Naked Science Forum
Non Life Sciences => Physics, Astronomy & Cosmology => Topic started by: chris on 25/03/2014 17:44:10
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What is the mechanism through which spacecraft temporarily lose touch with the ground during re-entry, the so-called "re-entry blackout" ?
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"A shockwave forms just in front of the nose and underside of the spacecraft. Between this shock and the vehicle itself temperatures may reach 10,000 to 12,000 Kelvin. (The heat resistant surfaces of the shuttle only reach a maximum of 1600 K themselves.) This very high temperature ionises the gas close to the shuttle forming a plasma cloud or miniature ionosphere around the spacecraft. The plasma frequency (that frequency below which radio communications is not possible) may rise to many gigahertz around the lower parts of the vehicle. This gives rise to a communication blackout for direct communications between the Shuttle and ground control. This typically lasts from 25 to 12 minutes prior touchdown, a total outage of 12 to 13 minutes. " from http://www.spaceacademy.net.au/spacelink/blackout.htm
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Wow, that's some heat! I wouldn't have guessed it was that high...
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What is the mechanism through which spacecraft temporarily lose touch with the ground during re-entry, the so-called "re-entry blackout" ?
The heat from re-entry causes the atmosphere passing by the capsule to turn into a plasma by ionizing it. This makes it a conducting medium and radiation (such as radio waves) can't pass through a conducting medium.
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You might enjoy this one Chris. https://en.wikipedia.org/wiki/Bubble_fusion
And there was that shrimp too that can kill by sound. (shrimpoluminescence:) https://en.wikipedia.org/wiki/Sonoluminescence