The space shuttle Challenger and its astronauts are back on Earth, but the work they began is not over. Besides the Solar Max observatory, now beginning a new life on orbit, they have left behind the massive long-duration exposure facility with its 57 experiments. This is to be recovered during a shuttle flight next February.
And there is the cargo of Solar Max parts, which engineers at the Goddard Space Flight Center in Greenbelt, Md., now will eagerly examine.
For the first time, they will be able to study satellite hardware that has been in space for four years - equipment whose unexpectedly early failure had crippled Solar Max.
Challenger brought this space treasure back to Earth Friday, touching down smoothly on the runway at Edwards Air Force Base, Calif., about 5 seconds past 8 :38 a.m. Eastern Standard Time.
Mission controllers had diverted the shuttle to California when lowering rain clouds ruined the weather at Cape Canaveral.
It was a last-minute decision that demonstrated the flexibility of the shuttle system, says Lt. Gen. James A. Abrahamson, speaking as associate administrator for space flight of the National Aeronautics and Space Administration (NASA).
General Abrahamson is leaving NASA to take the new post of director of strategic defense - i.e. head of President Reagan's ''star wars'' program - where he will report directly to the secretary of defense.
But for the post-landing press conference last Friday, his heart was still with NASA.
He was obviously proud of his agency, whose competence and grit had turned incipient failure of the Solar Max rescue into perhaps the shuttle team's greatest success to date.
This, he said, ''gives a great deal of confidence'' in the satellite recovery technique. It supports studies NASA has been making of how to recover the Westar VI and PALAPA-B2 communications satellites, owned respectively by Western Union and Indonesia. Rocket boosters on the two satellites failed after they were launched Feb. 3 from the shuttle.
It's up to the satellites' owners to decide whether to go after them, Abrahamson said. But, he added that he hoped they would make their decision ''with our success today in mind.''
Those failed payload-assist module (PAM) boosters are still a problem.
Because the PAM failures are not adequately understood, the shuttle Discoverer will not launch a TELESAT-1 communications satellite, as originally scheduled, during its maiden flight in June. Other subsequent launches of satellites that use the PAM system may also be postponed.
This is affecting the shuttle schedule for many months to come.
Abrahamson noted that this is indeed disappointing. But, he said, ''It isn't an end-of-the-world situation. We will recover. And it (the schedule) will be recovered by the end of the year.''
He explained that there is another, more ''conservative'' design for a booster that can be phased in if the PAM mystery is not quickly solved.
Abrahamson also said he expects that disrupted schedules can be reworked.
He explained that there is ''the kind of flexibility in the system'' that will let it recover from such dislocations.
Abrahamson's management - marked by unusually thorough attention to all aspects of the space flight program - is widely credited with making a basic contribution to the shuttle system's strength.
When he arrived at NASA in 1981, there was muttering about a military ''takeover.'' Now General ''Abe'' is leaving and there are many within the agency - and in the press corp that regularly covers it - who are sorry to see him go.
This feeling erupted spontaneously at the end of Friday's press conference.
Burton I. Edelson, associate administrator for space science and applications , thanked him for the ''warm spirit of cooperation'' he had established. NASA public affairs officer Hugh Harris praised him for the candid, informative way he handled sometimes difficult press relations.
Indeed, a special bond has grown up between ''Abe'' and the space reporters - a bond he acknowledged in his final remarks as a NASA official when he said:
''There was a reason that our forefathers had the wisdom to . . . ensure that , in fact, there is freedom of the press. It's an important institution. I have never felt - even though some of your questions sometimes are critical or perhaps you don't share the viewpoint that we have - that you don't have a legitimate and important reason for asking those questions. And, by the way, they're very, very helpful because they provide an objective viewpoint.''