This story was updated at 8:45 p.m.
EST.
An attempt by astronauts to repair a
new water recycler designed to convert urine into drinkable water met with
mixed results Sunday aboard the International Space Station.
Space station skipper Michael Fincke
and Endeavour shuttle astronaut Don Pettit removed a set of washer-like
vibration dampeners from a centrifuge used to distill
water from urine, which engineers hoped would solve the system's early
shutdown woes.
During recent start-up tests, the recycling
system's urine processor shut down after only two hours in action. A
separate sweat and wastewater processor has been working more or less as
expected.
After Sunday's repair attempt, astronauts
reported hearing a new sound from the device, though it initially continued
functioning even after flight controllers began seeing symptoms related to the
earlier shutdowns. But less than three hours after its new start-up the unit
shut down once more after processing about a gallon (3.8 liters) of urine
collected by the station crew.
"That's a third of a tank right
there, so that sounds like potential," said Fincke. "It looks like we made
things better, but we're still maybe not there yet."
The urine processor is designed to
run for about four hours at a time, but vibrations within its spinning
centrifuge may be leading to some unexpected contact inside the intricate
machine, forcing it to draw more power, slow its motor and ultimately shut
down, mission managers have said.
Astronauts delivered the system last
week aboard NASA's shuttle Endeavour, which also toted a spare kitchen,
bathroom and other equipment to support
larger station crews. The water recycler is part of a vital $250 million
NASA life support system that must perform properly in order for the space
station to jump to double-sized, six-person crews next May.
Vital for larger station
crews
The new recycling system is designed
to reduce the space station's reliance on water shipments from visiting NASA
shuttles and other spacecraft from Russia, Europe and Japan. Endeavour, for
example, is delivering 1,000 pounds (453 kg) of water on this trip alone, the
shuttle's commander Chris
Ferguson told reporters today.
"We really want to be confident that
the system will run long term," space station flight engineer Courtenay
McMillan said late Sunday. "So that when we start six-person crews in May,
we'll know that we've got a stable platform for life support systems operations."
McMillan said engineers are
optimistic that removing the dampeners will work, but they are also eyeing
other possible causes for the malfunctioning system.
"We're not 100 percent sure by any
means that this is the mechanism causing the problem, but it is one way it
could try and slow the motor down," McMillan said.
With the dampeners removed, the
urine processor will make more noise inside the station, but astronauts may be
able to muffle that effect if their fix is successful, she added.
Some samples collected
Astronauts aboard the station have
managed to run some urine through the water recycler, as well as a batch of
moisture siphoned from the station's atmosphere, but not the amount flight
controllers had hoped for.
The processor has produced water
samples composed of mostly of wastewater, with just 10 percent - about
one-third of that expected - made up of recycled urine, McMillan said.
Engineers plan to spend about 90 days testing the water recycling system before
approving its use by station astronauts.
Mission Control has told Endeavour's
astronauts that flight controllers currently don't plan to extend their mission
by one extra day to prolong troubleshooting with the troublesome urine
processor.
But McMillan said the option is
still on the table should engineers decide they have to return the urine
processor to Earth for an extensive overhaul. There are no spares of the system
in existence, but the decision to bring the unit home will not be made lightly,
she added.
"We haven't started talking about
when we'd stop troubleshooting on orbit and decide to bring the unit home,"
McMillan said. "That's a pretty big decision to make."
NASA is providing live coverage of
Endeavour's STS-126 mission on NASA TV. Click here for SPACE.com's
mission coverage and NASA TV feed.
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