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Space shuttle Challenger was the second shuttle to be built by NASA.
Space Shuttle Challenger was NASA's second space shuttle orbiter to be put into service. Space shuttle Challenger's maiden flight was on 4 April, 1983. Space shuttle Challenger completed nine missions before disintegrating 73 seconds after the launch of its tenth mission, on January 28, 1986, killing all seven crew members. Space shuttle Challenger was replaced by the space shuttle Endeavour which made its first flight in 1992, six years after the disaster.
History of the Space shuttle Challenger.
Space shuttle Challenger was named after the HMS Challenger, a British corvette which carried out a pioneering global marine research expedition in the 1870s.
Construction of Space shuttle Challenger.
The shuttle 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 found that recycling it would be less expensive than refitting the test shuttle Enterprise (OV-101) to be spaceworthy, as originally planned.
Challenger (and the orbiters built after it) had fewer tiles in its thermal protection system than Columbia. Most of the tiles on the payload bay doors, upper wing surface and rear fuselage surface were replaced with DuPont white nomex felt insulation. This modification allowed Challenger to carry 1130 kg (2500 lbs) more payload than Columbia. Challenger was also the first orbiter to have a heads-up display system similar to those found in military and newer civilian aircraft. This system eliminated the need to look at the instrument panel during descent and allowed the crew to concentrate more on flying the orbiter.
Flights and modifications of Space shuttle Challenger.
After its first flight, Challenger quickly became the workhorse of NASA's Space Shuttle fleet, flying far more missions per year than Columbia. In 1983 and 1984, Challenger flew on 85% of all Space Shuttle Missions. Even when the orbiters Discovery and Atlantis joined the fleet, Challenger remained in heavy use with three missions a year from 1983-85.Challenger, along with Discovery, was modified at Kennedy Space Center 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's many spaceflight accomplishments included the first American woman, African-American, and Canadian in space, three Spacelab missions, and the first night launch and landing of a Space Shuttle. Sadly, Challenger was also the first space shuttle to be destroyed in an accident during a mission. 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. When this happens, they are collected and transported to the silos for storage. Because of her early loss, Challenger was the only space shuttle that never wore the NASA "meatball" logo.
Loss of Space Shuttle Challenger.
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(SRB) failed. The O-rings failed primarily due to repeated over-compression during assembly. This failure allowed a plume of flame to leak out of the SRB and burn through the external fuel tank (ET). Liquid hydrogen spilled out of the ET and caught fire, severing the clamps holding the SRB in place. The SRB swung around wildly and slammed into Challenger's right wing. This caused the whole shuttle assembly to swerve off course and the supersonic airflow quickly tore Challenger apart. 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 logic behind the change was that at the temperature of liquid hydrogen (-252.87ºC/-423.17ºF) or liquid oxygen (-183ºC/-297.3ºF), any gasket material would be frozen solid. The flaw in this thinking was that the compression set (rebound characteristics) of SBR allowed only for one compression while maintaining a seal. Any more compressions would require that the entire O-ring assembly be replaced to keep the joint sealed. Although this information was known, the tanks were taken apart and put together three times without replacing the SBR. 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.
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