Propellant Sourced from Moon

tahanson43206 · 2022-04-13 18:29:59

For SpaceNut ... we have numerous topics that contain the word "Propellant" but none was a good fit for this article

It is a report on a study done in 2017, by Caltech students.

I decided to pursue it because Dr. Johnson was asked about sourcing propellant from the Moon for the Mars flight.

Here is a list of existing topics:

In-Situ Propellant Production, design a opensource demonstrator by SpaceNut [ 1 2 3 4 5 ]
Unmanned probes 105 2021-10-19 01:41:00 by SpaceNut
ISRU propellant production - energy requirement for the BFR? by louis [ 1 2 3 … 8 ]
Interplanetary transportation 179 2021-10-05 21:23:22 by SpaceNut
A new propellant(s) for Mass Driver propulsion methods. by Void
Interplanetary transportation 6 2021-09-06 20:50:40 by Void
Algae based solid propellant? by Calliban
Interplanetary transportation 17 2021-08-17 10:20:38 by GW Johnson
Using the landing propellant tank as a storm cellar by Quaoar
Interplanetary transportation 14 2020-12-20 16:47:19 by tahanson43206
Powering a Propellant Plant Facility by louis [ 1 2 ]
Human missions 47 2019-10-22 20:41:16 by Oldfart1939
High Isp storable propellant rocket by Quaoar [ 1 2 ]
Interplanetary transportation 28 2019-03-19 12:27:30 by tahanson43206
Liquid stage propellant tank design by RobertDyck
Interplanetary transportation 5 2018-12-28 14:29:03 by SpaceNut
excess of propellant for safety margin by Quaoar
Interplanetary transportation 6 2018-11-22 13:18:58 by SpaceNut
Best propellant & stuff for a Mars spaceship and lander by Quaoar [ 1 2 3 ]
Interplanetary transportation 63 2018-10-02 18:07:35 by kbd512
Detailed consideration of Mars ISRU propellant plant by louis
Human missions 3 2018-06-27 19:40:37 by SpaceNut
Sample Return with In-Situ Propellant Production by JoshNH4H
Unmanned probes 9 2017-01-14 14:05:55 by SpaceNut
Organometallic Propellant by Quaoar
Interplanetary transportation 23 2014-04-14 16:13:53 by GW Johnson
Pages:1

(th)

tahanson43206 · 2022-04-13 18:30:20

https://theconversation.com/mining-the- … icle-99974

Mining the moon for rocket fuel to get us to Mars
Published: May 14, 2017 8.04pm EDT •Updated: May 18, 2017 9.01am EDT
Authors
Gary Li
Ph.D. Candidate in Mechanical and Aerospace Engineering, University of California, Los Angeles
Danielle DeLatte
Ph.D. Student in Aeronautics & Astronautics, University of Tokyo
Jerome Gilleron
Ph.D. Candidate in Aerospace Engineering, Georgia Institute of Technology
Samuel Wald
Ph.D. Student in Aeronautics and Astronautics, Massachusetts Institute of Technology (MIT)
Therese Jones
Ph.D. Candidate in Public Policy, Pardee RAND Graduate School
Disclosure statement
Gary Li receives funding from the American Society for Engineering Education (ASEE).
Danielle DeLatte receives funding from the University of Tokyo.
Jerome Gilleron is a member of Space Generation Advisory Council.
Therese Jones receives funding from the Homeland Security Operations and Analysis Center and the National Defense Research Institute. She is affiliated with RAND.
Samuel Wald does not work for, consult, own shares in or receive funding from any company or organization that would benefit from this article, and has disclosed no relevant affiliations beyond their academic appointment.
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Republish our articles for free, online or in print, under a Creative Commons license.
Between the Earth and the moon: An artist’s rendering of a refueling depot for deep-space exploration. Sung Wha Kang (RISD), CC BY-ND
Forty-five years have passed since humans last set foot on an extraterrestrial body. Now, the moon is back at the center of efforts not only to explore space, but to create a permanent, independent space-faring society.
Planning expeditions to Earth’s nearest celestial neighbor is no longer just a NASA effort, though the U.S. space agency has plans for a moon-orbiting space station that would serve as a staging ground for Mars missions in the early 2030s. The United Launch Alliance, a joint venture between Lockheed Martin and Boeing, is planning a lunar fueling station for spacecraft, capable of supporting 1,000 people living in space within 30 years.
Billionaires Elon Musk, Jeff Bezos and Robert Bigelow all have companies aiming to deliver people or goods to the moon. Several teams competing for a share of Google’s US$30 million cash prize are planning to launch rovers to the moon.
We and 27 other students from around the world recently participated in the 2017 Caltech Space Challenge, proposing designs of what a lunar launch and supply station for deep space missions might look like, and how it would work.

