The next stage is a new infrared space telescope -- the James Webb Space Telescope (JWST) -- to replace Hubble, currently due to be launched in 2013.

CNN: Telescope set to reveal 'Big Bang'

Then there's the replacement for Hubble, the James Webb Space Telescope (JWST), which has been very expensive with lots of cost overruns, and now this asteroid mission.

BBC: Is Nasa looking in the wrong place for life?