Satellites Are Vulnerable to Meteoroids, but Repairs Could Be Possible

On Friday morning local time, a ten-ton, 6-foot-diameter meteoroid broke up some 20-30 miles above Chelyabinsk, Russia, about 1,000 miles east of Moscow. The resulting shock wave blew out windows, injuring hundreds of people. The event, along with Friday's coincidental buzzing of Earth by asteroid 2012 DA14, points up the need for eyes in the sky?such as those proposed by space startups B612, Planetary Resources, and Deep Space Industries?focused on large incoming asteroids to warn of impending impacts.

But small rocks are hard, maybe even impossible to spot before they do damage. Most of the thousands of such objects that hit the atmosphere every day don't make it as close to the ground as Friday's impactor, but on the way in, they also have the potential to strike satellites, which aren't protected by the atmosphere.

Jay Gullish, Director of Space and Telecommunications at analyst firm Futron Corporation thinks meteoroid strikes on satellites are more common than one might think. "When a satellite anomaly pops up, sometimes that can be traced back to a specific problem," Gullish tells PM. "Sometimes it can't, and so my gut tells me that this is happening." Because we can't closely observe a communications satellite that's 22,000 miles away, there's no way to be sure why a particular breakdown has occurred, but Gullish figures a malfunction that can't be traced to a manufacturing defect or predictable failure might well be due to a fast moving pellet slamming into the satellite.

The damage done to satellite by a strike depends on the size and trajectory of the object that hits it, says Gullish. A large object hitting head on would likely cause enough damage to the satellite to render it completely inoperative. Even if the satellite survived such an impact more or less in one piece, it could be shoved out of its orbit, perhaps too far for its limited fuel supply to allow it to return to its operational orbit.

A strike by a smaller object, on the other hand might just blow through a solar panel or other system, leaving the rest of the satellite operational, says Gullish. "If you were to use the analogy of a gunshot, you hear crazy stories of someone being shot...and the bullet goes through and doesn't do any damage. That's conceivable. Otherwise you hear of the same gunshot grazing someone, and it hits the artery and they end up bleeding out. So, using that analogy, in a satellite it could be almost a nick, and it hits a fuel line and causes it to empty out." Or some other system could be taken out, leaving the rest of the satellite otherwise functional.

These two scenarios?fuel leaks and localized damage?present the intriguing possibility of on-orbit refueling and repair.

NASA recently conducted a successful test of its Robotic Refueling Mission on the International Space Station. In the test, a robot opened up and transferred fuel to a simulated satellite attached to the outside of the station. The test proved the technical feasibility of refueling spent communications satellites. Deep Space Industries sees satellite refueling services as a major part of its business in the future.

In another effort, the Phoenix program from DARPA, the mad science wing of the US Department of Defense, seeks to establish the technical feasibility of on-orbit satellite repairs. The program calls for robotically repairing disabled satellites using parts salvaged from other, perhaps more heavily damaged satellites. The program has successfully tested robotic cutting, grasping, and reattachment of satellite parts on the ground.

Gullish points out that for either of these bleeding-edge technologies to actually make it from the realm of demonstrations to actual use, they have to meet three main criteria: they must not only be technically feasible, but also operationally practical, and financially viable. He doesn't see that happening anytime soon. He says satellite refueling and repair tech will remain firmly in the test phase for at least the next 15 years. And once operational, he says, it will likely be prohibitively expensive for use on any but the most mission-critical of military sats, at least at first.

One of the many challenges to consider regarding satellite repair, is the issue of where to store harvested parts. "You may not know exactly what you need [for a given repair]," he says, "So what are you doing? You're starting to collect space junk and having a junk yard, right? And where is that junkyard going to sit?" A space junk yard in orbit would likely be difficult and expensive to maintain all in itself, says Gullish

For now, at least, satellites in orbit are sitting ducks for incoming meteoroids, likely causing at least some of the mysterious anomalies that add to the cost of doing business in space.

Source: http://www.popularmechanics.com/science/space/news/satellites-are-vulnerable-to-meteoroids-but-repairs-could-be-possible-15106435?src=rss

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