Living Underground on Mars – The 9 Drilling Challenges

One day we may have the ability to live on Mars. But, this may mean living underground on Mars. This presents many unspoken tunnel drilling challenges.

We all love the sun. On Mars though, we can’t be too picky. Living underground may be the only option to survive.

Living underground shields us from:

  • Deadly radiation from the sun
  • Super chilly weather
  • Blinding dust storms

It sounds simple enough. Dig some holes like our subways here on Earth, and that’ll become Martian life.

But the reality of digging large enough holes pose huge challenges. I’m going to go over some challenges using my engineering experience with tunneling.

My analysis is for an edge case mission. A mission that I don’t even see as possible in the next century.

But before we dive into my analysis, let’s talk a little about Mars. More specifically, why Elon Musk and many others have their focus set on this red planet.

Why Mars makes the best choice for colonization?

Mars is the easiest planet to colonize hands down. It has some amazing qualities that make it a great choice:

  • Gravity: it has a moderate gravity (3.711 m/s2) like on Earth (9.807 m/s2). Roughly 38% of Earth’s gravity. This means it’s easier to launch a spacecraft off from Mars than from Earth.
  • Water: it has liquid water under its surface.
  • Atmosphere: it lacks an Earth-like atmosphere. But, it still has one even though it’s thin. Also, it doesn’t have a crushing atmosphere that’ll crush everything that enters.
  • Temperature: temperatures aren’t extreme, even though the average temperature is -81°F
  • Distance: the shortest distance from Earth to Mars is 33.9  million miles. So, it’s not super far away.
  • Martian day: a Martian day is near the same as an Earth day. One Martian day is roughly 24 hours, 37 minutes.

Plus, Mars is one of the least hostile places in our solar system. The keyword is “least”.

Here’s a closer comparison between Mars and Earth:

 EarthMars
Diameter7,917.5 miles4,212.3 miles
Average distance from Sun93 million miles142 million miles
Mass (10^24 kg)5.970.639
Surface pressure101.3 kPa0.5 - 1 kPa
Year length 365.25 days687 days
Length of day23 hours 56 minutes24 hours 37 minutes
Temperature range-88°C to 58°C-140°C to 30°C
Temperature average13.9°C-62.7°C
Surface gravity2.66 times that of Mars0.375 that of Earth
Surface pressure1 bar0.006 to 0.007 bar
Max sunlight1370 W/(m^2)590 W/(m^2)
Radiation0.62 rads/year8 rads/year

All of this said, Mars still isn’t a place we could call home anytime soon.

Why living on Mars is a challenge?

Mars true color
The true color of Mars (Photo Credit: European Space Agency)

Mars has a very thin atmosphere. The surface pressure on Mars is less than 1% of Earth’s surface pressure.

This is one of the big issues Mars has. One option is to build an atmosphere to heat the poles of Mars.

We can try to do this in many ways. For example, by sublimating the frozen carbon dioxide on the planet.

As a result, 12-14 millibars of CO2 would be released. Thus, tripling Mars’ atmosphere from 6 to around 20 millibars.

Still a far stretch from Earth’s atmosphere of 1,013 millibars at sea level.

To top it off, Mars’ thin atmosphere is 95% carbon dioxide. Here’s a breakdown of the atmosphere content of Earth versus Mars.

 EarthMars
Carbon Dioxide0.03%95%
Nitrogen78%2.7%
Oxygen21%0.13%
Argon0.9%1.6%

Clearly, humans can’t breathe Martian air. We need more nitrogen and oxygen to comfortably live on Mars.

Mars’ magnetosphere

What’s more, Mars doesn’t have a magnetosphere. The great planetary shield that we rely on to safely live on Earth.

What’s the importance of a magnetosphere? It’s like a shield that deflects away a lot of the bad solar activity that comes from the Sun.

For example, charged particles from solar winds rush towards us almost daily. These particles would strip Earth’s ozone layer over time, without our magnetosphere.

As a result, leaving us exposed to dangerous UV radiation. It’s why we need this shield.

For the most part, Earth’s magnetosphere does a great job protecting us. As long as we’re not hit by a powerful Coronal Mass Ejection (CME).

On Mars though, it’s a different story. Because it has no shield, we’ll become exposed to all types of nasty things:

  • Higher levels of radiation
  • Solar flare blasts
  • CMEs

Living underground on Mars – the drilling challenges

tunnel boring machine
Tunnel boring machine (Photo Credit: Cooper.ch)

Because of Mars’ thin atmosphere, living underground is the way to go.

According to Mars one, we’ll need 16-feet of Martian soil to cover us. This should provide us with the same protection we get from Earth’s Atmosphere.

My view on drilling into Mars

Drilling would be the practical approach on Earth. But, many people don’t realize all the problems that come with drilling.

I’m talking about drilling with large Tunnel Boring Machines (TBM).

I’ve been a part of large engineering projects for drilling underground water tunnels. Tunnels ranging in diameter from 10-feet to 40-feet.

Tunnels were drilled horizontally. Also, some tunnels required going 150 plus feet underground before drilling horizontally.

From what I’ve seen with these projects, the only constant is problems.

On Earth, drilling can quickly turn into a nightmare if not properly managed. Even then, problems always happen. And this doesn’t even address all the arm twisting required for funding.

What I’m trying to say is, drilling is a huge headache on Earth. I can’t imagine what it’d be like 33.9 million miles away in a hostile environment.

To better explain, I’m going to go over the 9 drilling issues I expect to see on Mars.

