Live in orbit: NASA mulls extra day, inspections

3:37 P.M. EDT Update: NASA's Mission Management Team is extending shuttle Discovery's stay at the International Space Station by a day, and more extensive inspections of the contaminated rotary joint on the starboard side of the outpost's central truss are being added to the fourth of five spacewalks planned for NASA's 120th shuttle mission. The details are below.

NASA likely will add an extra day to Discovery's stay at the International Space Station so spacewalkers can extensively inspect a giant rotary joint designed to turn outpost solar wings and keep them face-on to the sun.

A highly anticipated test to a new shuttle heat-shield repair technique likely will be cancelled as a result, and the inspections would take place Thursday during the fourth of five spacewalks scheduled during Discovery's visit to the outpost.

The mission extension would enable flight directors to insert a day between the fourth and fifth spacewalks, with the final outing coming on Saturday rather than Friday. The shuttle's departure would move from Sunday to next Monday and landing would be scheduled for Nov. 7 rather than Nov. 6.

NASA originally planned to perform the last two spacewalks of the mission back-to-back because the heat-shield repair test would be a short, four-hour excursion.

Discovery's astronauts already expect NASA mission managers to give the go-ahead for the plan -- one which mirrors what the crew has been figuring.

"This wouldn't be the first time we all were thinking the same thing at the same time," shuttle skipper Pam Melroy told Capcom Tony Antonelli in NASA's Mission Control Center. "We're ready to go do whatever you guys need us to do."

The extra inspection of the starboard Solar Alpha Rotary Joint -- know by the acronym SARJ (pronounced "sarge") -- would involve removing 21 of 22 thermal covers that protect the 10-foot wheel from extreme temperatures in low Earth orbit. The covers ring the wheel.

During a quick inspection on Sunday, spacewalker Dan Tani looked beneath one of the 22 covers and discovered what appeared to be widespread metal shavings -- an indication that gear teeth or other internal components were being sheered.

The discovery prompted mission managers to park the starboard wings in a stationary position so that permanent internal damage would not be done to the joint. The parked position limits the amount of electricity the wings can generate.

In what amounted to a rudimentary science experiment today, station commander Peggy Whitson put some collected shavings on a plain white piece of paper and then placed a magnet nearby. The shavings were drawn to the magnet, a sure sign that the contamination is ferrous metal. That indicates gear teeth or other internal steel components are rubbing when the joint rotates.

A decision on the extra day and the extra inspections is expected later today.

If approved, spacewalkers Scott Parazynski and Douglas Wheelock will do a quick inspection of an identical rotary joint on the portside of the station during an excursion aimed at mounting a solar array truss to the far left end of the outpost's metallic backbone.

The relocation of the truss is now critical to plans to launch Atlantis and the long-awaited European Columbus laboratory on Dec. 6. If the massive solar wings on the truss cannot be fully unfurled -- and the starboard wings are kept in a stationary position -- the station would not be able to generate enough electricity to support delivery of the Columbus lab.

Parazynski and Wheelock will head outside the U.S. Quest airlock around 5:28 a.m. EDT Tuesday.

With an assist from the spacewalkers, crane operator Stephanie Wilson -- relying on cameras views and verbal cues from Parazynski and Wheelock -- will try to guide the 35,000-pound girder into place on the outboard port end of the station's central truss.

The station's 57.5-foot robot arm will have to be fully-extended -- placing it in its weakest position -- in order to do the job, which is considered the most daunting astronauts will face during construction of the outpost.

Now stowed in blanket boxes at the top of the truss, twin solar wings then must be fully unfurled. The glimmering gold solar wings are designed to unfurl like venetian blinds, but past assembly crews already have encountered trouble extending and retracting them.

The array deployments are scheduled to take 11:58 a.m. and 1:28 p.m. Tuesday.

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