Author Topic: Envisioning Amazing Martian Habitats  (Read 318050 times)

Offline lamontagne

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Re: Envisioning Amazing Martian Habitats
« Reply #1560 on: 12/07/2018 01:50 pm »
Te actual strength of the liners would come from external hoops of carbon fiber wires, post tensionned, eventually replaced by locally produced steel. Longitudinal strength would be from rods set between the blocks.

Why not extruded basalt? (And not just basalt fibre in a matrix. Extruded basalt rods and mesh are already used in building to reinforce concrete. Well, technically the concrete is the matrix, but you get what I mean. Half inch rods are not "fibre".)

that is basically what National Geographic proposed in a recent issue.

And that god-awful series they made.



how will you expand? With prefab habs? Building habs on the surface? Both methods are mass prohibitive. Even if you pile regolith on surface structures you still need to bring those structures in the first place.

If you can't build an airtight shell, IMO you're not capable of settling Mars.

A basic airtight shell is the equivalent of building a lean-to in a forest. It's the absolute technological minimum cost of entry if you expect to do more than short exploration-and-return.

When tunnelling you only need machinery and energy (and the energy is there). The rest, i.e. the MASS LIMITED raw materials, are already there.

Plus the consumables of the machines.

If you want to build an airtight chamber in raw rock, the walls have to be non-permeable, that rules out soft rock, if you want it to self-support over fairly large areas, that also rules out soft-rock. So you're looking at hard granites. You are going to be consuming a surprising amount of parts to keep the, for example, road-headers running. If that mass is greater than the mass of a shell equivalent to that volume, you haven't saved anything.

Likewise, is the mass of digging equipment necessary for cutting underground structures higher than the mass of equipment for making ISRU airtight shells?

(This argument holds for my suggestion of cut'n'cover. You do need machines to work regolith anyway, but if you bury every hab, the rate of wear on those machines is much higher than if you're just levelling roads and landing-pads.)

It is pretty clear to me that it is the reason why Musk is actively exploring exponential improvements in tunneling technology.

Perhaps, but it's worth noting that the savings he suggests came from reducing the diameter of the tunnel, by using electric "skateboards" instead of having to have full lanes for running cars and full height for trucks. Halve the diameter, quarter the volume dug. He hasn't actually changed tunnel boring the way he has launch costs, distributed power storage, and electric cars.
Extruded basalt is ok if we set up in a basaltic area.  I'm thinking more of settling in a sediment rich area.  Then the equivalent would be fiber glass from SiO2.  I think the energy requirement to make steel wire may be similar to the energy requirement to make fiber and the fiber binder. 

Cut and cover vs tunneling machines is not always a clear cut decision even here on Earth.  The consensus is cut and cover is cheaper, but if the Boring company really improves boring processes by a factor of 10, then boring would become chepaer most of the time, I expect.
And for the base, we select the rock formation for optimum conditions.  On Earth, in most cases, cities are pre existing for completely different reasons, and the rock is not of very good quality, tunnel wise.  So excavation usually wins.

I suggest using soft rock, but strong tunnel liners.  I don't expect any rock to really be competent against 15 psi of air, so liners of some sort will always be required anyway, even in granite or basalt.



« Last Edit: 12/07/2018 02:07 pm by lamontagne »

Offline lamontagne

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Re: Envisioning Amazing Martian Habitats
« Reply #1561 on: 12/07/2018 01:55 pm »
Here is my first element for my tunnel system: a Mars adapted drill rig, with a extended stay cabin and a large solar array, battery system for power.

Every construction and mining site today starts with a visit from one of these guys.

The rig can stay at an interesting spot for a few days and drill cores, then change crews (using a second shuttle vehicle carrying supplies) and keep drilling.  When the core box is full it returns home for analysis of the cores.

