SIRTF昨日已经成功发射。

Astro News Briefs
By the Editors of Sky & Telescope

Space Infrared Telescope Facility Finally Takes Flight
August 25, 2003 | After a four-month delay, the last of NASA's four "Great Observatories" lifted off from Cape Canaveral, Florida, early this morning. SIRTF, the Space Infrared Telescope Facility, will complement the Hubble Space Telescope and Chandra X-ray Observatory, providing longer-wavelength views of the cosmos. The infrared universe is especially rich for study, both because infrared light penetrates interstellar dust and because much of the light from the early universe has been redshifted deep into infrared wavelengths. The new telescope, set to be operational in about three months, will see back to the earliest galaxies and into dust cocoons where stars are forming.

The Delta II Heavy rocket intended to loft SIRTF last April was used instead used for Opportunity, the second of NASA's Mars Exploration Rovers, on July 7th. But within two weeks SIRTF's replacement rocket was set up on the pad. This launch was a little unusual in that the Delta's second stage will accompany the observatory into solar orbit instead of being left behind. Once clear of Earth the engine will fire to place SIRTF in an Earth-trailing solar orbit that drifts 15 million kilometers farther from home every year.

When it is situated, the spacecraft's solar-cell panels will also serve as a sunshade to protect the cryogenic vessel holding liquid helium for cooling SIRTF's detectors. Given this pointing constraint the telescope can view any target roughly perpendicular to the Sun-spacecraft line, with about 35 percent of the sky accessible at any one time. SIRTF is equipped with a 0.85-meter-wide Cassegrain telescope and carries three instruments: IRAC (a near-infrared camera), IRS (an infrared spectrograph), and MIPS (a far-infrared camera). Mission scientists expect to release the observatory's first images at the end of this year, at which time NASA plans to announce a new name for SIRTF.