yee@trident.arc.nasa.gov (Peter E. Yee) (02/28/89)
RELEASE: 89- IMMEDIATE THIRD TRACKING AND DATA RELAY SATELLITE TO BE DEPLOYED BY STS-29 Deployment of the third Tracking and Data Relay Satellite (TDRS-D) will highlight the 28th Space Shuttle mission (STS- 29). The assessed launch date is no earlier than March 10, 1989. Three TDRS, operating from geosynchronous orbit, are required to complete the constellation known as the Tracking and Data Relay Satellite System (TDRSS). TDRSS will increase communications, between Earth-orbiting spacecraft and a ground- based tracking station, from 15 to 85 percent per orbit and facilitate a much higher rate of data flow. TDRS-C was successfully deployed on STS-26 in September 1988 and is located in geosynchronous orbit at 171 degrees W. longitude, south of Hawaii. TDRS-D will be located at 41 degrees W. longitude, east of Brazil. TDRS-A, deployed on STS-6 in April 1983, then will be moved to a parking orbit and used only if a failure occurs with one of the remaining two satellites. TDRS-B was lost in the 51-L Challenger accident. Commander of the five-man crew is Michael L. Coats, captain, USN. Coats was pilot of STS 41-D, the maiden flight of orbiter Discovery. John E. Blaha, colonel, USAF, is pilot of the mission. STS-29 will be his first space flight. Rounding out the crew are three mission specialists: James F. Buchli, colonel, USMC; Robert C. Springer, colonel, USMC; and James P. Bagian, M.D. Buchli is making his third Shuttle flight having flown as a mission specialist on STS 51-C, the first Department of Defense Shuttle mission, and STS 61-A, the West German Spacelab flight. Springer and Bagian are making their first Shuttle flights. Discovery, making its eighth flight, is assessed to be ready for launch no earlier than 8:11 a.m. EST, March 10, from the Kennedy Space Center, Fla., launch pad 39-B, into a 160 nautical mile, 28.45 degree orbit. Nominal mission duration is 5 days, 1 hour, 7 minutes. Deorbit is planned on orbit 80, with landing scheduled for 9:48 a.m. EST, March 15, at Edwards Air Force Base, Calif. In the event of a slip in the launch, liftoff would occur 1 minute earlier for each day the launch is delayed. - more - - 2 - TDRS-D will be deployed 6 hours, 13 minutes into the mission on flight day 1. Two additional deployment opportunities are available on that day and one the following day. An Air Force-developed inertial upper stage (IUS) will boost the TDRS to geosynchronous orbit (22,300 miles above Earth) after deployment from the Shuttle. The IUS is mated to the TDRS-D and the combination spacecraft and upper stage will be spring ejected from the payload bay of the orbiter. Following deployment, Discovery will maneuver to a safe position behind and above the TDRS-D/IUS before the first stage of the two-stage IUS motor ignites about an hour after deployment. The three-axis, stabilized upper stage will maneuver TDRS to the desired attitude where it will be configured for operation by the NASA White Sands Ground Terminal, N.M. CONTEL, Atlanta, Ga., owns and operates the TDRSS for NASA. TRW's Defense and Space Systems Group, Redondo Beach, Calif., builds the satellites. The Orbiter Experiments Program Autonomous Supporting Instrumentation System (OASIS) will be flown again on STS-29 to record environmental data in the orbiter payload bay during flight phases. OASIS will measure TDRS vibration, strain, acoustics and temperature during launch ascent using transducers affixed directly to the payload. OASIS flight hardware consists of signal conditioning, multiplexing and recording equipment mounted on a Shuttle adaptive payload carrier behind the TDRS. Command and status interface is achieved through the standard mixed cargo harness and the general purpose computers. In addition to TDRS-D and OASIS, Discovery will carry the Space Station Heat Pipe Advanced Radiator Element (SHARE) in the payload bay. Several secondary payloads will be carried in the middeck of Discovery, including the IMAX camera, two student experiments, a protein crystal growth experiment and a chromosome and plant cell division experiment. After landing, Discovery will be towed to the NASA Ames- Dryden Flight Research Facility, hoisted atop the Shuttle Carrier Aircraft and ferried back to the Kennedy Space Center to begin processing for its next flight scheduled for August. (END OF GENERAL RELEASE, BACKGROUND INFORMATION FOLLOWS) - more - - 3 - GENERAL INFORMATION NASA Select Television Transmission