My guess is that the range would be about 200 km from home base. Up to 400 km with a way station (a way station being a solar array with a battery pack, a Supercharger station, in effect).
« Last Edit: 12/07/2018 02:04 pm by lamontagne »

Offline lamontagne

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Re: Envisioning Amazing Martian Habitats
« Reply #1562 on: 12/07/2018 02:03 pm »
And here is the second element, a roadheader with four to six dump trucks.  100 tonnes for the roadheader, about 40 to 60 tonnes for the trucks.
Not illustrated here is the battery swapper truck ,that carries batteries in and out more or less continuously to power the roadheader.

The roadheader has a rated output of 350 m3 per hour.  This would allow for the excavation of the volume of a suburban house every 2 hours! The entire volume of the Starship in three.  Of course, the system througput is much lower, one would hope at least 10% of that, so perhaps about one house per day.  Present performance of roadheader is usually lower than 35m3 per hour, but that is the type of ratios the Boring company is trying to improve through automation, batteries and use of locally produced liners.

A battery powered roadheader will run much cooler than a diesel powered one.

Offline lamontagne

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Re: Envisioning Amazing Martian Habitats
« Reply #1563 on: 12/07/2018 11:34 pm »
Perhaps not my most convincing machine, but part 3 of my grand scheme, a kludge built on Mars:

Hopper, additive hopper, crusher and press.  A Compact Earth Block system

Plus a pile of CEBs.   And a little utility machine.

Offline Oersted

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Re: Envisioning Amazing Martian Habitats
« Reply #1564 on: 12/07/2018 11:36 pm »
Then there are the steep, smooth cliffs of the North Pole region. These are about two km tall (but I suspect actually 800m), slope is ~80 degrees:



That's my bet for a first base. Tunnel into the base of the cliffs. From the tunnelled habitat drill small tubes upwards into the bottom of the glaciers. Pump hot air into the tubes and collect the water running down. Make rocket fuel and grow hydroponics.

In addition the lay-out of the cliffs lends itself to naturally sheltered landing sites for the spaceships, to avoid pelting structures and previously landed spaceships with rocks.

Also such a landscape is highly motivational due to its sheer beauty (and cliffs).
« Last Edit: 12/07/2018 11:39 pm by Oersted »

Offline Paul451

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Re: Envisioning Amazing Martian Habitats
« Reply #1565 on: 12/07/2018 11:54 pm »
I'm wondering if a good place to tunnel would be the base of a five or six kilometre high cliff in Valles Marineris.
It would mostly be loose rocks and soil for several hundred metres. The deeper you tunnel towards the actual base of the cliff, the higher the pressure over your head. By the time you are directly underneath the top of the cliff, you have the equivalent of two kilometres of Earth rock bearing down on you. At those depths, rock is basically plastic and tunnels are eventually squeezed shut.
But Valles Marineris is not actually a cliff, more like a medium slope (20 or so degrees) in most places. The vertical scale is heavily exaggerated in the 3D flyarounds you see.

You also don't want to build near the base of any cliff because there's a probably a reason it's a cliff.

Offline Paul451

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Re: Envisioning Amazing Martian Habitats
« Reply #1566 on: 12/08/2018 02:04 am »
Only question: will the lava tube be in the right spot?

My point was that the lava tube itself might innately be the right spot. Not just giving you shelter, but water at well.

Sure, you might not have loads of high quality metal ore around, but initially you can use a couple of billion years of accumulated unweathered metallic meteorite debris, which will be fairly evenly spread around the planet. (And, IMO, that's something you'd do anyway, even if your first settlement was right on top of alternating layers of haematite and bauxite.)

By the time you've cleared all the metallic iron around you, you'll need to be large enough for specialised mining and hence large enough to support remote-site mines and associated secondary settlements. And you will need multiple mines because you generally won't get enough elements from a single spot, iron/aluminium/copper/uranium/sulphur/phosphorus/arsenic, etc etc etc, no matter how free you are to pick your initial site. (Or at least not discoverable from orbital surveys and minimal ground work.)



But the tunnels are lined with precast concrete blocks made on the surface and sequentially bolted into place. There's gravel and grouting between the tunnel wall and the blocks.

