The Martian

I went to see The Martian this weekend, the movie with Matt Damon as the astronaut stranded on Mars.

Matt DamonI don’t really want to review the movie here, I would just like to talk about the scene in the movie where he digs up a RTG that the astronauts had buried previously and marked with a scary flag as a warning to anyone who might stumble across it, you know radioactivity and all.

Here is a photo of a real RTG powered by plutonium 238. This one was used on Cassini.

RTG from CassiniHere are a few facts regarding RTGs

1. Plutonium 238 is an alpha emitter. These particles can be stopped by a sheet of paper. Real RTGs have sheet metal shielding. Humans can safely be next to these without any worries. (see the photo above.)

2. The radioactivity of the plutonium 238 releases enough energy to make itself red hot from the heat.

3. The heat is harnessed to produce electricity directly with hundreds of thermocouple junctions.

4.  RTGs have been used in deep space probes for decades. They will continue working when the light from the sun is very dim and solar panels aren’t feasible.

That being said, there is no reason for the movie astronauts to have buried the RTGs. They would still be working day and night producing electricity and heat for the astronauts. The rover shown on the movie should have been powered by RTGs. Then, Mark Watney (Matt Damon) could have driven the rover day and night.

Furthermore, serious adults who consider actual Mars missions include nuclear power in their plans, both for propulsion and for heat and electricity.


2 thoughts on “The Martian

  1. Anneb says:

    I suppose you are right about the safety of the device, but how about the safety of the fuel Plutonium? It is an extremely toxic chemical, and can be very easily used to create a nuclear bomb. How about the fission waste products? I think the lifetime of most practical waste storage containers does not come close to what is actually required? Thorium may not have these disadvantages. I think it is not a good idea to confuse uranium/plutonium based technology with thorium fission and nuclear fusion technology?

    • admin says:

      The isotope of plutonium used for RTGs is Pu238. It is NOT fissionable and CANNOT be used to create a bomb, ever. As to the safety of the fuel, did you see the photo of the woman in street clothes next to the RTG? Is this not safe?

      Regarding the extreme toxicity of plutonium – Dr. Bernard Cohen dealt with this almost 30 years ago. You can read his paper here.

      Also, to prove the myth of the extreme toxicity of plutonium, Dr. Cohen challenged Ralph Nader to eat as much caffeine as Dr. Cohen would eat plutonium. Nader refused.

      As for long lived waste, Kirk Sorensen has discussed this here. Thorium molten salt reactors produce significantly less waste per unit of electricity generated and have few long lived fission products that require storage beyond a century. This is a technical problem that is solvable.

      Please show me where I have confused “uranium/plutonium based technology with thorium fission and nuclear fusion technology?” BTW, thorium is not fissionable. It is fertile. It has to be bred to U233, then it can be fissioned.

      As for fusion, the old joke was that it is the energy of the future and always will be. Various governments have spent 50 years and $50 billion attempting to make a working fusion reactor. We still don’t seem to be any closer, though now it is more like 60 years and $60 billion.

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