To RTG or not to RTG the size is the question

SpaceNut · Yesterday 14:25:39

tahanson43206 wrote:

For SpaceNut re new posts in MOXIE topic ...
Thanks for the new posts you added, with what sure looks like ** very ** encouraging news of larger scale operations on Earth.
My point was (and remains) that the original small MOXIE unit could be replicated in large numbers and deployed to Mars with an RTG able to provide the 300 watts it needs. It does NOT need to be mounted in a rover. That was convenient for the research mission.
Your posts show that researchers/engineers are working on larger scale versions.
That is all good, but the fact remains, the ONLY such system tested on Mars is the 300 watt version.
So we should be able to figure out how many 300 watt units are needed to supply oxygen for humans or fuel and oxidizer for machinery.
***
In one of your posts you seemed (as I read it) to think that carbon monoxide had never been tested on Earth for internal combustion engines. I am 95% confident that kbd512 researched that long ago and found that such engines had most definitely been tested on Earth.
An internal combustion engine that runs on CO and O2 will produce less power than would an engine that has hydrogen in the fuel, but I question why that makes a difference. To make hydrocarbon fuels will consume energy that you might be able to get back if you have an engine designed for it, but why bother? CO and O2 make a perfectly acceptable energy storage system and the whole process is so much simpler, I just don't see why anyone would go to all the trouble of fooling around with hydrogen.
(th)

SpaceNut · Yesterday 14:35:01

Well the desire to use an RTG of the Perseverance size just does not make to common test of financial responsibility.

The Perseverance rover's power source is a Multi-Mission Radioisotope Thermoelectric Generator (MMRTG), essentially a nuclear battery using heat from plutonium-238 decay to generate steady electricity (around 110 watts) and heat for its systems on Mars, providing reliable power for its long mission unlike solar panels. Provided by the U.S. Department of Energy, this compact device uses the Seebeck effect with thermocouples, offering dependable power for years in the cold Martian environment, crucial for science and operations.
How it Works:
Heat Source: The MMRTG contains plutonium-238 dioxide, a ceramic material that releases heat as it naturally decays.
Conversion: Thermoelectric couples (semiconductors) convert this heat directly into electrical current through the Seebeck effect, creating a temperature difference.
Electricity & Heat: The system produces both electricity for the rover and heat to keep its instruments and systems warm in extreme cold.
Reliability: With no moving parts, MMRTGs are highly reliable and provide continuous power for extended missions, essential for deep space and Mars exploration.
Key Features:
Power Output: Starts at about 110 watts and gradually decreases over time as the plutonium decays.
Fuel: Uses plutonium-238, a robust and long-lasting radioisotope.
Heat Management: Has "fins" to radiate excess heat and also provides warmth for the rover.
Provider: Supplied to NASA by the U.S. Department of Energy (DOE).
Why it's Used:
Provides consistent, long-term power, independent of sunlight, making it ideal for Mars exploration.
Compact and durable for space travel.
Enables long-duration missions and complex scientific operations far from the Sun

https://en.wikipedia.org/wiki/Perseverance_(rover)

While the total Perseverance rover mission cost around $2.7 billion, the specific Radioisotope Thermoelectric Generator (RTG) powering it isn't itemized in the overall budget, but similar NASA RTGs cost roughly $100 million each, requiring plutonium and years of production, with Perseverance using about 10.6 pounds of plutonium for its.
RTG Specifics
Cost: While not a separate line item, similar NASA RTGs cost around $100 million to produce.
Plutonium Content: The system on Perseverance uses about 10.6 pounds of plutonium-238.
Production: RTGs are complex systems built at national labs (Oak Ridge, Los Alamos) and assembled at Idaho National Laboratory (INL) over years, involving robotic assembly and rigorous testing.
Perseverance Rover Total Cost Breakdown
Total Mission: ~$2.7 billion (including inflation, closer to $2.9 billion).
Spacecraft Development: ~$2.2 billion.
Launch Services: ~$243 million.
Operations (2-yr prime): ~$200-300 million.
So, while the RTG is a critical component, its significant cost is bundled into the overall spacecraft development, with estimates placing it around $100 million for the power system alone.

https://en.wikipedia.org/wiki/Multi-mis … _generator

The MMRTG cost an estimated US$109,000,000 to produce and deploy, and US$83,000,000 to research and develop. For comparison the production and deployment of the GPHS-RTG was approximately US$118,000,000.

it only produced the 100 watts that was used for the cycle of 3.5 hours which gave us the stated 300 watts for the device to make oxygen and the co as its is an incomplete design.

Yes an RTG gives continuous power but its at a very low level, at a very high cost and the device to use that power is a mismatch as its cycles.

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#26 Yesterday 14:25:39

Re: To RTG or not to RTG the size is the question

#27 Yesterday 14:35:01

Re: To RTG or not to RTG the size is the question

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