That was a point I was trying to make to Oersted previously. In order to make a viable underground volume, if you end up have to make a structural or pressure vessel anyway, how are you saving anything from making the same structural/pressure-vessel and leaving it on the surface (or covering it with regolith.) Or if excavating a large volume uses more resources (parts/labour/energy/etc) than the machinery needed to build a shell on the surface, how is it worth it?

Or how much energy does it take to excavate each cubic metre of suitable rock (if you don't want to also manufacture a lining)? Vs how much energy does it take to merely enclose an equivalent volume on the surface with ISRU material? (Note cube/square.)

I think building underground is one of those ideas that seems like a "simple" solution (like transparent greenhouses, or domes) but when you add in all the things you need in order for it to work, it ends up being harder than solving the initial problem(s) directly.

Offline Paul451

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Re: Envisioning Amazing Martian Habitats
« Reply #1567 on: 12/08/2018 02:30 am »
Here is my first element for my tunnel system: a Mars adapted drill rig, with a extended stay cabin and a large solar array, battery system for power.

On Mars I'd expect the wheels to be more spread out and with greater ground clearance.

And particularly with independent-wheel electric drives, it's mechanically simpler than trying to run a single power-source through multiple axles, even allowing independent all-wheel steering. You might end up with a modular chassis-drive-steer components, like the EFT-truck concept. (Although with more clearance, you need to travel over raw terrain. Unless the very first vehicle is a tracked dozer-grader. [edit: Turns out they have adjustable lift, tons of clearance.]) Connect two drive modules and it's a 4x4 rover chassis, two and a cabin and it's a manned rover. A third and it's a general-purpose 6x6 utility chassis. Five and it's a loader. 10-15 and it's a multi-articulated long distance transport. Oops, did your truck break? Just grab three modules off the long-hauler and swap over your cabin and service units and go back to working while we salvage what we can off the old parts.





[It's the lots-of-standard-units-because-it's-electric concept I'm interested in. (Or hybrid-electric in EFT's case.)]

(a way station being a solar array with a battery pack, a Supercharger station, in effect).

This is clever. I occasionally hear a throw-away mention of "way stations" to extend range, I've yet to see anyone actually flesh out a minimum version of such a thing. Yours lends itself to standardisation.

[This also gets back to battery-vs-ICE/fuel-cell question. It is vastly more efficient to have a solar array charge a battery and a battery power an electric drive, compared to having the solar array power a fuel/oxide-maker, then fuel an inefficient chemical-fuel generator. But in the former case, once that small battery is charged... that array is doing nothing. Are you better off having it trickle-generate and store fuel/oxygen over long periods, for use in bursts? The latter also gives you a handy emergency oxygen supply. Not suggesting that for your Mars-contest entry, not futurey enough for judges.]
« Last Edit: 12/08/2018 03:04 am by Paul451 »

Online rakaydos

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Re: Envisioning Amazing Martian Habitats
« Reply #1568 on: 12/08/2018 02:40 am »

(a way station being a solar array with a battery pack, a Supercharger station, in effect).

This is clever. I occasionally hear a throw-away mention of "way stations" to extend range, I've yet to see anyone actually flesh out a minimum version of such a thing. Yours lends itself to standardisation.

[This also gets back to battery-vs-ICE/fuel-cell question. It is vastly more efficient to have a solar array charge a battery and a battery power an electric drive, compared to having the solar array power a fuel/oxide-maker, then fuel an inefficient chemical-fuel generator. But in the former case, once that small battery is charged... that array is doing nothing. Are you better off having it trickle-generate and store fuel/oxygen over long periods, for use in bursts? The latter also gives you a handy emergency oxygen supply. Not suggesting that for your Mars-contest entry, not futurey enough for judges.]
eh, ICE has the same problem when the methane tanks are full.
On the other hand, though it risks complicating the design and is climate dependant, what about a atmospheric water condensor hooked up to an ice cube mechine and a shadecloth? The idea being to store water outside of a tank, for the next rover to come by and take back to the fuel plant.

it'll be lossy as all hell, but since you only run it when the batteries are full, lossy with unlimited storage beats standing around doing nothing.
« Last Edit: 12/08/2018 10:23 pm by rakaydos »

Offline Paul451

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Re: Envisioning Amazing Martian Habitats
« Reply #1569 on: 12/08/2018 11:09 am »
eh, ICE has the same problem when the methane tanks are full.

