Washington

More than 200 leading astronomers crowded into a meeting room in Washington DC last week to grapple with a thorny dilemma: when, or even whether, to shut down the 13-year-old Hubble Space Telescope.

NASA wants to decommission Hubble in 2010, saving the money to prepare the larger and more capable James Webb Space Telescope (JWST) for launch in 2011 (see Nature 416, 112; 2002). But a growing number of astronomers think that would be a mistake. Riccardo Giacconi, a Nobel laureate and former director of the Space Telescope Science Institute in Baltimore, Maryland, warned that they “would look like fools” if they didn't keep the highly productive Hubble going at least until the JWST is launched.

So charged has the debate become that NASA has thrown the question over to a heavyweight panel of astronomers led by John Bahcall of the Institute for Advanced Study in Princeton, New Jersey. The panel will solicit views from astronomers and report to NASA in October.

NASA currently favours a last upgrade for Hubble in 2005, before attaching a rocket booster to the telescope in 2010 that would steer it to burn up over the ocean. A team at the agency's Marshall Space Flight Center in Huntsville, Alabama, is studying how to do this, with a report due at the end of this month. Many astronomers say it would add relatively little to the $700-million cost of the 2010 trip to prolong Hubble's life, and even add new instruments. The Marshall team considers this to be too difficult at present.

In an extraordinary gesture of support for Hubble, astronaut John Grunsfeld said that US astronauts opposed “risking human lives for the purpose of disabling great science”, but would support a mission to extend Hubble's life or ensure its safe re-entry.

But George Rieke, an astronomer at the University of Arizona who is building one of the JWST's instruments, said that it would be unwise to improve Hubble's ability to survey distant galaxies in the infrared when “we're building another instrument to do that even better”.

Giacconi, however, pointed to Hubble's unique ability to see across visible, ultraviolet and infrared wavelengths — something that the more sensitive JWST won't be able to match. Astronomers viewing in X-rays and γ-rays have come to rely on supporting observations from Hubble, he said.

John Huchra of the Harvard-Smithsonian Center for Astrophysics in Cambridge, Massachusetts, who chairs the Association of Universities for Research in Astronomy (AURA), called Hubble “the Energizer Bunny of astronomy”. He said that a poll of AURA members ranked continued space-based observations in visible and ultraviolet wavelengths as their highest priority.

→ http://hst-jwst-transition.hq.nasa.gov/hst-jwst