The six-person crew of the Discovery, before boarding the shuttle earlier today
As dusk approached yesterday, the space shuttle Discovery blasted off. It was an appropriate time of day, as the entire shuttle program has entered its twilight hours. When the Discovery returns after its eleven-day mission, it will be mothballed and shipped off to the Smithsonian, leaving only the Endeavour and Atlantis to each fly once more, with the final mission coming in the summer of this year.
After that, NASA will have to find other ways to get astronauts into space. NASA’s had gaps in its spaceflight capabilities before, such as during 1975 to 1981, after the Apollo rockets and spacecraft were retired and before the shuttle started flying. But, unlike the late 1970’s, NASA can’t just choose to skip sending anyone into space – today, people and supplies must be routinely sent to the International Space Station (ISS), currently operating with a crew of six in low Earth orbit.
NASA always knew that the shuttles couldn’t fly forever, but its attempts to develop a successor failed, most notably including the VentureStar, an ambitious single-stage-to-orbit spacecraft that was cancelled in 2001 after over a billion dollars had been spent in development. This left the agency with no clear alternatives, prompting NASA to begin studying how to keeping the shuttle flying until at least 2020, until the disintegration of the Columbia during re-entry in 2003 cast doubts on the wisdom of prolonging the working life of the vehicles. The agency then begun working on the Constellation program, but the future of that program remains clouded, and only one preliminary test flight of the launch rocket has occurred to date. After this summer, NASA will have to rely solely on hitching rides on Russia’s cramped three-person Soyuz spacecraft to get its astronauts to and from the ISS.
Fortunately, a number of strong candidates to replace the shuttle, as least with regards to resupplying the ISS, have emerged in the last few years from the private sector, as outlined in the latest Briefing from Technology Review. SpaceX is furthest along, successfully testing an automated version of its Dragon space capsule and Falcon 9 launch rocket in December. Dragon will begin supplying the ISS this year with cargo, and is designed to be easily upgraded to accommodate astronauts–if NASA is willing to buy tickets.