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<span style="font-weight:bold">From: </span>"Peter St. John" <<a href="mailto:peter.st.john@gmail.com">peter.st.john@gmail.com</a>><br>
<span style="font-weight:bold">Date: </span>Friday, June 21, 2013 1:26 PM<br>
<span style="font-weight:bold">To: </span>Mark Hahn <<a href="mailto:hahn@mcmaster.ca">hahn@mcmaster.ca</a>><br>
<span style="font-weight:bold">Cc: </span>"<a href="mailto:beowulf@beowulf.org">beowulf@beowulf.org</a>" <<a href="mailto:beowulf@beowulf.org">beowulf@beowulf.org</a>><br>
<span style="font-weight:bold">Subject: </span>Re: [Beowulf] Server Sky - Internet and computation in orbit<br>
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<div>I'd love computation on the moon; just as good solar collection as orbit, but radiation shielding from craters. But what about cooling? The article sounded a bit glib. I'm thinking, unless there's appreciable available water, computing in space will be
limited to low GHz because heat dissipation would be limited to IR radiation? There's no coolant in space, right? How do satellites deal with that?</div>
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<div>>Any given place on the moon has daylight 2 weeks and darkness 2 weeks (except for near the poles, where it's always pretty low angle sun)</div>
<div>> Cooling is classic radiation, and you get to radiate to cold space (roughly 3K). It's all about T^4. If you really want to reject heat, and you have an excess of power, you can pump the heat from your computer at 300K up to a radiator at, say, 600K,
and get a factor of 16 improvement in radiation. Spacecraft cool by conduction and radiation. There are heatpipes to help move heat from inside to outside. Interestingly, for a lot of spacecraft, staying warm is more of a challenge than staying cool (this
is certainly the case for Mars spacecraft)</div>
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<div class="gmail_quote">On Fri, Jun 21, 2013 at 3:52 PM, Mark Hahn <span dir="ltr">
<<a href="mailto:hahn@mcmaster.ca" target="_blank">hahn@mcmaster.ca</a>></span> wrote:<br>
<blockquote class="gmail_quote" style="margin:0 0 0 .8ex;border-left:1px #ccc solid;padding-left:1ex">
<div class="im">> The correct location for the Exascale HPC Datacentre of the future is of<br>
> course the Moon.<br>
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I apologize for a relatively sober response, but whenever I see<br>
a documentary on geothermal vents in the ocean, I think about<br>
putting exascale DCs down there ;)<br>
<br>
all that nice cold water in close proximity to gigawatts of free hot water...<br>
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