The raw materials for rocket fuel
Right now all space missions are based on, and launched from, Earth. But Earth’s gravitational pull is strong. To escape Earth’s gravity, a rocket has to be traveling 11 kilometers a second – 25,000 miles per hour!
Any rocket leaving Earth has to carry all the fuel it will ever use to get to its destination and, if needed, back again. That fuel is heavy – and getting it moving at such high speeds takes a lot of energy. If we could refuel in orbit, that launch energy could lift more people or cargo or scientific equipment into orbit. Then the spacecraft could refuel in space, where Earth’s gravity is less powerful.
The moon has one-sixth the gravity of Earth, which makes it an attractive alternative base. The moon also has ice, which we already know how to process into a hydrogen-oxygen propellant that we use in many modern rockets.
Roving Luna
NASA’s Lunar Reconnaissance Orbiter and Lunar Crater Observation and Sensing Satellite missions have already found substantial amounts of ice in permanently shadowed craters on the moon.
Those locations would be tricky to mine because they are colder and offer no sunlight to power roving vehicles. However, we could install big mirrors on the craters’ rims to illuminate solar panels in the permanently shadowed regions.

Mining operations on the moon, an artist’s rendering. Sung Wha Kang (RISD), CC BY-ND
Rovers from Google’s Lunar X Prize competition and NASA’s Lunar Resource Prospector, set to launch in 2020, would also contribute to finding good locations to mine ice.
Imagining a moon base
Depending on where the best ice reserves are, we might need to build several small robotic moon bases. Each one would mine ice, manufacture liquid propellant and transfer it to passing spacecraft. Our team developed plans to accomplish those tasks with three different types of rovers. Our plans also require a few small robotic shuttles to meet up with nearby deep-space mission vehicles in lunar orbit.

An artist’s rendering of lunar rover concepts. Sung Wha Kang (RISD), CC BY-ND
One rover, which we call the Prospector, would explore the moon and find ice-bearing locations. A second rover, the Constructor, would follow along behind, building a launch pad and packing down roadways to ease movements for the third rover type, the Miners, which actually collect the ice and deliver it to nearby storage tanks and an electrolysis processing plant that splits water into hydrogen and oxygen.
The Constructor would also build a landing pad where the small near-moon transport spacecraft we call Lunar Resupply Shuttles would arrive to collect fuel for delivery as newly launched spacecraft pass by the moon. The shuttles would burn moon-made fuel and would have advanced guidance and navigation systems to travel between lunar bases and their target spacecraft.
A gas station in space
An artist’s rendering of a fuel depot for refueling deep-space missions. Sung Wha Kang (RISD), CC BY-ND
When enough fuel is being produced, and the shuttle delivery system is tested and reliable, our plan calls for building a gas station in space. The shuttles would deliver ice directly to the orbiting fuel depot, where it would be processed into fuel and where rockets heading to Mars or elsewhere could dock to top up.
The depot would have large solar arrays powering an electrolysis module for melting the ice and then turning the water into fuel, and large fuel tanks to store what’s made. NASA is already working on most of the technology needed for a depot like this, including docking and fuel transfer. We anticipate a working depot could be ready in the early 2030s, just in time for the first human missions to Mars.
To be most useful and efficient, the depot should be located in a stable orbit relatively near both the Earth and the moon. The Earth-moon Lagrangian Point 1 (L1) is a point in space about 85 percent of the way from Earth to the moon, where the force of Earth’s gravity would exactly equal the force of the moon’s gravity pulling in the other direction. It’s the perfect pit stop for a spacecraft on its way to Mars or the outer planets.
Leaving Earth
Our team also found a fuel-efficient way to get spacecraft from Earth orbit to the depot at L1, requiring even less launch fuel and freeing up more lift energy for cargo items. First, the spacecraft would launch from Earth into Low Earth Orbit with an empty propellant tank.

