The Space Telescope will live several years longer than it appeared just a few months ago. NASA Administrator Michael Griffin’s announcement Tuesday of a fifth and final Hubble servicing mission brought cheers from scientists and ordinary citizens alike — essentially everyone who appreciates the fundamental science and stunning images Hubble has returned since its 1990 launch.
Here at Astronomy, everyone was bouncing off the walls (figuratively, of course) with excitement and anticipation at the pending May 2008 shuttle launch. When Griffin’s predecessor, Sean O’Keefe, canceled the fifth servicing mission in the wake of the February 2003 Columbia disaster, it looked like Hubble would die a slow death. Griffin took another look at the flight possibilities after the shuttle’s return to space. Three successful missions convinced Griffin that flying to Hubble posed no more than a minimal risk — which is all anyone involved in spaceflight can ask — so he gave it the go-ahead. (A second shuttle will be on the launch pad during the Hubble mission in case anything goes wrong.)
The most important aspects of the servicing mission concern maintenance. The orbiting observatory needs new batteries and gyroscopes to keep operating — Hubble would survive only another 2 to 3 years without them. In addition, astronauts will install a refurbished Fine Guidance Sensor and thermal blankets.
The more exciting aspects of the servicing mission are two new instruments: the Wide Field Camera 3 (WFC3) and the Cosmic Origins Spectrograph (COS). WFC3 will replace the current Wide Field Planetary Camera 2 (WFPC2), which has returned over 100,000 images since it was installed on the first servicing mission in 1993. WFC3 will be able to image more of the sky at much better resolution than WFPC2, and do it at ultraviolet, visual, and infrared wavelengths.
COS replaces the Corrective Optics Space Telescope Axial Replacement (COSTAR), the “eyeglasses” that allowed astronomers to compensate for the spherical aberration in Hubble’s primary mirror. All the instruments now contain their own corrective optics, so COSTAR no longer is necessary. COS will explore the large-scale structure of the universe some 30 times more efficiently than previous Hubble spectrographs.
You can hear more about Griffin’s decision and the upcoming mission on my podcast. And, as always, I’d love to hear your reactions to what promises to be another 5 years or more of exciting science from Hubble.