The schedule for television transmission from the orbiter and for the change-of-shift briefings from Johnson Space Center, Houston, will be available during the mission at Kennedy Space Center, Fla.; Marshall Space Flight Center, Huntsville, Ala.; Johnson Space Center; and NASA Headquarters, Washington, D.C. The television schedule will be updated daily to reflect changes dictated by mission operations. NASA Select television is available on RCA Satcom F-2R, Transponder 13, located at 72 degrees west longitude. Special Note To Broadcasters Beginning in February and continuing throughout the mission, approximately 7 minutes of audio interview material with the crew of STS-29 will be available to broadcasters by calling 202/269- 6572. Status Reports Status reports on countdown and mission progress, on-orbit activities and landing operations will be produced by the appropriate NASA newscenter. Briefings An STS-29 mission press briefing schedule will be issued prior to launch. During the mission, flight control personnel will be on 8-hour shifts. Change-of-shift briefings by the off- going flight director will occur at approximately 8-hour intervals. - more - - 4 - STS-29 QUICK LOOK Assessed Launch Date: March 10, 1989 Launch Window: 8:11 a.m. - 10:41 a.m. EST Launch Site: KSC, Pad 39B Orbiter: Discovery (OV-103) Altitude: 160 nm Inclination: 28.45 degrees Duration: 5 days, 1 hour, 7 minutes Landing Date/Time: March 15, 1989, 9:48 a.m. EST Primary Landing Site: Edwards AFB, Calif., Runway 17 Alternate Landing Sites: Return to Launch Site - Kennedy Space Center, Runway 33 Transoceanic Abort Landing - Ben Guerir, Morocco Abort Once Around - Edwards AFB, Calif. Crew: Michael L. Coats, Commander John E. Blaha, Pilot James F. Buchli, Mission Specialist Robert C. Springer, Mission Specialist James P. Bagian, Mission Specialist Primary Payload: Tracking & Data Relay Satellite (TDRS-D) Secondary Payloads: Space Station Heat Pipe Advanced Radiator Element (SHARE) Chromosomes & Plant Cell Division (CHROMEX) Protein Crystal Growth (PCG) Shuttle Student Involvement Program (SSIP) - 2 experiments Orbiter Experiments - Autonomous Supporting Instrumentation System (OASIS) IMAX Camera STS-29 MISSION OBJECTIVES The primary objective of this flight is to successfully deploy the Tracking and Data Relay Satellite-D/Inertial Upper Stage (TDRS-D/IUS). TDRS-D is scheduled to be deployed on flight day 1, orbit 6. Several backup deployment opportunities exist during the flight. Secondary objectives are to perform all operations necessary to support the requirements of the middeck and payload bay experiments. - more - - 5 - LAUNCH PREPARATIONS, COUNTDOWN AND LIFTOFF After the successful STS-26 mission, Discovery was returned to KSC from Dryden Flight Research Facility on Oct. 8. The next day, Discovery was towed to the processing hangar for post-flight deconfiguration and inspections. As planned, the three main engines were removed in October and taken to the main engine shop in the Vehicle Assembly Building for the replacement of several components. During post- flight inspections, technicians discovered a small leak in the cooling system of the main combustion chamber of the number one main engine. That engine was shipped back to the vendor where repairs could be made and a new engine was shipped from the Stennis Space Center, Miss. Discovery's three main engines were installed before the end of last year. Engine 2031 is installed in the number one position, engine 2022 is in the number two position and engine 2028 is in the number three position. The right hand orbital maneuvering system pod was removed in late October and transferred to the Hypergolic Maintenance Facility where a small internal leak was repaired. One of the orbiter's cooling systems, called the flash evaporator system, was replaced after some in-flight problems. Post-flight inspections revealed that the system was clogged with foreign material. Once the turn-around activities were completed, Discovery was transferred from the Orbiter Processing Facility to the Vehicle Assembly Building on Jan. 19. Solid rocket motor (SRM) segments began arriving at KSC in September, and the first segment - the left aft booster - was stacked on Mobile Launcher 2 in VAB high bay 1 on Oct. 21. Booster stacking operations were completed by early December and the external tank was mated to the two boosters on Dec. 16. The OASIS payload was installed in Discovery's payload bay for flight on Dec. 9. Flight