Robots to rescue Hubble?

NASA weighs Hubble rescue options


By Frank Sietzen
United Press International


Washington, DC, Apr. 26 (UPI) -- A review of more than two dozen ideas
for robotic servicing of the Hubble Space Telescope has identified
several promising concepts that may be pursued by NASA before the end
of the year, the space agency's space chief scientist told United
Press International.

"Am I optimistic? Yes. Is it a done deal? No," said Ed Weiler, NASA
associate administrator for space science.

Weiler said that in response to an agency request for information, 26
proposals have been submitted on ways the telescope could be serviced
or de-orbited without the use of human crews.

The proposals have come "mostly from commercial companies," Weiler
added. NASA had asked for ideas to identify what technologies might be
available to use on a Hubble repair mission and what companies might
be interested in participating in such an effort.

On Jan. 16, NASA Administrator Sean O'Keefe announced that the agency
would no longer use the space shuttle fleet to service the telescope's
ailing systems due to safety issues.

Following the Feb. 1, 2003, shuttle Columbia accident, the board
investigating the disaster called for limiting shuttle flights to
those where the crew of a damaged craft could take refuge aboard the
International Space Station. Such contingencies would arise if a
shuttle's crew lacked a specific onboard repair capability or if
damages sustained during launch exceeded the crew's capacity to save
the spacecraft.

A shuttle flight to service Hubble would not be able to fly on to the
station in the event it was damaged and would have to rely exclusively
on onboard repair capacity.

O'Keefe decided that because any Hubble mission would lack the space
station refuge option, the increased risk to the crew outweighed the
value of the Hubble.

Without the shuttle, there appeared to be no other way to conduct the
repairs to the telescope, which confronted the astronomy community
with the grim possibility the Hubble could die of malfunction years
before before a replacement space telescope could be launched. But
that possibility has raised such a public outcry that O'Keefe relented
slightly on his initial decision and agreed to 1) convene a special
inquiry to evaluate the risks of and alternatives to a Hubble repair
mission and 2) ask the aerospace industry for ideas on other ways to
save, service or de-orbit the craft.

The National Academy of Sciences is studying both the decision to
cancel the shuttle servicing mission and possible robotic flights to
the telescope.

Weiler said even before the NAS study -- now set for summer -- is
completed, the chances for a robotic rescue will be increasing.
Failing a repair mission, he said, NASA is considering sending a
robotic craft to take control of the telescope and send it into fiery
atmospheric re-entry.

The 26 proposals included complete robotic mission scenarios as well
as "pieces of missions," Weiler said. In a sense, any rescue or return
mission is racing the clock, as Hubble's batteries slowly drain and
the craft's critical gyroscopes -- used to aim and hold the telescope
in position -- break down.

"They can last until the end of '07," Weiler said of the batteries.
After that, failure of the power system would send the telescope out
of control, making any robotic mission impossible.

Even the review by the national academies, due out this summer, might
be too late.

"We need to be ready to get (a request for proposals) in June," Weiler
said. "If we want a robotic mission in '07 or '08, we need to get
contracts out this fall."

Weiler also said a two-month study of the Hubble issue is underway at
the Goddard Spaceflight Center in Greenbelt, Md., as well as five or
six other NASA facilities. That in-house review also is looking at
robotic systems that could be flown to the telescope, he said.

Whatever is decided will be a tradeoff, Weiler suggested, between the
cost of such a mission and the value of the years that could be added
to Hubble's usefulness. He pointed out that no nation has ever
conducted a purely robotic servicing of a spacecraft.

Crews aboard space shuttles conducted satellite rescues in 1984 and
1985, and tested a satellite refueling concept in October 1984. But
the refueling technique was never used. Use of the shuttle as a
servicing system for commercial and civil satellites was canceled
following the January 1986 Challenger disaster.

Russia has conducted robotic docking of supply craft to the MIR and
International Space Station, but cosmonauts and astronauts aboard
always have been in final control of the tasks. Japan has tested a
small robotic docking spacecraft, but has developed it into an
operational system.

Thus, if NASA chooses a fully robotic mission to Hubble, it would
become another first for U.S. space technology.

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Frank Sietzen covers aerospace for UPI Science News. E-mail