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 1989 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 Sandra Faber, an astronomer at the University of California in 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," said a senior astronomer, speaking on the condition of anonymity.
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 US$600 million, said 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," Kinney said. "There is a lot of anxiety in the astronomical community about it. You have to listen to them."
Kinney has appointed a panel of scientists led by John Bahcall, an astrophysicist at the Institute of Advanced Study in Princeton, New Jersey, 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," 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 Barry Barish of the California Institute of Technology; Jacqueline Hewitt of the Massachusetts Institute of Technology; Christopher McKee and Charles Townes, both of the University of California at Berkeley; and Martin Rees of Cambridge University in England.
"They are my dream team," 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," Kinney said.
In an interview, 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.