A few years ago, the beginning of each new space probe brought many critical letters to my desk. But this year's shuttle program has provoked only one negative comment.

Sunday's long-delayed launch may have triggered some additional letters of criticism that have not yet had time to reach me. But thus far the only disapproving comment I have received has been from a correspondent who wrote:

"I do not understand how NASA could be going forward with its newest joyride to nowhere at a time when we are told that we cannot afford social programs aimed at alleviating human suffering.

"If we do not have enough money to care for the ill, the elderly, the poor or the hungry, why are there billions available to send all sorts of sophisticated vehicles into space?

"Why does Congress appropriate the huge sums that are being spent to satisfy somebody's curiosity about remote regions that are unfit for human habitation -- regions in which man did not belong in the first place?

"What good will it do us if John Young and Robert Crippen are successful? What purpose will it have served if they are not successful and lose their lives in a pointless venture?

"If the space program originally had some value, that era is behind us. The program has outlived its usefulness. We orbited the earth, we went to the moon, we studied Venus, Mars, Jupiter and Saturn. So what? What good did it do those of our people who must go without food because we fritter away our money on space ventures?"

An earnest protest, to be sure, but in my view not a logical protest.

I reject the notion that this country must choose between exploring space and helping those of its citizens who are hungry, ill or in need of similar assistance.

In fiscal 1981, Congress allocated less than 1 percent of our national budget to NASA, and NASA devoted only about one-third of its funds to the shuttle program. The shuttle cost less than $2 billion, out of a total national budget of $616 billion.

The sums spent on social programs during 1981 were many times those spent on the shuttle program, but I see no need for a detailed comparison. I will not waste my time discussing a "correct" ratio between expenditures for space exploration and expenditures for human needs because both budgets should be set at levels that are reasonable and prudent, not at levels that maintain an arbitrary and undeviating ratio.

This country is committed to doing whatever needs to be done for those who are unfortunate enough to require help. It has a commitment of another kind to foster science, invention and exploration. And it has the financial strength to do both. It is no more necessary for us to choose between space and human needs than it is to choose between Social Security and the navy.

One who questions the need to search out the truth about the universe in which he lives lacks more than intellectual curiosity. He lacks understanding of the practical value of science, research and exploration.

Those who see no value to exploring the unknown seem unaware that men would still be living in caves if they had not been curious -- and blessed with brains big enough to satisfy their curiosity.

Picture how our lives might have been changed if Columbus and Magellan had not been curious about what was over the horizon. Suppose Leonardo and Copernicus and Edison and Einstein hadn't been curious. Suppose Yuri Gagarin had been timid. Suppose lives and dollars had not been risked, and sometimes lost, to build skyscrapers and bridges and dams and railroads and spy satellites that can read the license tag on an auto in the Kremlin parking lot.

Suppose Lindbergh had seen no practical reason for flying the Atlantic on a "joyride to nowhere." Suppose the Eastern Airlines shuttle to New York leads to a no-reservations hourly shuttle to the moon some day. What makes you so sure it won't?

And suppose the Russians were the ones who thought it was worth risking lives and money to create a space shuttle, but we didn't. Suppose their spy satellites could read our license tags. Would that suit you better?

Ordinarily, I like to get a lot of mail on a subject of current interest. But this time I'm glad I received only one letter. It may be an indication that we are becoming more sophisticated about man's role on earth -- and in the universe.