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Small Object Hit Space Shuttle Last Month
UglyTool writes "A small object, possibly a micrometeoroid, hit a radiator panel on the Space Shuttle Atlantis in September. The impact also damaged a one-inch (2.5-centimeter) area in the radiator's honeycomb-like aluminum mesh, but did not sever any of the panel's 26 vital coolant tubes as it passed through the half-inch wide panel.
This brings up some interesting questions. Is there a better way to protect the shuttle in orbit? Will a serious mishap in space be the end of our manned space program?"
From the article: "The impact left a hole about one-tenth of an inch in diameter, NASA reported Thursday on its Web site. The damage 'didn't endanger the spacecraft or the crew, nor did it affect mission operations,' NASA said. The radiators were brought inside the bay before the shuttle's landing last month, so the damaged area did not encounter searing heat during re-entry through Earth's atmosphere."
The hubble gets hit by particles of sand every month. So far none has done anything more than leave blemishes on it yet. But you get something like the space shuttle pushing 18,000 miles per hour in orbit even a pebble that is a centimeter wide could be very damaging.
Like one of the above posters said, it won't be something bit that ends the space program, it will be something that is seemingly innocuous that causes problems.
This type of responsible maintenance is nothing new to some trades. I worked in radition and contamination areas. We had very strict guidlines for tools and containment and everything was logged in and out, including scrap o-ring pieces, connectors, zip ties, pieces of pipe lagging etc..). Every piece that went into the controled area HAD to come back out and every piece dislodged or removed from equipment had to come out as well. Precautions were taken to prevent mistakes (tape, string, velcro, bags, etc). I imagine working in an environment without gravity would be different but not necessarily harder.
This is exactly what i was thinking - they can come up with deflector shields for tanks these days, why not apply this to space-based craft? while they aren't technically 'shields' - at least they would suffice for protecting a craft from objects large enough to potentially damage them...if they can pick out rpg's, why not a piece of space debris...
mind you, space debris is typically flying a LOT faster than an rpg...
Gekido's Lair
qv: Whipple Shields
The idea behind whipple shields is that you put several thin barriers in front of a hypervelocity threat, and the shock waves induced inside the moving body (from rapidly loading and unloading it with compressive forces) tears it apart. What emerges from the other side of the whipple shield is a cloud of dust rather than a rock (or steel bolt, or whatever), and this cloud of dust is incapable of penetrating the side of your spacecraft.
The document linked above describes research which demonstrates that the strength and thickness of the individual barriers is much less important than the number of barriers, and the ratio of barrier thickness vs space between the barriers. Thus whipple shields can have extremely high mass efficiency against hypervelocity threats, equivalent to 0.6 of the same thickness of hardened steel. A foamed polystyrene solution (where the cell foam wall thicknesses are tuned to the correct ratio of foam cells' widths) could therefore provide the same level of protection as ~135 times its weight in hardened steel plate.
This technology is being actively developed for protecting battletanks from shaped charges (which generate explosively-formed penetrators moving at high hypervelocity speeds of 8,000m/s and more), but its relatively low thickness efficiency (0.6x, as opposed to ~3x-4x for some modern composite armor systems) limits its usefulness in this role, as battletanks have limited space to play with. Spacecraft are much less limited in this respect.
Other so-called "Active Defenses" developed for battletanks might also be applicable.
-- TTK
That's their design for the shuttles successor.
mcgrew's razor: Never attribute to stupidity that which can be explained by greedy self-interest