||This article includes a list of references, but its sources remain unclear because it has insufficient inline citations. (May 2008)|
|Mission duration||15 days, 17 hours, 40 minutes, 22 seconds|
|Distance travelled||10,500,000 kilometres (6,500,000 mi)|
|Spacecraft||Space Shuttle Columbia|
|Payload mass||10,592 kilograms (23,350 lb)|
|Start of mission|
|Launch date||22 February 1996, 20:18:00UTC|
|Launch site||Kennedy LC-39B|
|End of mission|
|Landing date||9 March 1996, 13:58:22UTC|
|Landing site||Kennedy SLF Runway 33|
|Perigee||277 kilometres (172 mi)|
|Apogee||320 kilometres (200 mi)|
|Commander||Andrew M. Allen
|Pilot||Scott J. Horowitz
|Mission Specialist 1||Jeffrey A. Hoffman
|Mission Specialist 2||Maurizio Cheli, ESA
|Mission Specialist 3||Claude Nicollier, ESA
|Mission Specialist 4||Franklin R. Chang-Diaz
|Payload Specialist||Umberto Guidoni, ASI
Mission objective 
The primary objective of STS-75 was to carry the Tethered Satellite System Reflight (TSS-1R) into orbit and to deploy it spaceward on a conducting tether. The mission also flew the United States Microgravity Payload (USMP-3) designed to investigate materials science and condensed matter physics.
The TSS-1R mission was a reflight of TSS-1 which was flown onboard Space Shuttle Atlantis on STS-46 in July/August 1992. The Tether Satellite System circled the Earth at an altitude of 296 kilometers, placing the tether system within the rarefied electrically charged layer of the atmosphere known as the ionosphere.
STS-75 mission scientist hoped to deploy the tether to a distance of 20.7 kilometres (12.9 mi). Over 19 kilometers of the tether were deployed before the tether broke. It remained in orbit for a number of weeks and was easily visible from the ground, appearing something like a small but surprisingly bright fluorescent light traveling through the sky.
The specific TSS1-R mission objectives were: characterize the current-voltage response of the TSS-orbiter system, characterize the satellite's 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 included: 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 consisted of four major experiments mounted on two Mission Peculiar Experiment Support Structures (MPESS) and three Shuttle Mid-deck experiments. The experiments were: 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).
STS-75 also was the first use of an operating system based on Linux kernel on orbit. An older Digital Unix program, originally on DEC Alpha servers, was ported to run on Linux on a laptop. The next use of Linux was a year later, on STS-83.
STS-75 was the shuttle mission described in the fictional NASA Document 12-571-3570, although this document was disseminated several years before STS-75 was launched. The document purports to report on experiments to determine effective sexual positions in microgravity. Astronomer and scientific writer Pierre Kohler mistook this document for fact and is responsible for a major increase in its redistribution in the early 21st century.
"UFO" incident 
Excerpts of video footage shot from STS-75 have been widely circulated by UFO enthusiasts, who believe that visual anomalies in the footage represent an unexplained paranormal phenomenon. The STS-75 crew identified the "UFOs" as small particles of debris filmed out of focus. Space journalist James Oberg wrote an analysis of the footage giving further detail.