> 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]
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....