An artist’s rendering of a solar electric propulsion tug above an asteroid. NASA
Then, the spacecraft and its cargo could be towed from Low Earth Orbit to the depot at L1 using a solar electric propulsion tug, a spacecraft largely propelled by solar-powered electric thrusters.
This would let us triple the payload delivery to Mars. At present, a human Mars mission is estimated to cost as much as US$100 billion, and will need hundreds of tons of cargo. Delivering more cargo from Earth to Mars with fewer rocket launches would save billions of dollars and years of time.
A base for space exploration
Building a gas station between Earth and the moon would also reduce costs for missions beyond Mars. NASA is looking for extraterrestrial life on the moons of Saturn and Jupiter. Future spacecraft could carry much more cargo if they could refuel in space – who knows what scientific discoveries sending large exploration vehicles to these moons could enable?
By helping us escape both Earth’s gravity and dependence on its resources, a lunar gas station could be the first small step toward the giant leap into making humanity an interplanetary civilization.
Editor’s Note: This story was updated to clarify the distinction between escape velocity and the velocity needed to achieve orbit.
How The Conversation is different
Every article you read here is written by university scholars and researchers with deep expertise in their subjects, sharing their knowledge in their own words. We don’t oversimplify complicated issues, but we do explain and clarify. We believe bringing the voices of experts into the public discourse is good for democracy.

Beth Daley
Editor and General Manager

(th)

SpaceNut · 2022-04-13 19:19:51

You are wanting a lunar insitu fuel and what the possibilities are are limited as the only water are in deep shadow craters, there is no source for carbon to speak of and the oxygen is locked up in oxides of metals. Sure for a period of time the sun will be constant but its followed by an equal time in which there is no power. That said nuclear is the stable option to make use of for processing and for mining.

Since we need an oxidizer and a fuel we are out of luck if only half of what we need can be made. Then what you make must be compatible to work with the engines that might not be of the same fuel types.

SpaceNut · 2022-04-17 18:48:00

Repost for topic reference point of GW's study.

tahanson43206 wrote:

Here is a direct link to a file prepared by GW Johnson as a preliminary response to a request from the North Houston chapter of National Space Society.
https://www.dropbox.com/s/i9ix4i04u8kjr … f.pdf?dl=0
This is a preliminary version of a study of lunar sourcing of propellant for Large Ship flights to Mars and return.
The document is intended for discussion in this evening's US/Canada/Mexico Zoom, hosted by kbd512 at Midnight UTC.
(th)

SpaceNut · 2022-04-17 18:58:31

We know that the first issue for lunar fuel is the hydrogen as its got to have a Zero boil-off active cooling for LH2 or you leave it as water until you need it. Its also why we have issues with it for On Orbit fuel depot with LO2/LH2
Void has suggested that Regolith Water Vapor or sub surface water not just ice may be possible and that really with the above forcing the Lunar economics etc as it requires us to look at the big picture of ISRU propellant production - energy requirement for the BFR? of which is dwafted by the large ships demands...

Solar in all forms of capture do not have a flat line power delivery as it follows the arc the sun traces when using a stationary collection point. So sizing the energy use of power must also follow that same curve. Its that use of convertors and batteries that flat line the power level to a predictable level across application time usage.

For the moon this is a different cycle and alignment problem than that of earth.

The other forms of energy do not follow this path as they generate constant power at a fixed rpm of rotation. They do suffer the same effects if you are varying the rpm as solar does.

Using solar to move a content to a higher energy potential allows for the flow to be metered to get the energy back out and its that control of flow to create rotation that allows for a constant power level once more from stored energy.

Of course gravity on the moon may not be of much advantage as it is here on earth.

Electrolysis on mars, earth, moon all have the issue of power constant use among other issues.

Mars_B4_Moon · 2022-07-09 15:47:30

Rotating Hygrogen-Oxygen detonation engine, tested by Florida and JAXA https://www.youtube.com/watch?v=dK2CbJNHnC0

A race is afoot to make billions from the Moon's resources.
https://www.sciencefocus.com/space/new-space-race-moon/

Also
Chinese scientists find potential in lunar soil to generate oxygen and fuel

global.chinadaily.com.cn/a/202205/06/WS62749881a310fd2b29e5b0c4.html

SpaceNut · 2022-08-02 19:40:42

Newest of space tug data is in the GW posting topic.

