The fate of the Hubble Space Telescope will be announced today by NASA chief Michael Griffin after months of debate over whether the payoff from one last shuttle mission to the orbital observatory is worth the risk to an astronaut crew.
"It's one of the greatest scientific instruments of all time," Griffin has said of Hubble. "It needs some refurbishment and repair. If we can do it safely, we want to do it."
NASA TV will broadcast today's Hubble decision at 10:00 a.m. EST. Click here.
"We're very hopeful that the decision will be positive," Mario Livio, a senior astronomer at the Space Telescope Science Institute (STScI) that oversees Hubble, told SPACE.com. "We will, of course, accept and respect the decision, whatever it is."
NASA officials initially canceled plans for one last Hubble servicing mission in 2004, a decision that prompted wide disapproval among scientists and the public. The space agency later discussed plans for a potential robotic mission to make necessary Hubble upgrades and repairs, but studies found the plan too costly and the agency later reverted back to an astronaut-crewed spaceflight.
A 2008 shuttle servicing mission would include five spacewalks to install a new camera, replace faulty attitude control gyroscopes, deliver a new spectrometer, make an unprecedented repair to another instrument and boost the telescope into a higher orbit.
Astronaut safety is key
NASA's greatest concern over a potential shuttle mission to Hubble is ensuring astronaut safety, especially given the 2003 loss of seven astronauts aboard the agency's Columbia orbiter.
"We have new constraints on the space shuttle," Griffin has said. "We have a new understanding of its fragility."
Investigators traced the Columbia accident to heat shield damage during launch, prompting NASA to modify its orbiter fuel tanks to shed less debris during flight, develop new in-flight inspection and repair tools, and ultimately create an emergency plan calling for shuttle astronauts to take refuge aboard the International Space Station (ISS) should their spacecraft suffer serious damage. Known as Contingency Shuttle Crew Support (CSCS), the emergency plan would keep shuttle astronauts aboard the ISS to be retrieved by a later rescue mission.
But an astronaut crew on a Hubble servicing mission would not be able to seek such refuge aboard the ISS in an emergency, and would likely require a second launch-ready shuttle and crew as safety net.
"We won't have CSCS and so we have to review our launch-on-need posture," Griffin said. "For Hubble, we're going to have to have a bird on the other pad.
"In the end it will be my decision, but it's [based on] input from all corners of the agency," Griffin said.
NASA has launched four shuttle missions to service Hubble since the observatory's April 1990 launch, first to repair a mirror defect and later to upgrade and maintain the space telescope. Left as is, Hubble could function through 2009-and maintain basic functions until 2011-but a servicing mission could add up to five years to space telescope's lifetime, NASA officials have said.
Hubble's mission results from a collaborative effort between NASA and the European Space Agency.
During its more than 16 years of observation, Hubble found the first evidence of an atmosphere around an extrasolar planet, aided in the search for dark energy and proven a vital tool in determining a clear age for the universe, astronomers said.
"I don't think there's a field in astronomy that it hasn't touched," said University of Texas astronomer J. Craig Wheeler, who serves as president of the American Astronomical Society (AAS) and has depended on Hubble for his studies of the supernova SN 1987A, in a telephone interview.
Wheeler said he is confident that today's decision will turn out to be positive for Hubble and its astronomical audience, if only because his colleagues continue to apply for research time on the telescope and NASA has put the servicing mission's astronaut crew on standby for a press conference later today. But despite those odds, Wheeler continues to hope for the best.
"I've got my fingers crossed," Wheeler said.
The Hubble story so far:
- NASA Cancels Shuttle Mission to Service Hubble
- Public Bombards Operators to Save Hubble
- NASA Chief: 'Let's Go Save the Hubble'
- Canadian Robot Top Choice for Hubble Servicing Mission
- Study: Hubble Robotic Repair Mission Too Costly
- NASA Prepares for Possible Shuttle Mission to Save Hubble
- NASA Review: Hubble Headed For Deorbit-Option Only
- Health Checkup: Engineers Work to Stall Hubble's Death
- Hubble Puzzle: How Safe is a Shuttle Servicing Mission?