(And LOx tanks.) However, for an equivalent mass, methalox is denser than batteries. Moreso, for the way-station itself, tanks with the same mass as the entire battery-pack when transported empty to the site, can have store vastly, vastly more energy than the batteries. (Hence the solar arrays can work longer to fill those tanks.) And the tanks can be built locally at a much lower technology level of the settlement.

Online Robotbeat

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Re: Envisioning Amazing Martian Habitats
« Reply #1570 on: 12/08/2018 01:23 pm »
Taking into account conversion inefficiencies and the need to carry LOx, and the difference between batteries and ICE is pretty small on Mars. And some kind of batteries actually exceed ICE.
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Online Jcc

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Re: Envisioning Amazing Martian Habitats
« Reply #1571 on: 12/08/2018 01:53 pm »
Taking into account conversion inefficiencies and the need to carry LOx, and the difference between batteries and ICE is pretty small on Mars. And some kind of batteries actually exceed ICE.

They will need to consider battery chemistries that can be produced from ISRU on Mars, which might have lower energy density than Li, but not need to be transported all the way from Earth. Solar energy capture will be a critical path and they need to do as much of it as possible in different modes.

Offline lamontagne

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Re: Envisioning Amazing Martian Habitats
« Reply #1572 on: 12/08/2018 03:15 pm »
Truck fleet from a common base.

Basically one tonne per wheel loading. 4 wheels to 10 or even 12 if we have a double front axle like the large cement trucks.  But the most common are four and six.  I expect the extra rear axle is also a steering one.

The rear axle is additive, just as described by Paul 451 (good idea!)

All electrical, with 200 kWh core battery. 

Offline lamontagne

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Re: Envisioning Amazing Martian Habitats
« Reply #1573 on: 12/08/2018 03:33 pm »
I'm working with a solar power base cost af a bit less than 1 $ per kWh, with the solar arrays from Earth, 20 years of operation and a very partial battery back up.  Surface transportation costs are a fraction of food and fuel production costs, so the useful optimisations are in fuel production and food production.  There will be about 1 charging station for 100 solar power arrays a the colony, so there is little point in optimising the charging stations.  When the exploration is over in one area, the array can be moved.  Arrays will usually be set up on long and actively travelled routes.
Folded and deployed solar array shown.  192 m2, 14 kW peak, 140 kWh per day on good days. 288 kG mass (no battery).
40 kWh per day during dust storms.

Offline lamontagne

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Re: Envisioning Amazing Martian Habitats
« Reply #1574 on: 12/09/2018 05:18 pm »
Taking into account conversion inefficiencies and the need to carry LOx, and the difference between batteries and ICE is pretty small on Mars. And some kind of batteries actually exceed ICE.

They will need to consider battery chemistries that can be produced from ISRU on Mars, which might have lower energy density than Li, but not need to be transported all the way from Earth. Solar energy capture will be a critical path and they need to do as much of it as possible in different modes.
The first decade on Mars will need to include a lot of geological exploration, including satellite obervations and surveys using drones, and latter geoplogists with hammers and drilling rigs.  Lithium, as a salt, may have interesting concentrations in old lake beds, perhaps?

Offline lamontagne

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Re: Envisioning Amazing Martian Habitats
« Reply #1575 on: 12/09/2018 05:22 pm »
eh, ICE has the same problem when the methane tanks are full.

(And LOx tanks.) However, for an equivalent mass, methalox is denser than batteries. Moreso, for the way-station itself, tanks with the same mass as the entire battery-pack when transported empty to the site, can have store vastly, vastly more energy than the batteries. (Hence the solar arrays can work longer to fill those tanks.) And the tanks can be built locally at a much lower technology level of the settlement.
There will only be a very few way stations compared to the number of solar panels required for food and propellant production.  I think it will probbly be more interesting to invest ressources in time and material in cleaning the large solar arrays near the colony.

