It begins to look as if something greater than the lone space shuttle Challenger exploded devastatingly over the Atlantic. The intervening two weeks offer evidence that America's space agency is also in danger of disintegration.

At the least, potentially irreparable harm is being done to public confidence in that crucially important U.S. institution -- a fact that the National Aeronautics and Space Administration belatedly has recognized with yesterday's decision to make available previously withheld internal documents.

Still, day by day, news headline by news headline, leak by leak, the portrait of NASA emerging is of a once-proud agency rudderless, uncertain, torn by dissension and low morale.

Damaging disclosures have accumulated daily in the newspapers and over television. They tell of safety problems, raise questions of structural soundness, recount old memos warning of potential catastrophes, cite contradictory accounts of actions taken and contain reports of internal stresses, political pressures and the toll of fatigue on personnel.

All these float to the surface of the nation's consciousness in the form of anonymous sources from people still within NASA, from past and present consultants who worked on various aspects of the shuttle program and from people who once played key roles in the space program. Taken together, the collective impression being created in the public mind is of possible negligence.

Until yesterday's turnabout, NASA allowed itself to be wounded by the way it responded publicly to its greatest crisis. The agency that for years provided the government's most glowing example of successful public relations, a model of how best to win public support and thus funds, appeared to have adopted a policy of stonewalling the press. It even left the impression of not being entirely forthcoming with the presidential commission investigating the shuttle disaster -- another point it now attempts to remedy.

A friend of long standing, of intimate acquaintance with the space program at highest levels over many years as an official, was talking about NASA's performance in the wake of the tragedy, and remarked sadly:

"They have not handled it well. Houston's not talking to Huntsville and Huntsville's not talking to the Cape and none of the three is talking to Washington. No one's pulling it together. And now you have NASA's own investigation being investigated by the president's commission. Now they're in the process of wanting to find a culprit, a scapegoat. They're searching for someone to accuse. What that does is breed dissent and distrust. And it does two other things. One is it develops a cover-up, cover-your-ass mentality. The other is it encourages reckless disclosure. Neither one is at all helpful. I think it's safe to say NASA will never be the same."

Witnessing a great institution in distress is always unpleasant. That's especially so with NASA at this critical moment in its history. The Challenger explosion came amid increasing numbers of long-term questions about NASA's future mission -- and increasing economic competition from Europeans and the Pentagon.

Just a year ago this week, Ronald Reagan's fourth State of the Union address gave NASA an immense boost with his ringing pledge to accelerate the shuttle program and build a space station.

"Our Second American Revolution," he said then, "will push on to new possibilities not only on Earth, but in the next frontier of space. Despite budget restraints, we will seek record funding for research and development. We have seen the success of the space shuttle. Now we are going to develop a permanently manned space station, and new opportunities for free enterprise . . . . "

Then came the crushing blow to agency morale when NASA Administrator James M. Beggs went on leave after being indicted on charges of manipulating Pentagon contract funds when he was at General Dynamics Corp. His replacement, acting administrator William R. Graham, was not well-known either to the public or inside NASA and he did not have a space program background. All this was prelude to the flight of Challenger bearing the first of what were to be many outside civilians in space.

None of this means NASA cannot recover. It does mean that both it and the presidential commission chaired by the distinguished public servant William P. Rogers have an immense and delicate job of repairing damage to a space agency that for a generation has been the nation's proudest symbol of U.S. technological genius and success.