Must useful spacecraft be silenced?

March 2 was the tenth anniversary for Pioneer 10, the first spacecraft to pass close by Jupiter. As the official announcement notes, it ''has traversed the asteroid belt, survived Jupiter's punishing radiation belts, and operated almost without flaw'' alone in space for a decade.

Now one wonders if it can survive pinch-penny budget cuts.

Pioneer 10 and its twin Pioneer 11 are slated to be turned off under the fiscal 1983 budget for the US National Aeronautics and Space Administration (NASA). So too is the Venus Orbiter spacecraft that still is returning valuable data from that cloud-shrouded planet.

US planetary scientists say they are appalled. They are appealing to Congress to restore the relatively small amount of money needed to continue tracking the spacecraft and to process data--$40 million out of the $6.6 billion requested for NASA. The latter figure represents an 11 percent increase over NASA's fiscal 1982 budget. Yet the administration can't find the money to keep the dividends coming in from the many hundreds of millions of dollars and more than a decade of effort already invested in some highly successful spacecraft.

These craft continue to provide important information. The Venus Orbiter, which has made the first radar maps of Venus's surface, is sending data needed to further understand that planet. The spacecraft is in good condition. It has been expected to go on observing Venus fruitfully through 1992. Among other benefits, it is well placed to monitor Halley's comet when this swings by the sun in 1986. Having been forced to abandon hopes of sending a probe to that comet, US space scientists now may be further disappointed by loss of this secondary opportunity to study it from space.

Loss of Pioneer 10 would be felt even more keenly. Part of its extended mission, and that of Pioneer 11, is to gather the first data ever taken about the outer reaches of the solar system. Scientists are especially interested in the zone where the sun's sphere of influence gives way to interstellar space.

Pioneer 10 now is in the midst of this phase of its mission. It is performing well. Space scientists await its findings ''with intense excitement,'' says veteran solar system explorer James A. Van Allen of the University of Iowa.

Here, then, is a great national resource--indeed, a resource of all humanity--that is threatened with extinction before all the benefits are harvested. Once turned off, those spacecraft cannot later be turned back on. They will be lost forever.

That would be a foolish thing to do merely for the sake of a minor budget trim. Congress should take a hard look at the details of NASA's budget. The damage done by seemingly small cuts here and there could be out of all proportion to the money saved.