STS-26 was the 26th mission and seventh for Space Shuttle Discovery, launched from Kennedy Space Center, Florida. It was the "Return to Flight" mission, being the first mission after the Space Shuttle Challenger disaster. This was the first mission to use the original Space Transportation System numbering system since STS-9, and the first to have all crew members wearing pressure suits for launch and landing since STS-4.
It was also the first mission for the crew to have a NASA "meatball" logo. However, at that time, Discovery still wore the NASA "worm" logo until 1998.
The primary payload for the STS-26 mission, a Tracking and Data Relay Satellite (TDRS), was successfully deployed, and 11 scheduled middeck scientific and technological experiments were carried out. The orbiter sustained only minor Thermal Protection System tile damage and the redesigned solid rocket boosters showed no signs of leakage or overheating at any of the joints.
Two minor problems occurred during the flight. After ascent, the Flash Evaporator System for cooling the orbiter iced up and shut down, increasing the crew cabin temperature to approximately 87 degrees Fahrenheit. The problem was resolved on Flight Day 4 and cooler temperatures resulted. A Ku-band antenna for communications was successfully deployed on Flight Day 2, but it failed to respond properly and had to be stowed for the remainder of the mission.
Space Shuttle Discovery holds the distinction of being the first ship to fly in space equipped with a VCU (Voice Control Unit), a "computer" that recognized and responded to human speech. This speech recognition system controlled the cameras and monitors that were used by the crew to monitor the mechanical arm mounted in the cargo bay. Because of the experimental nature of speech recognition this system was not used for any critical operations. Initial problems almost sidelined the tests when the voice templates that were created prior to liftoff were found to have less than 60% for one crew member and less than 40% for another. This problem was corrected by retraining the templates. It was retested and found to be operational with a recognition success rate of over 96%. It was concluded that weightless conditions caused a fundamental change in human speech which made the templates created prior to liftoff virtually useless. The VCU was created by a group of engineers and scientists that worked for SCI Systems in Huntsville, Alabama. It was based on technology licensed from the Votan company.
Besides conducting the various experiments, crew members practiced suiting up in new partial-pressure, or launch-and-entry, flight suits, and unstowing and attaching the new crew escape system. On October 2, the day before the mission ended, the five-man crew paid a moving tribute to the 51-L Challenger crew.
Discovery landed on Runway 17, Edwards AFB, California, at 12:37 p.m. EDT on Oct. 3. Mission duration was 4 days and 1 hour. Capsule Communicator Blaine Hammond Jr. welcomed the crew, saying it was "a great ending to a new beginning."
TDRS-C, which became TDRS-3 in orbit, and its attached Inertial Upper Stage (IUS), were deployed from Discovery's cargo bay 6 hours, 13 minutes, into the flight. The first stage of the IUS placed TDRS-3 in a transfer orbit, and the IUS second stage placed the vehicle in geosynchronous orbit on Sept. 30. TDRS-3, the second operational Tracking and Data Relay Satellite, moved into position over the Pacific Ocean south of Hawaii at 171 degrees west longitude. It joined TDRS-1 in tracking Earth-orbiting spacecraft. TDRS-B was lost in the Challenger accident. Also in the payload bay was the Orbiter Experiments Autonomous Supporting Instrumentation System (OASIS). OASIS recorded environmental data on the orbiter and the TDRS payload during various inflight phases.
All the middeck experiments were deemed to have operated or performed successfully. But there were some glitches with two of the five experiments that involved materials science. In the Protein Crystal Growth experiment, two of the 11 proteins processed did not produce crystals suitable for analysis. That includes a key enzyme in the replication of AIDS. Also, there were some equipment problems with the Automatic Directional Solidification Furnace, an experiment to investigate the melting and solidification of various materials.
The materials processing experiments included two Shuttle Student Involvement Projects, one on titanium grain formation and the other on controlling crystal growth with a membrane. Another materials science experiment, the Physical Vapor Transport of Organic Solids, was a joint project of NASA's Office of Commercial Programs and the 3M Company.
Three experiments were in life sciences, including one on the Aggregration of Red Blood Cells, which will help to determine if microgravity can play a beneficial role in clinical research and medical diagnostic tests. Two experiments involved atmospheric sciences and one was in communications research.
Orbiter Experiments Autonomous Supporting Instrumentation System-I (OASIS-I) recorded variety of environmental measurements during various inflight phases of orbiter. Ku-band antenna in payload bay deployed; however, dish antenna command and actual telemetry did not correspond. Also, orbiter cabin Flash Evaporator System iced up, raising crew cabin temperature to mid-80s.