crew members came to KSC to perform the Crew Equipment Interface Test on Dec. 11 to become familiar with Discovery's crew compartment and equipment associated with the mission. The Tracking and Data Relay Satellite (TDRS-D) arrived at the Vertical Processing Facility (VPF) on Nov. 30, and its Inertial Upper Stage (IUS) arrived Dec. 27. The TDRS/IUS were joined together on Dec. 29 and all integrated testing was performed the first week of January. As part of those tests, Astronauts James Bagian and Robert Springer participated in the mission sequence test to verify payload functions that occur post-launch and during deployment. - more - - 6 - A variety of middeck payloads and experiments, some of which are time critical and installed during the launch countdown, are processed through various KSC facilities. Discovery was moved from the OPF to the VAB on Jan. 23, where it was mated to the external tank and SRBs. A Shuttle Interface Test was conducted to check the mechanical and electrical connections between the various elements of the Shuttle vehicle and onboard flight systems. The assembled Space Shuttle vehicle was rolled out of the VAB aboard its mobile launcher platform for the 4.2 mile trip to Launch Pad 39-B on Feb. 3. TDRS-D and its IUS upper stage were transferred from the VPF to Launch Pad 39-B on Jan. 17. The payload was installed into Discovery's payload bay on Feb. 6. A countdown demonstration test, a dress rehearsal for the STS-29 flight crew and KSC launch team and a practice countdown for the launch, was completed on Feb. 7. Launch preparations scheduled the last 2 weeks prior to launch countdown include change-out of the orbiter SSME liquid oxygen pumps; final vehicle ordnance activities, such as power- on, stray-voltage checks and resistance checks of firing circuits; loading the fuel cell storage tanks; pressurizing the hypergolic propellant tanks aboard the vehicle; final payload closeouts; and a final functional check of the range safety and SRB ignition, safe and arm devices. The launch countdown is scheduled to pick up at the T- minus-43-hour mark, leading up to the first Shuttle liftoff for the year. The STS-29 launch will be conducted by a joint NASA/industry team from Firing Room 1 in the Launch Control Center. - more - - 7 - MAJOR COUNTDOWN MILESTONES COUNT EVENT T-43 Hours Power up the Space Shuttle vehicle. T-34 Hours Begin orbiter and ground support equipment closeouts for launch. T-30 Hours Activate orbiter's navigation aids. T-27 Hours (holding) Enter first built-in hold for 8 hrs. T-27 Hours (counting) Begin preparations for loading fuel cell storage tanks with liquid oxygen and liquid hydrogen T-25 Hours Load fuel cell liquid oxygen T-22 Hours, 30 minutes Load fuel cell liquid hydrogen. T-22 Hours Perform interface check between Mission Control and Merritt Island Launch Area (MILA) tracking station. T-20 Hours Activate and warm up inertial measurement units (IMUs). T-19 Hours Enter the 8-hour, built-in hold. Activate orbiter comm system. T-11 Hours (holding) Start 18-hour, 10-minute, built-in hold. Check ascent switch list on orbiter flight and middecks. T-11 Hours (counting) Retract Rotating Service Structure. T-9 Hours Activate orbiter's fuel cells. T-8 Hours Configure Mission Control communications for launch. Start clearing blast danger area. T-6 Hours, 30 minutes Perform Eastern Test Range open loop command test. T-6 Hours Enter 1-hour built-in hold. T-6 Hours (counting) Start external tank chilldown and propellant loading. T-5 Hours Start IMU pre-flight calibration. T-4 Hours Perform MILA antenna alignment. - more - - 8 - T-3 Hours Begin 2-hour built-in hold. Loading external tank completed and tank in stable replenishment mode. Ice team to pad for inspections. Closeout crew to white room to begin preping orbiter's cabin for flight crew entry. Wake flight crew (launch minus 4 hours, 55 minutes). T-3 Hours (counting) Resume countdown. T-2 Hours, 55 minutes Flight crew departs O&C Building for 39-B (Launch minus 3 hours, 15 minutes). T-2 Hours, 30 minutes Crew enters orbiter vehicle (Launch minus 2 Hours, 50 minutes). T-60 minutes Start pre-flight alignment of IMUs. T-20 minutes (holding) 10-minute, built-in hold begins. T-20 minutes (counting) Configure orbiter computers for launch. T-10 minutes White room closeout crew cleared through area roadblocks. T-9 minutes (holding) 10-minute, built-in hold begins. Perform status check and receive Mission Management Team "go." T-9 minutes (counting) Start ground launch sequencer. T-7 minutes, 30 seconds Retract orbiter access arm. T-5 minutes Start auxiliary power units. Arm range safety, SRB ignition systems. T-3 minutes, 30 seconds Orbiter goes on internal power. T-2 minutes, 55 seconds Pressurize liquid oxygen tank and retract gaseous oxygen vent hood. T-1 minute, 57 seconds Pressurize liquid hydrogen tank. T-31 seconds "Go" from ground computer for orbiter computers to start the automatic launch sequence. T-28 seconds Start SRB hydraulic power units. T-21 seconds Start SRB gimbal profile test. - more - - 9 - T-6.6 seconds Main engine start. T-3 seconds Main engines at 90 percent thrust. T-0 SRB ignition, holddown-post release and liftoff. T+7 seconds Shuttle clears launch tower and control switches to Houston. STS-29 TRAJECTORY SEQUENCE OF EVENTS _________________________________________________________________ RELATIVE EVENT MET VELOCITY MACH ALTITUDE (d:h:m:s) (fps) (ft) _________________________________________________________________ Launch 0:00:00:00 Begin Roll Maneuver 0:00:00:09 157 .14 593 End Roll Maneuver 0:00:00:17 356 .32 2,749 SSME Throttle Down to 65% 0:00:00:28 652 .58 7,588 Max. Dyn. Pressure (Max Q) 0:00:00:52 1,173 1.08 26,089 SSME Throttle Up to 104% 0:00:00:57 1,274 1.20 30,768 SRB Staging 0:00:02:06 4,169 3.77 155,892 Negative Return 0:00:03:58 6,862 7.09 327,981 Main Engine Cutoff (MECO)* 0:00:08:32 24,507 22.70 363,209 Zero Thrust 0:00:08:39 OMS 2 Burn** 0:00:39:53 TDRS/IUS Deploy (orbit 5) 0:06:13:00 Deorbit Burn (orbit 80) 5:00:06:00 Landing (orbit 81) 5:01:07:00 * Apogee, Perigee at MECO: 156 x 35 ** Direct insertion ascent: No OMS 1 required Apogee, Perigee post-OMS 2: 160 x 160 Apogee, Perigee post-deploy: 177 x 161 - more - - 10 - SPACE SHUTTLE ABORT MODES Space Shuttle launch abort philosophy aims toward safe and intact recovery of flight crew, orbiter and payload. Modes are: * Abort-To-Orbit (ATO) -- Partial loss of main engine thrust late enough to permit reaching a minimal 105-nm orbit with orbital maneuvering system engines. * Abort-Once-Around (AOA) -- Earlier main engine shutdown with the capability to allow one orbit around before landing at Edwards AFB, Calif.; White Sands Space Harbor (Northrup Strip), N.M.; or the Shuttle Landing Facility (SLF) at KSC, Fla. * Trans-Atlantic Abort Landing (TAL) -- Loss of two main engines midway through powered flight would force a landing at Ben Guerir, Morocco; Moron, Spain; or Banjul, The Gambia. * Return-To-Launch-Site (RTLS) -- Early shutdown of one or more engines and without enough energy to reach Ben Guerir, would result in a pitch around and thrust back toward KSC until within gliding distance of the SLF. STS-29 contingency landing sites are Edwards AFB, White Sands, Kennedy Space Center, Ben Guerir, Moron and Banjul. SUMMARY OF MAJOR FLIGHT ACTIVITIES DAY ONE Ascent, Post-insertion checkout Pre-deploy checkout, TDRS-D/IUS deploy; PCG activation, SSIP DAY TWO TDRS-D/IUS backup deploy opportunity AMOS, CHROMEX, IMAX, PCG, SSIP, SHARE test 1 DAY THREE AMOS, CHROMEX, IMAX, PCG, SSIP, SHARE test 2 DAY FOUR AMOS, CHROMEX, SSIP DAY FIVE Flight control systems checkout, Cabin stowage, Landing preps CHROMEX, SSIP; PCG deactivation, SHARE deprime DAY SIX SHARE cold soak test, SSIP Deorbit preparation, Deorbit burn, Landing at EAFB - more - - 11 - LANDING AND POST-LANDING ACTIVITIES KSC is responsible for ground operations of the orbiter once it has rolled to a stop on the runway at Edwards AFB. Operations include preparing the Shuttle for the return trip to Kennedy. After landing, the flight crew aboard Discovery begins "safing" vehicle systems. Immediately after wheelstop, specially garbed technicians will first determine that any residual hazardous vapors are below significant levels for other safing operations to proceed. A mobile white room is moved into place around the crew hatch once it is verified that there are no concentrations of toxic gases around the forward part of the vehicle. The crew is expected to leave Discovery about 45 to 50 minutes after landing. As the crew exits, technicians enter the orbiter to complete the vehicle safing activity. Once the initial aft safety assessment is made, access vehicles are positioned around the rear of the orbiter so that lines from the ground purge and cooling vehicles can be connected to the umbilical panels on the aft end of Discovery. Freon line connections are completed and coolant begins circulating through the umbilicals to aid