Type of nuclear power plant is needed by Mars astronauts ?

louis · 2008-04-04 06:41:35

Swoosh -

These calculations get a bit tricky. I did some before and ended up with a figure of 400KW for a surface area of 100,000 square metres (100x100). This was achieved by dividing what is possible on earth by 10, also to allow for night time, reduced performance of PV film as opposed to solid solar panels, dust storms and distance from the sun. Of course one has to add in on the plus side the thin atmosphere which boosts PV film performance on Mars.

So dividing by 10 seems fairly conservative to me.

The weight of the film would be 1000 KGs = roughly one tonne or 100 grams per square metre.

I'd like to have a go at my calculations again when I have time. Unfortunately it is quite difficult to get figures on weight of solar film.

Anyway 400KW is more than enough for the requirements of the initial colony if there were say six people there.

The average electricity use in the domestic home is something like 7 KW per person I think. So 7x6 is only 42 - and they aren't going to be using all sorts of electrical gadgets. On the down side they will have to store energy and there is power wastage in storage. Let's assume 50% loss. They'd probably want to be budgeting to save 100Ws - producing energy storage of 50watts. So every day in operation they'll be storing enough to operate another day in the event of the failure of the solar power system.

It may be we won't need all the 400KW, although vehicles, diggers, hydroponic farming and the like to consume a lot of power.

JoshNH4H · 2008-04-05 08:46:06

what about batteries, or power storage systems? those weigh A LOT. What about vacuums to clean 10-100 km^2 of solar panels. What is you cover something you want to explore?

Gregori · 2008-04-05 11:07:15

what about batteries, or power storage systems? those weigh A LOT. What about vacuums to clean 10-100 km^2 of solar panels. What is you cover something you want to explore?

There heavy, but so is a nuclear reactor. Power storage is nothing that hasn't been done before...

louis · 2008-04-05 11:40:35

You'll still need batteries with a nuclear reactor for many applications e.g. vehicles, back packs etc.

But batteries aren't a huge item. I'm thinking in terms of taking along the equivalent of 12 car batteries for 6 people - about 500 kgs' worth. That's a lot of battery power. In itself it could probably keep the habitat running on low power for several days.

More important though is to take along the means to make and store methane which can then be burned to produce motor power which can then be used to generate electricity, run the habitat and farm zone and recharge batteries.

Compressed air is another good way of storing energy.

We'll need to take inflatables to line trenches for gas storage, a steam engine, and turbines for driving generators or compressing the air.

JoshNH4H · 2008-04-05 15:17:15

what about batteries, or power storage systems? those weigh A LOT. What about vacuums to clean 10-100 km^2 of solar panels. What is you cover something you want to explore?

There heavy, but so is a nuclear reactor. Power storage is nothing that hasn't been done before...

2 Sp-100's (200 KW) are 10 mT. Only 1 is really needed. and batteries will have to be used for those things with solar panels, too.

knightdepaix · 2018-12-16 17:37:36

https://nssdc.gsfc.nasa.gov/planetary/f … sfact.html

Mars has 0.8ppm hydrogen-deuterium-oxide. By fractional distillation on demand of Martian atmosphere (fractional distillation of air on Earth has been performed), could the extracted HDO be used fusion?
Step 1) fractional distillation to get HDO as part of water
Step 2) HDO is enriched to become D2O in process(s)

elderflower · 2018-12-18 05:53:02

Deuterium will be in equilibrium with near surface ice deposits. So mining these, which we will likely be doing anyway, can produce abundant HDO. Electrolysis has been used to concentrate deuterium as D2O and we will probably be doing a lot of that as well. The D2O would be suitable for generating fusion fuel, but at the moment we don't have a satisfactory method of using this reaction to produce power. If we also had a source of tritium we could generate fusion power but tritium has a short half life so must be freshly made.
Heavy water fission reactors are good at making tritium and a major part of the cost of these is the heavy water moderator, which we shall have as a byproduct of water mining on Mars.

kbd512 · 2018-12-18 15:17:42

From testing, most Martian surface water ice is expected to contain significant concentrations of Deuterium in it. Although humans can ingest quite a bit of heavy water before it becomes a problem for cellular processes, my thinking is that this should be separated out since it has deleterious effects on the specific impulse of rocket fuel and human health effects, yet would be a valuable resource for fusion rockets.

