Trade.Information

Company Name: Servicing Mission 3A

Company Type: Nasa Project

Company Profile

STS-103 on Space Shuttle Discovery, landed at 7:01 EST, Monday, December 27, 1999, 12:01 am GMT, December 28, 1999. Mission Elapsed Time: 7 days, 23, hours, 10 minutes. Launch Date: 7:50 pm EST, December 19, 1999; 12:50 am, GMT December 20, 1999. STS-103 Launch/Landing Opportunities The failure of a fourth gyroscope on November 13, 1999 placed Hubble in safe hold until the SM3A rendezvous and grapple on December 20, 1999. Servicing Mission 3A successfully replaced equipment and performed maintenance upgrades to the Hubble Space Telescope. Although no new scientific instruments were installed, many activities took place over 3 EVA days. The originally planned 4 days of EVA were changed to 3 days because of the weather-delayed launch. The deorbit time was fixed for this mission in order to avoid any possible Y2K problems. Listed below are a few of the main activities that have taken place

About Company

Hubble Space Telescope (HST) Servicing Mission 3A was launched on December 19, 1999 and the Space Shuttle Discovery landed on December 27, 1999. Its seven-member crew included two Hubble Servicing veterans. NASA decided to split the HST Third Servicing Mission (SM3) into two parts, SM3A and SM3B, after the third of Hubble's six gyroscopes failed. The second part of the mission, SM3B, is tentatively scheduled for mid-2001. The gyros, part of Hubble's sophisticated pointing system, help hold the telescope steady during observations. Hubble only needs three gyros to conduct science operations. In addition to the gyros, astronauts have also replaced a guidance sensor and a transmitter, and install a new, advanced central computer, a digital data recorder, an electronics enhancement kit, battery improvement kits, and new outer layers of thermal protection. The eight-day flight included three scheduled spacewalks, each lasting six hours. On November 13, 1999, the Hubble Space Telescope was placed into safe-hold after the failure of a fourth gyroscope. This mode had been thoroughly tested and used twice since Hubble's launch in 1990. The telescope was not at risk. This protective mode allows ground control of the telescope, but with only two gyros working, Hubble cannot be aimed with the precision necessary for scientific observations of the sky. The aperture door had been closed to protect the optics, and the spacecraft was aligned to the sun to ensure that adequate power was received by Hubble's solar panels.