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Challenger
Challenger launches, STS-51-L
OV Designation	OV-099
Country	United States
Contract award	26 July 1972
Named after	HMS Challenger
First flight	STS-6 4 April 1983 – 9 April 1983
Last flight	STS-51-L 28 January 1986
Number of missions	10
Crews	60
Time spent in space	62.41 days
Number of orbits	995
Distance travelled	25,803,939 miles
Satellites deployed	10
Status	destroyed 28 January 1986

Space Shuttle Challenger (NASA Orbiter Vehicle Designation: OV-099) was NASA's second Space Shuttle orbiter to be put into service, after Columbia. Its maiden voyage was on April 4, 1983, and it made eight further round trips to low earth orbit before disintegrating 73 seconds after the launch of its tenth mission, on January 28, 1986, killing all seven crew members. (For more on the Challenger disaster, see Space Shuttle Challenger disaster.) It would be replaced by the space shuttle Endeavour, launched six years after the 51-L disaster.

Challenger was constructed using a body frame (STA- 099) that had initially been built as a test article. STA-099 was not originally intended for spaceflight, but NASA discovered that recycling it would be less expensive than refitting the test shuttle Enterprise (OV-101) to be spaceworthy, as originally planned. The spacecraft was named after the HMS Challenger, a British corvette which carried out a pioneering global marine research expedition in the 1870s[1]. Unlike Columbia, Challenger was the first Orbiter to be delivered with fewer tiles on its Thermal Protection System. Most of the tiles were replaced with DuPont white nomex felt insulation on the payload bay doors, upper wing surface and rear fuselage surface, allowing Challenger to carry 2,500 lbs. more than Columbia. It was also the first Orbiter to have a heads-up display system similar to those found in military and newer civilian aircraft to allow the commander and pilot to see important data during reentry and landing, eliminating the need to look at the instrument panel during descent and allowing them to concentrate on flying the Orbiter.

Challenger, along with Discovery was modified at KSC to be able to carry the Centaur-G upper-stage in its payload bay. Had STS-51-L been successful, Challenger's next mission would have been the deployment of the Ulysses probe with the Centaur to study the polar regions of the Sun.

Challenger was one of two space shuttles destroyed in an accident during a mission, the other being Columbia. The collected debris of the vessel are currently stored in decommissioned missile silos at Cape Canaveral Air Force Station. From time to time, further pieces of debris from the orbiter wash up on the Florida coast.^{[citation needed]} When this happens, they are collected and transported to the silos for storage. Because of her early loss, Challenger is the only space shuttle that never wore the NASA "meatball" logo.

Challenger's rollout from Orbiter Processing Facility (OPF) to the Vehicle Assembly Building (VAB). Photo courtesy of NASA.

Challenger while in service as structural test article STA-099.

[edit] Loss of Challenger

The crew of the Challenger's final flight.

Main article: Space Shuttle Challenger Disaster

Challenger was destroyed in the second minute of STS-51-L, the orbiter's tenth mission, on January 28, 1986, when an O-ring seal on its right solid rocket booster failed due to record low temperatures. The O-rings failed primarily due to repeated over-compression during assembly which allowed a plume leak to stream out of the tank's ET external fuel tank, that reached Challenger's engines leading to the orbiter's rapid break up. A subsequent investigation concluded that poor application of the SBR (styrene-butadiene rubber) seals, unusually cold temperatures, repeatedly over-compressed O-rings during assembly, and lack of inspection were to blame for the disaster.

The engineering purpose behind the decision to use SBR instead of the previously used silicone rubber was strictly cost savings as a directive from NASA. The engineering logic behind the change was that at the temperature of liquid hydrogen (−252.87°C/−423.17°F) or liquid oxygen (-183°C/-297.3°F), any gasket material would be frozen solid. The flaw in the logic was that the compression set (rebound characteristics) of SBR allowed only one compression to maintain a seal. Although this information was known, the tanks were taken apart and put together three times. The colder temperatures of the morning may have further impeded the already marginal seal. Silicone rubber gaskets, which had been used previously, have a better rebound after compression, even with the low temperatures, but had been deemed too expensive.

[edit] See also

• Challenger flag
• List of space shuttle missions
• Rendez-vous Houston
• Space Shuttle Challenger disaster

[edit] Bibliography

• Vaughan, D. (1996) The Challenger Launch Decision: Risky Technology, Culture and Deviance at NASA ISBN 0-226-85176-1

[edit] External links

Wikimedia Commons has media related to:

Space Shuttle Challenger

• Ronald Reagan: Address to the Nation on the Explosion of the Space Shuttle Challenger
• Space Shuttle Challenger Explosion video
• Shuttle Orbiter Challenger (OV-99)
• Rogers Commission Report
• Astronautix on Challenger
• Challenger Mission Videos of the Accident from Spaceflightnow.com
• NASA film on the accident and investigation downloadable from archive.org The Internet Archive
• Memorial to Greg Jarvis in Hermosa Beach, California at "Sites of Memory"
• RealPlayer video of Feynman's O-Ring demonstration (low quality)
• CBS Radio news Bulletin Anchored by Christopher Glenn of the Challenger Disaster from 1/28/86 , Part 2 of CBS Radio coverage of Challenger Disaster , Part 3 of CBS Radio News coverage of Challenger disaster, Part 4 of CBS Radio news coverage of challenger disaster

STS-51L Main articles: STS-51L, Space Shuttle Challenger, Space Shuttle Challenger disaster Crew: Scobee (Cmdr), Smith, Resnik, Onizuka, McNair, Jarvis, McAuliffe

v • d • e Space Shuttle program
Main articles	Space Shuttle · Space Shuttle program
Components	Orbiter · SRB · External Tank · SSME · OMS
Orbiters	Enterprise · Columbia · Challenger · Discovery · Atlantis · Endeavour
Launch sites	Kennedy Space Center LC-39 · Vandenberg Air Force Base SLC-6
Developments	Shuttle-Derived Launch Vehicle · Shuttle-C · Ares I · Ares V
Testing	Pathfinder · MPTA · MPTA-ET
Other articles	Missions (cancelled) · Decision to build · Crews · Abort modes · Space shuttles in fiction · Crawler-transporter · Space Shuttle America (motion simulator ride)  · Shuttle Mockup Explorer

v • d • e  Space Shuttles
	US Space Shuttle program Enterprise (atmospheric tests) Pathfinder (ground tests) Columbia (destroyed 2003) Challenger (destroyed 1986) Discovery (active) Atlantis (active) Endeavour (active)	Soviet Buran program OK-GLI (BST-02) (aerotester) Buran (retired, destroyed 2002) Ptichka (95–97% completed, unused) 2.01 (incomplete) 2.02 (partially dismantled) 2.03 (dismantled)