Few telescopes in history have had such a profound effect on astronomical research as the Hubble Space Telescope. Yet its influence is not what most people think. By and large, it has not made singular discoveries--achievements that are its and its alone. Instead Hubble has taken what were hints and suspicions from ground-based observations and turned them into near certainties. It has worked in concert with other observatories to provide a multihued view of the cosmos. It has forced theorists to rethink broad-brush theories and to construct new ones that explain astronomical phenomena in much finer detail. In short, Hubble has been extremely influential not by standing apart from other instruments and techniques but mainly by becoming deeply integrated with them.

In April the telescope passed its 16th anniversary in space. Its achievements, both in providing astronomers with unprecedented detail and in bringing a glimpse of the wonders of the universe to homes worldwide, have been somewhat overshadowed of late by the debate over its future. As NASA struggles to resume space shuttle flights, Hubble continues to deteriorate; unless astronauts can reach and refurbish it, the telescope could reach the end of its useful life as early as mid-2008. Arrival at this crossroads has spurred me to take stock of Hubble's--and astronomy's--past decade and a half, which many -researchers consider a golden age of their field.