Hubble Successor Takes Shape

NASA, in signing a contract last month with TRW Inc to build the next-generation space telescope, has taken a big step toward peering at objects that are around 400 times fainter than are visible with current ground- or space-based telescopes. The move means that, after months of “blackout” associated with the NASA selection process, research groups can start working with the engineers on integrating the science instruments into the spacecraft, says Peter Jakobsen of the European Space Agency, a partner in the new observatory. The telescope has been named the James Webb Space Telescope, after NASA’s second administrator, who served in the 1960s.

The JWST design calls for at least six times the light-collecting area of the 2.4-meter Hubble Space Telescope (HST) but the same 0.1-arcsecond resolution. “The original requirements were chosen to complement the capabilities of other telescopes, both existing and planned,” says John Mather, JWST project scientist at NASA’s Goddard Space Flight Center in Greenbelt, Maryland. In September, a JWST science working group was formed to construct a research program for the telescope. “New discoveries over the last few years do call for some updates to the proposed observing plan,” says Mather. The JWST will mainly study the early universe, giant extrasolar planets, supernovae, and supermassive black holes.

The competition for the $824.8 million contract came down to TRW and Lockheed Martin Corp, and industry observers were not surprised by the outcome. The contract, which NASA and TRW signed on 11 October, is for the design and construction of the observatory’s 6-meter primary mirror and spacecraft chassis. The JWST design has a primary mirror consisting of 36 semirigid hexagonal segments, similar to those used by the ground-based Keck telescopes, that will unfurl from the spacecraft once it reaches orbit. “I’m anxious to begin moving ahead on JWST,” says Marcia Rieke, a working group member from Steward Observatory in Tucson, Arizona. “I’m glad that a contractor has been finally selected.” TRW is responsible for integrating the module containing the three science instruments from the US and international partners—a near-infrared camera, a multiobject spectrometer, a mid-infrared camera and spectrometer—and the guider into the spacecraft, and for performing pre-flight testing and an in-orbit checkout of the observatory. The JWST, which, unlike the HST, is not designed to be serviced by astronauts, is scheduled to be launched in 2010. It will be positioned 1.5 million kilometers beyond Earth’s orbit at the second Lagrange Point (L2), where the gravity of the Sun and Earth cancel each other out. The L2 location will allow the JWST to be easily cooled to 30–50 K, as a single Sun shield can block light and heat from both the Sun and Earth. This will simplify the design of the spacecraft, which is expected to last 5–10 years.

The JWST is the first NASA observatory not named after a scientist or astronomer. “It is fitting that Hubble’s successor be named in honor of James Webb,” says current NASA Administrator Sean O’Keefe, who chose the name. “Indeed, [Webb] laid the foundations at NASA for one of the most successful periods of astronomical discovery.” Astronomers seem more resigned to the name change. “As a scientist, I would have preferred the telescope to be named after a very prominent scientist, but clearly Webb had major accomplishments,” says Mario Livio, head of the science division at the Space Telescope Science Institute in Baltimore, Maryland. “It is a change from tradition,” says working group member Simon Lilly of ETH Zürich in Switzerland. “But I have no particular problem with it myself. Europeans and Canadians may find it less easy to identify with a NASA administrator than with a prominent scientist, but in the end, it is a case of “he who pays the piper calls the tune.’ ”