I was wondering about the refueling of a starship to transfer it to LEO amount to make it turn into a vehicle for lunar to earth orbit. I need to reread the papers to see if it's been answered.
Sire the amount of fuel being delivered from the moon to LEO would be greater than from earth to LEO but then again, the expense is how to get it back to the moon to get more and whether the moon can support this refueling.

Grypd · 2022-11-16 05:49:26

[Electrolysis on mars, earth, moon all have the issue of power constant use among other issues.]

That is not necessarily true as one of the reasons for going to the poles on the Moon is those peaks of eternal light and we can make infrastructure light so we can get more light and in that way solar power.

One of the options we can have is the use of solar electric tugs these tugs using magnetism for all intents could be a slow but reliable way of being able to bring fuel probabily in the form of tanks of methane or ammonia from low to high earth orbit but when mixed with oxygen extracted from the moon able to power missions further into space even to fueling a potential Mars to Earth cycler

Void · 2022-11-16 10:34:14

I like the idea. Are you thinking of riding the solar wind with magnetic bubbles?

Done.

GW Johnson · 2022-11-16 11:13:28

Any base near the south pole of the moon is going to be a very cold place. Surface sunlight is dim at a low angle of incidence, so the surface regolith temperatures will resemble lunar night temperatures, around 200 F below zero. It will take a lot of power to keep any crews there from freezing to death, and rather quickly.

Yes, there is solar available with panels stood up essentially vertically (facing the right directions) on those peaks in perpetual sunlight, but you have to build a transmission line from those rugged mountains down onto the plains where you can actually land and build a base. Building a transmission line in rugged topography, in vacuum, and in extreme cold, is a way tougher proposition than anybody here seems to think.

Myself, I'd go nuclear with a heat engine to convert reactor heat into electricity, which is a process that will have an energy efficiency in the neighborhood of 25%, thanks to the laws of thermodynamics for heat engines. There's inherently a lot of waste heat from that. Instead of trying to radiate all that waste heat to space, use it (or at least some of it) to heat the base. We know how to build and insulate hot fluid lines, and how to build "radiators" of the type seen in late 19th century and early 20th century homes to use it.

The real solutions are not always high-tech.

GW

Last edited by GW Johnson (2022-11-16 11:15:11)

kbd512 · 2022-11-16 11:24:15

GW,

Since you're trying to extract liquid water to make rocket propellant, would it make more sense to pipe some of that heat below the surface of the ice to melt the ice?

It's also as cold as -250F in orbit on the other side of the Earth, but the major problem seems to be getting rid of waste heat rather than retaining it.

A base on the surface would obviously incur some conduction losses to the lunar regolith, but lunar regolith is also a good thermal insulator.

Calliban · 2022-11-17 07:09:25

Most materials are brittle at -100°C. It won't be easy designing excavator equipment that can stand up to such cold temperatures and handling cold materials. The problem with using nuclear waste heat is that the heat source is a centralised, stationary machine. It won't be easy to distribute it to machines and people that are moving. It is a cumbersome solution. We could power machines with individual kilopower devices. But that is an expensive solution.

Maybe NASA's new lattice confinement fusion experiments will be helpful. If that development bares fruit, it would allow small kW scale fast fission reactors, weighing a few tens of kg, fuelled with low enriched or even natural uranium. These small, portable reactors, will be far cheaper than existing kilopower units because they won't require HEU. Natural U is a commercially available raw material. But no one has built these yet.

In the absence of a portable fission reactor, a closed cycle IC engine would work. The vehicle would burn compressed hydrogen and oxygen in a small gas turbine engine. Water vapour exhaust would vent into a tank containing a condenser coil. The coil would circulate waste heat through the vehicle. The vehicle would recharge by hooking up with a power cable. Onboard electrolysis would them convert stored water back into H2/O2 in a closed cycle. No need for hydrogen or oxygen refuelling lines.

Last edited by Calliban (2022-11-17 07:17:59)

kbd512 · 2022-11-17 08:21:57

Calliban,

The ICF tech sounds great, but I was thinking that something more akin to a RTG would supply the downhole thermal power for doing the melting. If ICF / "cold fusion" can be translated into a working fission-fusion reactor, then that would be a boon to space exploration in general. In the mean time, a piece of equipment with a "hot tank" of molten salt for ice melting, brought up to temperature using reactor waste heat, and a high temperature Sodium-Nickel Chloride battery for motive power seems like the most practical solution. KiloPower does not need HEU, and at present NASA is pursuing HALEU fuel to address the prohibition President Trump put on sending HEU into space. HEU makes the reactor core smaller and lighter, but it's not a show-stopper.

