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Joris
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« Reply #60 on: 11/12/2012 04:08 PM » |
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New article confirming that the rover is to be nuclear powered.
http://www.china.org.cn/china/2012-08/13/content_26214399.htm
Sorry to be getting in on this way late, but that reference says,
Using plutonium-238, the battery will be able to power the 100-kilogram vehicle for more than 30 years, said Ouyang Ziyuan, chief scientist of China's lunar exploration program.
Pu-238? AFAIK, brewing Pu-238 is not a trivial matter. Do we have any other information about China's production of it?
China has about 1.8 +/-0.5 tons of Plutonium atm, they could probably miss 3kg for the prestige value of this moon rover. http://belfercenter.hks.harvard.edu/files/INMM-PU2.pdf
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Watchdog
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« Reply #62 on: 11/12/2012 10:41 PM » |
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Decay of Pu239 seems not to be the limiting factor of this lunar vehicle, its radioactive half life is about 24 years in comparison to Pu238/about 88 years. What other technical component could limit its working conditions to just 30 days? If they mean "moon days" the rover of Chang´e 3 would operate about 2.5 earth years on the lunar surface surpassing the active life of the solar powered Soviet Lunochod vehicles.
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savuporo
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« Reply #63 on: 11/12/2012 10:51 PM » |
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MERs were planned to last for 90 sols, too.
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ChileVerde
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« Reply #64 on: 11/12/2012 11:31 PM » |
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Decay of Pu239 seems not to be the limiting factor of this lunar vehicle, its radioactive half life is about 24 years in comparison to Pu238/about 88 years.
Make that 24,000 years, though Pu-239 isn't relevant to an RTG discussion. My question stems from the fact that, AFAIK, the only significant sources of Pu-238 to date have been Russia and the US. It's somewhat special-use material and producing it by either transmutation of neptunium-237 or isotopic separation of plutonium from irradiated reactor fuel is troublesome and expensive. Assuming China hasn't just bought some from Russia, that seems to imply that they foresee enough need for it to have set up their own production facility. Which would be interesting.
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plutogno
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« Reply #65 on: 11/13/2012 06:16 AM » |
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the rover of Chang´e 3 would operate about 2.5 earth years on the lunar surface
IIRC the lander is RTG-powered. the rover is solar-powered and well isolated to survive the lunar night. I don't expect it to last more than a few months
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Galactic Penguin SST
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« Reply #66 on: 11/15/2012 06:26 PM » |
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The latest model of CE-3 on display right now at the 2012 Zhuhai Airshow..... (with a CE-1 model as bonus  )
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KelvinZero
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« Reply #67 on: 11/15/2012 08:36 PM » |
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The chinese fake moon landings apparently still have a long way to go to catch up with the american fake moon landings  But seriously, Im really looking forward to this.
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Dalhousie
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« Reply #68 on: 11/15/2012 11:51 PM » |
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IIRC the lander is RTG-powered. the rover is solar-powered and well isolated to survive the lunar night. I don't expect it to last more than a few months
On the other hand it might last for years, which would be great.
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Dalhousie
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« Reply #69 on: 11/15/2012 11:55 PM » |
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The latest model of CE-3 on display right now at the 2012 Zhuhai Airshow..... (with a CE-1 model as bonus )
I am very interested in the painted backdrop. One spacecraft shown is the Chang'e 3 lander apparently shining a light on the surface. What appears to be a lamp is also visible on the model (above and to the right of the thruster quad). Do you know what the prupose of this is? Night operations? Imaging of possible frost build up on the surface? I would not have though Sinus Iridium was far enough north for that. the other spacecraft appears to include an ascent vehicle. Is this to do with future sample return missions? The Chang'e 3 and possible sample return mission landers in the art work are almost identical, suggesting a common desig, as with the Russian heavy Luna missions of course. However the tanks are larger and fifferent in shape to those shown in the model.
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Ben the Space Brit
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« Reply #70 on: 11/16/2012 11:42 AM » |
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One spacecraft shown is the Chang'e 3 lander apparently shining a light on the surface. What appears to be a lamp is also visible on the model (above and to the right of the thruster quad). Do you know what the prupose of this is? Night operations? Imaging of possible frost build up on the surface? I would not have though Sinus Iridium was far enough north for that. It might not be an optical-wavelength emitter; it might be part of a near-UV or near-IR-wavelength system for some other experiment on board.
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ChileVerde
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« Reply #71 on: 11/16/2012 03:21 PM » |
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Night operations?
Maybe. The very little that's come out about this suggests that the RTG may provide more than just keep-alive power during the night. Or not -- the wording, at least in English, is a bit ambiguous. http://www.china.org.cn/china/2012-08/13/content_26214399.htm
China's moon rover to use domestic nuclear battery
August 13, 2012
<snip>
[The rover] will be powered by the sun during daytime and by nuclear power during the night...
The battery will be the only source of energy during [the lunar night] and will prevent the equipment from freezing.
<snip>
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Dalhousie
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« Reply #72 on: 11/19/2012 01:03 AM » |
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It might not be an optical-wavelength emitter; it might be part of a near-UV or near-IR-wavelength system for some other experiment on board.
Quite possible, but again, what for?
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luhai167
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« Reply #73 on: 11/19/2012 03:35 AM » |
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Pu-238? AFAIK, brewing Pu-238 is not a trivial matter. Do we have any other information about China's production of it?
China may just buy it, if not. There plenty fast reactors in China to process it Neptunium-237, and plenty of spent fuel to provide the Neptunium given now nearly 50 years of reactor operations.
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randomly
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« Reply #74 on: 11/19/2012 03:48 AM » |
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There is nobody to buy Pu238 from. You don't need a fast reactor, just a reactor designed to have target irradiation sites where you can easily insert and remove the Neptunium-237 targets. Similar to weapons grade Plutonium production you don't want to over expose the target to the neutron flux before you remove it and process it to recover the Pu-238. Over exposure results in additional neutron absorptions creating other unwanted isotopes.
So you do a lot of target swapping. and a lot of target processing, and a lot of target fabrication. You need facilities purpose built that can handle that process cycle of radioactive material.
However they may just use another radioisotope like Strontium-90 and compensate with extra shielding etc.
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