ISS Solar Panel Punctured by Small Stone | Hacker News Reader

ISS Solar Panel Punctured by Small Stone

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How dangerous are small flying rocks? I mean does it really pose a big threat to the station and the crew? His tweet seems to imply so.

I also don't know what kind of contingency plans you can have in the ISS,but I'm not aware of how space-structural integrity works

Further down in the tweet thread, it is stated that they would seal the section off. If it was leaking too fast they would determine if the Soyuz could be used as an escape pod. (NOTE: There are a few tweets in the thread claiming things that were obviously not true, this might be false as well.)

My intuition has always been that a stone striking a satellite is statistically unlikely because of the vastness of space. The theoretical possibility was always there to create immense damage (or completely destroy smaller satellites) because of the kinetic energy involved, but so unlikely to be near-zero.

That's what caught my eye about this tweet. It's the first time I've heard of an actual collision between a satellite and a small stone.

As far as your question regarding the ISS, I can only imagine what would happen if it had struck the hull. A satellite in LEO travels at around 7-8 km/s (kilometers per second). I'm not sure what that means for the relative velocity between the satellite and a stone---probably slower, but by how much? Using the orbital velocity as an estimate of the relative velocity, that's about an order of magnitude faster than most firearms, so I find it improbable that the hull is armoured against such a strike.

if we have the camera precision to catch a small rock miles away, laser interception might be doable.

http://www.amsmeteors.org/fireballs/faqf/#12: "Meteoroids enter the earth’s atmosphere at very high speeds, ranging from 11 km/sec to 72 km/sec (25,000 mph to 160,000 mph."

They will slow down in the atmosphere, but there is little air above the ISS.

This gives even tiny ones enormous kinetic energy. So, unless they happen to be of the slowest kind and move parallel to and in the direction of the ISS (which does in the order of 10km/s itself), they pose danger to the crew.

Contingency plans? You hope to see large ones coming and move out of the way. For small ones, I think you hope they won't go through your body and hope to plug the holes before you leak too much air, or to be able to make it in the escape vehicle, if that wasn't hit, too. I guess there are intermediate sizes where you are hosed, regardless of what you do.

NASA says: The ISS is the most heavily shielded spacecraft ever flown. Shielding is designed to protect critical components such as habitable compartments and high-pressure tanks from the nominal threat of an aluminum sphere approximately 1 cm in diameter. The ISS also has the capability of maneuvering to avoid tracked objects.

http://www.nasa.gov/centers/wstf/laboratories/hypervelocity/...

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