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Author
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Topic: Protecting Hasselblad cameras on the Moon
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Apolloman
Member Posts: 152
From: Ledignan, Gard (30), France
Registered: Mar 2009
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posted 12-10-2010 11:47 AM
   
I would like to know what was the protection of Hasselblad used on the lunar surface... on documents found indicate that it is: The Data Camera was given a silver finish to make it more resistant to thermal variations that ranged from full Sun to full shadow helping maintain a more uniform internal temperature. Okay, but what is its reflection coefficient? Would you have records showing the manufacture of equipment and modifications? |
Apolloman
Member Posts: 152
From: Ledignan, Gard (30), France
Registered: Mar 2009
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posted 12-10-2010 04:04 PM
I finally find. We must look towards the emissivity of materials. The text NASA says "a silver finish."I looked up the rate of emissivity of polished silver. I found a rate of 0.02 / 0.003, assuredly a pretty good protection. |
dsenechal
Member Posts: 548
From:
Registered: Dec 2002
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posted 12-10-2010 09:11 PM
The finish on the Hasselblad EDC was not polished silver. It was silver paint, sprayed over the original anodized black finish of the camera. Nothing too exotic, but obviously did the job. |
Apolloman
Member Posts: 152
From: Ledignan, Gard (30), France
Registered: Mar 2009
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posted 12-11-2010 04:53 PM
Would you have sources on what you advance? |
Rick Mulheirn
Member Posts: 4208
From: England
Registered: Feb 2001
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posted 12-12-2010 05:16 AM
It is my understanding that changes were made to lubricants used in the camera mechanism to minimise the risk of out gassing in the vacuum of space. |
KA9Q
New Member Posts: 3
From: San Diego, CA
Registered: Mar 2012
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posted 07-15-2012 09:56 AM
There are *two* critical parameters that determine a surface's thermal properties: absorptance (alpha) and emittance (epsilon). Alpha is a measure of how visually dark it is, how much visible and near IR light it absorbs from the sun. Emittance is a measure of how "dark" the surface would appear if you could see in the far IR around 10 microns where objects near room temperature emit their thermal radiation.Leave an object in the sun and it will reach an equilibrium temperature where it radiates as much heat as it absorbs. The temperature at which it does this depends strongly on the ratio of alpha to epsilon; lower ratios mean colder, higher ratios mean hotter.
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