LIVE: Chang'e-3 lunar probe and rover, CZ-3B - Xichang - December 1, 2013

[Joris]

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

[ChileVerde]

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

That's Pu-239: different stuff, differently produced.

[Watchdog]

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. 

[savuporo]

MERs were planned to last for 90 sols, too.

[ChileVerde]

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.

[plutogno]

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

[Galactic Penguin SST]

The latest model of CE-3 on display right now at the 2012 Zhuhai Airshow..... (with a CE-1 model as bonus 

[KelvinZero]

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.

[Dalhousie]

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.

[Dalhousie]

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.

[Ben the Space Brit]

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.

[ChileVerde]

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>

[Dalhousie]

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?

[luhai167]

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.

[randomly]

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.

[ChileVerde]

However they may just use another radioisotope like Strontium-90 and compensate with extra shielding etc.

But the article that started this discussion (and there's just the one article that I know of) specifically says Pu-238:

http://www.china.org.cn/china/2012-08/13/content_26214399.htm

    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.

[ChileVerde]

Here's some more information about the mission.

Chinese battery will power country's first moon rover
Created: 2012-8-13
Author:Yang Jian

A CHINESE nuclear battery will power the country's first moon rover after it lands on the lunar surface next year on board Chang'e-3, China's third lunar probe, according to the chief scientist of China's lunar project.

The battery, using plutonium-238, will be able to power the 100-kilogram vehicle for more than 30 years, Ouyang Ziyuan said over the weekend.

"The nuclear power system will make China the third country apart from the United States and Russia to be able to apply nuclear technology to space exploration," Ouyang said.

The rover will patrol the surface for at least three months with the vehicle being controlled by scientists on Earth, Ye Peijian, chief commander of the Chang'e-2 and Chang'e-3 missions has said.

Ouyang said the rover would be powered by the sun during daytime and by nuclear power during the night.

A lunar night lasts for 14 days with temperatures reaching below minus 100 degrees Celsius. The battery will be the only source of energy during that time and will prevent the equipment freezing, he said.

An expandable solar panel will absorb the sun's energy during the day.

As plutonium-238 decays to increase its temperature to around 600 degrees Celsius, the battery system will turn the heat into electricity, said Li Guoxin, a researcher with the Shanghai Space Energy Research Center.

The Chang'e-3 is expected to be launched from the Xichang Satellite Launch Center in southwest Sichuan Province.

<snip>

Ouyang said the rover and the Chang'e-3 would stay on the moon until the Chang'e-5 probe arrived to take samples and the rover back to the Earth.

He said China was currently working on the Chang'e-5 as well as a new Long March-5 rocket to carry the probe.

[Watchdog]

Isn´t that a nice idea to combine solar and nuclear power in a single vehicle? Chinese scientists don´t just copy, rather they learn and improve. Switching the RTG between heat and heat/power modus perfectly matches the needs on the lunar surface. When solar power is available the extra electricity from the RTG is used to power scientific instruments. However, let us first wait until the landing has been successful before applauding.

[cheesybagel]

This video from CCTV 13 shows the probe being assembled, as well as rover tests:

[Galactic Penguin SST]

This video from CCTV 13 shows the probe being assembled, as well as rover tests:

A bit of interesting facts from the report:

1. The rover can tolerate moving on a 20 degree slope and crossing over 20cm high obstacles (note that the landing zone at Sinus Iridium only has slopes up to 7 degrees)

2. The lunar simulation lab uses volcanic ash as a lunar soil replacement