JUST before and after its launch into space on April 24, the Hubble Space Telescope (HST for short) was hailed as the answer to scientists' prayers; the best thing to come along since Galileo's telescope. It was going to probe to the edge of the universe and, with a bit of luck, possibly discover planets around other stars. These great expectations seemed confirmed when the first admittedly fuzzy pictures were released a month or so later with much fanfare. Soon after, however, NASA announced to universal consternation that the HST mirror was stricken with the optician's nightmare: spherical aberration. Worse, nothing could be done for the moment to fix it in orbit. Suddenly the HST was declared a ``techno-turkey,'' as Sen. Barbara Mikulski put it.
Since then, the situation has grown more confusing. A board of inquiry was set up, directors of important ground-based observatories claimed that their telescopes could do better, and the Europeans complained that their 15 percent contribution to the program had gone down the drain. NASA technicians flailed away at unsuccessful attempts to come to grips with the problem.
Then somebody, by chance, took a quick picture of a bright cluster of stars in the Magellanic Clouds. That image sent a new tidal wave through the system because it looked pretty good. In fact, a lot better than what one could achieve from the ground. Some sanity returned and NASA quickly established a largely successful program to take more useful pictures of the cosmos. Enthusiasm was so high that it prompted one NASA bigwig to declare that the HST was A-OK or soon would be.
But is it really? After all the hype, one could certainly be excused for wondering. Is the space telescope worth the time, effort, and cost needed to continue operating it, or should we just close it down and wait for the replacement parts to reach it in 3 to 4 years?
Here are some facts that might be useful to consider. What has really been lost is sensitivity not resolution, which is the ability to separate two or more objects from each other. This simply means that we can still resolve stars with the same accuracy as before provided they are bright enough. Nothing has changed here, and the HST can still do up to 10 times better in this regard than is possible from the ground. We have already started to resolve and understand the inner workings of a number of complex, relatively nearby objects which were just a blur from the ground.
That's the good news; the bad is that you have to pay a steep price for this advantage by sacrificing sensitivity. This means that we simply cannot reach as far into the universe as was originally expected. The loss here is real and painful and no amount of fiddling with the data or hocus-pocus with computers is going to get us out of this pickle.
It's particularly serious because many of the science programs that HST was specifically designed for depended on its ability to see individual objects in very distant galaxies - to establish the size of the universe or witness the birth of a galaxy, for example. It also means that HST almost certainly will not be able to discover planets around other stars beyond our own solar system. Those kinds of breathtaking results are not likely any time soon, unfortunately, or at least not until some of the current instruments are replaced in orbit in several years time.
Another important fact to keep in mind is that almost everything else on board is working flawlessly. This is a miracle by itself considering the complexity of the device. Even the much maligned main mirror has an exquisitely smooth surface, reflecting beautifully all the way from the deep ultraviolet to the infrared.
Support equipment like the solar arrays, batteries, tape recorders, and on-board computers are all performing as well or better than expected. This means that a lot of interesting and fundamentally new science can be accomplished with the HST, provided more time and care is taken to gather and analyze the data. To accomplish the task, scientists will need to reassess their projects and ruthlessly weed out the losers and concentrate the precious observing time on those few that are still worthwhile.
In summary, the experience of taking the first images of the cosmos with the HST is bittersweet, in some respects. We look at these images and marvel at the natural phenomena that appear for the first time on the screen at the control center. But the initial warm feeling is quickly replaced by the urge to imagine what that image could have revealed had the mirror not been flawed.
It is heartbreaking in this respect for the thousands of people who have put in so many years of work on HST, but it is certainly not as bad as it has been depicted. I am certain this conclusion will be shared by more people as the results begin to trickle down. In many ways, this endeavor has been a tremendous success and we should not lose faith or patience in the slow process required to wring good science out of this otherwise magnificent undertaking.