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. |
Griffin and
other top NASA officials are expected
to announce their Hubble decision in a 10:00 a.m. EST (1500 GMT) press
conference at the agency's Goddard Space Flight Center in Greenbelt, Maryland.
If positive, a second briefing featuring the astronaut crew to actually perform
the Hubble-bound mission in 2008 will begin at 12:45 p.m. EST (1745 GMT). [Click
here
to watch the press conference live on SPACE.com's NASA TV feed.]
"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.
"This is an
incredible moment," said Livio, who has been involved with Hubble since 1991
and bore witness to the telescope's successes and trials. "I have gone through
all of the rollercoaster ride, from the initial drama when the mirror was not
working as expected to now, with this very exciting possibility of the
telescope be able to work another five years if not more."
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.
Vital
eye in the sky
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:
Podcast:
Hubble:
The First Great Space Observatory
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