Grypd · 2022-11-18 08:39:07

Remember that in the low lunar gravity it is possible to build very thin towers and simply dangle mirrors on them to reflect light down either for use in solar panels or for industrial purposes. Our missions to the moon and our own modelling indicate that going one metre under the surface will give a constant tempature of between -20 and -30 degrees C no matter the surface conditions. Since we will probably require a lot more depth to insulate the crews from radiation we can easily design habitats designed to deal with this constant tempature. Actually thinking about it we can use a variant heat pump system to provide some power using these variables.

Grypd · 2022-11-18 08:44:54

Void wrote:

I like the idea. Are you thinking of riding the solar wind with magnetic bubbles?
Done.

Oh magnetics yes but utilising long cables and solar power to create electrodynamic tugs which use lorentz forces on the earths magnetic field to either slow or speed up a vehicle.

Nasa proved the technology works on its TSS and TSR missions from the space shuttle

tahanson43206 · 2022-11-18 11:20:09

For Grypd re #15

You joined the forum back in 2004, so I went back to see how you entered the fray. At the time, there appears to have been a proposal in the works to ship prisoners to Mars. Your opening post was part of that discussion.

Your more recent interest in harvesting materials from the Moon includes an idea I've not seen before, and I'm hoping you might be willing to develop it a bit.

The specific concept was:

build very thin towers and simply dangle mirrors on them to reflect light down either for use in solar panels or for industrial purposes.

Your 1800+ posts probably contain information about your background, but to save me (and perhaps others) the time it would take to find out, by any chance do you have an engineering background?

You will (no doubt) have noticed that Calliban is a working engineer, and kbd512, while not an engineer, ** is ** adept at computing relevant numbers in many areas of discussion.

In this case, I am hoping the NewMars members who participate in this topic can reveal if your idea has merit, and (assuming it does) how to ship unlimited amounts of solar power to wherever it is needed on the lunar surface.

(th)

Void · 2022-11-18 11:38:52

If I understand, these will be electrodynamic tethers, for in orbit propulsion. Yes, there are many things almost lost. This is one to have a strong look at in my opinion. (th), I will keep you in mind as I speak to hope to develop a shared view. This apparently on Grypd's mind, let's consider that he is the current master of corrections for me, should I goof up.

Here is a Wiki, for those who might desire to investigate it: https://en.wikipedia.org/wiki/Electrodynamic_tether

Quote:

Electrodynamic tether
From Wikipedia, the free encyclopedia
Jump to navigationJump to search
Medium close-up view, captured with a 70 mm camera, shows tethered satellite system deployment.
Electrodynamic tethers (EDTs) are long conducting wires, such as one deployed from a tether satellite, which can operate on electromagnetic principles as generators, by converting their kinetic energy to electrical energy, or as motors, converting electrical energy to kinetic energy.[1] Electric potential is generated across a conductive tether by its motion through a planet's magnetic field.
A number of missions have demonstrated electrodynamic tethers in space, most notably the TSS-1, TSS-1R, and Plasma Motor Generator (PMG) experiments.

I will speak as if I understand this a little. This could be considered a bit like an electric train engine/generator. Going up the hill you use electric power to the motor to travel against gravity. Going down the hill you use gravity to power your generator.

If we could liquify the Moon and conduct it down a spout as a liquid and run a turbine, we could generate power and cover the Earth in Liquid Moon. Good thing that is not a real likelihood. We would use magnetic drag, to drop the load, and also generate electricity, if I am thinking correctly. If I understand you Grypd, you do want to liquify part of the Moon, and conduct it to lower Earth orbits. The liquid being Oxygen. But of course, we don't use a turbine or a normal generator. So, if it can be done, the inputs needed are to create Oxygen on the Moon, and to get it into at least a Lunar orbit. Then to use the tethers in generator mode to draw the load towards lower Earth orbits.

The contest between the Earth's magnetic field and the solar wind, causes the Earth's solar wind to impinge on the Moon periodically.
https://science.nasa.gov/science-news/s … gnetotail/
The propulsive devices can also work with the solar wind, but perhaps not quite as well. But once a month for a period of time the Earth's magnetic field envelops the Moon. Also, the clash between the solar wind and the Earth's magnetic field may create magnetic compression, and I am interested in how that could be utilized, if possible.

