NASA administrator Sean O'Keefe told researchers at the agency's Goddard Space Flight Centre in Maryland about the plan on Monday, instructing the engineers there to begin serious work to put the robotic mission in to space in 2007.
"Everybody says, 'We want to save the Hubble' - well, let's go save the Hubble," O'Keefe was quoted as saying by the Orlando Sentinel. "Rather than just sitting there and talking about how we think we're going to do it, we've got an option we're ready to go with."
It will cost at least $1 billion and possibly $1.6 billion to save the telescope, which has peered back to the very beginnings of the universe, found planets outside our solar system and taken dramatic pictures of stars being born.
Scientists who have used the telescope to explore the origins of the cosmos and look for places that extraterrestrial life might exist are delighted by the decision.
"Everybody says, 'We want to save the Hubble' - well, let's go save the Hubble"
Al Diaz, associate administrator for NASA's Science Mission Directorate, told reporters it might be possible to add another five years to the life of the aging telescope.
Diaz described the next nine months as "a design and testing phase" in which engineers will work out details of the mission to prove that a robotic servicing mission can be done, the Washington Post reported.
Shuttle mission off
NASA has been thinking about letting Hubble slowly die and drift out of orbit, because it otherwise must be maintained by space shuttle astronauts or some kind of robotic mission.
But a shuttle mission was ruled out by NASA after the shuttle Columbia fell apart as it headed toward a landing in 2003, killing all seven astronauts aboard.
NASA later cancelled a shuttle mission set for next year that would have replaced batteries and repaired broken gyroscopes used to aim the telescope.
Hubble has sent eye-popping
images of the universe to earth
If they are not replaced, the orbiting telescope is expected to stop providing useful information by 2007 or 2008.
After intense public outcry, O'Keefe said a robotic repair mission was possible, and NASA has been studying that option.
An expert panel reported in July that NASA should try to keep Hubble alive and should look at using a robot.
Goddard scientists have expressed interest in the Canadian Space Agency's Special Purpose Dextrous Manipulator, or Dextre, built to service the International Space Station.
It can open panel doors, change batteries and perform other tasks with its two robotic arms.
The 14-year-old Hubble telescope has overcome problem after problem since it was launched in 1990. One camera was out of focus and shuttle astronauts had to repair it in 1993.
The 14-year-old Hubble telescope has overcome problem after problem since it was launched in 1990
Just this week NASA said one key instrument, the Space Telescope Imaging Spectrograph, had broken down, perhaps with an electrical fault.
Hubble's replacement, the James Webb Space Telescope, is not scheduled for launch until 2011 at the soonest.