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How the Curiosity Rover's Nuclear Battery Works

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Re: How the Curiosity Rover's Nuclear Battery Works

#91

Post by nodata »

grecy wrote: post #10

Many people here in the far north have extensive solar setups and live completely off-grid. Unfortunately in winter, we only get ~4 hours of sunlight, and it's a pain to sweep snow off the panels every day at ~ -30C to -40C We don't get much wind, and rivers are only liquid for ~4-5 months, so wind and hydro are not popular. I've been investigating commercial thermoelectric couplings as a source in the winter. Everyo…

Toshiba makes a small nuclear reactor for your home: http://www.engadget.com/2007/12/19/toshibas-building-a-micro...

Re: How the Curiosity Rover's Nuclear Battery Works

#92

Post by nickolai »

shirro wrote: post #81

Given the MSL has a constant power source does that mean it can operate 24hrs and 40 minutes a day? Do they have driving lights or can drive with IR or other sensors? If so they could get a lot more science done than the MER mission. Or do they have to channel the power into heaters each evening?

>Or do they have to channel the power into heaters each evening?

AFAIK, No. The battery generates 2kw of heat in addition to the electricity, so I dont think the rover even has any heaters.

Re: How the Curiosity Rover's Nuclear Battery Works

#93

Post by iridium »

MichaelApproved wrote: post #89
nnnnnnnn wrote: post #27

Earlier quoted context omitted.

Is radio communication with the rover even possible at night? We only have line of sight to mars during the martian daytime.

Not sure about this specific mission but I think we have had satellites around mars in the past that have helped relay messages when line of sight isn't available.

Yup. The 3 satellites will be used for primary communication along with an X-band transmitter on the rover itself to talk to earth.

Edit: Link (communications): http://en.wikipedia.org/wiki/Curiosity_rover#Specifications

Re: How the Curiosity Rover's Nuclear Battery Works

#94

Post by potkor »

grecy wrote: post #10

Many people here in the far north have extensive solar setups and live completely off-grid. Unfortunately in winter, we only get ~4 hours of sunlight, and it's a pain to sweep snow off the panels every day at ~ -30C to -40C We don't get much wind, and rivers are only liquid for ~4-5 months, so wind and hydro are not popular. I've been investigating commercial thermoelectric couplings as a source in the winter. Everyo…

The sensible way to get electricity out of burning wood would be a steam turbine or stirling engine-based micro CHP (https://en.wikipedia.org/wiki/Micro_combined_heat_and_power).

Re: How the Curiosity Rover's Nuclear Battery Works

#95

Post by i_cannot_hack »

bigiain wrote: post #62
sehugg wrote: post #8

Earlier quoted context omitted.

According to Wikipedia, 125 watts when it was launched, down to about 100 watts in 14 years. The JPL guys claim that the RTG is really just a trickle charger for the batteries that actually handle the load -- which likely has transients that the thermocouple in the RTG couldn't handle. I don't know the lifetime of the lithium-ion battery pack but I'm guessing it'll degrade way before the RTG power decreases below the…

There's a LiPo technology called "thin film lithium" which is claimed good for 10,000 cycles - assuming one charge/discharge cycle per day (and incorrectly using earth-days for simplicity), that'd give you ~27 years lifetime from the battery. (I wonder if this'll end up with the same "over engineered" reliability that let the Spirit rover last over 6 years when intended for a 90 day mission?)

The Opportunity rover is still up and running, which means it has exceeded its planned duration of activity more than thirty times over.

Re: How the Curiosity Rover's Nuclear Battery Works

#96

Post by Erifcit »

grecy wrote: post #33
Erifcit wrote: post #15

Earlier quoted context omitted.

This might interest you. http://www.biolitestove.com/campstove/camp-overview/features...

Thanks. I looked into that a while ago (and a similar one), and it looks like any power produced from the TEC is considered a bonus, and is in the range of 1-5W, probably only enough to charge a phone, etc. I'm looking to produce a sustained 150W + to charge deep cycle batteries.

Sorry, this is the one I meant to link to (probably the similar one you mention). Might be a better design to scale up. Don't know if the TEC is any more efficient though.

http://www.kickstarter.com/projects/tpod1/tpod1-thermoelectr...

Re: How the Curiosity Rover's Nuclear Battery Works

#97

Post by wcoenen »

shirro wrote: post #81

Given the MSL has a constant power source does that mean it can operate 24hrs and 40 minutes a day? Do they have driving lights or can drive with IR or other sensors? If so they could get a lot more science done than the MER mission. Or do they have to channel the power into heaters each evening?

> does that mean it can operate 24hrs and 40 minutes a day?

Not if it consumes electrical energy from the batteries faster than the MMRTG replenishes it. Then it needs to "rest" to give the MMRTG a chance to recharge the batteries.

> Or do they have to channel the power into heaters each evening?

Besides 125 watts electric, the MMRTG also continuously outputs 2000 watts of heat. Heat can be pumped around the rover (either for cooling or heating) to keep the instruments at optimal temperature [1][2]

[1] https://www.youtube.com/watch?v=fBtXnug-rgM#t=89s

[2] http://www1.nasa.gov/mission_pages/mars/images/20081209_msl....

Re: How the Curiosity Rover's Nuclear Battery Works

#98

Post by swalsh »

stcredzero wrote: post #23

[In the voice of old "Gauntlet" game] "About-robots.com needs editing badly!" > The first time I heard about the Curiosity Rover nuclear battery, I was thinking this must be top notch technology. What a surprised I had when I saw it has been used for more that 40 years already. Évariste Galois came up with mathematics in the early 1800's which only in just the past several decades had widespread applications in crypt…

e-ink is another good example. The technology was originally developed in the 70's.

Re: How the Curiosity Rover's Nuclear Battery Works

#99

Post by SpikeDad »

joaorj wrote: post #13

this article is wrong on many things. one being that the rover can drive during night. the small power output of the "nuclear battery" is not used to drive the rover. it used to recharge batteries during day and night so that the rover can operate on the batteries during the day.

Correct. If the writer had only watched the NASA broadcast he would have heard it right from the horse's mouth. Because of the low temps at night, the power requirements to heat up the rover and devices would not make it worthwhile. In addition, the total output of the generator and batteries on a particular day is not enough for it to run continuously for the entire day.

Another interesting point brought up was that the rover was tested to 3x life but not to failure. It's certainly possible for it to run for many years longer than the stated life.

Re: How the Curiosity Rover's Nuclear Battery Works

#100

Post by maxerickson »

JoeAltmaier wrote: post #50
Shadow6363 wrote: post #35

Earlier quoted context omitted.

Isn't the friction dependent upon the normal force which on Mars would be less. Therefore, shouldn't the force required to overcome that also be less?

Wheels need friction to develop acceleration. So its a negative not a positive.

It's only a negative if the vehicle needs to accelerate quickly. So sufficient friction is sufficient, not a negative or a positive.

Given that the batteries store roughly 2.4 kW-h, it's probably safe to assume that the max drive power is less than 500 watts (2.4 kW-h / 10 hours -> 240 watts). Earth side electric vehicles commonly have drive power over 100 kilowatts.

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