Solar system search from space station.

President Reagan's order of a year ago that NASA develop a permanently manned U.S. space station (SN: 2/4/84, p. 69) came only four months after a National Academy of Sciences panel has reported finding "no scientific need" for such a station "during the next 20 years" (SN: 9/24/83, p. 199). Some space researchers have feared that visible support might result in their field's being saddled with a disproportionate share of the station's multibillion-dollar cost, and proposals for scientific studies to be conducted from the facility have been relatively slow to emerge.

Last week, however, NASA and the University of Arizona signed a memorandum of understanding to pursue what Eugene Levy, director of the university's Lunar and Planetary Laboratory in Tucsn, calls "the most exciting scientific project that one could think of doing from this space station."

Its goal: the detection and study of planetary systems around other stars.

The plan calls for the development of an extremely accurate astrometric telescrope, designed to detect the presence of planets it cannot actually see but which would make their presence known by their gravitational effects on the motions of the stars they circle. The instrument, to be based on the design of one now in operation at the University of Pittsburgh's Allegheny Observatory, would be carried up by the space shuttle and installed on the station to operate for as long as 20 years. Above earth's atmosphere, says Levy, it could be capable of detecting planet-caused stellar "wobbles" as small as 0.00001 second of arc, and the long lifetime is needed because even a massive planet may have to circle its star completely to produce an observable effect. (Jupiter takes about 12 years to orbit the sun.) Such an instrument could be flown as an independent satellite, Levy admits, but it would then be necessary to provide all of a satellite's "housekeeping" functions, whereas the space station might already have them available. The station could also be a far easier way to deal with whatever servicing needs might show up during two decades in space.

Furthermore, Levy says, locating individual planets is not really the point. "The real question of intellectual substance," he says, is to find out whether planetary systems are a "general, natural consequence" of star formation.

The plan (if it gets funded) calls for the NASA Ames Reserach Center at Moffett Field, Calif., to manage the design, construction and deployment of the telescope, while the University of Arizona establishes control facilities on the ground and manages the observing program.