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Germany To Test Actively-Cooled Spacecraft
FleaPlus writes "The German Aerospace Center is planning to launch a novel reusable spacecraft in 2011, incorporating flat, damage-resistant tiles. Nitrogen will be pumped through the porous tiles, creating a protective gas layer that actively cools and shields the hottest parts of the spacecraft from the searing heat of reentry. The €12.5M unmanned 'SHEFEX II' project is a major technological step toward the team's eventual goal of a reusable space glider, which will be cheaper and easier to build than NASA's space shuttle."
I've thought of active cooling myself. I always wondered, if you used an active cooling system, where would you radiate the heat? In other words, you can carry heat away from the underside of the ship by pumping a fluid through the tiles or whatever, but then you still have to re-radiate that heat someplace. OK, you might be able to transform some of the heat into useful work too; but we're talking about a lot of heat, and even if you got right to the Carnot efficiency the waste still has to go someplace.
I never got as far as doing the "back of the envelope" calculations on some substance with a heat capacity to absorb re-entry heat (and light enough to carry onboard) or the more tricky calculation of how you would conduct the heat from the underside and radiate it topside. I kind of assumed that actual aerospace engineers had done the calcs, and decided it just wouldn't work.
Weight kills in space, so I'd be curious to know how much the system weighs vs tiles or Russian-style ablative coatings. I'm assuming the Russians still use ablatives. I'm sure somebody will correct me if I'm wrong.
For all intensive purposes, "whom" is no longer a word. That begs the question, "who cares"?
It is one thing I wish they would save a shuttle for.
NASA as a publicity fund raising stunt should save one shuttle's worth of parts and go retrieve the Hubbell Space telescope instead of crashing it into the ocean. Have the shuttle land and the load it directly for a flight to DC. Giving the whole pile (shuttle with Hubbell inside) to the Smithsonian.
Now that would be an awesome display. Heck I would donate money to help make that happen. To bad NASA doesn't think like awesome anymore.
i thought once I was found, but it was only a dream.