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A spin-off from the pneumatic tool discussion. I am about to start a new job, so my time on the board will be more limited from today onwards. But in light of discussion around the AHR on other threads, I thought this topic was timely.
The need exists for construction equipment that can be put to work at a developing Mars base, with minimal requirements, in terms of total mass imported from Earth. Ideally, the solution would also be simple, requiring minimal maintenance and able to complete many thousands of hours of work without the need for additional supplies from Earth. Numerous options are possible and it is my intention that total system mass be compared here, to identify the most desirable option in terms of system resilience and total cost.
An example piece of construction equipment is the JCB JS330 excavator, which has total mass 36,228kg and maximum engine power 210kW.
1. Nuclear powered construction equipment. Investigations into the Aqueous Homogenous Reactor have revealed that it is possible to produce extremely compact nuclear reactors, with high power density. The Oak Ridge AHR had an inner core diameter of 32" (81cm) and thermal power 1MW. It was coupled to a steam turbine and produced 150kW of electrical power. In this scenario, I would propose that a compact AHR be used to generate heat at 250°C within an excavator or other piece of equipment. The vehicle would carry a tank of liquid CO2. The AHR would heat the L-CO2 to 250°C using a stainless steel heat exchangers. Superheated CO2 would then expand through a turbine, powering a hydraulic motor and charging a hydraulic accumulator. The vehicle would then draw power from the accumulator for movement and digging. Liquid CO2 would either be piped to the construction site from a well, or generated by a compressor at the site and stored within a tank. Refilling the tanks on the construction machinery would be via a hose, with L-CO2 draining into the tanks by gravity.
2. Radioisotope power sources (Sr-90) have been mentioned as possible power sources for vehicles on this forum before. They would operate in much the same way as a reactor, but would likely produce thermal energy that is stored in molten salt. This would then raise power by boiling a working fluid in a heat exchanger (as above). The main advantage with RTG power is that shielding is not needed to protect people in the area. Disadvantages are limited power and unless the isotopes are produced on Mars, the need to launch highly radioactive materials from Earth.
3. A third option is to power equipment with stored chemical propellant, such as L-CO and L-O2, liquid methane, methanol, or hydrazine. This is simpler than a nuclear powered option and may involve lower total mass at the vehicle. However, the propellants must be manufactured and a CO2 buffer gas is still needed to reduce engine temperatures and prevent piston heads from melting.
4. Battery electric equipment is also possible and has been explored on this forum under a separate thread. Advantages are relative simplicity. Disadvantages are the limited power density and high mass of batteries and long recharge cycles. There is the possibility of direct electric power for some equipment as well.
Last edited by Calliban (2021-04-18 07:47:48)
"Plan and prepare for every possibility, and you will never act. It is nobler to have courage as we stumble into half the things we fear than to analyse every possible obstacle and begin nothing. Great things are achieved by embracing great dangers."
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For Calliban re new topic! Best wishes for success with this promising concept.
It seems (to me at least) that design teams around the planet will be thinking along similar lines. I hope that a way can be found to bring them together, or at least insure communication is shared between them.
Edited 2024/04/06 (th)
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Zeno demonstrates its first Sr-90 radioisotope heat source
https://www.ans.org/news/article-5499/z … at-source/
DARPA tasks Northrop Grumman with drafting lunar train blueprints
https://www.theregister.com/2024/03/20/ … oon_train/
China building 20-storey nuclear space engine to power mission to Mars…with boffins ordered to ‘innovate or DIE’
https://www.thesun.co.uk/tech/26792968/ … gine-mars/
too many random events and unforeseen danger that need a human touch to fix?
Equipment at first on Mars could be mini-size vehicles that unfold, some small excavators, the lifting crane, wheel loaders, crawler dozers, international companies like Caterpillar, Hyundai probably already have plans to connect to unusual power sources or smaller digger designs to work at high altitudes, desert and polar conditions on Earth. Compniaes like Volvo have their own design for articulated haulers and road pavers in difficult Nordic conditions.
The Elusive Dream of Fully Autonomous Construction Vehicles
https://www.wired.com/story/the-elusive … -vehicles/
Robot excavators and other equipment held big promise for heavy equipment makers—like self-driving cars, the technology has proven difficult to perfect.
Some fully autonomous vehicles are on the road in China and the US, but just as the dream of driverless cars and robotaxis has yet to come to true, the promise of AI in construction appears to have fallen short.
Major companies like Caterpillar in the US, Doosan in Korea, and Volvo in Europe started experiments with fully autonomous heavy-duty machinery for construction sites a few years ago, but the idea has yet to advance beyond the prototype stage or become widely available.
and if something gets stuck what kind of human fixes stuff?
'Elon Musk says Tesla Optimus robot should cost ‘less than half of a car’'
https://electrek.co/2024/03/27/elon-mus … -half-car/
also remote operation
https://www.youtube.com/watch?v=zBPlGz1T5gs
Last edited by Mars_B4_Moon (2024-04-06 01:30:48)
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