While the Electrodynamic tethers are exciting, I would also wonder how they might be used in conjunction with other propulsion methods.

Perhaps it is time for me to be done, and to hope for a reply of some kind.

Done.

Last edited by Void (2022-11-18 11:55:50)

Calliban · 2022-11-18 13:18:33

Once you have harvested water, it must then be transported from the poles to the base. This could be achieved using a tanker convoy, a pipeline, cableway, or maybe even by firing ballastic shells full of ice into a predetermined target area.

Last edited by Calliban (2022-11-18 13:31:02)

tahanson43206 · 2022-11-18 15:46:04

For Calliban re #18

The ballistic delivery concept in your post would seem (at first reading) to be about the most energy efficient of all the possibilities.

The "catcher" system needs to be capable of preventing release of material into the environment, but (I'm hoping) a creative engineering team could handle that.

It's not ** all ** that different from the ballistic delivery system for Mars, that awaits an entrepreneur willing to put it into operation.

***
For Void ....

I'm ** hoping ** we are talking about two different things, but will have to wait for an update from Grypd to be sure.

The "thin towers" would be secured to the surface of the Moon, and the tethers would flow form moving vehicles in orbit.

I am hoping Grypd will elaborate on the tower idea, and perhaps enlist some engineering support to show material requirements for the towers and mirrors.

(th)

kbd512 · 2022-11-18 16:17:28

An insulated pipeline is the most energy-efficient means of transport if the base is more than a few kilometers away from the water source, but that requires a lot of equipment and time if a significant volume of water has to be pumped, possibly a heating element embedded within or wrapped around the pipeline, and pumping stations every few kilometers or so, assuming line pressure is kept reasonably low so the piping is light and leakage / repair is easier to deal with. Acceptable flow velocity for Earth-bound systems seems to vary between 1m/s to 2m/s, so pumping water or water-like substances at 2m/s means 8 minutes and 20 seconds of "cool-down" time as the water covers 1 kilometer from the extraction point to the remote base (hopefully located in perpetual sunlight). Higher flow velocities are possible, and it seems that cavitation / noise are why those velocities are limited to those values here on Earth.

SLS core stage contains 196,000 gallons of LOX, 537,000 gallons of LH2, or 733,000 gallons total.

A 1.5 inch diameter pipe with a 1.1m/s flow rate will transport 20 gallons per minute. Over 24 hours, that's 28,800 gallons of water. A pair of such pipes, possibly from different extraction sites, would require a little less than 13 days to fill both propellant tanks with water. The most likely limitation is electrical power to first split the water and then cryogenically cool the LOX/LH2 propellant.

The ice has to be turned into liquid at some point, either at the extraction site or at the base, but if the base is in perpetual sunlight then solar thermal energy can be used for that purpose. The extraction site almost requires nuclear power, the only possible exception being a molten salt or molten metal transfer of thermal power from a solar thermal energy collection system, which requires even more tonnage of materials (collector troughs or lenses, pipes, potentially a storage medium although the water itself could eventually serve that purpose, etc) to initially be landed on the moon.

Hysata's new reverse fuel cell, which is remarkably efficient, requires an input of 41.5kWh to produce 1kg of H2. SLS core stage contains 143,789kg of H2, so 5,967,243,500Wh of energy. Divided over 13 days, that's a constant power input requirement of 459,018,731Wh or 459MW of power. That figure does not include cryocooler power input or losses of any kind, so refueling a SLS core stage in 2 weeks would require an enormous amount of power. At 25% overall efficiency, assuming constant illumination, a photovoltaic array sufficient to provide 459MW of constant input power would cover 1,836,000m^2 (1,355m by 1,355m), with an input power of 1kW/m^2.

At 2kg/m^2, which seems realistic given what I know about the weights of the components, that's 3,672t of landed hardware for the panels alone, or 25 Starship flights, which each requires 5 to 7 tanker flights, or 150 total flights just for the photovoltaic arrays. No idea about the power transformers and power conditioning equipment, but it won't be light at that power level.

Is that still doable?

Yes, but not easily.

This 300MWt / 95MWe PWR has a core diameter of 2.2m, height of 2.25m, and is loaded with 19.8t of LEU:

Passive Safe Small Reactor for Distributed Energy Supply System Sited in Water Filled Pit at Seaside

It's feasible to transport a reactor that small to the moon, even if it weighs upwards of 100t.

