Still useful

The problem is funding.

As we’ve mentioned, last month our astronomer attended the winter meeting of the American Astronomical Society.  One of his observations has to do with older (and normally smaller) telescopes.

In a very real sense, telescopes don’t wear out.  Lenses ground two centuries ago still focus light.  The mountings don’t spin fast enough to wear out bearings the way motors or pumps do.  There’s the normal housekeeping maintenance, of course, which is not negligible (as any homeowner knows).  But the main cost of professional telescopes is in their operation: power and other utilities, and especially the people who take care of them.

They can become obsolescent.  The large refractors built for visual observing in the nineteenth century were less than ideal for photography, though many found a niche in the new techniques.  The telescopes sited in the 1950s-70s in the new observatories at Kitt Peak and Cerro Tololo were controlled by analog electronics and designed for glass-plate photography.  However, they were brought into the digital age in control and detectors at a relatively small cost.  They are now much more capable than when they were first built.

But they are no longer cutting-edge.  In the age of eight- and ten-meter mirrors, a 1.5 or 2.1 seemed puny; and indeed there is much that the larger telescopes can do that is just beyond any reasonable effort for the smaller ones.  Ever larger and more sophisticated installations have been the norm for a long time, as the older questions get answered and the new ones get more difficult.  The catch is that the big new telescope (or satellite) is also much more expensive to build, and the budget is finite.  So the operating expenses of the smaller telescopes were redirected to the building of bigger ones.  It is no use pointing out that the budget for operations of yesterday’s telescopes amounts to no more than a rounding error in the construction estimates for tomorrow’s.  When the funding agency goes to Congress to ask for an increase to cover overruns, it has to be able to say it has made all the cuts it possibly can.

[There will always be cost overruns when trying to build something that’s never been built before, using technology that doesn’t yet exist.  We don’t intend disparaging comments on high-technology program management.]

So should we just get rid of these installations as just relicts of the past, kept on so far for sentimental reasons only?  Well, they’re much more than that.  They continue to turn out good science, and more astronomers want to use them than there is time for.  Two particular reasons come to mind, one of them emphasized at the AAS meeting.

Calibration is the bugbear of precise measurement.  Comparing images or spectra taken by different telescopes with different instruments at different times, there is a myriad of reasons why the changes you see are artifacts and not in the star at all.  So you want to use the same setup all the time if possible.  Here is an example: the lowly 0.9m at Cerro Tololo, kept in the same configuration over the years, has measured the orbit of a close double star.  The orbit lasts (if we recall) nearly a century, so one needs measurements over decades.  The 0.9m has provided them.

And the sky is a big place.  There are many more things to watch than the cutting-edge telescopes can possibly cover.

Many of the smaller telescopes have scraped by on various combinations of private funding.  May they long continue.