Discovery approaching ISS:Image by TopTechWriter.US via Flickr
The final mission of the space shuttle Discovery has been postponed again because of a fuel leak. After 26 years of service, the vehicle is due to make one last flight to the International Space Station (ISS) before being retired to a museum. Escaping hydrogen detected midway through fuelling left Nasa no choice but to stand Discovery down once more.
The agency is now planning a launch date on 30 November, to give plenty of time to fix the leak. Nasa has simply run out of time in the current launch window, which ends on Monday. There then follows a three-and-a-half-week period of unfavourable sun angles at the orbiting platform that make a docking very difficult because of the heating experienced by an approaching shuttle. The leak occured at the ground umbilical carrier plate, an attachment point between the external tank and a 18cm pipe that carries vented hydrogen safely away from Discovery to a flare stack, where it is burned off. Discovery’s six astronauts had yet to board the spaceplane when the leak was detected. When the ship does get up, she will deliver a storeroom to be attached to the ISS, along with much needed supplies and spares.
Discovery is the oldest of the surviving ships. First launched in 1984, it has since completed 38 missions, travelling some 230 million kilometres in the process. Its commander on the final mission, Steve Lindsey, says Discovery is probably the most important of three remaining shuttles. “It is obviously a very historical vehicle, having flown the ‘return to flight’ test missions after both the Challenger and Columbia accidents,” he said. “It deployed Hubble (and) it’s the fleet leader in terms of number of flights – it’ll have flown about a year on orbit by the time we’re done with it, which is pretty remarkable for a space shuttle.”
After Discovery returns, only the Endeavour shuttle has a firm date to launch, in February next year. Atlantis could fly in June if the budget allows. Beyond that, American astronauts will use Russian Soyuz rockets to get into space until a range of commercial US launch systems are introduced in the middle of the decade.
Robonaut 2, a dexterous, humanoid astronaut helper, will fly to the International Space Station aboard space shuttle Discovery on the STS-133 mission.
The k2p blog 