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Article #155Re: nasa-celebrates-successful-mars-landing
From: Jim Yanik
Date: Wed, 08 Aug 2012 15:12
Date: Wed, 08 Aug 2012 15:12
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3744 bytes
Adrian Jansen <adrian@qq.vv.net> wrote in news:5021A7CD.9010208@qq.vv.net: > > On 8/8/2012 7:04 AM, Jon Kirwan wrote: > >>>> >>>> Which reminds me of another thing. How do they convect the >>>> internally generated heat away. I recall hearing about >>>> multiple power systems, operating around 32V at near 2A. More >>>> than one. This power must be convected/conducted away -- no >>>> way they want to radiate it. I wonder if they push it >>>> (costing more heat) towards a vane or arm and drag it around >>>> on the surface to get rid of it? >>> >>> The atmosphere won't help much. >>> >>> Why not? Thermal conductivity of air is pretty much constant till >>> you get below 1 Torr or so. Wiki says the mean pressure on mars is >>> about 0.1 psi, which is ~5 torr. >> >> Good point. >> > > In earth atmosphere, I understand most heat above around 300K ( 'room' > temp ) is carried by radiation and convection. Conduction is a minor > part. > > No idea what convection is like at 5 torr in a CO2 atmosphere, but I > suspect its a lot lower. > FYI,Wikipedia has a great page on the Mars lander,and describes the thermal management very well. It appears the problem is keeping everything in the lander warm,not getting rid of excess heat. the Radioisotope Thermal Generator provides both leectric power and extra heat,and there's a system of cooling tubes that can route heat to where it's needed or to take it away. One neat factoid; the tires have a tread pattern that spells out JPL in Morse,and the tread pattern left in the dirt is used to measure the distance travelled by the lander. -- Jim Yanik jyanik at localnet dot com
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Newsgroups: sci.electronics.design,aus.electronics
Subject: Re: nasa-celebrates-successful-mars-landing
From: Jim Yanik <jyanik@abuse.gov>
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