In the days since the announcement of the cancellation of the last servicing mission to Hubble Space Telescope, I’ve been reading a number of pages and discussions about what can be done to help HST along in its last few years. I think that Steve Beckwith, director of the Space Telescope Science Institute, has written a fairly concise summation of the announcement and his thoughts on the issue. You can read it here.
The American Astronomical Society has had some discussion in its members’ email letters, and of course, the far-flung members of the observing community dependent on HST for their observations are quite concerned. Time and again the issue of using ground-based telescopes outfitted with adaptive optics is brought up, and while those are viable options, they do present limitations in terms of the field of view they can cover (along with other considerations). To put it bluntly, even if those are available all the time, when HST closes its lid for the last time and is de-orbited into the drink, optical astronomy will suffer limitations. Of course, historically it always has, but this past decade and a half since HST’s launch have been good years for space-based optical astronomy observations.
And, I would be remiss if I didn’t point out that adaptive optics-equipped facilities can and do outstrip some of HST’s gains in some observations. HST may well have been one of the driving forces behind the steady improvements in AO technology, so in some sense, its legacy is felt on the ground as well. (Not that it has been the only driver… not by a long shot… but in the days after spherical aberration was discovered in the HST mirror, people began looking for ways to improve images made lousy by any kind of distortion!) Astronomy is blessed with a good number of outstanding ground-based observatories that can and will bear increased observing loads.
I don’t want to lose sight of the fact that HST is good for a year or three more, and that its discoveries will keep researcher busy for decades, mining the data from its vast treasure trove of images and spectra. The disappointment at NASA’s announcement last week is fading, although I am still very suspicious of the political timing of the announcement, coming as it did in tandem with the administration’s unveiling “Bush Rogers” style missions to the Moon and Mars that I think have less than a snowball’s chance in hell of surviving serious scientific scrutiny. (But since when has science ever trumped politics?) Scientists will always make do with what they have, and when they do, their results stem from the kind of ingenuity I admire in science (and which is all too lacking in the political sphere of tax-cut and spend practices).
So, the question in front of the community now is, “How do we get the most out of HST and also extend its life as much as possible?” The issues are complex — some of HST’s most compelling observations do take a toll on its operations (particularly on the gyros, which help it slew around and hold position during observations). I think that with clever scheduling and maximization of resources, HST can be kept going for quite some time (or at least until its gyros fail, or some other component finally wears out). Of course, once its orbit decays (not an issue for a while yet), there will be little we can do to prevent it from re-entering the Earth’s atmosphere on the final descent). But until that time, astronomers are looking for ways to get the most out of a very productive observatory. And, I’m sure that as they do, the ground-based observatories will see increased use. It will be an interesting next few years!2
