Nasa chief Sean O'Keefe has asked for a firm mission proposal to be worked up in a year, after which a decision whether to proceed will be made.
"Everybody says: 'We want to save the Hubble'. Well, let's go save the Hubble," Mr O'Keefe said.
Nasa ceased manned missions to service Hubble after the Columbia disaster.
Mr O'Keefe instructed engineers at the Goddard Flight Center in Maryland to begin serious work to put the robotic mission in to space in 2007.
Some reports suggest a leading candidate for the mission is a robot called Dextre, developed by the Canadian Space Agency.
The two-armed robot, whose name is short for "dexterous", was developed for work on the International Space Station.
New funding
Mr O'Keefe said he would ask Congress for funds to finance the repair mission, which is estimated to cost between $1bn (£550m) and $1.6bn (£8.7m).
Mr O'Keefe asked for ideas from industry for a robotic servicing mission in June.
Hubble is considered to be one of the most important telescopes ever built.
It has peered back to the very beginnings of the universe, found planets outside our Solar System and taken dramatic pictures of stars being born.
The telescope's fate has been in doubt since Mr O'Keefe announced in January that manned servicing missions would be cancelled in light of a new safety regime brought in for space shuttle flights following the Columbia disaster.
Space shuttle Columbia disintegrated as it re-entered Earth's atmosphere on 1 February 2003, killing seven astronauts.
The robot repair mission could add another five years to the telescope's life, which will expire in 2008 without help.
