This
story was updated at 10:50 p.m. EST.
A small
chunk of space trash made an uncomfortably close pass by the
International Space Station late Friday, but not close enough to force the
astronauts aboard to take shelter in their Russian lifeboats.
NASA's
Mission Control woke the six astronauts on the station from their sleep late
Friday as the space
debris approached, but ultimately decided not to send the crew into their
Soyuz spacecraft to ride out the orbital trash's near miss. The astronauts were
told they could go back to sleep.
"Sorry we
had to do it that way, and we had to wake you up in the middle of the night,"
the station's Russian Mission Control radioed the crew. The debris was expected to
fly within 1,640 feet (500 meters) of the orbiting laboratory Friday night at
10:48 p.m. EST (0348 Saturday GMT).
Sending the
astronauts into their Soyuz lifeboats would have been a precaution only.
Earlier today, NASA officials said the space junk posed no threat to the
station or its crew, but news of its close approach came too late to steer the
massive orbiting lab clear using its Russian thrusters.
"It's
pretty unusual," Kirk Shireman, NASA's deputy station program manager, told
SPACE.com Friday. "I wouldn't be surprised if the need to do it for this
[debris event] goes away."
That is
exactly what happened. A closer analysis of the object by NASA Friday found it
to be a small, 2-inch (5-cm) piece of space trash that would not hit the space
station.
"Good
news," NASA's Mission Control told the station crew. "The tracking data
has come through, and shown that the conjunction's no longer a threat to station."
The object
was very small, making it difficult to
track initially, NASA spokesperson Rob Navias told SPACE.com. Station
astronauts thanked Mission Control for the news and were looking forward to
grabbing more shut-eye. They went to sleep at about 4:30 p.m. EST (2130 GMT)
and were due awaken to begin their Saturday in space in a few hours.
"I'll
get around to all my crewmembers here, and we can go back to sleep," replied
station commander Frank De Winne, a Belgian astronaut representing the European
Space Agency. "Thanks a lot for working all this tonight, Houston."
The space
station is currently home to two Americans, two Russians, a Canadian and De
Winne, who commands the team's Expedition 21 mission.
This is not
the first time a piece of wayward space junk has come close for astronauts to
consider taking refuge in their Russian lifeboats.
A close pass
by an old rocket engine remnant sent three station astronauts into
their Soyuz spacecraft earlier this year in March. Since then, however, the
space station's crew size has doubled to six astronauts, so two Soyuz vehicles
are currently docked to the station.
NASA also delayed
the departure of a Japanese cargo ship from the space station last week
because of a space debris threat.
NASA
typically prefers to move the space station when the odds of a space debris
impact are within a 1-in-10,000 chance. Astronauts take shelter when debris is
expected to fly within a so-called "red zone" and the space station doesn't
have time to dodge, Shireman told SPACE.com
There is
also a box-like buffer around the station that mission managers prefer to keep
free of any debris. That safety zone extends about 15 miles (25 km) around the
space station, as well as about a half-mile (0.75 km) above and below it. The
station flies in an orbit about 220 miles (354 km) above Earth at a speed of
about 17,500 mph (28,163 kph).
But a
debris avoidance maneuver – as dodging space junk is known at NASA – can take
days to plan. The space station's Mission Control team did not have that time
because of the short lead time, Navias said.
Space
debris has been a growing threat for manned spacecraft and other satellites in
orbit today.
The
collision between two
communications satellites earlier this year brought the issue to the
forefront. It, as well as China's intentional destruction of a satellite during
a 2007 anti-satellite test, have sparked a renewed push to better track, and
possibly reduce, the more than 20,000 pieces of space junk currently watched by
various agencies.
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