STS-75 (75)

Columbia (19)
Pad 39-B (36)
75th Shuttle Mission
19th Flight OV-102
KSC Landing (29)


Andrew M. Allen (3), Commander
Scott J. Horowitz (1), Pilot
Franklin R. Chang-Diaz (5), Payload Commander
Maurizio Cheli (1), Mission Specialist (ESA)
Jeffrey A. Hoffman (5), Mission Specialist
Claude Nicollier (3), Mission Specialist (ESA)
Umberto Guidoni (1), Payload Specialist (Italy)


OPF -- Nov 05, 1995
VAB -- Jan 23, 1996
PAD -- Jan 29, 1996
FRR -- Feb 09, 1996



Mission Objectives:

The primary objective of STS-75 is to carry the Tethered Satellite System Reflight (TSS-1R) into orbit and to deploy it spaceward on a conducting tether. The mission will also fly the United States Microgravity Payload (USMP-3) designed to investigate materials science and condensed matter physics.

The TSS-1R mission is a reflight of TSS-1 which was flown onboard Space Shuttle Atlantis on STS-46 in July/August of 1992. During that flight, the tether was deployed a distance of 860 feet. STS-75 mission scientist hope to deploy the tether to a distance of over 12 miles (20.7km).

The Tether Satellite System will circle the Earth at an altitude of 296 kilometers which will place the tether system within the rarefied electrically charged layer of the atmosphere known as the ionosphere. The conducting tether will generate high voltage and electrical currents as it moves through the ionosphere across the magnetic field lines of the earth. Scientists will be able to learn more about the electrodynamics of a conducting tether system to deepen our understanding of physical processes in the near-Earth space environment. These studies will help provide explanations for events such as the formation and behavior of comet tails and bursts of radio "noise" detected from other planets.

The specific TSS1-R mission objectives are: characterize the current-voltage response of the TSS-orbiter system, characterize the satellites high-voltage sheath structure and current collection process, demonstrate electric power generation, verify tether control laws and basic tether dynamics, demonstrate the effect of neutral gas on the plasma sheath and current collection, characterize the TSS radio frequency and plasma wave emissions and characterize the TSS dynamic-electrodynamic coupling.

TSS-1R Science Investigations include: TSS Deployer Core Equipment and Satellite Core Equipment (DCORE/SCORE), Research on Orbital Plasma Electrodynamics (ROPE), Research on Electrodynamic Tether Effects (RETE), Magnetic Field Experiment for TSS Missions (TEMAG), Shuttle Electrodynamic Tether System (SETS), Shuttle Potential and Return Electron Experiment (SPREE), Tether Optical Phenomena Experiment (TOP), Investigation of Electromagnetic Emissions by the Electrodynamic Tether (EMET), Observations at the Earth's Surface of Electromagnetic Emissions by TSS (OESSE), Investigation and Measurement of Dynamic Noise in the TSS (IMDN), Theoretical and Experimental Investigation of TSS Dynamics (TEID) and the Theory and Modeling in Support of Tethered Satellite Applications (TMST).

The USMP-3 payload consists of four major experiments mounted on two Mission Peculiar Experiment Support Structures (MPESS) and three Shuttle Mid-deck experiments. The experiments are: Advanced Automated Directional Solidification Furnace (AADSF), Material pour l'Etude des Phenomenes Interessant la Solidification sur Terre et en Orbite (MEPHISTO), Space Acceleration Measurement System (SAMS), Orbital Acceleration Research Experiment (OARE), Critical Fluid Light Scattering Experiment (ZENO) and Isothermal Dendritic Growth Experiment (IDGE).


Launch February 22, 1996 3:18:00.061 pm EST. Launch window was 2 hours 30 min. There were no unscheduled holds. Winds at liftoff were from approximately 63.4 degrees at 5.76 knots. Ambient temperature was 72.8 F, barometric pressure was 29.94in Hg and relative humidity was at 78%.

About four seconds after liftoff, Shuttle Commander Andy Allen reported that his instruments showed that one of the shuttle main engines was operating at only 45% of its normal power level. Flight controllers in Houston quickly responded that all engines were performing nominally. The engines throttled as expected about 1 minute into the launch, and operated normally all the way to main engine cutoff at 8 and a half minutes into the flight. Engineers will look at data from the launch to try to understand the faulty reading. ( Reference STS-75 MCC Status Report # 01)

On Tuesday, 2/20/96, the mission management team met briefly to discuss an incident that occurred overnight at Pad 39B. At about 1 a.m., a neutralizing agent, believed to be sodium hydroxide was spilled over the left-hand solid rocket booster and the left side of the external tank. This non-toxic liquid is used to neutralize any potential hazardous vapors that may be present during normal operations to remove covers off the reaction control system thrusters on Columbia. The incident has not seriously delayed the launch countdown. However, engineering evaluations are in work to determine if any concerns exist for the liquid contacting the flight hardware. (Reference KSC Shuttle Status 2/21/1996).