in heat rejection and protect the orbiter's electronic equipment. Other lines provide cooled, humidified air to the payload bay and other cavities to remove any residual fumes and provide a safe environment inside Discovery. A tractor will be connected to Discovery and the vehicle will be towed off the runway at Edwards and positioned inside the Mate/Demate Device at the nearby Ames-Dryden Flight Research Facility. After the Shuttle has been jacked and leveled, residual fuel cell cryogenics are drained and unused pyrotechnic devices are disconnected. The aerodynamic tail cone is installed over the three main engines, and the orbiter is bolted on top of the 747 Shuttle Carrier Aircraft for the ferry flight back to Florida. A refueling stop is necessary to complete the journey. Once back at Kennedy, Discovery will be pulled inside the hangar-like facility for post-flight inspections and in-flight anomaly troubleshooting. These operations are conducted in parallel with the start of routine systems reverification to prepare Discovery for its next mission. - more - - 12 - TRACKING AND DATA RELAY SATELLITE SYSTEM The Tracking and Data Relay Satellite, TDRS-D, is the fourth TDRS communications spacecraft to be launched aboard the Space Shuttle and completes the constellation of on-orbit satellites for NASA's advanced space communications system. TDRS-1 was launched during Challenger's maiden flight in April 1983. The second was lost during the Challenger accident in January 1986. TDRS-3 was launched successfully on Sept. 29, 1988, during the landmark mission of Discovery, which returned the Space Shuttle to flight. TDRS-1 is in geosynchronous orbit over the Atlantic Ocean, just east of Brazil (41 degrees west longitude at the equator). When it was launched, it failed to reach its desired orbit because of a failure in the upper-stage booster rocket. A NASA- industry team subsequently conducted a series of delicate spacecraft maneuvers, using on-board thrusters, to place TDRS-1 into the desired 22,300-mile-altitude orbit. TDRS-3 is in geosynchronous orbit over the Pacific Ocean, south of Hawaii (171 degree west longitude, also over the equator). It has performed flawlessly in tests and helped support the STS-27 mission in December 1988. After its launch, TDRS-D will be designated TDRS-4. Following its arrival at geosynchronous orbit and a series of tests, it will replace the partially degraded TDRS-1 over the Atlantic. TDRS-1 then will be moved to 79 degrees west longitude, above the Equator, where it will be used as an on- orbit spare. The two operational TDRS -- those located at 41 and 171 degrees west longitude -- will support up to 23 user spacecraft simultaneously and provide two basic types of service: a multiple-access service that simultaneously relays data from as many as 19 low-data-rate user spacecraft; and a single-access service that provides two high-data-rate communications relays from each satellite. TDRS-4 will be deployed from the orbiter about 6 hours after launch. The solid-propellant Boeing/U.S. Air Force Inertial Upper Stage (IUS) will transfer the satellite to geosynchronous orbit. IUS separation will occur about 13 hours after launch. The concept of using advanced communications satellites was developed in the early 1970s, following studies showing that a system of communications satellites operated from a single ground terminal could support Space Shuttle and other low-Earth-orbit space missions more effectively than a worldwide network of ground stations. The current ground station network can only provide support for a small fraction -- typically 15 to 20 percent -- of the orbits of user spacecraft. The modern, space- based TDRS network covers at least 85 percent of the orbits. - more - - 13 - The new system also will facilitate a much higher information flow rate between the spacecraft and the ground. This will be particularly important as NASA resumes regular Shuttle flights and launches satellites with high data rates. NASA's Space Tracking and Data Network ground stations, managed by the Goddard Space Flight Center, Greenbelt, Md., will be reduced significantly in number. Three of the network's present ground stations -- Madrid, Spain; Canberra, Australia; and Goldstone, Calif. -- already have been transferred to the Deep Space Network, managed by the Jet Propulsion Laboratory, Pasadena, Calif. The remaining ground stations, except those needed for launch operations, will be closed or transferred to