Satellite repairmen complete their first service call
Space shuttle astronauts have a new motto - ''We pick up, repair, and deliver.'' That word from the spaceship Challenger just about sums up one of the most successful missions the United States shuttle team has yet fulfilled.
A rejuvenated Solar Maximum Mission observatory is back on orbit, circling Earth at a distance of 308 miles. As of this writing, its controllers at the Goddard Space Flight Center in Greenbelt, Md., were reporting ''zero rates (no spin or tumble) on the spacecraft.'' As relayed by Mission Control here, they also said that ''Solar Max is dead on the sun - precisely pointed, that is.''
Now Goddard controllers will be checking out the observatory methodically, probably for several weeks. But as of now, Solar Max seems to be healthy.
The repairs carried out Wednesday appear to have given the observatory a new life expectancy of two years. It could very likely function for another two years beyond that, according to Frank Cepollina, Goddard project manager for the repair mission. Thus the observatory may be serving solar astronomers at least through 1988.
Also, Mr. Cepollina notes that because of the shuttle's now-demonstrated capacity to repair the satellite and boost it to a higher orbit, Solar Max might remain operational perhaps through 1990 - if refurbishment were considered desirable. Such a reboost would be necessary, since drag on the satellite associated with powerful solar flares causes its orbit to decay slowly over time. Were Solar Max to drop to an orbit below about 230 miles' altitude, the drag of Earth's tenuous outer atmosphere would become important and would quickly bring the satellite down.
With their mission objectives accomplished, the astronauts, at this writing, were preparing for their planned landing at Cape Canaveral Friday morning at 7: 07 Eastern standard time.
They have the option of going into Edwards Air Force Base in California if weather at the cape is unfavorable. Also, they can spend an extra day on orbit and land on Saturday, if necessary.
Meanwhile, here at the Johnson Space Center, Cepollina says he is ''absolutely ecstatic'' with the Solar Max repair operation. Wednesday's marathon work session by astronauts George (Pinky) Nelson and James (Ox) van Hoften have given him and the rest of the Goddard Solar Max team everything they had wanted.
And, he adds, mission commander Robert Crippen was able to deliver the ''third order'' objective of testing the shuttle's capability to reboost a satellite.
Although it was by no means a requirement for mission success, the test was quite helpful, Cepollina explains. Challenger was to have boosted Solar Max 15 miles higher. The shuttle lacked the maneuvering propellant for that.
But Astronaut Crippen was able to spare enough propellant for four brief engine pulses. This gave the Goddard team engineering data on the effect of such a maneuver on the combination of shuttle with a satellite hanging on the manipulator arm - data that will help in designing future satellites to take advantage of shuttle reboost. Also, Crippen was able to trim the Solar Max orbit to make it almost perfectly circular at a height of about 308 miles. Cepollina calls that a bonus which will improve Solar Max's performance.
Thus, when Solar Max was released from the shuttle's arm at 4 hours, 26 minutes, 32 seconds Thursday morning, Crippen felt amply justified in declaring: ''Satellite servicing is here to stay.''
Later, during an orbit-to-ground press conference, the astronauts stressed that they considered the key to their success to have been ''practice, practice, practice.'' Astronaut van Hoften said this was behind the apparent ease with which they carried out the Solar Max repairs. The generally good condition of the satellite also helped. He said that when they went to work on it, ''Everything looked like it was brand new. . . . (It was) easy to take apart.''
While running through the busy work schedule for the repair, van Hoften had noted that they had ''learned something from the bees'' on board Challenger. He reported that the bees had indeed been busy. The honeycomb they had been building had grown to extend about halfway across the transparent lid of their container. They appeared healthy, with only about 20 dead bees among them.
Thus the nonhuman astronauts also seem to be making a habit of success.