It's not clear to me if the same number of flights will be required, but 5 flights are reserved for the reactor pressure vessels, another 5 for site preparation equipment (assumes use of lunar regolith for reactor shielding), and possibly another 5 for all the radiator arrays, support equipment, etc. Solar is a lot more mass-competitive closer to the Sun, but it's still a non-starter for Mars since the total power requirements range well into the gigawatts for a city of a million people.

Nothing larger than one of these 300MWt units can realistically be landed by near-term or projected launch and lander vehicles. These reactors require complex assembly, just not as complex as deploying photovoltaic arrays spanning multiple kilometers. If there are practical deployment schemes that use vehicles, then I would favor the PV if the total tonnage of the panels could be reduced, but it would have to come down to 1kg/m^2 or less, and that's hard to do. For a Venus colony, I can't think of any justification for using nuclear power.

kbd512 · 2022-11-18 17:34:35

Speaking of heavy loads, one of those reactors could feasibly be supported by 16 of those 35 inch diameter "Bushwheels" tires on the lunar surface, which means each tire is supporting about 1,042kg of reactor weight, plus the weight of the vehicle or trailer. This is comfortably within the load limits for this type of aircraft tire, at low pressure, over rough ground, especially at low speeds.

Bushwheels are a type of fully enclosed "balloon tire" made by Airframes Alaska, whereby the entire tire is a fully pressurized unit independent of the Aluminum wheel its mounted on, which allows the tire to "spin on the wheel" during a rough landing without shearing off the valve stem, unlike more traditional aircraft tires that use inner tubes or tubeless radial types. During the vulcanization process, numerous thin layers of kevlar fabric and rubber are bonded together. Although kevlar is very abrasion-resistant, we probably want to take abrasion resistance to the next level using thin tapes of CNT tape / fabric. One "approved" field modification involves spraying the entirely smooth tread surface with a pickup truck bed-liner compound that contains, of all things, volcanic pumice. That modification allows the tire to roll over sharp rocks and land on conventional without punctures (rough field landings) or accelerated wear (hard concrete runways) to the soft rubber. The surface treatment is re-applied periodically because it flakes off.

The Aluminum aircraft wheel would also need to act as an electrical heat spreader to impart heat into the tire if the vehicle was operated in shadow on the lunar surface. The tires are rated to handle Arctic / Antarctic temperatures, but colder temperatures require active thermal management.

35" Bushwheels:
TSA-3.jpg?v-cache=1654088146

There are 2 variants of this tire, one for light aircraft pictured (44 pounds each), and one for the Porter and Beaver (60 pounds each). I can't recall what the Aluminum wheels weigh for the heavier aircraft, but 20lbs to 25lbs is my guesstimate, and 13lbs for the lightweight wheels.

Beringer's lightweight conical steel axles for the Pilatus Porter aircraft weigh in at 41lbs each. The Aluminum wheel weighs 14.5lbs each. The brake assembly weighs 11lbs each. All told, 126.5lbs for a "lightweight" setup, or 2,024lbs for all 16 axles / wheels / tires. Braking torque is 1,408ft-lbs per unit. Static load rating is 3,080lbs per wheel and limit load is 8,160lbs per wheel. I think braking torque is marginal at best. It's sufficient to lock up the wheels on a modest incline, but steeper inclines would require more detailed analysis.

Anyway, the static load rating for the Porter / Beaver tires is 5,600lbs per tire (here on Earth, obviously), at 10psi to 30psi of inflation pressure using Nitrogen (manufacturer's recommendation) or air. I'm proposing loading each tire with 2,297lbs of reactor weight on the moon, which should leave plenty of load margin for the transport vehicle.

This is all FAA-approved aerospace hardware used by STOL transport aircraft, in case that point isn't clear, not randomly selected automotive components.

