Tunneling into Martian equatorial ice deposits

[steveleach]

When I saw the cross-section illustration from the Mars Express equatorial ice discovery, I started thinking about tunneling (largely) horizontally to reach it, with the tunnels providing habitable space as an additional benefit.

I know that both finding/extracting water ice and living in tunnels on Mars have been discussed previously on these forums, but has there been much discussion about combining the two?

Is it even remotely feasible?

https://www.space.com/mars-water-ice-equator-frozen-ocean

(Image credit: CReSIS/KU/Smithsonian Institution)

[zubenelgenubi: Thread title spelling edited.]

[LMT]

Is it even remotely feasible?

Much depends on purity and cover thickness.  Radar shows layering, which might give very dirty tunnelling.  (Compressive strength variation is also a concern there.)  And what min cover thickness do you see?

Would a glacier give easier tunnelling?  Glacier ice should be clean, as with a terrestrial glacier.  Melt-out excavation 1 2 is at least conceivable there, even under negligible dirt cover, e.g., where "'X' marks the spot".

Ice in the center of Zone 2 East [red outline] appears to be ~ 700 m thick...  Conceivably, glacier melt-habs at this location could be accessed from the glacier surface above and also from the plain below.  Basal tunnels could open onto moraine slopes of Zone 3; esp. incised gullies of Gallagher and Balme 2015 Fig. 8 "(i)".  The southern gully cuts right into Zone 2 East:  Gallagher and Balme 2015 Fig. 4a.  "X" marks the spot.

[spacenut]

I don't think they will need to tunnel.  Using directional boring equipment, heating elements, and pumps, a lot of water could be removed without tunneling.  One drilled hole then direct the drilling horizontal in many different directions, extracting the ice or water to the surface.  If it is not so deep, just plain front end loaders with sealed cabs could strip mine the ice.  Not as much equipment needed as tunneling and supports. 

[steveleach]

I don't think they will need to tunnel.  Using directional boring equipment, heating elements, and pumps, a lot of water could be removed without tunneling.  One drilled hole then direct the drilling horizontal in many different directions, extracting the ice or water to the surface.  If it is not so deep, just plain front end loaders with sealed cabs could strip mine the ice.  Not as much equipment needed as tunneling and supports.

Yep, and I suspect that drilling will end up being a better use of available power, but that's a completely different concept and doesn't have any synergies with habitat. I'm asking about horizontal tunnelling rather than vertical drilling so that you get the benefit of the tunnels as a protected environment to live in: you can't live in a drill hole.

[steveleach]

Is it even remotely feasible?

And what min cover thickness do you see?

Cover will vary from negligible at first to hundreds of meters eventually, as the point is to make use of the natural gradient (which is obviously highly exaggerated in the illustration).

[LMT]

Is it even remotely feasible?

And what min cover thickness do you see?

Cover will vary from negligible at first to hundreds of meters eventually, as the point is to make use of the natural gradient (which is obviously highly exaggerated in the illustration).

No, reverse it.  The tunnel would slope down to the insulated entrance, so that water flows out naturally.

Also, you wouldn't excavate at the top of the buried ice; that would cause collapse.  You'd enter lower down, to use the compressive strength of ice (if that uncertain Medusae Fossae ice had compressive strength).

And we see the scale.  What's the actual min cover thickness there, i.e., the number?  How does that compare to the few meters of cover on a glacier gully / terminus?

[Lampyridae]

I don't think they will need to tunnel.  Using directional boring equipment, heating elements, and pumps, a lot of water could be removed without tunneling.  One drilled hole then direct the drilling horizontal in many different directions, extracting the ice or water to the surface.  If it is not so deep, just plain front end loaders with sealed cabs could strip mine the ice.  Not as much equipment needed as tunneling and supports.

Yep, and I suspect that drilling will end up being a better use of available power, but that's a completely different concept and doesn't have any synergies with habitat. I'm asking about horizontal tunnelling rather than vertical drilling so that you get the benefit of the tunnels as a protected environment to live in: you can't live in a drill hole.

If anything, you will absolutely *not* want to introduce biological contamination into the ice, which would happen if you tunnel into it to create habitats.

You will want to do drilling in any case for xenobiology and geological studies. And geotechnical studies: Mars rock is essentially unknown and tunnelling requires geotechnical assessment through drilling and wireline logging. Nothing beats a core sample. Or rock chips from a reverse circulation/percussion drill. If they're from Mars, universities and research institutions will climb all over each other for those.

The rock overlying the ice deposits is dry sediments – about the easiest thing there is to drill through. Mineral exploration drill rigs don't also weigh that much, generally a few tonnes. They're essentially drill rods, casing, a motor (often a truck's engine like your regular borehole driller) and a gearbox plus some other equipment. Maximum attainable depth is constrained by the power of the motor and the drill diameter, plus the type of drilling done. On Earth, a reverse circulation drill would easily rip through soft sedimentary rock. A hole a few hundred metres deep would be drilled in a matter of days. On Mars, whatever would limit your drilling would limit your tunnelling.

You could also bring along a shaft sinker and make a series of silos to live in. Although, with so much water on tap from the drilling, you could simply use the ice as the principal material for some domes or other surface habitat.

Since you are working with a Mars budget, you could easily design a roadheader to drive a drill derrick if you want to create underground habitats, though you will still have to airproof them. But why? This is the era of Starship, not Constellation. Bring both if you want them.

[Twark_Main]

just plain front end loaders with sealed cabs

Just a minor implementation detail, but surely you'll prefer teleoperation here.

Sealing the cab from air leakage is the least of your worries. You need to strengthen it to hold the enormous internal pressure loads, and now for your troubles.....  you just placed a vulnerable spacecraft pressurized cabin right next to your hazardous work zone.   

Instead, just bolt on a camera and a radio. Control can be done from a centralized base, or (for deep underground sites) a nearby "work trailer" habitat connected via a local mesh networking.



... plus, it gives you extra guys to fight at the climax of the movie. 

[Lampyridae]

A lot of mines use teleoperation for underground vehicles nowadays. The tradeoff is that a human-in-the-cab driver (currently) can drive about twice as fast as a teleoperation driver, about 20-30km/h. They have a better "feel" and situational awareness while in the cab, seeing hazards, feeling the vibration and feedback etc. In the 2040s, who knows how good they might become, maybe nearly fully autonomous while retaining the same production advantage as hu-manned vehicles.

[DistantTemple]

https://forum.nasaspaceflight.com/index.php?topic=55813.msg2559624#msg2559624
Teleoperation demo this year.

[Slarty1080]

I can't see tunneling into Martian equatorial ice deposits being a near term thing at all. Eventually perhaps, but the nature of the terrain is likely to be unpredictable with all sorts of mixed up materials with the ice such as boulders, stones, sand and dust. The trafficability of such sites is also questionable, there may well be a lot of steep gullies, crevasses, seracs and lose material.