NASA said a piece of Chinese space junk would fly harmlessly past the International Space Station and called off an alert for the three crew members in orbit.
On Tuesday afternoon, Mission Control at NASA's Johnson Space Center in Houston told the station crew — commander Dan Burbank of NASA and Russian flight engineers Anton Shkaplerov and Anatoly Ivanishin — that a piece of shrapnel from a Chinese weather satellite that was destroyed in 2007 might be coming a little too close for comfort.
The crew members were told at the time that they might have to take shelter inside a Russian space capsule as a safety measure. But hours later, NASA reported that the alert was downgraded.
The object was about 4 inches (10 centimeters) in diameter, and initial projections had it coming within 2,800 feet (850 meters) of the station on Wednesday.
The concern about the debris made for a somewhat chaotic start for the three space station crew members, who arrived at the lab Nov. 16 to begin their months-long mission.
Three other spacefliers — NASA's Mike Fossum, Japanese astronaut Satoshi Furukawa and Russian cosmonaut Sergei Volkov — completed their turns on the station and landed in Kazakhstan Monday night .
Space junk risk
If space junk is on track to fly within a predetermined pizza box-shaped zone around the space station, NASA and its partners direct the crew to seek shelter aboard their Soyuz spacecraft, which are continually docked at the outpost, in case they need to make a speedy escape.
The last time spacefliers had to make such a maneuver was on June 28, when a piece of unknown space debris came within 850 feet (260 meters) of the space station. That was only the second time in history that the station crew has had to take shelter from space debris.
Space junk is a growing problem. Spent rocket stages, lost spacewalking tools, broken satellites and pieces of destroyed satellites are all clogging the orbital corridors of space. There is so much trash up there, in fact, that even if no more were added, it will collide with itself to continually produce more and more, scientists say.
Certain events, such as the 2007 event when China intentionally destroyed a defunct weather spacecraft in an anti-satellite test, have contributed greatly to the total amount of space debris.
Even though most pieces of space junk are much smaller than the football field-size space station, if an object traveling at 17,000 miles per hour (28,000 kilometers per hour) collided with the outpost, it could do devastating damage.
You can follow Space.com assistant managing editor Clara Moskowitz on Twitter @. Follow Space.com for the latest in space science and exploration news on Twitter and on . This report was updated by msnbc.com.