Humbled by a last-second launch failure June 26, the National Aeronautics and Space Administration (NASA) now wants to show what the space shuttle Discovery can do.
It is preparing for a second attempt to launch Discovery's maiden flight at 8 :35 a.m. Eastern daylight time Aug. 29. To get the shuttle program back on schedule, the flight plan combines objectives of both the original mission and a second mission that had been scheduled for August.
Also, assuming the success of this maiden flight, the shuttle team is preparing to send Discovery on a mission to recover one or both of the two communications satellites that were stranded in useless orbits when their booster rockets malfunctioned last February.
Success with these ambitious missions would help brighten the shuttle's somewhat tarnished image as a reliable way to launch and service satellites.
The spectacular retrieval and repair of the Solar Maximum Mission Satellite in April has been overshadowed by the delay due to the June 26 abort and the stranding of the communications satellites. Now NASA officials hope to use those setbacks as opportunities to demonstrate the flexibility and effectiveness of the shuttle.
On June 26, the launch was aborted four seconds before liftoff, when a fuel valve in one of the three main shuttle engines operated improperly. Although test engineers have not been able to duplicate the failure, flight director Randy Stone has said it probably was due to contamination in the hydraulic system that opens the valve.
NASA officials also note that the abort demonstrated the inherent safety of the shuttle system. Jesse W. Moore, NASA associate administrator for space flight, has explained that ''we are able to control the launch process down to the last split seconds, to launch when everything is right, and to stop without danger to crew, ship, or cargo when something is wrong.''
Although Mr. Moore didn't say so, NASA officials would like to leave the impression that this kind of flexibility might not be available with unmanned throwaway launch rockets such as the shuttle's competitor, the European Ariane.
Now the shuttle team wants also to show that it can get its overall satellite delivery manifest back on schedule. On Aug. 29, Discovery is to carry the Hughes Aircraft/Navy Leasat satellite, a biochemical processing experiment, and a large-scale experimental solar-cell array from its June payload.
Two other satellites - for Satellite Business Systems and the American Telephone & Telegraph Company - scheduled for August launching have been added.
Mission commander Henry Hartsfield, pilot Michael Coats, and mission specialists Judy Resnik, Steven Hawley, Richard Mullane, and Charles Walker told a press conference last Friday that they are well trained and ready for this demanding double-mission workload.
Meanwhile, another shuttle crew led by astronaut Frederick H. Hauck is preparing for the even more ambitious mission to rescue one or both stranded satellites.
Last February, the shuttle Challenger successfully deployed Indonesia's Palapa B-2 and Western Union's Westar 6 communications satellites. These were to have been boosted to a circular orbit 22,300 miles high. But due to booster rocket failures, they entered elliptical orbits whose high and low points respectively are 661 by 639 miles and 666 by 649 miles.
For shuttle retrieval, controllers would use maneuvering jets on these satellites to bring them down to about 230 miles altitude.
As was done with the Solar Max retrieval, astronaut Hauck and shuttle pilot David M. Walker could then bring Discovery close enough for astronaut Joseph P. Allen to fly to the Palapa or Westar satellite using a jet-powered backpack. He would then attach a ''stinger'' rod to help the shuttle's mechanical arm grapple the satellite.
With astronaut Dale A. Gardner also working in space and mission specialist Anna L. Fisher operating the shuttle arm, a retrieved satellite would eventually be locked down on a payload pad in the Discovery's bay.
Insurance underwriters already have paid $75 million to Indonesia and $105 million to Western Union in compensation for the satellites' losses. Last Thursday NASA announced an agreement with the underwriters to recover Palapa B-2 . Negotiations for Westar 6 recovery were still under way at this writing.
NASA would charge $4.8 million to retrieve one satellite, or $5.5 million to pick up both of them. After paying this charge, plus refurbishment costs, insurance underwriters could resell the satellites, which originally cost $35 million each. It would be the first used-satellite transaction in history.
NASA officials would like very much to have that happen. It would demonstrate something else an unmanned launch rocket system cannot do - enable recovery and reuse of stranded satellites.