As the critiques continue to roll in on NASA's failure to test adequately the optical system of the Hubble Space Telescope, there appears to be a growing inclination to question the space agency's (and even the nation's) ability to carry off large-scale engineering endeavors such as exploration of the Moon and Mars. This is the wrong conclusion to draw from an admittedly trying situation.

Doubtless the flaws that went undetected in the great observatory should have been discovered and corrected during the extensive development and testing that is an integral part of any engineering program. The inquiry now underway will help us learn how such errors can occur and, in the process, will add more skills to our management and engineering repertoire. That's what progress is all about: learning from our mistakes. Constant improvement of our ability to operate in space is, in fact, one of NASA's main tasks. We have made mistakes before and, no doubt, will make them again. But in doing so, we will create a truly space-faring civilization.

Does this mean we should try to make mistakes? Of course not. It does mean we should seek projects that at first appear to exceed our grasp but offer unequaled opportunities to learn. We have done exactly that in the Hubble program.

But have we not made such a grievous error this time that we are guilty of wasting millions of taxpayer dollars? By reading the press accounts of the Hubble situation, one could surely come to this conclusion. No doubt many intelligent taxpayers already have.

Again, the truth lies elsewhere. The Hubble program was planned with just such unforeseen happenings in mind. Hubble was designed and built to be served and maintained by Space Shuttle crews, and its instruments were designed -- and funded -- to be replaced as new technology evolved. U.S. capability to retrieve and/or repair spacecraft in orbit has been demonstrated several times with both scientific and commercial satellites. In planning for use of this new capability to maintain and upgrade the Hubble telescope, NASA managers were able to save considerable tax dollars by making the system simpler than it would need to be if on-orbit maintenance were not available.

Some ask why we didn't start with smaller, less complex space telescopes. That's easy to answer: we did. NASA began launching and operating space telescopes in the 1960s and has successfully operated more than a half-dozen since. Some scientists believe we have learned more about astronomy and astrophysics from these space-based instruments than from all ground-based observatories ever. But progress in science, as in all other endeavors, cannot be achieved simply by doing more of what we've already done. The Hubble telescope was conceived and designed to go beyond where smaller telescopes could take us. To do so, it had to be larger and more complex. But it was the proper "next step."

Because of NASA's careful planning we will, fortunately, be able to fix the Hubble telescope, and during its intended 15-year lifetime it will achieve almost all its objectives. More problems will almost certainly arise, as they do in any complex endeavor. We will deal with them, and we will continue to learn. That's precisely what good engineering is, and that's what NASA's job is.

Incidentally, we won't be wasting time while we wait for the telescope to be repaired. Experiments that don't require the finest focus will be done sooner, and scheduled early work will come later. True, some science we have waited centuries to accomplish must wait another few years. This is an understandably severe disappointment for some scientists but a stroke of luck for others whose work can begin now.

So should we have been more careful in the Hubble program? Of course. Should we have taken fewer risks? The answer remains to be seen, but when managing within budgetary limits, risks are inevitable. I suspect that in this case, the risks were probably well justified. Time will tell.

Finally, and perhaps most important: should we now shrink from adventurous and challenging projects because we are not perfect? Of course not. That would be precisely the wrong conclusion to draw from the "Hubble hubbub." We must take on challenges to help us grow, develop and evolve. Our engineering talent, as demonstrated by the Hubble situation, is clearly up to the job. Humanity's future lies in growth. Let's get on with it. The writer is vice president for public policy of the American Institute of Aeronautics and Astronautics.