other agencies. The White Sands Ground Terminal (WSGT) is situated on a NASA test site located between Las Cruces and White Sands, N.M. A colocated NASA facility provides the interface between the WSGT and the NASA space network facilities at Goddard Space Flight Center. A technologically advanced second ground terminal is being built near White Sands to provide back-up and additional capability. The tracking and data relay satellites are the largest privately owned telecommunications spacecraft ever built, and the first to handle satellite communications through the S and Ku frequency bands. Each weighs about 2 tons, spans almost 60 feet across its solar panels and contains seven antennas. Each of the two gold-plated, single-access antennas measures 16 feet in diameter and, when fully deployed, spans more than 42 feet from tip to tip. The combination of satellites and ground facilities is referred to as the Tracking and Data Relay Satellite System or TDRSS. NASA leases the TDRSS complement of services from CONTEL, Atlanta, Ga., which is the owner, operator and prime contractor. CONTEL's two primary subcontractors are TRW's Space and Technology Group, Redondo Beach, Calif., and the Harris Corporation's Government Communications Systems Division, Melbourne, Fla. TRW designed and built the spacecraft and software for ground terminal operation, and integrated and tested the system. Harris designed and built the ground terminal equipment. The Space Shuttle, LANDSAT Earth Resources satellites, Solar Mesosphere Explorer, Earth Radiation Budget Satellite, Solar Maximum Mission satellite and Spacelab have been primary users of TDRSS. They will be joined in the future by the Hubble Space Telescope, Gamma Ray Observatory, Upper Atmosphere Research Satellite and others. - more - - 14 - INERTIAL UPPER STAGE The Interial Upper Stage (IUS) will be used to place NASA's TDRS-D into geosynchronous orbit during the STS-29 Space Shuttle mission. The STS-29 crew will deploy the combined IUS/TDRS-D payload approximately 6 hours, 13 minutes after liftoff, in a low-Earth orbit of 160 nautical miles. Upper stage airborne support equipment, located in the orbiter payload bay, positions the combined IUS/TDRS-D into its proper deployment attitude -- an angle of 52 degrees -- and ejects it into low-Earth orbit. Deployment from the orbiter will be by a spring-ejection system. Following deployment, the orbiter will move away from the IUS/TDRS-D to a safe distance. The IUS first stage will fire about 1 hour after deployment. After the first stage burn of 146 seconds, the solid fuel motor will shut down. After coasting for about 5 hours, 13 minutes, the first stage will separate and the second stage motor will ignite at 6 hours, 12 minutes after deployment to place the spacecraft in its desired orbit. Following a 108-second burn, the second stage will shut down as the IUS/TDRS-D reaches the predetermined, geosynchronous orbital position. Thirteen hours, 9 minutes after liftoff, the second stage will separate from TDRS-D and perform an anti-collision maneuver with its onboard reaction control system. The IUS has a number of features which distinguish it from previous upper stages. It has the first completely redundant avionics system developed for an unmanned space vehicle. It can correct in-flight features within milliseconds. Other advanced features include a carbon composite nozzle throat that makes possible the high-temperature, long-duration firing of the IUS motors and a redundant computer system. The IUS is 17 ft. long, 9 ft. in diameter and weighs more than 32,500 lb., including 27,400 lb. of solid fuel propellant. The IUS consists of an aft skirt, an aft stage containing 21,400 lb. of solid propellant which generates approximately 42,000 lb. of thrust, an interstage, a forward stage containing 6,000 lb. of propellant generating 18,000 lb. of thrust, and an equipment support section. The equipment support section contains the avionics which provide guidance, navigation, telemetry, command and data management, reaction control and electrical power. The IUS is built by Boeing Aerospace, Seattle, under contract to the U.S. Air Force Systems Command. Marshall Space Flight Center, Huntsville, Ala., is NASA's lead center for IUS development and program management of NASA-configured IUSs procured from the Air Force. - more - - 15 - SECONDARY PAYLOADS SPACE STATION HEAT PIPE ADVANCED RADIATOR ELEMENT (SHARE) SHARE flight experiment will be mounted on the