VENUS, the cloud-shrouded planet, has lost much of its tantalizing mystery. Magellan spacecraft radar has penetrated that cloudy veil to produce a more detailed view of the Venusian surface than we have of the surface of Earth, given the paucity of data about the sea bottom. Completion of Magellan's first global survey of Venus - and hence of its primary mission - is a scientific and technological triumph. Once again, planetary textbooks will be rewritten as our on-site knowledge of the solar system expands. Once again, the spacecraft managers and engineers at the NASA Jet Propulsion Laboratory in Pasadena, Calif., have shown they have the "right stuff" to pull off a technically demanding feat.
Magellan has an on-board fault-protection system that is almost as complex as the spacecraft as a whole. This system can automatically diagnose faults and take corrective action or call for help from Earth. This has enabled the Magellan team to deal routinely with engineering problems, such as intermittent loss of radio contact, that would have caused a less capable spacecraft to fail.
Certainly the United States can be proud of this achievement. Yet this latest planetary success also underscores the critical question with which the country continues to wrestle - what does it really want to do in space? Should it continue to invest a major share of its space-program resources in manned space flight projects, such as the space station Freedom? Would it be wiser to reorder priorities to emphasize unmanned programs, where the space effort has succeeded so brilliantly?
This question has remained undecided for over a decade. Congressional ambivalence has forced repeated delays, redesigns, and cutbacks in the space station effort to the point where many knowledgeable critics seriously doubt the value of the present scaled-down design. Moves in Congress to sharply cut or even eliminate space station funds in the fiscal 1992 budget alarm the program's international partners. Europe and Japan again wonder whether the United States can be a reliable partner in an expensive u
ndertaking to which they have already committed substantial resources.
The United States space program cannot continue to build a record of achievement in a climate of chronic indecision. Congress and the administration have a responsibility to agree decisively on a space program that will be sustained and adequately funded without an annual budget crisis. If this means sharply curtailing manned space flight ambitions, so be it.
Meanwhile, we can all enjoy this month's planetary spectacle from the new space-age perspective. Venus and Mars are passing Jupiter in the western evening sky. When they form a tight triangle June 15 with the crescent moon standing close by, we can visualize what those celestial bodies look like at close range and remember that humans have even walked on the moon.