NASA is experiencing problems with a $250 million machine for recycling urine and other wastewater into drinking water for astronauts, the space agency said on Friday.

Glitches triggered two shutdowns during initial attempts on Thursday and Friday to begin the distillation process on pre-collected samples of urine.

NASA delivered the water regeneration system to the $100 billion International Space Station this week to prepare for its crew to grow from three members to six in May.

Residents of the station must recycle water because the space shuttles, which produce water as a byproduct of their electrical systems, will no longer fly to the outpost after 2010 and it is too expensive to haul as much water as the crew will need on unmanned cargo ships from Earth.


The recycler problems, which pointed to a sensor, were not unexpected, said mission commentator Rob Navias.

NASA still expects the machine to work well enough for astronauts to bring back batches of purified water for analysis when shuttle Endeavour returns to Earth next week. The shuttle has been at the station since Sunday to deliver more than 7 tonnes of cargo to support an expanded crew.

Contaminated joint

In addition to the water recycling gear, the shuttle astronauts delivered two new sleeping compartments, a second toilet, a galley and more exercise equipment.

Improvements to the station’s exterior are also under way.

Astronauts on Friday prepared for the third of four spacewalks to fix a problem with a joint in the station’s truss. The 3-metre-wide rotary joint is needed to position solar panels so they can collect light from the Sun as the station orbits about 340 km above Earth.

Last year, NASA discovered one of the two joints had been contaminated with metal filings and designed a complicated series of spacewalks to fix the problem and prevent it from happening to the other joint.

Spacewalking schedule

Space station managers estimate up to 10 spacewalks may be needed to resolve the problems.

Shuttle Endeavour’s astronauts have completed two of four planned spacewalks already, despite the loss of a $100,000 tool kit on Tuesday and a buildup of carbon dioxide in one astronaut’s spacesuit near the end of the second spacewalk on Thursday.

The third outing is scheduled for Saturday.

Endeavour is due to leave the station next Thursday after an 11-day stay and return to the Kennedy Space Center in Florida next Saturday.

NASA plans eight more missions to the station and a final servicing call to the Hubble Space Telescope before the shuttle fleet is retired in 2010.