To replace around a quarter of the water in your body to begin to see measurable health effects in cellular processes, I believe you'd have to drink pure deuterated / heavy water for around a week or so. Given how expensive heavy water is to make here on Earth (hundreds of dollars per liter), it's more likely that we separate out the heavy water and use it to produce resources required to use fusion driven rockets.

They say that fusion is the energy source of the future and that it always will be. That may be true for electrical power production, but rocket propulsion is an entirely different story if you're smart about how you use fusion. Using a special type of rocket that doesn't attempt to make a single watt of electrical power from the fusion reaction that also intentionally allows the superheated fusion products to escape from a magnetic rocket nozzle to carry the heat from fusion with it, Deuterium from natural Martian sources could prove to be a vital propulsion energy source for practical use of fusion energy. The energy is used to vaporize a light metal foil propellant such as Lithium, Aluminum, or Magnesium. The light metal takes the heat from fusion with it out the back of a rocket nozzle and captures more than 90% of the neutrons as well, minimizing required thermal management and neutron shielding mass since the foil storage rolls absorb nearly every neutron that's left. The system uses solar panels to charge super capacitors for input electrical power. The super caps discharge their energy in a fraction of a second, causing a supersonic implosion of the foil liner around an injected D-D pellet. In experiments, the speed of implosion (~3km/s) didn't exceed the plastic deformation limits of the Aluminum foil liner and was compressed into a little cylinder (Aluminum was used instead of Lithium because Aluminum is easier to handle in an Earth sea level atmosphere than pure Lithium metal). The supersonic implosion of the foil creates an exponentially increasing electromagnetic field inside it that traps a separately injected D-D pellet that the foil traps, compresses, and heats it until it fuses. The fusion reaction turns the metal foil into a very hot plasma that absorbs most of the neutrons and heat generated. The magnetic rocket nozzle then directs the hot metal plasma out the back of the rocket at tremendous velocity, although from the way the D-D pellet and foil are injected / formed they're already on their way out the back. That process only has to be repeated every 10 seconds for this propulsion scheme to work, which turns out to be far below what's already been demonstrated using current COTS technology solar panels and super capacitors. There are no high-field superconducting electromagnets required, either, just Aluminum wiring electromagnets.

As with every technology, there are some downsides:

1. This is pulsed power that produces significantly more thrust than a traditional electric system (1.47kN), so it basically jackhammers on the end of the rocket like the Orion style nuclear weapon detonation propulsion scheme. This mandates use of a highly reliable shock absorber system to prevent the propulsion system from literally rattling the spacecraft apart.

2. It requires around 180kWe of electrical power for the 10 second pulse repetition rate, which is quite a bit for a lightweight but rigid solar array to generate. The radiator array is comparatively tiny, but that also has to accept the thrust pulses. If the habitation module can take loads associated with ascent, then it shouldn't have any issues. In order to also return to Earth in 90 days, you need a solar array that produces roughly twice as much electricity as that since Mars receives roughly half as much solar radiation at 1.5AU. The 90 day transit only provides a 50% to 60% mass fraction. A lot less propellant and solar array area would be required with a 6 month transit and that protects a free return option that doesn't exist if you get there faster, even if the mass of the consumables is substantially reduced.

3. There is neutron radiation to contend with. It's a lot less than an operating fission reactor, but it's still requires some shadow shielding. Most of the shielding is provided by the metal propellant, but when your tanks are nearly depleted then you need shadow shielding. Transit through the Van Allen belts also poses a radiation shielding issue. A person at Earth sea level receives a natural dose of 4mSv/year. A person aboard ISS receives a dose of 1mSv/day. A person in the Van Allen belts receives a dose of 144mSv/day (on average; this can vary greatly dependent upon where you are in orbit around the Earth). The fusion rocket is expected to thrust for a period of 7 days to transit the Van Allen belts, which equates to a dose of 1,008mSv or 1.008Sv. The LD50 for humans (50% of those so exposed die within a month) is about 5Sv, but a 1Sv dose would cause minor radiation sickness in approximately 10% of those so exposed. That mandates some kind of radiation shielding inside the habitation module beyond what ISS uses. PE foam or plates of some kind or PE water tanks, most likely. A launch over the poles would also substantially mitigate the dose received, but that requires a greater dV for a more substantial plane change on the way out to Mars.

4. This scheme still requires 4 Falcon Heavy launches, 1 for the habitation module, 1 for the fusion propulsion module, and 2 for the lander sent to Mars ahead of the humans, so on-orbit mating of the propulsion modules with the habitation module is required, as is Mars Orbital Rendezvous. I presume that isn't a show stopper since that's how we built ISS and did the Apollo missions, but it's still a complication.

