Risky space mission

Atlantis blasted off yesterday for the Hubble Space Telescope on the most delicate and dangerous repair job ever in orbit, a mission so risky that for the first time a second shuttle stands ready to rescue the seven astronauts if something goes wrong.

It will be the last visit to the ageing observatory, and the work will include five spacewalks in an especially high orbit strewn with space junk.

The astronauts will not have the option of using the international space station as a safe harbour in a crisis.