Offline lamontagne

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Re: Envisioning Amazing Martian Habitats
« Reply #1576 on: 12/09/2018 05:27 pm »

(a way station being a solar array with a battery pack, a Supercharger station, in effect).

This is clever. I occasionally hear a throw-away mention of "way stations" to extend range, I've yet to see anyone actually flesh out a minimum version of such a thing. Yours lends itself to standardisation.

[This also gets back to battery-vs-ICE/fuel-cell question. It is vastly more efficient to have a solar array charge a battery and a battery power an electric drive, compared to having the solar array power a fuel/oxide-maker, then fuel an inefficient chemical-fuel generator. But in the former case, once that small battery is charged... that array is doing nothing. Are you better off having it trickle-generate and store fuel/oxygen over long periods, for use in bursts? The latter also gives you a handy emergency oxygen supply. Not suggesting that for your Mars-contest entry, not futurey enough for judges.]
eh, ICE has the same problem when the methane tanks are full.
On the other hand, though it risks complicating the design and is climate dependant, what about a atmospheric water condensor hooked up to an ice cube mechine and a shadecloth? The idea being to store water outside of a tank, for the next rover to come by and take back to the fuel plant.

it'll be lossy as all hell, but since you only run it when the batteries are full, lossy with unlimited storage beats standing around doing nothing.
Depends on what the vehicles going through the way stations are carrying.  If they carry supplies on the way up and geological samples on the way down, or tired geologists, then there might not be much margin for water/propellant recovery. 
Some of the power could be used for telecommunications, and perhaps it would be interesting to power drones, or similar light vehicles from the way stations to explore the intermediate areas.

Offline lamontagne

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Re: Envisioning Amazing Martian Habitats
« Reply #1577 on: 12/09/2018 05:30 pm »
Here is my first element for my tunnel system: a Mars adapted drill rig, with a extended stay cabin and a large solar array, battery system for power.

On Mars I'd expect the wheels to be more spread out and with greater ground clearance.

And particularly with independent-wheel electric drives, it's mechanically simpler than trying to run a single power-source through multiple axles, even allowing independent all-wheel steering. You might end up with a modular chassis-drive-steer components, like the EFT-truck concept. (Although with more clearance, you need to travel over raw terrain. Unless the very first vehicle is a tracked dozer-grader. [edit: Turns out they have adjustable lift, tons of clearance.]) Connect two drive modules and it's a 4x4 rover chassis, two and a cabin and it's a manned rover. A third and it's a general-purpose 6x6 utility chassis. Five and it's a loader. 10-15 and it's a multi-articulated long distance transport. Oops, did your truck break? Just grab three modules off the long-hauler and swap over your cabin and service units and go back to working while we salvage what we can off the old parts.





[It's the lots-of-standard-units-because-it's-electric concept I'm interested in. (Or hybrid-electric in EFT's case.)]

(a way station being a solar array with a battery pack, a Supercharger station, in effect).

This is clever. I occasionally hear a throw-away mention of "way stations" to extend range, I've yet to see anyone actually flesh out a minimum version of such a thing. Yours lends itself to standardisation.

[This also gets back to battery-vs-ICE/fuel-cell question. It is vastly more efficient to have a solar array charge a battery and a battery power an electric drive, compared to having the solar array power a fuel/oxide-maker, then fuel an inefficient chemical-fuel generator. But in the former case, once that small battery is charged... that array is doing nothing. Are you better off having it trickle-generate and store fuel/oxygen over long periods, for use in bursts? The latter also gives you a handy emergency oxygen supply. Not suggesting that for your Mars-contest entry, not futurey enough for judges.]
These vehicles are concepts?
I think it would be great to have the way stations as storage places for water and oxygen.  Perhaps if they can be arranged in a loop it might make sense to have 'harvesters' move from one way station to the next.  Then the way stations would serve a dual purpose.  There may not be a specific advantage to having all of the production equipment in a single spot, if we have distributed solar, might as well spread it over a wide are.
« Last Edit: 12/09/2018 05:57 pm by lamontagne »

Online docmordrid

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Re: Envisioning Amazing Martian Habitats
« Reply #1578 on: 12/09/2018 07:34 pm »
DM

Offline groknull

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Re: Envisioning Amazing Martian Habitats
« Reply #1579 on: 12/09/2018 07:39 pm »
Here is my first element for my tunnel system: a Mars adapted drill rig, with a extended stay cabin and a large solar array, battery system for power.