5. It's definitely not mass-efficient and quite possibly infeasible to aerobrake at the interplanetary transit velocities involved due to excessive vibration if you tried to aerobrake into the Martian atmosphere, so propulsive capture is more or less mandatory, even if it still requires less propellant mass than heat shield mass.

Now onto the substantial benefits:

1. This propulsion system provides enough dV capability for a pair of 90 day transits or a 1-way 30 day transit if you don't include the lander mass and instead send that ahead of the astronauts for a Mars Orbital Rendezvous mission architecture. It's also the only system with enough dV capability to return to Earth if there's a life support problem mid-way through the transit. The one-way 30 day transits could enable an opposition class mission that provide a 150 days at Mars and 60 total days spent on transit times. That requires pre-position of the lander and an Earth return propulsion stage, but launch costs are still less than a single SLS flight. The expanded dV capability enables trades between payload mass fraction and transit time. It's possible to get very high payload mass fractions for one-way cargo transfers that arrive in 6 to 9 months, perhaps even better than most other SEP options, and using economical propellants like Aluminum instead of Xenon to boot.

2. The total cost of the Lithium foil propellant and Deuterium at current market prices for D-D fusion (all experimentation thus far has used D-D fusion because Tritium is mind-blowingly expensive) for in-space propulsion for the 210 day opposition class mission with a 30 day surface stay amounts to around $1M, minus launch costs, which amount to around $82M for the propellant alone. The propellant costs to fuel the rocket required to achieve orbit could easily exceed the costs of the propellants used in space, mandating the use of more economical propellants like LOX/LCH4 to further drive down the cost of going to Mars. Subsequent missions may be achievable with as little as 1 Falcon Heavy launch to provide additional fuel and consumables, since the Lithium foil canisters are replaceable, and 1 Falcon 9 launch to deliver the crew, presuming development of a reusable Mars lander that only reenters at Mars from orbital velocity. Mars might just be a side exploration campaign that costs about as much as maintaining ISS.

3. This would provide our first practical application of fusion energy, rather than just being a fun but incredibly expensive science experiment for nuclear physicists to conduct. It's great that we can fuse atoms together at all, but we need a near term practical application that benefits humanity by providing the advanced propulsion system required to travel to other planets to determine how Earth relates to other planets like Mars and Venus for purposes of discovering how environmental factors affect different planetary bodies in our solar system. A practical way to send explorers or colonists to Mars is a nice side benefit, but the "meat and potatoes" practical science experiments are determining how the Sun and planetary environment compare between planets that experienced wildly different evolutionary paths with similar sizes and compositions and how humanity can learn to live other places as a "backup plan" for human civilization.

SpaceNut · 2018-12-19 20:39:04

https://www.space.com/37348-nasa-fissio … olony.html

aHR0cDovL3d3dy5zcGFjZS5jb20vaW1hZ2VzL2kvMDAwLzA2Ny8zMDQvb3JpZ2luYWwvS2lsb3Bvd2Vycy1vbi1NYXJzLUVNQ19GaWVsZC5qcGc=

http://etec.energy.gov/Operations/Major … rview.html

https://ntrs.nasa.gov/archive/nasa/casi … 007114.pdf

NASA engineers figure human expeditions to Mars will require a system capable of generating about 40 kilowatts of power.

https://www.space.com/33123-nasa-human- … mages.html

SpaceNut · 2020-02-05 21:43:24

Possible other topics for small reactors....
Nuclear power - How much is needed?

Thorium reactors are go! (In India)

GE Hitachi Nuclear Energy and CEZ signs small modular reactor tech deal with Czech Republic

The BWRX-300 is a 300 MWe water-cooled, natural circulation SMR with passive safety systems that leverages the design and licensing basis of GEH's U.S. NRC-certified ESBWR. Through dramatic design simplification, GEH projects the BWRX-300 will require significantly less capital cost per MW when compared to other water-cooled SMR designs or existing large nuclear reactor designs.

I think this is rather large for the home neighborhood....

http://www.nuclearfueldaily.com/index.html

tahanson43206 · 2020-02-05 22:22:39

For SpaceNut re #35

The link to www.nuclearfueldaily.com did not work for me.

ping: www.nuclearfueldaily.com: Name or service not known

I tried nuclear fuel daily but Google wasn't able to find a match.

