Space shuttle Challenger's ''extremely successful'' six-day mission has shown that the United States manned space flight team is mastering the intricate shuttle system.
* A flawless night launch at 2:32 a.m. eastern daylight time Aug. 30, followed by the smooth night landing at 3:41 a.m. EDT Monday has given shuttle officials confidence they can schedule missions without concern about night or day.
* The complex shuttle machine itself is performing so well that shuttle flight now can be considered almost as routine as that of an airliner.
* The Tracking and Data Relay Satellite has shown that the TDRS system can provide extended - and eventually nearly continuous - communications.
* The Canadian-supplied remote manipulator arm easily handled a bulky 8,000 pound test object. Astronaut Dale Gardner said there should be no problem handling the much heavier load when the shuttle undertakes a satellite retrieval and repair mission next year.
* And, as Astronaut-Physician William Thornton found, so-called space sickness is ''a very transient thing and not the dreaded thing that people might talk about sometimes.'' He said he thinks it will be brought under control. He added that, as with a number of other medical concerns that had been raised, this too should ''become a problem of the past.'' He noted that even the six space rats on board coped well with their weightless condition.
Commenting on the progress represented by what he called this ''extremely successful'' eighth shuttle flight, Mission Commander Richard H. Truly recalled his experience on the second flight a year and a half ago. At that time, he said , ''we were worried about the safety of the vehicle, the thermal protection system (tiles), the engines, those kinds of things.'' Now, he added, ''we have graduated to a system that routinely is deploying satellites, meeting our committments to customers.''
A 24-minute press conference between the astronauts and reporters at the Johnson Space Center, Houston, illustrated this point. Astronaut Truly noted: ''This news conference is coming from space in the most complicated machine in the world . . . and it runs itself (while the conference was held).'' He added, ''We've made great strides and I think it's a great future for America in space.''
Flight Director Harold Draughon pointed out, also, that such a conference could not have been held without the TDRS communications relay satellite. Orbiting 22,300 miles high - well above the shuttle's 137-mile height - the TDRS can keep a shuttle in view for extended periods. Without this link, the shuttle would have passed in and out of contact with a ground station too quickly for such a lengthy conference to be held. Eventually, there should be two TDRS in orbit at a time. This should provide nearly continuous contact with shuttle crews.
Successful communication through the TDRS system augers well for the next mission also. As now scheduled, the shuttle Columbia is to carry the European-built Spacelab into orbit Oct. 28. Scientists working in Spacelab, and the many instruments carried, will be sending a massive data flow, which requires at least one TDRS.
Meanwhile, as has happened with every manned mission, the space flight experience has left a deep personal impression on the astronauts themselves - especially on Guion S. Bluford Jr., the first black American in orbit, and William Thornton, the oldest American so far to go into space.
Expressing his sense of awe at seeing Earth in a new perspective, Guy Bluford also acknowledged his leadership role. ''. . . this shows . . . that there are many other opportunities for other blacks to fly in space,'' he said.
Dr. Thornton, commenting on the question of age, said people should not count ''age'' by the calendar, but by the fitness of the individual. He said he sees no reason to bar heathly people from space just because of age.
Referring to what the flight has meant to him personally, Thornton called it ''a pretty humbling experience.'' He said it made him think ''that this may be the only spot that supports life in at least five light years and maybe more. . . . It is a very unique spot indeed, and I think one that deserves very careful assessment of our responsibilities to it.''