Competing budget priorities for space missions and safety concerns for astronauts may add up to the death knell of the Hubble Space Telescope.

Funding for a planned servicing mission that would have replaced vital Hubble parts, like gyroscopes and batteries, have been cut from the proposed White House budget for NASA next year.

NASA saw a 2.4 percent overall increase in the White House's 2006 fiscal year proposed budget. The $16.45 billion budget included funding for planned manned missions to the moon and Mars.

According to the proposed NASA budget, there is $6.7 billion for space exploration, with $4.5 billion dedicated to resume the space shuttle program and $1.85 billion proposed for the international space station.

A total of $175 million is budgeted for Hubble, with most of that funding scheduled to build a system to crash the telescope harmlessly into the ocean.

UA astronomers said the loss of a servicing mission could end scientific observations by 2007, three years before Hubble's scheduled decommission.

Rodger Thompson, a UA astronomy professor, said Hubble is the greatest scientific instrument in NASA's arsenal.

Thompson said he felt NASA's decision not to fund the planned servicing mission was arbitrary and made against the advice of the National Academy of Sciences, which advises the federal government on scientific issues.

"They ignored the scientific advice," Thompson said.

In December, the NAS released a report commissioned by NASA on options for extending Hubble's life. The report emphasized the need to repair the telescope, citing the crucial nature of Hubble to scientific research.

In January, outgoing NASA Administrator Sean O'Keefe said safety concerns for its astronauts would scrap a manned mission to Hubble. After the Columbia disaster, NASA outlined new safety procedures for all shuttle missions. NASA, however, has 25 manned missions to the international space station planned.

Plans for a robotic mission to the telescope have been scrapped.

Thompson said the robotic mission is necessary to replace the six gyroscopes, which keep it steady. He said they are slowly failing, and the telescope has three functioning gyroscopes.

A study by NASA suggests the telescope could operate with two functioning gyroscopes, Thompson said.

Thompson said Hubble is in a unique position to get images unavailable to ground-based telescopes. Hubble can see images in the infrared spectrum with the UA's Near Infrared Camera and Multi-Object Spectrometer, while all ground-based telescopes are blinded to these wavelengths by the atmosphere and inaccessible from Earth.

Thompson, the principal investigator for the NICMOS team, said a replacement for Hubble is not slated to begin until 2011.

Marcia Rieke, a UA astronomy professor and a former investigator for the NICMOS team, said the time window between the end of Hubble's usefulness and the launch of the James Webb Space Telescope could pose problems for astronomers.

"If there was any new discovery (in astronomy), we wouldn't have a space telescope to view it," Rieke said. "It is definitely a science opportunity that would be missed."

Rieke said NASA announced it would provide funding to astronomers for archival studies of unused data from Hubble.

"NASA said it would fill the gap (between the two space telescopes)," Rieke said.

Thompson said the time span could be more than a few years, noting how Hubble was delayed from anticipated launch in 1984 to its deployment in 1997.

Thompson estimates 30 to 40 UA faculty members work on Hubble research projects. Many undergraduate students and graduates also study the data gathered with the telescope.

Hubble's fate is not sealed, however, because it is possible for members of Congress to add funding for a planned servicing mission back into the budget, Thompson said.

According to CNN, in 1973, President Nixon zeroed out funding for Hubble while it was in the development phase. Congress restored funding for the project into the budget.

A NASA representative was unavailable for comment.