Grypd · 2022-11-20 07:32:27

tahanson43206 wrote:

For Grypd re #15
You joined the forum back in 2004, so I went back to see how you entered the fray. At the time, there appears to have been a proposal in the works to ship prisoners to Mars. Your opening post was part of that discussion.
Your more recent interest in harvesting materials from the Moon includes an idea I've not seen before, and I'm hoping you might be willing to develop it a bit.
The specific concept was:
build very thin towers and simply dangle mirrors on them to reflect light down either for use in solar panels or for industrial purposes.
Your 1800+ posts probably contain information about your background, but to save me (and perhaps others) the time it would take to find out, by any chance do you have an engineering background?
You will (no doubt) have noticed that Calliban is a working engineer, and kbd512, while not an engineer, ** is ** adept at computing relevant numbers in many areas of discussion.
In this case, I am hoping the NewMars members who participate in this topic can reveal if your idea has merit, and (assuming it does) how to ship unlimited amounts of solar power to wherever it is needed on the lunar surface.
(th)

Hi Tahanson
I have been involved with space from a very young age and though I do have a degree, its in electrical engineering which I was involved as hobby long before I was a teen. Incidentally my career went completely a different direction ces la vie.

The moons lack of atmosphere and of course 1/6 th gravity means that creating lightweight but tall structures are a lot easier. Of course we will not be sending large supplies of solar power elements the idea and one that has been shown in a lab is to use the lunar regolith to create insitu solar cells. Actually we have a thread somewhere were the whole process of solar cell production could be completely automated and power issues with mirrors also made insitu could easily be a non issue. (At the poles only though)

My knowledge of magnetics came through my own experimentation and of course keeping an eye on academic works as time has passed.

tahanson43206 · 2022-11-20 07:51:11

For Grypd re #22

Thank you for your detailed reply .... a degree in electrical engineering puts you in good company! And that's even if your career went in a different direction.

I am going to take the liberty of noting that you came up with (what sounds like) a terrific idea, and then seem to have pulled the rug out from under it in the next breath. Or perhaps what's happening is that in the process of transfer of an idea from your mind to the collective minds of the readership, errors have occurred during transmission/reception, and the result is new ideas for your consideration.

So! Assuming for a moment that what arrived/developed in the minds of your readers is different from the original created in ** your ** mind, please consider/evaluate the result.

What I ** think ** you might have meant was to mount solar panels on tall towers at the poles, and then to send electrical power by cable or other suitable means to the surface of the Moon away from the poles.

What ** I ** read was that you were planning to mount mirrors on tall towers at the poles, and to send reflected photons to receiving stations in the parts of the Moon away from the poles.

The supply of power from the poles would (of course) only be needed during the lunar night, so the mirrors mounted at the poles need to be able to rotate to direct photons to the surface of the Moon NOT illuminated by the Sun.

Thus, the immense cost of cables could be eliminated, and the photons could be directed to the receiving stations at no cost whatsoever.

The key concept I'm picking up on is the height of the towers at the poles.

A question you may not be able to answer is how tall would a tower need to be to reflect photons into a receiving station at the lunar equator?

Fortunately, we have members who can (if so inclined) readily answer that question.

We also have members who are adept at poking sticks at new ideas to see if they can hold up.

While this topic is about making propellant on the Moon, power is needed so a focus on delivery of power to where it is needed seems (to me at least) to be compatible with the topic.

Todo item:

Compute height of towers needed to reflect photons from the lunar poles to receiving stations on the equator.

(th)

tahanson43206 · 2022-11-20 09:19:30

Addendum to Post #23

The placement of towers and their height ** should be solvable using trigonometry.

A consideration (that may influence placement of towers) is that the higher the towers at the poles, the greater the amount of solar photons they can direct towards the equator of the Moon.

While a mirror tower at the center of a pole could rotate to serve customers in the night side of the Moon, a mirror tower located away from the pole could serve for part of the lunar day, so a number of such towers would be needed to provide constant coverage.

If we have members with the combination of skills required, we might hope to see drawings of the networks at some point in the near future.

As a reminder for anyone who is NOT already a member, and who would like to contribute, details for procedure are available in the Recruiting topic.

(th)

SpaceNut · 2022-11-20 09:50:30

The tower at the poles no matter how high cannot send light to the equator without redirection mirrors at key locations on other towers.

It would be easier to use a light pipe or tunnel for light to bounce within the tube shape until it reaches the equator. Once the light enters the top of the directional section that rotates at the top of the tower it would bounce downward to the bottom where a reflective mirror would redirect it into the tunnel that would bring it to the equator where another collection redirection mirror would be placed to send it to the surface.

Light at the poles still only will be received on half the moons diameter and that is every 14 days or rotation of a 28-day cycle with respect to earth. For a fixed location so, a tower as described above solves that issue.

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