After nearly 11 days, the crew of the Discovery orbiter undocked this morning from the International Space Station, leaving the ISS a better place than they found it.
At 5:32 am EST, Pilot George Zamka backed the orbiter about 400 feet from the ISS and performed a fly-around to allow crew members to collect imagery of the station in its new configuration, according to NASA. That configuration includes the newly attached Harmony portal and a newly deployed solar power array. Both were primary tasks of the complicated
The STS-120 crew already had a challenging agenda on its hands when it docked with the space station on 25 October. They were scheduled to: load the 16-ton Harmony utility hub; connect the P6 portside truss segment and extend its solar-cell wing; examine a malfunctioning starboard solar-panel rotary joint; deliver Mission Specialist Daniel Tani, the newest ISS crew member, and pick up his returning counterpart, Flight Engineer Clayton Anderson; and perform an experiment in space to test damage repair techniques on the shuttle's exterior. They were initially tasked with making five spacewalks over nine days to accomplish the technical chores.
However, the schedule began to unravel on Sunday, 28 October, when Tani opened the housing of the starboard Solar Alpha Rotary Joint and found metallic debris adhering to it (see our previous entry "Spacewalkers Carry On Despite New Glitch"). That's when things got a little dicey. In order to investigate the problem with the rotary joint, which keeps the starboard solar wings oriented toward the sun, NASA managers re-jiggered STS-120's priorities. The mission was extended a day, the spacewalks were reduced from five to four, the shuttle repair experiment was scrapped, and emphasis was placed on the demands of the port and starboard solar array work.
That's when the next shoe dropped. While deploying the P6 4B solar array, the material holding the delicate solar cells snagged on a guide wire and ripped in two spots, forcing ground controllers to halt the maneuver in place in order to come up with a workaround (see our previous entry "Space Station Woes Affect Shuttle Schedule"). Yesterday, Mission Specialist Scott E. Parazynski performed a daring spacewalk to repair the damaged but electrically active solar wing (which took him further from a spacecraft than anyone had ever attempted).
With the portside solar wing repaired and deployed and the starboard rotator joint further examined (with debris samples collected for analysis), NASA administrators decided the crew of STS-120 had done enough to chalk up a resoundingly successful mission and gave them the green light to head home. They are now scheduled to attempt to land at Cape Canaveral on Wednesday afternoon.
This flight to the ISS was initially publicized as an historic meeting between the first two spacecraft commanders who happen to be women, Commander Pamela A. Melroy and Commander Peggy Whitson, skippers of the shuttle and station, respectively (see our recent entry "Women Set to Take Charge of Space"). The circumstances that soon arose, however, changed the focus of the storyline to one in which astronauts and cosmonauts had to exercise quick thinking, imagination, and courage to solve problems on the fly to save the day.
It didn't matter what gender they were in the end. Both crews exhibited the "right stuff" when the going got tough, following in a long tradition. Congratulations are due to both teams.