On Mars I'd expect the wheels to be more spread out and with greater ground clearance.

And particularly with independent-wheel electric drives, it's mechanically simpler than trying to run a single power-source through multiple axles, even allowing independent all-wheel steering. You might end up with a modular chassis-drive-steer components, like the EFT-truck concept. (Although with more clearance, you need to travel over raw terrain. Unless the very first vehicle is a tracked dozer-grader. [edit: Turns out they have adjustable lift, tons of clearance.]) Connect two drive modules and it's a 4x4 rover chassis, two and a cabin and it's a manned rover. A third and it's a general-purpose 6x6 utility chassis. Five and it's a loader. 10-15 and it's a multi-articulated long distance transport. Oops, did your truck break? Just grab three modules off the long-hauler and swap over your cabin and service units and go back to working while we salvage what we can off the old parts.





[It's the lots-of-standard-units-because-it's-electric concept I'm interested in. (Or hybrid-electric in EFT's case.)]

(a way station being a solar array with a battery pack, a Supercharger station, in effect).

This is clever. I occasionally hear a throw-away mention of "way stations" to extend range, I've yet to see anyone actually flesh out a minimum version of such a thing. Yours lends itself to standardisation.

[This also gets back to battery-vs-ICE/fuel-cell question. It is vastly more efficient to have a solar array charge a battery and a battery power an electric drive, compared to having the solar array power a fuel/oxide-maker, then fuel an inefficient chemical-fuel generator. But in the former case, once that small battery is charged... that array is doing nothing. Are you better off having it trickle-generate and store fuel/oxygen over long periods, for use in bursts? The latter also gives you a handy emergency oxygen supply. Not suggesting that for your Mars-contest entry, not futurey enough for judges.]
These vehicles are concepts?
I think it would be great to have the way stations as storage places for water and oxygen.  Perhaps if they can be arranged in a loop it might make sense to have 'harvesters' move from one way station to the next.  Then the way stations would serve a dual purpose.  There may not be a specific advantage to having all of the production equipment in a single spot, if we have distributed solar, might as well spread it over a wide are.

The EFT MT-240 is/was under construction, and may be in use by now.  It appears to be the pathfinder for a family of modular mining vehicles.
https://i.pinimg.com/originals/a6/55/17/a6551734992c0a3ae5632106fb2f9d6c.jpg


The WTW220E has been in use for a while now.  It uses individual electrically powered bogies.
https://i.pinimg.com/originals/8c/c6/88/8cc6882430dcad0696be68176d0642a4.jpg

Multiple bogie heavy vehicle propulsion is well understood from decades of use in Self Propelled Mobile Transporters (SPMTs).  The WTW220E is proving the use of bogies in very heavy mining trucks.  The EFT MT-240 is expanding the knowledge base to include modularity on the subsystem level, vehicle level, and multi-vehicle level in mining applications.

There appears to be a trend towards multiple bogie systems in mining vehicle designs [1].  AIUI, tire wear is a big issue on mining vehicles.  Individual bogies allow near-zero scrub angles on all tires, reducing tire wear.  In addition, bogies allow raising individual wheel sets to change tires, avoid soft surfaces or hazardous objects, or disable a non-working motor, wheel, or tire.  Also, smaller tires often have lower cost due to higher production volume.

Tire/wheel wear for Mars vehicles probably needs some research.  The Curiosity rover has suffered wheel damage during its lifetime.  Initially it might be useful to choose a drive layout that is highly modular and fault tolerant.

[1] Mining is not my field of expertise.  This is just an observation about heavy vehicle design.

EDIT: Added EFT MT-240 Run 2 YouTube video.
« Last Edit: 12/09/2018 08:09 pm by groknull »