image courtesy of NASA

Space Station: A Close Call With Space Junk
| published July 17, 2015 |

By Thursday Review staff

By some estimates of NASA and the European Space Agency, there are more than 400,000 pieces of man-made junk and debris floating or orbiting the Earth, along with thousands of still operating satellites. That sounds like it can make for heavy traffic on a good day, but, in reality—the vastness of space around the Earth is so great that rarely do those objects collide.

Still, the International Space Station—the largest of all those circling objects—makes for a good target for any of that random debris. Even a tiny object no larger than a marble poses a risk for the ISS, which has grown over the years to about the size of an American football field.

Typically, NASA and the various other international agencies that monitor the movements of satellites and space junk are able to predict days ahead of time when something being tracked poses even a marginal risk of slamming into the space station. When those computer models and tracking devices show a risk of a collision, space station astronauts and cosmonauts simply nudge the vast complex out of the way. Sometimes this requires moving the space station only a few feet, other times as much as a mile or two; almost always, the adjustments are just the routine business of keeping the multi-billion dollar station out of harm’s way.

But on Thursday of this week, NASA engineers and ESA trackers were late in discovering a small object moving at more than eight miles per second—an object about the size of a soccer ball travelling at a dizzying speed of roughly 32,000 miles per hour. An impact with the space station could have been catastrophic. Astronaut Scott Kelly and Russian cosmonauts Mikhail Kornienko and Gennady Padalka had less than 90 minutes to prepare—not nearly enough time to fire up the boosters and the small jets used to adjust the station’s orbit. So the three crew members instead took brief shelter inside the Russian Soyuz spacecraft docked to the ISS. If there had been a serious impact to the station, causing decompression or major damage, the crew could have made their escape via the Soyuz craft and returned safely to Earth.

As it turned out, the object missed the space station by about one mile, and the crew did not have to use the Soyuz as a lifeboat for a return trip to Earth. Instead, the crew went back to their normal activities.

NASA says that only twice in the last year (since the American Kelly arrived) has the space station had to adjust its orbit to make way for circling debris. The emergency procedure implemented Thursday is the only the fourth time such a contingency was necessary in the 15-year life of the station, though the station’s orbit has been adjusted or tweaked hundreds of times. The object which whizzed past the ISS on Thursday was a fragment of an obsolete Russian weather satellite, debris which has been orbiting the Earth for decades.

The ISS orbits the Earth at a speed of 17,500 miles per hour.

The American Kelly and the Russian Kornienko are nearly four months into a mission scheduled to last a year. One of the central goals of the mission is to study the effects of long-duration stays in space on the human body, down to the smallest medical detail. NASA scientists plan to study even the smallest changes—like DNA and blood markers—by comparing Scott Kelly to his twin brother Mark Kelly. Kelly and Kornienko are scheduled to return to Earth in March of 2016.

In the meantime, if all goes as planned, an additional three crew members will join the team already aboard the space station later next week. Weather permitting, the new crew—its mission called Expedition 45—will be launched aboard a Russian rocket on July 22 from Kazakhstan. The full crew aboard the space station will (after Padalka’s scheduled departure) consist of Kelly, Kornienko, Oleg Kononenko, Sergey Volkov, Kjell Lindgren, and Kimiya Yui. Lt. Colonel Yui comes to the ISS operations by way of the Japan Aerospace Exploratory Agency (JAXA). Sergey Volkov is a colonel in the Russian Air Force and a seasoned cosmonaut. Kononenko also is a veteran of previous space missions, including more than 12 hours of extra-vehicular activity.

Related Thursday Review articles:

New Horizons Phones Home; Keith H. Roberts; Thursday Review; July 15, 2015.

The View From Above; Thursday Review staff; Thursday Review; March 3, 2015.