgravity and five NASA Human Life Sciences (HLS) investigations.
Some experiment hardware will be removed from Mir and transferred to Discovery to be returned to Earth, including the Space Acceleration Monitoring System (SAMS), the Queens University Experiment in Liquid Diffusion (QUELD); Co-Culture (COCULT) biotechnology experiment to research the growth and development of human tissue; the Diffusion Controlled Crystallization Apparatus for Microgravity (DCAM); and Protein Crystal Growth (PCG) GN2 Dewar experiment.
In addition to the SPACEHAB Module and the AMS, Discovery's payload bay will be the site where eight Get-Away Special (GAS) experiments are conducted. They include the NASA-sponsored educational Space Experiment Module (SEM) and other GAS experiments that will conduct research in areas of biology, materials science, gamma rays, oil recovery and space dust. The Cosmic Radiation Effects and Activation Monitor (CREAM), Radiation Monitoring Equipment III (RME-III), Solid Surface Combustion Experiment (SSCE) and Commercial Protein Crystal Growth CPCG) investigations will be conducted in the middeck crew cabin area while Discovery is in orbit. An experiment will also be conducted with the orbiter's thrusters and ground-based radar to study their effects on the ionosphere.
The first Space Shuttle superlightweight external tank (ET) will provide the liquid hydrogen fuel and liquid oxygen oxidizer for Discovery's three main engines during the STS-91 liftoff and ascent. This lightweight ET was developed to increase the Shuttle payload capacity on ISS flights. The tank is externally identical to, but 7,500 pounds lighter than, conventional metal alloy ETs. The weight reduction is due to the use of aluminum lithium internal liquid hydrogen and liquid oxygen tanks.