Water-cooled lander |
Water-cooled lander |
Aug 22 2007, 05:22 PM
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#1
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Member Group: Members Posts: 214 Joined: 30-December 05 Member No.: 628 |
There is a recent posting on Emily's Planetary Society blog, which must be Doug's because she's not there herself, although her name is the only name on it. The subject is using water to cool a long-lived surface probe on Venus. It sounds far more practical than any of the other proposals for landing giant atomic-powered refrigerators, or developing a whole new family of high-temperature semiconductors, etc.
But I didn't understand the whispered criticism to the effect that the Ekonomov paper assumed that the water would absorb heat only from the one watt of power driving the instrument package itself. I simply can't believe that he went to the podium and presented his model without taking into account the fact that the surface of Venus is a pretty hot place, and that the proposed probe would be absorbing the ambient heat. This is an interesting proposal and I would like to understand both the original calculation of 50 days to bring the water to a boil, and the cited flaw in the calculation. I too find it hard to believe that it would take 50 days to bring water to a boil on the Venusian surface, but where exactly is the error, and what remains after we correct it? Doug is busy of course, but I hope he will find the time to address this when he returns, if someone else hasn't done so by then. |
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Aug 22 2007, 09:03 PM
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#2
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Founder Group: Chairman Posts: 14434 Joined: 8-February 04 Member No.: 1 |
Unfortunately - the guy's english wasn't very good, and his details were fairly thin on the ground. He talked about the power consumption of the electronics being only 1 watt to minimize the energy put into the water - and perhaps through langauge barrier rather than anything else - it seemd that he was infering that only 1W of energy would be heating the water. (and it was Earth days he was talking about - he wanted to reach a significant part of a Venus year - 100-200 Earth days)
Obviously - the cable from the batteries itself will be sinking more than that, ditto any other connectors to the 'outside' world in terms of instrumentation, comms, the vent for steam etc etc. I don't think the language barrier between the speaker and the audience helped when people were asking about the 1w etc. Think about what the rovers do when they're on 240 whrs - 10 watts average. Now think what a venus lander would do with 1 watt average. There was another point made to me - a seismic instrument on 1 bps? Forget it. Seismic measurements from inside a boiling kettle? Crazy. Like I said in the blog - most agreed that the principle would obviously work - but just not how he was describing it. Doug |
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