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 26 2007, 03:05 AM
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#2
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Merciless Robot Group: Admin Posts: 8785 Joined: 8-December 05 From: Los Angeles Member No.: 602 |
True enough, actually; there's only so much data you can get from a stationary location with a fixed instrument set, However, I think that Venus is still ripe for such initial forays...the Veneras provided very limited data (but simultaneously acknowledging the fact that they were MAJOR engineering achievements!)
-------------------- A few will take this knowledge and use this power of a dream realized as a force for change, an impetus for further discovery to make less ancient dreams real.
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Aug 26 2007, 04:39 AM
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#3
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Senior Member Group: Members Posts: 2530 Joined: 20-April 05 Member No.: 321 |
True enough, actually; there's only so much data you can get from a stationary location with a fixed instrument set, However, I think that Venus is still ripe for such initial forays...the Veneras provided very limited data (but simultaneously acknowledging the fact that they were MAJOR engineering achievements!) Venus surface science can largely be broken into two categories: Seismic studies, and everything else. Seismic studies need long durations on the surface, and I don't think the water-cooled approach will cut it. On the bright side, a seismometer is a lot easier than most sensitive instruments to engineer for 500C. I think at some point, we have to have 2 to 4 seismometers on the surface working for at least a year. Those landers can have additional instrument packages and it might make sense to engineer only part of the package to survive: Do your landing panorama in the first half hour and who cares (much) if the camera dies after that -- not much is going to change. The trick is that *some* electronics even on a seismography-only package have to keep working at Venus temperatures. Maybe there's a way to refrigerate a tiny electronics "brain" that controls and runs telemetry for a cruder (vacuum tube?! just kidding) seismometer. Just about everything else could play by Venera rules: 90 minutes is plenty. All of the atmospheric studies could actually be done during the end of descent. This kind of mission wouldn't cover all of the needs we have at Venus, but nothing is going to get around the need for a seismic network sooner or later. Some of the other surface science can ride along. |
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