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Author Topic: What causes re-entry blackout?  (Read 1473 times)

Offline chris

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What causes re-entry blackout?
« on: 25/03/2014 17:44:10 »
What is the mechanism through which spacecraft temporarily lose touch with the ground during re-entry, the so-called "re-entry blackout" ?



 

Offline yor_on

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Re: What causes re-entry blackout?
« Reply #1 on: 25/03/2014 18:42:43 »
"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
 

Offline chris

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Re: What causes re-entry blackout?
« Reply #2 on: 25/03/2014 21:57:34 »
Wow, that's some heat! I wouldn't have guessed it was that high...
 

Offline Pmb

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Re: What causes re-entry blackout?
« Reply #3 on: 26/03/2014 08:45:47 »
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.
 

Offline yor_on

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Re: What causes re-entry blackout?
« Reply #4 on: 26/03/2014 15:37:31 »
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
 

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Re: What causes re-entry blackout?
« Reply #4 on: 26/03/2014 15:37:31 »

 

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