News: Hubble plans and policy

http://www.nytimes.com/2003/07/27/sc...27HUBB.html?hp
As Clock Ticks for Hubble, Some Plead for a Reprieve
By DENNIS OVERBYE


One astronomer compared it to the fate of the faithful dog in the movie "Old
Yeller." On Thursday, astronomers will crowd into a hotel ballroom in Washington
to discuss when and how NASA should put down one of its and astronomy's most
spectacular successes, the Hubble Space Telescope.

Since it was launched in 1990 with a flawed mirror and then repaired by
spacewalking astronauts, the Hubble, floating above the murky atmosphere, has
been a matchless time machine, providing astronomers with views of unprecedented
clarity deep into space and time. "The Hubble is the single most important
instrument ever made in astronomy," said Dr. Sandra Faber, an astronomer at the
University of California at Santa Cruz.

But its days (and nights) have always been numbered. NASA has long planned to
end Hubble's spectacular run and bring it down in 2010 to make way in the budget
for the James Webb Space Telescope, scheduled to be launched in 2011.

Still, some astronomers are urging that Hubble's life be extended. They argue
that the telescope has grown even more productive in its years in orbit, thanks
to periodic service calls by astronauts.

These astronomers say that killing Hubble in its prime makes little sense,
either scientifically or from the standpoint of public relations. "Hubble is by
far the best news NASA has now," a senior astronomer said.

An extension of Hubble's life, they say, will ensure that there is no gap in
coverage before the Webb telescope goes into operation, but it would require an
extra shuttle visit to Hubble late in the decade. That would cost at least $600
million, said Dr. Anne L. Kinney, director of astronomy and physics in NASA's
Office of Space Science, and the money would have to come at the expense of the
Webb telescope or some other project.

As a result, whatever NASA does is bound to make someone unhappy. "It's terribly
important," Dr. Kinney said. "There is a lot of anxiety in the astronomical
community about it. You have to listen to them."

Dr. Kinney has appointed a panel of scientists led by Dr. John Bahcall, an
astrophysicist at the Institute of Advanced Study in Princeton, N.J., to
evaluate NASA's plans for Hubble and to see if there is justification for a
change. "Our charge is to advise about how to maximize the science. We are going
to focus on just that task," Dr. Bahcall said.

He called the topic of Hubble's demise "a hot potato," adding, "But someone has
to do it."

The other members of the panel are Dr. Barry Barish of the California Institute
of Technology; Dr. Jacqueline Hewitt of the Massachusetts Institute of
Technology; Dr. Christopher McKee and Dr. Charles Townes, both of the University
of California at Berkeley; and Dr. Martin Rees of Cambridge University in
England.

"They are my dream team," Dr. Bahcall said. "We may catch hell for what we do,
but we will learn a lot while we do it."

The group has set up a Web site (hst-jwst-transition.hq.nasa.gov
/hst-jwst/home.cfm) on which astronomers can post their opinions and read a
growing assortment of policy and fact sheets. It is holding a public meeting at
the Loew's L'Enfant Plaza Hotel in Washington on Thursday.

"It's going to be high opera," Dr. Kinney said.

In an interview, Dr. Edward J. Weiler, NASA's associate administrator in charge
of the Office of Space Science, pointed out that the Hubble's mission had been
extended once. The telescope was originally designed to last 15 years and come
down in 2005.

The next and final astronaut visit to the telescope is scheduled for next year,
but might not happen until 2005 or even 2006, depending on when the shuttles
start flying again in the wake of the loss of the Columbia in February. On that
occasion the telescope will be fitted with two new instruments, and astronomers
say it should work well until the end of the decade.

The decision about what happens then has been complicated by the breakup of the
Columbia. The telescope is too big to leave to fall out of orbit and crash
uncontrollably to Earth on its own. NASA had originally planned to fetch it with
the space shuttle and put it in the Smithsonian's Air and Space Museum, but that
now seems "exceedingly unlikely," in Dr. Kinney's words.

Such a mission would take the shuttle into an orbit in which it could not
rendezvous with the space station if anything went wrong.

Instead NASA is studying the possibility that a robotic rocket could be sent to
attach itself to the telescope and ease it out of orbit safely into the ocean.
That would require developing new technology. If it seems feasible, Dr. Kinney
explained, astronauts could add attachments for the rocket to hook onto during
the upcoming service mission.

The telescope is in no imminent danger even if the next service mission is put
off indefinitely. It is now in an orbit about 350 miles high. How long it could
stay there depends on sunspot activity, which bloats the atmosphere, causing
drag on the telescope. Even under the worst circumstances, Hubble would not fall
until 2013, according to a NASA study. But with a series of small altitude
boosts supplied by the shuttle in 2005 and 2009, it could stay up until 2020 or
beyond.

Leading the charge for another extension are the astronomers of the Space
Telescope Science Institute on the Johns Hopkins campus in Baltimore.

In a policy statement full of statistics testifying to Hubble's dominance of
contemporary astronomy, Dr. Steven V. W. Beckwith, the director of the
institute, argued that as a result of the astronauts' service calls, Hubble had
essentially been reborn every few years, allowing it to stay on top of its game.

"A servicing mission to Hubble is comparable in science value to the launch of a
new satellite and should be judged as such," Dr. Beckwith wrote.

As a result, the number of scientific papers based on Hubble observations still
grows every year.

Dr. Beckwith argued that sending astronauts to fit the telescope with a
propulsion module would be less risky than trying to develop a robot. If such a
trip was necessary, he said, the marginal cost of fixing it up for a few more
years of science would be a bargain.

Dr. Kinney of NASA said the agency was merely following the wishes of the
astronomical community, as expressed in a recent report prepared under the
auspices of the National Academy of Sciences. That report listed what would
become the Webb telescope, designed to probe early cosmic history when galaxies
and stars were first forming, as the highest priority.

"We have to ask, what is the best research for the taxpayer's dollar?" she said.

Dr. Robert Kirshner of the Harvard-Smithsonian Center for Astrophysics said in
an e-mail message that he thought Hubble was working better than it ever had,
"so the equation has changed." He said it would not be easy to decide how best
to serve science.

Dr. Wendy Freedman, director of the Carnegie Observatories in Pasadena, Calif.,
said NASA was asking the right questions with the Bahcall committee. "At some
point, it makes sense to go on and do new things - the risks, budget and promise
of greater potential make this easy to determine," she said. "The question is,
is H.S.T. at this point? Or not?"

Dr. Faber of the University of California said she thought there was a lot of
support to keep Hubble going.

"Hubble is unique. Nothing else can do what it can do," she said. "Once it's
gone, we're going to be paralyzed. We've gotten hooked. We're addicted."