Johnson Space Center director Aaron Cohen has denied claims by former chief astronaut John Young that Young was bumped from the 1989 shuttle mission because of his age and removed as chief astronaut because of his public criticism of the space agency.

"Neither of those statements are valid, neither the age discrimination nor the outspokenness," Cohen said. "In fact, I want him to be outspoken. That's exactly why I put him where he is."Cohen said Young is even more outspoken now and voices his criticisms directly to Cohen. He said NASA has acted on "an awful lot" of Young's suggestions.

Young, 57, America's most experienced astronaut, told the Houston Chronicle he may never fly in space again after being bumped as commander of the 1989 mission. He also told the newspaper he is ready to quit if NASA no longer needs him.

"It depends on what happens around that place," he said. "If they don't want me, all they got to do is say that. I can't get straight answers from them."

Young talked with the Chronicle in a telephone interview from Cape Canaveral, Fla., where he was working last week.