Mars Atmospheric Kinetic Engine

elderflower · 2020-03-08 06:25:47

Use of CO2 for power would probably be by splitting it into CO and O2. These can be liquefied and stored, then boiled off and reacted together to recover the power required. Exhaust is CO2 which might be recovered or dumped to Atmosphere.
No novel technology here.

louis · 2020-03-08 08:33:28

Methane and oxygen (produced in the equatorial regions) would suffice and of course, just because you are at the poles doesn't mean you can't use solar power in any case. A summer expedition would have many hours of solar power available during the sol.

SpaceNut wrote:

That would require nuclear power levels in order to keep equipment and personnel from freezing leaving energy for the mining and processing of it for use elsewhere.
There is no need to have it roar to life on the first cycle as it can do a warm slow build up where the exhaust not going back into the atmosphere as it can be sent to a tank for later reuse until we gain enough co2 to make sure that it will have the capacity to run. Its the heat source that when its concentrated can make the low level of co2 work even harder.

SpaceNut · 2020-03-08 09:48:11

elderflower, co to o2 processing is not needed just melt and collect to send through the pipeline back to the main base. This can be small (4" dia.)at first as its continually operating. We want the co2 for use at base camp for many things.

Louis conversion to methane and oxygen will waste the solar energy which is of limited time to setup and take it down that stops it from being even close to useable. It takes months to move across the mars surface as there are no roads.

As man moves towards the pole we lay the tubing pipeline as we go. Once there we setup the reactor using the waste heat to melt the ice and collect the vapor as it rises pushing it down the tube to the awaiting tank at its end. The system works fully or semi automated until the area is clear. The reactor then is moved to its next site on the vehicle it rests on with the operation of melt and collect being performed once more..

elderflower · 2020-03-09 05:44:37

Spacenut. Are you proposing a thousand miles of pipeline? That will need a number of compressor/pump stations (depends whether it is moving gas or air), pig launchers and traps and intermediate storage, just like pipelines on earth. That all involves a lot of power and a lot of mass.
You need the lightest possible, highly portable energy store and that means nuclear fission or a tank of fuel in current technology. Maybe big batteries in the near future. For Mars fuel you have to have oxidant as well.
Local power distribution can be by compressed gas, hydraulic pressure or electricity but for long distance energy transport I can't see anything other than portable systems coming into use for many years. When this does happen I expect it to be by HV DC overhead lines just like on Earth.

Calliban · 2020-03-09 06:32:28

Shipping liquid CO2 from the poles is a long term aspiration. It will only make sense when we are producing 100's thousands of tonnes of steel each year on Mars. But as Elderflower says, it may be more efficient to put a nuclear reactor at the poles, use machinery to load mined dry ice into boilers and to transmit power using HVDC powerlines. I guess it will depend upon how much material you need to transmit the average MW using each option.

The point about compressing atmospheric CO2, is that on Mars the typical air temperature is far beneath CO2 critical point. Very little compressor work is needed to compress it to liquid and Mars night-time temperature is beneath the liquefaction point at a pressure of 6bar. So atmospheric compression could be a very efficient way of storing energy and low temperature solar heat could be converted into mechanical power very efficiently. Who knows, we may be able to store enough energy in liquid CO2 and solar heat to power a Martian base through a dust storm.

Storing solar heat will be easier on Mars, because at the near vacuum pressure of the Martian atmosphere, loose Martian fines are about as good an insulator as rock wool on Earth. We could store liquid CO2 in a pre-stressed concrete vessel and solar heat would be stored in natural rock formations beneath the ground. Liquid CO2 would be injected into a boiler using a centrifugal pump. The boiler will contain a heating tube that transfers heat from the ground into the liquid CO2 using a low melting point fluid, probably brine. Boiler tubes could be plastic. The CO2 vapour would then expand adiabatically through a turbine or could even be distributed through a manifold that powers various air tools.

The equipment involved is very simple and should be the sort of things that we can build on Mars from native materials: Compressors, pumps, pressure vessels and pipework. On Earth, air tools are cheaper than electric tools thanks to their simplicity. I would therefore expect air tools to be made before electric tools on Mars.

Last edited by Calliban (2020-03-09 06:49:12)

SpaceNut · 2020-03-09 16:49:50

Lets see if we can make a 1000 gallon tank transport that would use the boiloff to suppliment power with solar panels on the roof of the tank, and batteries which could be nuclear charged and supplimented for the journey from the poles to the near temperate zone where we will have landed as we want the co2 and any water that we mine at the base.

elderflower · 2020-03-10 05:00:14

Such tanks would probably be wound with locally produced mineral fibres (glass/ basalt/asbestos) and imported resin. For LCO they wouldn't need a liner but for LOX they probably would. This is to ensure that the optimum resin doesn't react with the oxygen. An explosion in this tank would be beyond embarrassing.

SpaceNut · 2020-03-10 16:08:27

That is a future state but for mars early period. I would favor taking the tanks out of any empty cargo lander to utilise in making the transport vehicle. Short of wheels and motors to make the vehicle out of we can bend metal from the empty cargo landers to build up a frame to place the tank onto..

elderflower · 2020-03-11 05:10:35

That would be what would happen to get over a disaster, but the normal state of affairs would be to refuel and return all or almost all the landers if they are not write-offs, wouldn't it?
Welding a tank would be quite straightforward on Mars, if that is what you want to do. Type 301 stainless could be welded with sticks or wire feed which must be imported. I'm not sure, but I expect that shielding gas will not be required in the Mars atmosphere.
Weld spatter probably is bad for space suits.

SpaceNut · 2020-03-11 17:59:09

The building of a pressurized transportation garage sounds like where we would want to do welding within as you noted so as to not be doing so in a space suit at the equatorial base camp.
The large scale refueling of the starship is just why its going to be a long time before cargo ships will be going back if at all for the future with there use.
Going with small mostly expendable cargo landers allow for the building and resources for a future on mars from the materials that we can make use of from them.

knightdepaix · 2020-03-12 16:26:17

Another thread can be relevant to this topic.
For the energy source to the compressor at the top of the mountain,
1) may Radioisotope thermoelectric generator generate electricity and heat to compress the CO2. Then an economy of importing Earth nuclear waste to Mar can be possible. Could a nuclear transmutation factory be built next to the compressor plant?
2) may a dish receiving microwave from solar panel on Mars orbit supply the energy?

SpaceNut · 2020-03-12 18:53:05

I gave a post after yours on use of the microwave heating as well http://newmars.com/forums/viewtopic.php?id=8916
and I think some of the thoughts can possibly worked together in the design...much like the em rail launcher topic its about getting the correct elements together in the discusion...

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