The National Aeronautics and Space Administration chief said the planning would take nine months to a year and would cost roughly 1.0 to 1.6 billion dollars. An amendment to the 2005 budget is being prepared and will soon be sent to Congress, he added.

In an interview with The Orlando Sentinel, O'Keefe said he met with the Hubble team on Monday at the Goddard Space Flight Center in Maryland to review recently submitted proposals to replace Hubble's batteries, gyroscopes and some of its scientific instruments with a robotic mission.

NASA announced mid-January it would stop, for safety reasons, sending astronauts to service the telescope, effectively condemning the Hubble to an early demise.

The decision devastated scientists, since the telescope has provided a wealth of information and stunning images of the universe since being dropped off in space in April 1990.

Among its achievements, Hubble has established the age of the Milky Way at between 13 and 14 billion years, helped gather evidence to support the Big Bang theory and provided the first convincing proof by an optical telescope of the existence of black holes.

NASA's next big orbiting telescope will be the James Webb Space Telescope -- like the Hubble a US-European venture -- but it is not scheduled for launch until 2011 and will only observe in infrared, not visible light.

Orbiting telescopes cost far more to build, deploy and maintain than terrestrial ones, but can be many times more effective because they are not hampered by light or atmospheric pollution or interference from manmade energy sources.

SPACE.WIRE