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Tiny Particle Blows Hole In European Satellite's Solar Panel (go.com)
An anonymous reader quotes a report from ABC News: A tiny piece of debris has punched a gaping hole in the solar panel of one of Europe's Earth observation satellites, causing visible damage but not enough to affect its routine operations, the European Space Agency said Wednesday. The unknown particle just a few millimeters big slammed into the back of a solar panel on Copernicus Sentinel-1A on Aug. 23. Using on-board cameras, engineers have determined that the hole is about 40 centimeters (16 inches) in diameter. The European Space Agency said the loss of power caused by the strike is "relatively small" -- less than 5 percent of the wing's usual output. The likelihood of such a strike is calculated at between 1:35 and 1:130 during the satellite's five-year lifetime, said Holger Krag, who heads the agency's space debris office. While the particle probably had a mass of less than 1 gram (0.04 ounces), scientists calculated that it was traveling at up to 40,000 kilometers an hour (24,856 mph) when it hit Sentinel-1A. Space.com has posted a video about the incident, showing images taken before and after the impact.
Using on-board cameras, engineers have determined that the hole is about 40 centimeters (16 inches) in diameter.
That's 0.00198838 furlongs for those too lazy to do the conversion.
I think slashdot readers are fine with having just the metric units. Anyone who couldn't do the conversion in their head if they cared probably isn't reading slashdot.
that space debris has created more space debris that will create more space debris that ...
does it need a flash video (of all things) to show a before and after image of the panel?
Donald 'Duck' Dunn: We had a band powerful enough to turn goat piss into gasoline.
When the density of the particle is high relative to the hardness of the target, there's a very high chance for penetration and low energy transfer.
But when the projectile density is relatively low compared to the target hardness, the projectle is usually deformed and stops inside the target. Or as in this case, is completely atomized, causing nearly perfect energy transfer. (approaching 100%)
So being able to ignore energy loss in the transfer make the math and modeling pretty easy. You just imagine an explosion at the point of contact, with about double the energy of the projectile. (since explosions are omnidirectional, wasting 50% of their energy in the other direction on impact, and in this case, 100% of the energy is transferred into the target)
And at orbital and escape velocities, delta-V is so high that even a very low M yields a lot of joules.
Final thing to consider, these panels aren't terribly sturdy. They're made to be extremely light, store compactly, and self-deploy/assemble in space, making them overall pretty delicate. This isn't built anything like the solar panel on your roof. It's more like the model car in your dad's display cabinet. Shoot that thing with an airsoft gun and see what happens.
I work for the Department of Redundancy Department.
Aren't particles microscopic, something that can be measured in millimetres doesn't seem like it ought to be described as a particle...
In physics, yes. But they were using the general definition, which does seem somewhat out of place in this case, but is correct. This is similar to talking about a particle of dust getting into a camera lens.