And a scientist's plea from the heart.

To the Editor: It is true that out of every $100 the US spends, the planetary program costs three cents. The result of this 0.03 percent investment, however, is supporting a great deal more than its share of our present US economy with such offshoots as communication satellites, image processing of satellite data (weather photos, lake pollution, crop growth, mineral and coal deposits, for example), a vast computer, calculator, and microelectronics industry, and the whole solar voltaics industry, to name but a few. Some of the top industries in the US today are direct space science spinoffs.

Most of today's great technological breakthroughs have come from the space program, and the present satellite surveillance, jet propulsion, computer missile monitoring and so on that give our country its present military edge are results of military applications of basic space science developed technology. And these are but some of the offshoots of trying to learn how worlds work - ours included.

We must watch our level of man-made CO2 pollution, the Venusian atmosphere has taught us. And the ozone layer must be kept intact or the ultraviolet rays from the sun will kill off our plant life, as arid Mars attests. What amazing insights into our own hurricanes and tornadoes, and what causes them, have been gained by studying them in the atmospheres of Jupiter and Saturn. One need only mention the earthquake-like faults on Jupiter's moon Ganymede and Saturn's Enceladus, and the volcanoes on Jupiter's moon Io to indicate how much our knowledge of such things has grown toward understanding, predicting, and some day perhaps preventing such uncontrolled forces on Earth.

And how vital is our understanding of the Sun, the source of all energy on Earth, if we are to solve an ''energy crisis.'' Finally, the prestige of the US is never more enhanced, (not with military might nor with economic clout), than when we demonstrate what freedom means by overcoming the confines of Earth for the peaceful purpose of discovering knowledge of our place in the universe for all mankind.

Thus you see I feel a great injustice is being done, to the vital scientific community in the immediate place, but to the entire US population in the very near run, by the present annihilation of what amounts to the space exploration part of NASA. The planetary program has sacrificed many years worth of funding and development time to get the space shuttle built - the promised source for much cheaper planetary probe launches among other things. Now that it is built, such planetary projects are being cancelled outright, virtually reducing NASA, (if this trend continues), to a mostly military orbital trucking service.

To put things in perspective, it may be helpful, for example, to point out that the cancelled US Halley's comet mission would have cost the US a little less than nine hours worth of its yearly military or welfare budget. And yet we are far better protected, far better fed, and I dare say, far more inspired as a people for such explorations.

The history of mankind's civilization and enlightenment is directly linked to (its) searching and growing awareness of (its) environment. I believe this pioneering spirit, a prime essential in the history of our country, is still undying in the hearts of our people. It is of essential importance now for them to let their government know.

Laurance Reeve DoyleSpace Image Processing GroupNASA Jet Propulsion Laborator