It ** did ** find lots of citations about nuclear fuel, of course.

(th)

Last edited by tahanson43206 (2020-02-05 22:24:18)

Calliban · 2020-02-06 07:07:10

For initial expeditions and an early Mars base with power demands between 50-10,000kWe; the best choice would be a small liquid metal cooled fast reactor, using uranium metal or nitride fuel with enrichment upwards of 10%. Power conversion cycle would probably be Stirling cycle with a multiple loop configuration, for high reliability. Thermoelectric generation is also possible and even more reliable, but generally less efficient. Fast reactors are compact with high power density and high operating temperature, which makes it more mass efficient and easier to set up at a fresh site with shielding and radiator panels.

As power levels climb as the base develops into a town, light water reactors may turn out to offer better overall economics. More components can be built on Mars using ordinary steels, pressure vessels can be built from pre-stressed concretes and ceramics and the technology is a basic steam cycle, which is cheap and well understood. In the longer term, as we start building cities containing a million people or more, my hunch is that that there will be economic incentive to close fuel cycles to reduce the need for uranium supplied from Earth or mined from (probably) weak deposits on Mars. The technically easiest route would be high conversion ratio boiling water reactors, using metallic fuel that can be electrorefined. This is a compact arrangement that reprocess fuels at high decay heats, removing fission products and recasting fuel pellets into fresh fuel.

Light water reactors have been designed with net breeding ratio (CR>1). However, these suffer from low coolant volume fraction which tends to limit power density and linear fuel power rating. In the real world, a CR of 0.8 would reduce uranium requirements by 80%, allowing weaker ores with higher mining costs to support the fuel cycle without imposing heavy costs on the price of power.

Last edited by Calliban (2020-02-06 07:13:07)

tahanson43206 · 2020-02-06 08:05:48

For Calliban re #37

Thank you for this concise summary of nuclear fission options for Mars settlement.

SearchTerm:NuclearFissionOptions Author:Calliban

http://newmars.com/forums/viewtopic.php … 50#p164950

(th)

Calliban · 2020-06-28 16:40:00

I have been reading up on pebble bed nuclear reactors recently. If we were to build a nuclear reactor on Mars, using native materials and 3d printed parts; this is probably the easiest reactor to build. They can be built at power levels starting at 10MWth and could ultimately be scaled up to GW sizes. These reactors are fundamentally simple. Essentially, the only materials needed in bulk are steel, concrete, graphite and carbon dioxide. We would probably arrange the core such that reactivity control is achieved by modifying neutron reflection, negating the need for control rods.

The fuel consists of uranium dioxide particles dispersed within pyrollitic graphite balls. The core can operate at relatively low pressures, given that power density is typically quite low. If coolant temperatures are no more than 300-400C, carbon dioxide can be used as coolant. The reactor is inherently safe, because at high temperatures the doppler effect tends to reduce the fission rate without need for any active intervention. Perhaps most importantly, a pebble bed can run on natural uranium. If we source a uranium ore body on Mars, enrichment would not be necessary. The uranium would undergo chemical purification, but would not require isotopic separation. Spent fuel could be stored in sand filled casks on the Martian surface and would cool by radiating heat to the environment by entirely passive means.

CO2 would be blown up through the pebble bed by blowers and would descend through boilers made from carbon steel. We would need to carefully control pH in the boilers to limit corrosion. If the boilers have sufficient head height above the pebble bed, the reactor can rely on natural circulation for decay heat removal. The pressure vessel could either be welded carbon steel or a pre stressed ceramic vessel, consisting of concrete or baked clay bricks, with steel prestressing cables.

I like the idea of a mobile reactor that could be driven out to a subsurface ice sheet and used to pump steam into the ground. This could be equipped with a water shielding tank that would be filled before the reactor is operated and drained when we want to move the unit. The reactor would sit on a flat bed trailer and would be towed by tractor.

Ultimately, if Elon is to realise his dream of actually building a city on Mars, then the new colony will need a lot of power and probably quite a lot of heat to keep pressurized greenhouses warm. We need a reactor that can be built quickly and cheaply using native resources. The PWR and BWR require enriched uranium, zirconium and lots of stainless steel. Though they would have better power density, they lack the advantage of being simple and easily constructable from very basic raw materials.

