Joint program for US-Soviet study of Mars is on the horizon

The red planet Mars, which now brightens the evening sky, also glows on the agenda of prospective Soviet-American space cooperation. ``It's a first step,'' declares William I. Purdy Jr., project manager for the Mars Observer mission at the NASA Jet Propulsion Laboratory. ``If there's going to be mutual cooperation in space,'' he explains, ``you've got to start some place. And some kind of interaction between [the two Mars programs] is kind of a natural.''

A formal arrangement for joint Mars research would be welcomed by the Martian science team at the Pasadena, Calif., facility, which is the main United States center for planetary exploration. Team members consider the US and Soviet Mars programs to be complementary rather than competitive.

Mr. Purdy outlined the possibility for Mars research cooperation during an interview in his JPL office last September. At that time, JPL director Lew Allen was in Moscow for secret discussions with Soviet space planners. Subsequent agreement, in principle, on space cooperation was worked out at the Iceland summit. This has cleared the way for US-Soviet talks in which some kind of joint Mars effort has high priority.

Interest centers on one American and two Soviet missions. In 1988, the Russians plan to send a craft to make a close-up study of Phobos, the largest of the two Martian moons. It will make only a limited and somewhat distant survey of the planet itself. Austria, Britain, France, and Sweden have joined several Eastern bloc countries as participants in this mission.

Later, during the first half of the next decade, the Soviets plan to send two spacecraft to make a more detailed study of Mars. Called Vesta, this project, as now discussed, would probably send balloons into the atmosphere and landers to the surface, as well as survey the surface from orbit. It also is to release a French comet/asteroid probe that will carry out an independent study of such objects.

Meanwhile, NASA should have launched the Mars Observer mission. It is to orbit the red planet for a full Martian year (two Earth years) to study Martian weather and climate. It will be an extensive close-in survey to complement the work of the earlier NASA Viking mission. That mission placed two landers on the Martian surface a decade ago. Purdy's team is preparing for a 1990 launch, although NASA's schedule now calls for it in 1992.

Purdy says it would be pretty easy for NASA and the Soviets to coordinate their Mars activities. That would primarily involve data exchanges. Right now, he explains, ``there isn't any forum for doing that kind of thing.'' But, he adds, ``there's still plenty of time to do something like that.'' Establishing a free-flowing mechanism for data exchanges would be an early payoff of Soviet-American space cooperation.

One effect of US-Soviet cooperation involving a planet mission could be to make NASA reconsider launching Mars Observer in 1990. Purdy and his team would like to stick with that time frame.

He explains that waiting until 1992 is not very appetizing. The Soviet Phobos mission would be history. Vesta might then overshadow Mars Observer. Also, it could be too late for Observer data to help Vesta planners.

In 1990, Purdy says, ``we have a mission that's every bit as attractive as their '88 mission. We're looking at different things. We're zeroing in on the planet itself.''