starboard sill of the Orbiter's payload bay with a small instrumentation package mounted in the forward payload bay. The goal of the experiment is to test a first-of-its-kind method for a potential cooling system of Space Station Freedom. The heat pipe method uses no moving parts and works through the convection currents of ammonia. Three electric heaters will warm one end of the 51-foot long SHARE. The heaters turn liquid ammonia into vapor which transports the heat through the length of the pipe, where a foot-wide aluminum fin radiates it into space. The fin is cooled by the space environment, and the ammonia is inturn condensed and recirculated. Two small pipes run through the center of the radiator down its length, branching out like the tines of a fork at the end which receives heat, called the evaporator. The top pipe holds the vaporized ammonia; the bottom holds liquid ammonia. In the evaporator portion, a fine wire mesh wick, which works along the same principal as the wick of an oil lamp, pulls the liquid ammonia from one pipe to the other, where it vaporizes. Small grooves allow the condensed ammonia to drop back to the bottom pipe. The radiator for SHARE weighs about 135 pounds, but with its support pedestals, support beam, heaters and instrumentation package, the total experiment weighs about 650 pounds. Crew members will switch the heaters on using controls located on the aft flight deck. Each of the experiment's two 500-watt heaters and single 1,000-watt heater is controlled individually and will be switched on in turn, applying heat that will increase steadily in 500-watt increments up to a maximum of 2,000 watts. The experiment will be activated for two complete orbits in two different attitudes, the first with the payload bay toward Earth and the second with the orbiter's tail toward the Sun. The heaters will go through a complete 500-watt to 2,000-watt cycle for each activation. This will simulate the heat that needs to be dissipated from the Space Station, and the two attitudes will provide data on the heat pipe's operation in different thermal environments. Other information also may be obtained during STS-29 if time permits, including a test of the heat pipe's minimum operating temperature, thought to be about minus 20 degrees Fahrenheit, and a test of its ability to recover from acceleration. - more - - 16 - The crew may fire the orbiter's aft reaction control system thrusters for about 6 seconds, an action that would push the fluid in SHARE to one end of the pipe. The heaters then may be turned on again to see if the heat pipe will automatically reprime itself and begin operating. CHROMEX This experiment will determine whether the roots of a plant in microgravity will develop similarly to those on Earth. Root- free shoots of the plants daylily and haplopappus will be used. The experiment will determine whether: o The normal rate, frequency and patterning of cell division in the root tops can be sustained in space. o The chromosomes and genetic makeup is maintained during and after exposure to space flight conditions. o Aseptically grown tissue cultured materials will grow and differentiate normally in space The criteria for comparison include: number of roots formed, length, weight and quality based on subjective appraisal as well as quantitative morphological and histological examination. Root tip cells will be analyzed for their karyotype, the configuration of chromosomes, upon return. Haplopappus dicatolydon is a unique flowering plant with four chromosomes in its diploid cells (2n=4). Daylily monocatolydon also has specific features of its karyotype 2n=22. Daylily and haplopappus gracilis will be flown in the plant growth unit (PGU), located in the orbiter middeck. The PGU can hold up to six plant growth chambers (PGC). One PGC will be replaced with the atmospheric exchange system that will filter cabin air before pumping through the remaining PGCs. The experimental plan is to collect and treat roots post flight, before the first cell division cycle is completed. Previous observations of some plants grown in space have indicated a substantially lowered level of cell division in primary root tips and a range of chromosomal abnormalities, such as breakage and fusion. PROTEIN CRYSTAL GROWTH EXPERIMENT STS-29 protein crystal growth experiments are expected to help advance a technology attracting intense interest from major pharmaceutical houses, the biotech industry and agrichemical companies. - more -