Last edited by Calliban (2020-06-28 16:52:36)

SpaceNut · 2020-06-28 17:11:33

I pulled up a few topics that we did talk pebble reactors within and I would agree that energy development insitu for mars needs to not rely on earth for delivery to make them

Ultimate power source? - Pebble-bed reactors

Calliban · 2020-06-28 17:22:42

Spacenut, thanks. I checked out the thread you pulled up but the formatting appears to have gone awry. The last few posts disappear off the edge of the page. Is there any way of putting that problem right?

Re the pebble bed: As someone in the old thread mentions, the low power density of the pebble bed makes it non-optimum for a reactor shipped from Earth. In my opinion, this only works well if we intend to build it on Mars using native materials. Otherwise, a light water reactor is probably the best option.

Last edited by Calliban (2020-06-28 17:28:05)

SpaceNut · 2020-06-28 17:25:03

working on it as that's from the old data base coding which are not supported.

Calliban · 2020-06-28 18:33:02

An RBMK reactor might be even cheaper than a pebble bed. In spite of their safety issues, there are good reasons why the Soviets chose to pursue this design. The fuel sits in water cooled pressure tubes and the graphite moderator is cooled by a lightly pressurised gas. As it is a direct cycle reactor, no boilers are needed. That saves a lot of capital cost. Scaling up the reactor means building a wider moderator stack and adding more pressure tubes. No huge pressure vessel is needed.
Also, an RBMK can run on natural uranium, as the water volume fraction is small and it is usually boiling within the core.

These advantages allowed the Soviets to build extremely powerful nuclear reactors very quickly and cheaply. Maybe this is the sort of technology that we need for power production on Mars, where a growing human settlement will need lots of power. We would need to satisfactorily solve the positive void coefficient problem of course. There are things that can be done to nullify this problem without excessive cost. Trip settings on feedwater temperature for instance. Fast acting shut down rods that drop by gravity in the event of excessive neutron detection. And of course, most importantly of all, good operator training.

On Mars, unless we can find abundant zirconium, the pressure tubes and fuel cladding would need to be aluminium. That would limit coolant temperatures to about 200C in normal operating conditions.

Last edited by Calliban (2020-06-28 18:36:29)

RobertDyck · 2020-06-28 18:36:09

Mars Global Surveyor mapped thorium. Look up thorium reactors. The first neutron converts Th-232 to Th-233, which decays in two steps to U-233. That's fissile, and slightly richer fuel than U-235. A second neutron splits the uranium atom. On Earth there's 3 times as much thorium as uranium, and 100% of thorium is the right isotope while only 0.7% of uranium is U-235.

If you still want to use uranium without enrichment, the CanDU (Canadian Deuterium Uranium) reactor does that.

Calliban · 2020-06-28 18:44:20

Thorium is a fertile, rather than fissile material. It would need to be used as part of a breeder cycle with fuel reprocessing. Maybe something we can do eventually, but it might be tricky until industrial capability on Mars is well developed. I was thinking more reactors that we could built early in the Mars colonisation phase, that don't require enrichment or reprocessing. Still quite an involved process, requiring uranium mining and chemical ore processing. But we can skip the enrichment and reprocessing steps with natural uranium reactors.

Agree that the CANDU would be a better option from a power density point of view. But separating enough heavy water would be very difficult, unless we can import it from Earth.

RobertDyck · 2020-06-28 18:53:11

The cycle that India already developed means no processing what so ever. Leave the thorium in the reactor. Each uranium atom splits with an average of 3 neutrons released. A traditional uranium reactor only needs one neutron to cause the next uranium atom to split. However, with a thorium reactor, 2 of the 3 neutrons must be productively used: one to convert thorium to uranium, the other to split uranium. No processing. You don't remove the fuel from the reactor. And India already got it to work.

SpaceNut · 2020-07-19 10:10:52

Calliban wrote:

A high breeding ratio, fast breeder reactor. Mars appears to have a poor abundance of fissile fuels. However, a fast breeder reactor yields so much energy from such a small amount of fuel, that it hardly matters. I would propose a gas-cooled fast reactor, with an S-CO2 direct cycle. The reasons are:
1. A harder neutron spectrum than a sodium cooled FBR, resulting in a shorter doubling time. For a sodium FBR, doubling time is typically 30 years. For a fast growing Martian colony, we would want to get that down to a decade of possible.
2. Direct cycle means no bulky heat exchanges.
3. The S-CO2 power generation equipment is very compact. When combined with a high power density core and a direct cycle, this allows very high system power density.
4. CO2 is non-corrosive, so all parts of the system (minus perhaps the fuel) can be made from low carbon steel, with a pre-stressed concrete pressure vessel.
5. A relatively low temperature cycle might be compatible with metallic fuel, that is suitable for electro-refining.
6. A high temperature cycle could drive thermochemical hydrogen production through the sulfur cycle. This would be the basis of synthetic fuel production, plastics and a Martian steel industry.
This probably wouldn't be the first reactor built on Mars. We would probably start with light water reactors burning enriched uranium. But as base power requirements grow and the spent fuel accumulates, we would eventually have enough plutonium to start an FBR programme.

