[Heiwa]

This MMRTG Nuclear Power Source

will provide electric power to the NASA Curiosity rover just sent off to Mars!
MMRTG uses PbTe/TAGS thermocouples (from Teledyne Energy Systems) and produce 125W electrical power. What DC voltage is coming out of the magic box is not known.
https://en.wikipedia.org/wiki/Multi-Miss ... _Generator

[rerevisionist]

Sunlight '... the average solar radiation arriving at the top of the Earth's atmosphere at any point in time is roughly 1366 watts per square meter...'

That's Wikipedia. Mars is typically 1.52 times as far from the sun as earth. So, near Mars, using the inverse square law, solar radiation is about 1366/1.52^2, i.e. 590 watts/ sq metre. So, to get 125 Watts, even aas far away as Mars, needs .2 sq. metre. This is less than one square of side 50 cm. (This assumes 100% efficiency, of course).

Looks like solar power is a definite winner. (I'm assuming you're quoting correctly - but it's unlikely to be 125 kW!)

[Heiwa]

The US MMRTG Nuclear Power Plant produced by US Teledyne Energy Systems is supposed to work during Mars nights (no sun!) to heat and light the NASA Curiosity Mars rover.
The Power¨Plant weighs <50 kgs (it is fitted aft on top of the rover) but contains about a kilogram of Plutonium that, one way or another, will produce 125-100 W electric power, at unknown voltage, for 14 years!

[rerevisionist]

Yes - of course the night issue doesn't arise in space, provided there are enough panels to intercept sunlight from any direction. With the tiny power consumption described, I'd have thought storage batteries would be easy to arrange and more convenient, lighter, and cheaper than anything nuclear....

... a standard car battery... is rated at 45 amp/hours. That means it can crank out 2.25 amps for 20 hours. ... averaging about 12 volts during the period. 2.25 amps times 12 volts equals 27 watts. 27 watts times 20 hours equals 540 watt/hours...

The Martian day is about the same as earth. Even the tilt of its axis resembles the earth's. So two or three car batteries would be fine for 125 watts. -- But if you invoice them for a few tens of millions of dollars for a supposed nuclear thing, you can pay a PR firm to tell lies, and pocket the rest.

[Heiwa]

And here something completely different:
https://www.military.com/news/article/na ... RC=navy.nl

This US rustbucket is 50 years!

[rerevisionist]

The specification of the 'MMRTG' says The MMRTG contains a total of 4.8 kg (10.6 lb) plutonium dioxide that initially
provides approximately 2,000 watts of thermal power and 120 watts of electrical power (that's the weight of radioactive stuff) and as to time: The design goals ... include ... optimizing power levels over a minimum lifetime of 14 years....

The blurb is curiously misleading - 'conversion of heat directly into electricity..' - there's a suggestion of something specifically nuclear, when in fact all the thing does is use heat and thermocouples. 'MMRGT' = Multi-Mission Radioisotope Thermoelectric Generator'.

Also there's a lot of emphasis on safety, which seems odd for something intended for outer space! This seems to be in case the systems fail, so the objects may fall to earth. It looks more like a political and legal issue than a scientific one. So does the 14 year lifespan.

[FirstClassSkeptic]

Does NASA really have a Rover on Mars? I don't think so. Convince me they do.