Only $75 million in the space agency's $16.5 billion budget would go toward Hubble's future, and all of that would be used to develop a robot mission to steer the orbiting observatory into the ocean at the end of its lifetime.
Hubble has enabled scientists to see distant galaxies and confirmed the existence of black holes.
No money is into send either a robotic repairman or shuttle astronauts to Hubble to extend its lifetime, a decision that is sure to anger astronomers and members of Congress. Critical telescope parts on Hubble are expected to conk out by 2007.
Late last year, a National Academy of Sciences panel recommended one final visit to Hubble by astronauts.
The proposed budget does set aside $9.6 billion for science, aeronautics and exploration, and $6.7 billion for exploration capabilities, including such space operations as the space shuttle and international space station programs.
Just over a year ago, Mr. Bush announced a new exploration vision for NASA geared around returning astronauts to the moon by 2020. Everything now revolves around that goal.
NASA's comptroller, Steve Isakowitz, said a robotic mission to install new parts on Hubble is proving too risky from a technological point of view, and a shuttle mission poses too many dangers in the wake of the 2003 Columbia accident.
Instead, NASA is working on ways to remotely manage the 14-year-old Hubble in order to keep it going as long as possible and is considering putting two already completed Hubble cameras on a separate yet-to-be-built spacecraft instead, Isakowitz said.
"We have been as eager as the Congress to try to save the Hubble, but at the end of the day, what we're trying to save is the science related to Hubble," he said.
A robotic repair mission has been estimated to cost as much as $1 billion to $2 billion, but Isakowitz said "the decision we made is largely being driven by the risk considerations. It was not driven by the budget."