With the long-expected announcement that former University of Utah President James C. Fletcher will step down as administrator of NASA, a major chapter in the history of space exploration is about to close.

Much of what the National Aeronautics and Space Administration is today, it owes to Fletcher, the father of the space shuttle program who during two terms has headed NASA for a total of nine years, longer than anyone else.During his first term from 1971 to 1977, Fletcher presided over the critical formative years of the shuttle program. After the Challenger disaster took the glamour off the space program, Fletcher returned to NASA and restored public confidence with his firm, unflappable style of administration and impeccable reputation as both a scientist and an executive.

As a result, NASA got money for a new shuttle to replace Challenger, completed a major management overhaul, kept the embattled space station alive and won congressional approval for an advanced solid-fuel rocket booster less susceptible to failure.

Even in retirement starting April 8, the 69-year-old Fletcher will still serve NASA. He is scheduled to begin an ambitious series of speeches across the country, emphasizing that the pool of human resources now available to NASA has dwindled because the space agency no longer has the appeal it enjoyed during the Apollo moon program.

A dynamic new leader at NASA could change that. What's needed in seeking a replacement for Fletcher is someone willing to fight hard on Capitol Hill for the space program's ambitious agenda, including a permanently manned space station by the end of the next decade.

The kind of replacement the White House picks for Fletcher will indicate how seriously the Bush administration takes space exploration.