A member of the Presidential commission that investigated the 1986 Challenger disaster charged today that the National Aeronautics and Space Administration had tried to conceal details about the deaths of the seven crew members aboard the space shuttle.

''Of course there was a cover-up,'' said the commission member, Robert B. Hotz, former editor of Aviation Week and Space Technology. ''I believe they couldn't face the fact that they had to put these guys in a situation where they did not have adequate equipment to survive.''

Mr. Hotz, confirming statements attributed to him in The Miami Herald's Sunday magazine, said in an interview that he believed that at least some of the seven crew members were alive, though probably not conscious, when the crew compartment smashed into the Atlantic Ocean more than two minutes after the shuttle exploded.

Shirley Green, a spokeswoman for the space agency, denied Mr. Hotz's allegations of a cover-up. ''I don't know on what he could possibly base such a conclusion,'' she said. ''I think the evidence is very clear that the agency tried through a number of methods to get as honest an investigation as it could. We were straightforward with the public.'' Breathing Packs Activated