Washington - The space shuttle Endeavour, scheduled to blast off Wednesday on its 20th mission, is the youngest of NASA's three still-active space shuttles. Endeavour replaced the Challenger shuttle, which blew up January 28, 1986, a little over a minute after launch.
Endeavour is named after the ship on which 18th century British explorer and seafarer James Cook set sail on his first voyage to the south seas.
On its maiden voyage in May 1992, three Endeavour crew members on a space walk caught a spinning 4.5-ton satellite, pulled it into the shuttle's cargo bay, repaired it and sent it back into orbit.
At 37.4 metres-long and with a launch weight of 109 tons, Endeavour is shorter and lighter than Discovery and Atlantis. Endeavour has spent the least amount of time in space of any of the shuttles. In its 19 flights so far, it logged 206.6 days in space and has orbited Earth 3,250 times.
One of its most important missions was a flight to the Hubble Space Telescope in December 1993. The telescope was delivering out- of-focus pictures, so the crew was sent on a maintenance mission to install a corrective optics package. It took a record five space walks to complete the work.
In February 2000, Endeavour was launched on NASA's 99th shuttle mission, the so-called Shuttle Radar Topography Mission. This involved using a set of radar antennas to map most of the Earth's surface. Data collected by a radar system on the ground was used later to calculate highly specific global models.
Endeavour's last mission was in November 2002. After the accident in which the space shuttle Columbia was lost on February 1, 2003, all shuttle flights were suspended. The shuttles were modernized during the suspension.
After its latest mission, Endeavour is scheduled to make four other trips to the International Space Station before being retired by 2010.