Question

Roughly how much plutionium-238 would be needed to run a Radioisotope thermoelectric generator for a mars rover that weighs 4000 lbs with a range of 500 mi? what would be the voltage output and the power needed? These calculations can be rough and any needed assumptions can be made. I'm just trying to get a general idea of how this could be calculated.

Answer 1

Considering the nature of the question, there are several assumptions I would make.

I will base several of these on existing technologies.

Assumptions

1. The top speed of the Mars Rover is . This figure is taken from the figure of the Curiosity Rover.

2. Our radioisotope generator has an efficiency of . Most generators have an efficiency in range, with efficiencies of over unrealistic.

3. The Curiosity Rover, weighing about , requires around to drive, which implies it requires this level of power to maintain its speed. Assuming forces such as friction are the only retarding forces ( Mars' atmosphere is too thin to cause noticeable drag ), and that friction scales with mass, we would require roughly two times or around to drive the rover.

4. The onboard use very little power. Most estimates say that they account for less that of the total generated power of the Curiosity's power supply. Assuming we have similar instruments, we would require around .

Therefore, for an estimate of the maximum power consumption, let us consider a rover maintaining its top speed and using all of its instruments.

Therefore, the total power required would be

Considering an efficiency of ,

We know that Plutonium-238 has a power density of about .

Therefore, we need

of Plutonium-238.

This is around or of Plutonium-238.