# How large could manmade, domeshaped caves inside the ice dome in Korolev crater on Mars become without the danger of collapsing?

Would not the right exploitation of the ice dome in Korolev crater be the most economical way to create Earthlike room for living on Mars, if they were safe to use?

With "Earthlike" I mean the area would have breathable air with a temperature of, for instance, minus 5⁰ C and an atmospheric pressure of about 100 kPa.

Screen shot of the elevation chart of Korolev crater produced by Mars Trek

The image above shows a vertical cross section of Korolev crater with the ice dome from north (left) to south (right).

The northern slope of the ice dome has a mean angle of about 6⁰, so starting at the base with a 100 m. long horizontal trench into the slope, at the end of the trench the real entrance into the ice dome would be a tunnel into the about 14 m. high vertical wall.

The northern slope would be suitable for tunnels because on the slope of the northern rim of the crater, facing the Sun, the most energy could be produced to mine the ice of the dome.

Mining the ice could create space large enough to live in, like dwellings, or maybe even large enough for a group of dwellings, like a dome shaped cave.

But can it be argued or reasoned if and how the safety of such a cave would depend on its size, or can it even be estimated with calculations ?

To get a calculation as simple as possible, we can suppose the cave to have the shape of a dome.

• Are you planning to fill the cave with atmosphere at liveable temperatures (say 20 deg C) ? If so how will you keep the ice below the freezing point? If you intend for the ice dome to be purely a weather & radiation barrier, then you just need to calculate a radial logarythmic thickness profile to keep it from collapsing, and keep the thinnest point (apex) thick enough to block radiation. Then you build your sub-housings to maintain 1 Earth-atm inside them. Commented Jun 21, 2021 at 13:41
• @CarlWitthoft Yes, the air inside would have to be below freezing point. It would be great if you could calculate that thickness profile. Wouldn't you have to know the mechanical strength properties of the ice with the varying pressure depending on the thickness above it ? Commented Jun 21, 2021 at 14:04
• @CarlWitthoft But a temporary temperature above the freezing point could be an easy way to let the cave grow ? Commented Jun 21, 2021 at 14:15

More of a comment, but I need the space.

Firstly, are you sure about the temperature of the ice being minus 5° C? That's just below freezing temperature and very close to melting temperature.

Using the assumption that the ice would be a crystalline solid analogous to a crystalline rock such as basalt, it would be best to keep the size of the openings within the ice small. Make them as large as they really need to be. This will reduce stability issues.

Making the tunnels and the caverns can be done via three methods:

• Conventional drill and blast - not recommended because of issues sourcing explosives and the damage the blasts will do to the walls. When blasting there is always a blast damage region around such openings. In rock, this can be between 2 and 5 meters, depending on the type of rock and the explosives used.
• Some for of grinding technology, such as tunnel boring machines or continuous miners. These would be less damaging to the walls of any openings.
• Some form of thermal tunneling where heat is used to melt the ice. This may need to be devised. However this method may erode the floors of the tunnels with the melt water. Edit, this may be involve using hot water jets to cut the ice, or even hot grinding, where some of the ice is sacrificed to create hot water to heat a grinding head. This would soften the ice & enable the grinding head to use less power.

One problem I see in having tunnels and habitats in ice how to overcome erosion of the floors of the travelways. In conventional tunneling and mining this is usually solved by continually maintaining the roadways with new gravel and grading with either a grader or the bucket of a loader. Having a bed of ice will be problematic, particularly one that always traversed upon.

Edit 21 June 2021

To get an idea of what might be possible regarding sub surface habitats on Mars and elsewhere, with some adjustments made for atmospheric issues, the opal mining town of Coober Pedy in South Australia offers a good example.

Edit 23 June 2021

Following on from comments made so far, a fourth option has been discussed: using diamond wire to cut blocks of ice. Given ice would not be as hard as rock, diamond in the wire could be replaced with tungsten carbide.

Edit 11 July 2021

Recently I watched a video which briefly mentioned the former "under ice" base the US military had on Greenland.

The construction of the in-ice base used in Greenland during the late 1950s to mid 1960s was different to what is proposed by this question. Trenches where cut into the surface of the ice covered, prefabricated buildings were placed in the trenches which were then covered with arched roofs.

The base was designed to be used for a period of 10 years, with suitable maintenance of the trenches. The trenches were occupied for 5 years and abandoned after 8 years. Trench deformation was a major problem, as was the location of the sewage sump, but that's another matter.

Part of the problem for the ice base was the movement of the glacier was faster than anticipated. This may not be an issue in your situation but the properties of ice will be.

snow and ice are viscoelastic materials, which slowly deform over time, depending on temperature and density.

Maintaining a cavity within a block of ice and ensuring its integrity (size and shape) will be more difficult than maintaining a similar cavity in competent rock.

• Thank you for this informative "comment", I get the impression that with the need for those boring machines the created room for living would not be that economical anymore. But given enough time melting the ice could be done in a slow way, with much less equipment, like flamethrowers. Commented Jun 20, 2021 at 21:14
• I've made some edits. I've added two option concerning thermal tunneling. I don't envisage flame throwing devices would be used, more control would be needed to excavate a uniform tunnel profile & openings of specific sizes (engineering requirements). I've also added a link to pictures of Coober Pedy as an example of sub surface living.
– Fred
Commented Jun 21, 2021 at 3:34
• Because the needed energy would have to come from solar panels, I think it would be most efficient to use electrical melting. High electrical resistance wires or rods heated by an electric current would give much more control to cut into the ice, Blocks of ice could be taken out of the wall to melt somewhere else. Commented Jun 21, 2021 at 9:08
• Regarding your idea for cutting blocks, cutting the first row of blocks would be problematic, but it would be fine for the others. The method would enable the sides, top & bottom of blocks to be cut, but cutting the back of the first row of blocks would initially be difficult. Your method reminds me of diamond wire mining of gold reefs in South Africa. There they had at least two, sometimes three faces of a block already made via drill & blast & they cut the other sides with diamond wire.
– Fred
Commented Jun 21, 2021 at 9:27
• Instead of using heat to cut the blocks you could use something like diamond wire, but because ice would be easier to cut than rock have a cheaper abrasive material such as tungsten carbide.
– Fred
Commented Jun 21, 2021 at 9:37