Panel prods NASA to seek unknown planets.

Panel prods NASA to seek unknown planets

Beyond the solar system may lie other planets or planets aborning, and a scientific advisory panel recommends that NASA undertake "a major scientific effort" to find them.

In a report released last week, the National Research Council's Committee on Planetary and Lunar Exploration asserts that technology is "on the brink of major advances" that will allow scientists to determine over the next 10 to 30 years whether "extrasolar" planets with masses between those of Jupiter and Uranus are "common or very rare."

Committee chairman Larry W. Esposito of the University of Colorado in Boulder says work on the report began in 1984, prompted by ground-based observations that some scientists interpreted as evidence of a planet orbiting the star Van Biesbroeck 8 (SN:8/20/83, p.116) and by the discovery of a disk of small particles around a star called Beta Pictoris -- a finding that some thought might be associated with planet formation.

No one has confirmed the existence of Van Biesbroeck 8's planetary "companion." Astronomers have not detected any planet-like objects in the Beta Pictoris disk, nor have they confirmed the existence of planets orbiting any other star, Esposito says.

Yet intensive scrutiny just might turn up such phenomena. The panel recommends that NASA start a program to measure the motions of 100 or more nearby stars to see whether they wobble due to the masses of planets that might encircle them. The advisory committee also wants the agency to examine the spectra of these and other stars to see whether the wavelengths of any star's light are being "Doppler shifted" due to one or more orbiting planets.

For a better understanding of our own solar system's formation, the report urges NASA to emphasize studies of the materials from which planetary systems form, such as rare grains in primitive meteorites, interplanetary dust and comets. The committee also wants NASA to support a range of theoretical studies, with the aim of enabling scientists to make "specific predictions regarding the observational properties of planetary systems at all stages of their evolution."

The new report, spanning planetary science, astronomy and astrophysics, is "unlike any that the Space Science Board [the panel's parent group] has ever tried before," says Robert O. Pepin of the University of Minnesota in Minneapolis, former chairman of the committee.