The countdown started at 4pm EST at the T-minus 43 hour mark on Monday, 2/19/96 and the payload bay doors were closed. The STS-75 crew arrived at the Shuttle Landing Facility at 3:30pm EST. (Reference KSC Shuttle Status 2/20/1996).

On Tuesday, 2/13/96, a faulty wire to one of the pyrotechnic devices at the 17-inch disconnect located between the orbiter and external tank was replaced and tested successfully. Also, problems with the crew hatch were resolved and final testing was successful. (Reference KSC Shuttle Status 2/13/1996).

On Friday, 2/9/96, Hypergolic loading operations took place and the Flight Readiness Review (FRR) was conducted. The countdown is scheduled to begin on February 19. (Reference KSC Shuttle Status 2/09/1996).

On Friday, 2/2/96, work continued to remove and replace the high pressure fuel turbo pump from main engine number 1. The new pump was installed and electrical hookup started. The Terminal Countdown Demonstration Test was also concluded. (Reference KSC Shuttle Status 2/02/1996).

On 1/29/96, the Shuttle Columbia was transferred to Pad 39B from the Vehicle Assembly Building. First motion occurred at 2:33 a.m. The vehicle was hard down on the pad at about 9:30 a.m. Later that evening, the three auxiliary power units (APU) were to be hot fired. After that, workers will start the week long process to remove and replace the high pressure fuel turbo pump from Space Shuttle Main Engine (SSME) No. 1.

On 1/23/96, Columbia was transferred to the Vehicle Assembly Building with first motion occurring at 10:45 p.m. From there it was lifted and mated with external tank. The Shuttle interface verification test was scheduled for 1/26/96. (Reference KSC Shuttle Status 1/24/1996).
On 11/27/95, work began on the removal and replacement of Window No. 6. The three main engines have been removed. The forward reaction control system removed on Tuesday 11/28/95 and the freon coolant loop No. 1 deserviced. Testing was started on the Ku-band antenna. In the Operations and Checkout building work on the the STS-75 payloads, Tethered Satellite and USMP-3, has been going smoothly and is nearing completion. They will be in preparation for final testing. (Reference KSC Shuttle Status 11/27/1995).


Altitude: 160 nm (184 statute miles)
Inclination: 28.45 degrees
Orbits: 251
Duration: 15 days, 17 hours, 41 minutes, 25 seconds.
Distance: 6.5 million miles


SRB: BI-078
SRM: 360W053A(left),360W053B(right)
ET : SN-76
MLP : 3
SSME-1: SN-2029
SSME-2: SN-2034
SSME-3: SN-2017


KSC Saturday, March 9, 1996 at 8:58:38 a.m EST, SLF Runway 33 Landing times: Main gear touchdown at MET 15days 17hours 40min 21sec, or 8:58:21 am EST. Nose gear touchdown at MET 15days 17hours 40min 36sec, or 8:58:36 EST. Wheels stop at 15days 17hours 41min 25 sec or 8:59:25am EST. (Reference KSC Shuttle Status 3/09/1995).

The first KSC landing opportunity for Saturday, March 9, 1996 was waived off due to cloud cover at KSC. This would have required a deorbit burn at 6:23am EST, with a landing at 7:24am EST. A "go" was given by Mission Control for the deorbit burn at 7:46am EST to support the 2nd KSC opportunity. Deorbit burn at MET: 15d16h37m43s on orbit 251 at 7:56am EST.

In the event of unacceptable weather at KSC, the shuttle would have landed during one of 3 landing opportunities at Edwards AFB. The first opportunity would have been on orbit 252 with a 9:25am EST deorbit burn leading to a landing at 10:26am EST (7:26am Dryden time).

On 3/9/96, flight controllers opted to forego KSC landing opportunities at 7:16 a.m., 8:52 am EST and 10:27 on because of forecast low clouds and the possibility of rain and gusty winds. Weather conditions did not inprove and at 9:25am EST, mission controllers waived off KSC's final landing opportunity for 3/8/96. ( Reference STS-75 MCC Status Report # 28)

Mission Highlights:

About four seconds after liftoff, instruments showed that one Space Shuttle Main Engine (SSME) was operating at only 45% of normal power. It was quickly determined that the problem was in the instrumentation and not in the engine. Over the next few days, the TSS-1R and USMP-3 payloads were powered up and prepared for science operations. Problems were noted with a payload interface device known as a "Smart Flex". The deployment of the TSS satellite was delayed 24 hours to perform additional testing on the device. On Flight Day 4 (2/25/95), deploy operations began at 2:45pm CST. At approximately 7:30pm CST, after TSS-1R had deployed 19.7km of tether and had almost reached full deployment, the tether broke.

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