tahanson43206 · 2020-07-26 12:50:31

Here's an update for the nuclear power topics. There are several of them. This one came up first in a search.

https://www.yahoo.com/news/us-eyes-buil … 28806.html

I'm glad to see signs folks at the National Labs are thinking along these lines.

(th)

SpaceNut · 2020-07-26 15:52:07

The Krusty reactor is the only one with a prototype with a scale up model built and tested thus far.

The reactor must be able to generate an uninterrupted electricity output of at least 10 kilowatts. The average U.S. residential home, according to the U.S. Energy Information Administration, uses about 11,000 kilowatt-hours per year.
In addition, the reactor cannot weigh more than 7,700 pounds (3,500 kilograms), be able to operate in space, operate mostly autonomously, and run for at least 10 years.

As the quote goes its about mass to location and in a benign operation of the unit until turned on at the site where it is to be used.

SpaceNut · 2020-07-29 17:30:17

The world’s largest nuclear fusion project began its five-year assembly phase on Tuesday in southern France, with the first ultra-hot plasma expected to be generated in late 2025.

New Mars Forums

Announcement

#26 2008-04-04 06:41:35

Re: Type of nuclear power plant is needed by Mars astronauts ?

#27 2008-04-05 08:46:06

Re: Type of nuclear power plant is needed by Mars astronauts ?

#28 2008-04-05 11:07:15

Re: Type of nuclear power plant is needed by Mars astronauts ?

#29 2008-04-05 11:40:35

Re: Type of nuclear power plant is needed by Mars astronauts ?

#30 2008-04-05 15:17:15

Re: Type of nuclear power plant is needed by Mars astronauts ?

#31 2018-12-16 17:37:36

Re: Type of nuclear power plant is needed by Mars astronauts ?

#32 2018-12-18 05:53:02

Re: Type of nuclear power plant is needed by Mars astronauts ?

#33 2018-12-18 15:17:42

Re: Type of nuclear power plant is needed by Mars astronauts ?

#34 2018-12-19 20:39:04

Re: Type of nuclear power plant is needed by Mars astronauts ?

#35 2020-02-05 21:43:24

Re: Type of nuclear power plant is needed by Mars astronauts ?

#36 2020-02-05 22:22:39

Re: Type of nuclear power plant is needed by Mars astronauts ?

#37 2020-02-06 07:07:10

Re: Type of nuclear power plant is needed by Mars astronauts ?

#38 2020-02-06 08:05:48

Re: Type of nuclear power plant is needed by Mars astronauts ?

#39 2020-06-28 16:40:00

Re: Type of nuclear power plant is needed by Mars astronauts ?

#40 2020-06-28 17:11:33

Re: Type of nuclear power plant is needed by Mars astronauts ?

#41 2020-06-28 17:22:42

Re: Type of nuclear power plant is needed by Mars astronauts ?

#42 2020-06-28 17:25:03

Re: Type of nuclear power plant is needed by Mars astronauts ?

#43 2020-06-28 18:33:02

Re: Type of nuclear power plant is needed by Mars astronauts ?

#44 2020-06-28 18:36:09

Re: Type of nuclear power plant is needed by Mars astronauts ?

#45 2020-06-28 18:44:20

Re: Type of nuclear power plant is needed by Mars astronauts ?

#46 2020-06-28 18:53:11

Re: Type of nuclear power plant is needed by Mars astronauts ?

#47 2020-07-19 10:10:52

Re: Type of nuclear power plant is needed by Mars astronauts ?

#48 2020-07-26 12:50:31

Re: Type of nuclear power plant is needed by Mars astronauts ?

#49 2020-07-26 15:52:07

Re: Type of nuclear power plant is needed by Mars astronauts ?

#50 2020-07-29 17:30:17

Re: Type of nuclear power plant is needed by Mars astronauts ?

Board footer