Spaceflight Now: STS-92 Mission Report

Next shuttle launch hinges on reusing spacesuit parts

Posted: September 18, 2000

Astronaut Jim Voss outside the international space station during a spacewalk in May. Photo: NASA
Running out of time, NASA plans to cannibalize parts from spacesuits currently aboard the shuttle Atlantis to clear the way for a complex space station assembly mission scheduled for launch in less than three weeks.

Even if the work goes smoothly, officials say, there is little margin for error in meeting Discovery's Oct. 5 launch target.

"Right now, the most critical thing we have, or the thing that's right on the bubble, is turning around the suits," shuttle integration manager Bill Gerstenmaier said late last week.

"Right now, that schedule is fairly tight," he added. "That's got to be all understood and all that processing has to go exactly right to make Oct. 5."

Atlantis is scheduled to make a pre-dawn landing Wednesday at the Kennedy Space Center to wrap up a successful mission to outfit and activate the space station's new Zvezda command module.

Three spacesuits are on board, but only two were used during a single six-hour 14-minute excursion last week by Edward Lu and Yuri Malenchenko to electrically connect Zvezda to the rest of the station.

Engineers will be standing by when Atlantis touches down, whether in Florida or California, to rush all three suits to a facility where their emergency oxygen packs will be removed and flown to the Johnson Space Center in Houston.

Two of the three secondary oxygen packs then will be installed in suits scheduled for use during Discovery's upcoming flight, a station assembly mission that includes four back-to-back spacewalks by a quartet of astronauts working in two-man teams.

A third suit slated for use aboard Discovery has been cleared for flight as is.

The unusual cannibalization is required because of a problem that cropped up in June when technicians discovered an oily residue in the regulator of a spacesuit's secondary oxygen pack, or SOP.

A spacewalker in a picturesque view. Photo: NASA
Shuttle spacesuits are equipped with two oxygen systems: A low-pressure supply that is used during normal operations and a high-pressure secondary oxygen pack that can provide about 30 minutes of air in an emergency.

While no spacewalker has ever had to use a secondary oxygen pack, NASA mounted a full court press to make sure the $2 million spacesuits were safe for use in any scenario, including unlikely mishaps that might knock a suit's primary oxygen system out of action.

"The likelihood of any such scenario is extremely remote," Gregory Harbaugh, a veteran shuttle spacewalker who now oversees spacewalk planning at the Johnson Space Center, told reporters July 14.

"Nevertheless, my concern is and has always been to ensure the safety of the crew. And hydrocarbon contamination in the environment of 6,000 psi oxygen is not a good mixture. It is something that has the potential of creating a fire if the right conditions are satisfied."

At that time, engineers did not know what caused the contamination. But Gerstenmaier said last week it apparently was caused by the failure of a nitrogen compressor used to service the suits between flights.

While NASA and its spacesuit contractor were able to clean the secondary oxygen regulators needed for Atlantis's mission, two of the three suits needed for Discovery's flight - shuttle mission STS-92 - will not be ready in time.

As a result, "we're going to take the spacesuits we just flew on this flight, the secondary oxygen packs that are used on these spacesuits, we're going to take those out of the orbiter as soon as it lands, either in Florida (or California)," Gerstenmaier said.

"Then we'll fly those to Houston to be processed, put back into EMUs and then get ready to go fly STS-92. So we'll actually use the secondary oxygen packs from this flight for STS-92."

Astronaut Jim Newman dangles from the space station in 1998. Photo: NASA
Robert Cabana, manager of international operations for the space station program, told Spaceflight Now early today the cannibalization was strictly a "one-time event" and that suits for subsequent missions will "absolutely" be ready in time for normal processing.

To make sure the suits used during Atlantis's flight were safe, engineers carried out a battery of tests at a NASA facility in White Sands, N.M. Generic spacesuit oxygen systems were subjected to extreme conditions and contamination levels far higher than anyone ever expects to see.

"In every instance, we found no indication of any potential for ignition," Harbaugh said in July. "We contaminated these regulators at roughly twice the level of contamination that we'd seen on the secondary side, which is almost 1,000 times what we've seen so far on the primary side. All results were negative.

Outside experts were called in to examine the results and all were in agreement "that that analysis and the testing is valid," Harbaugh said. "And therefore we're OK to proceed (with flights) with the primary side being in the condition we now know it to be."

Asked if any previous spacewalkers were in danger or if NASA dodged a bullet by discovering the contamination issue in June, Harbaugh said "there's no way to know how far we could go without having a problem."

"It is conceivable we could do the next five years and 165 EVAs (spacewalks) and not have any problem at all," he said. "But that's not the approach we're going to take. I'm going to make certain there's no problem."