With one spacecraft successfully landed on Venus Feb. 28 and a second expected to land March 5, the Soviet Union is continuing exploration of the solar system at a time when the United States has all but dropped out of the field.
Indeed, the arrival at Venus of the Venera 13 and 14 spacecraft virtually coincides with a statement issued by the American Astronomical Society, which expresses deep concern for the future of US planetary science.
This statement notes that President Reagan's proposed budget for fiscal 1983 severely reduces the US planetary effort in the following ways:
* The US spacecraft now orbiting Venus, which has made the first radar maps of that planet's surface, would likely be turned off prematurely. It has been scheduled to return data through 1992.
* The Venus Orbiting Imaging Radar (VOIR) mission would be canceled. It has long been planned as a follow-up of the present Venus orbiter to make detailed surveys of the Venusian surface. This would leave the Galileo project to send a spacecraft to orbit Jupiter and a probe into the Jovian atmosphere as the only new US planetary mission. Even this project had been considered for cancellation in the budget preparations.
* The Voyager 2 spacecraft, which had been threatened with shutdown, will be kept alive as it heads for the planet Uranus. But Pioneer 10, which has just completed its 10th year in space, and Pioneer 11 will likely be shut down. This is in spite of the fact that these twin probes now are returning the first data ever gathered on the outer reaches of the solar system.
* The Lunar Curatorial Facility, which houses the rock samples brought back from the moon, would be closed. This would mean that even scientists with funds for lunar research projects would be denied access to the lunar samples.
In short, the statement notes, US planetary research (including lunar research) is being cut nearly in half compared with fiscal 1981 while mission operations (including data handling) are being cut by about two-thirds.
In contrast, the Soviet Union appears to be maintaining momentum in its planetary effort. Soviet space engineers have previously soft-landed six probes on Venus, something the US has never done. Among other things, Venera 9 and 10 took the only photos yet made of the Venus surface.
The newest landers, Venera 13 and 14, are the most sophisticated yet. They, too, may take surface photos. More important, however, they are believed to be equipped with drills that can sample the surface. Such samples would be brought inside the craft for analysis. This would open the field of Venusian mineralogy - direct analysis of the mineral content of Venusian surface materials.
Many US planetary scientists blame cuts in their programs on what they perceive as hostility toward planetary science on the part of the Reagan administration. The Astronomical Society statement attributed such hostility specifically to presidential science adviser George Keyworth.
Dr. Keyworth, however, has denied being hostile to planetary science. But he insists that the planetary program needs to be redefined with emphasis being placed on finding cheaper ways to carry out its explorations. As one indication of this, the National Aeronautics and Space Administration now is exploring ways to carry out a Venus radar mapping mission using a considerably less expensive spacecraft than had been planned for the VOIR project.