The shuttle Atlantis was formally cleared Wednesday for blastoff April 5 on a flight featuring the launch of a new astronomy satellite and the first American spacewalk in more than five years.

Space agency managers reviewed the status of Atlantis' launch processing during a flight readiness review at the Kennedy Space Center Tuesday and Wednesday and found no problems that would prevent a liftoff one week from Friday at 9:18 a.m. EST."The launch team has done a super job getting us ready to fly," shuttle program director Robert Crippen said in a statement.

Atlantis' countdown is scheduled to begin at 5:30 a.m. Tuesday with the ship's four-man, one-woman crew expected to arrive at the Kennedy Space Center later in the day for final preparations. The $2 billion orbiter will be fueled for launch starting at 12:58 a.m. next Friday.

The goal of the 39th shuttle mission, the first of six planned for 1991, is the launch of the $617 million Gamma Ray Observatory, the second in a series of advanced astronomy satellites expected to revolutionize humanity's knowledge of the universe.

The day after the satellite's deployment, astronauts Jerry Ross and Jay Apt plan to conduct the first post-Challenger U.S. spacewalk, a six-hour excursion in Atlantis' payload bay to test space station construction techniques.