ISS Crew Size To Double
By Frank Morring, Jr.
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The crew of the International Space Station (ISS) is scheduled to double in size when Russia's Soyuz TMA-15 arrives on May 29, marking the first time all of the station-program partners are represented onboard.
When Canada's Bob Thirsk, Belgian Frank De Winne of the European Space Agency, and Russia's Roman Romanenko join the Expedition 20 crew, they will roughly triple the amount of time available to carry out scientific experiments on the orbiting laboratory. "This is a big transition from what we've had on previous increments, when we've continuously been short of crew time in order to do science," said Ben Pawlik, Expedition 20 increment manager at Mission Control Center-Houston. "On this increment we're faced with the opposite problem. We have a surplus of time."
Pawlik said the increment crew - which will change over the six-month period as some members are replaced - will have a total of about 600 hours for science, increasing on average from about 20 hours a week for the old three-person crews to as many as 70 hours a week. Initially there won't be all of the scientific hardware and supplies onboard required to use that extra crew time, Pawlik explained, and the crew will be assigned other tasks. Ultimately station managers expect to strike a balance among science, maintenance and the crew time available to handle it.
By the end of the increment crew members will have completed assembly of the three-part Japanese Kibo laboratory by adding its external experiment facility, welcomed the first robotic Japanese H-II Transfer Vehicle (HTV) with fresh supplies, and helped set the stage for delivery of the first of two more Russian laboratory modules.
Dan Hartman, integration and operations manager for the ISS program at NASA, said the limiting logistics factor for supporting the larger crew will be food, which is stocked in sufficient quantity to support both the station crew through a missed space shuttle arrival, plus a shuttle crew stranded there by orbiter damage for as long as 70 days. Present supplies won't start causing concern as long as they are replenished by about Oct. 25, he said.
Despite a recurrence of bacteria growth in the potable water dispenser on the newly installed water recycling system, flight surgeons are expected to clear the crew to drink the water by the end of next week because the bacteria levels are well below dangerous levels. The system recycles urine, water used for hygiene and the moisture from perspiration and respiration in the cabin atmosphere for reuse by the crew and for oxygen generation.
The urine processing assembly, which had to be replaced in March because the original unit didn't work, is out of action again with a "sticky check valve," Hartman said. But that problem should be fixed next week, he said.
The Soyuz crew arriving at the end of the month will join Russia's Gennady Padalka, NASA's Mike Barratt and Koichi Wakata of the Japan Aerospace Exploration Agency to make up the first fully international crew on the station. Padalka and Barratt are scheduled to don Russian spacesuits twice next month to set up the Zvezda service module's zenith port to receive a Mini Research Module scheduled for launch on a Proton rocket in November or December.
International Space Station photo: NASA