#1 Drill repairs and replacement parts for a TBM

Drill cutting bits need constant replacement. It’s like your regular drill that becomes soft from too much usage. Over time you need to replace it.

The same concept applies to mega drills. You need to replace the drill cutting bits after too much usage.

Sometimes this means removing the drill from under the ground. This may be the case if other problems are found in the replacement work.

To top it off, these mega drills can break down, and get stuck. It’s very common.

Even worse, TBM crews need to rescue these drills from underground too when they get stuck. Who’s going to rescue a drill that’s far down underground in Martian soil?

We can’t send autonomous mega drills to Mars and expect them to work remotely.

Good luck trying to get a mega drill unstuck without hands-on human help.

#2 The electrical power demand of a TBM

TBMs need megawatts of power to operate.

The TBM projects I’m involved in have huge power requirements. The power requirements range from around 2-megawatts to 8-megawatts each.

Also, for a less than 100-mile tunnel run, we designed several substations at various intervals. The substation designs were for transformers connected to the power grid at 115,000 volts.

The transformers were rated 30 to 40 MVA. Some much larger as they had to feed large 5,000 HP plus-sized pumps to remove underground water.

On Mars, I don’t think we’ll find water where we’re drilling. So we wouldn’t need massive pumps with the supporting infrastructure.

Regardless, where would the power for our mega drills come from on Mars? The only option I see it to bring nuclear reactors from Earth.

#3 The speed of drilling with a TBM

These mega drills are slow. Very slow.

They drill around 15 miles per year give or take. It depends on the geological conditions underground.

Also, in how well the crew maintains the TBM and supporting equipment.

In bad conditions, TBMs don’t operate consistently. I would say 50% of the time the drills are not in operation.

All in all, the reduced running time is due to many different factors:

  • Ground conditions
  • Removing muck
  • Fixing electrical problems
  • Inflow problems from underground water
  • Replacing and fixing drill parts due to wear and tear
  • Repairing the drill’s infrastructure
  • Waiting on orders over critical parts
  • Safety issues

The recent work I’m involved in is a decade-plus long project for less than a 100-mile tunnel run. On Mars, we don’t have this luxury of time.

We need to work fast as radiation is high.

Because of this, we need to get below the Martian surface quickly. Staying on the Martian surface for weeks on end is not safe for humans.

Plus, unprotected electronic devices could fail from too much radiation.

Even more, every day could bring a new problem that we never planned for. So, speed is a huge concern.

To illustrate the time length of these projects, let’s look at a list of epic projects done by Robbins. They’re one of the industry leaders in tunneling:

ProjectLocationTunnel diameterTunnel lengthProject timeline
Túnel Emisor Poniente (TEP) IIMexico City, Mexico28.5 feet3.6 miles5 months
Grosvenor Decline Tunnel Queensland, Australia26 feet1.1 miles3 months
Pinglu TunnelShanxi Province, China15.7 feet15.8 miles4 years 2 month
The Niagara Tunnel ProjectQueenston, Ontario, Canada47.5 feet6.5 miles4 years 8 months
Boston Harbor ProjectBoston, Massachusetts, USA26.5 feet9.4 miles4 years 2 months
The Manapouri Hydroelectric ProjectLake Manapouri, New Zealand33 feet6 miles2 years 9 months

Several things to keep in mind:

  1. Number of TBMs: some projects have many TBMs working together. This is not an option on Mars, even though it’s a huge time saver. It’s a huge challenge alone to get one mega drill there, let alone two or more.
  2. Prep time: these large projects need years of prep time. You don’t just say you want a tunnel and start drilling tomorrow. The Robbins’ timeline only includes drill time.
  3. Challenges: you could easily triple the timeline for these Robbins’ projects. If the drill hits something unexpected, work will slow to a snail’s pace.

#4 The physical size of a TBM

tunnel boring machines
Photo Credit: Brisbane City Council

These drills are not only huge but very heavy. Sure, we don’t need to drill a 50-foot diameter tunnel on Mars.

But even still, let’s assume a 10-foot diameter tunnel. The drill will still be very heavy.

We don’t have any rockets that can get something this large safely to Mars. Including all the required infrastructure.

The large TBMs are over 1-million pounds in weight. And they’re 400-feet in length with all their trailing gear.

Then there’s the size of all the supporting infrastructure. A 30 MVA 115,000 to 12,000 volts transformer will weigh around 75,000 pounds.

To put things into perspective, the NASA Mars Curiosity Rover weighed 1,982 pounds.

Important Note: we want to send as many things preassembled as possible to Mars. This will make life easier for our space travelers. 

Plus, it’s much easier to troubleshoot on Earth than on Mars. 

#5 Removing excavated soil from the drilled tunnel

The ground that’s cut needs to be removed from inside the tunnel. So, it needs to be brought to the surface and transported away.

On Earth, the soil grated away is taken out of the tunnel in large rail cars. Then typically recycled in some way.

On Mars, this part of the work would become an engineering challenge.

To illustrate, let’s look at the Purple Line Extension Transit Project in Los Angles. It’s two 21-foot diameter tunnels 9.1 miles long.

At the end of this project, the TBMs will cut 495,000 cubic yards of soil. That’s equal to 2.3 million bathtubs filled with dirt. Crazy!

Important Note: the excavated ground is typically mixed with certain compounds. This makes the removal of the cut soil easier. 

So, the 495,000 cubic yards of cut soil, becomes 650,000 cubic yards of removed soil. This doesn’t make the work any easier on Mars though.

#6 Problems with the geology on Mars in drilling

On Earth, a contractor always has a plan of action to cover all possible issues. On Mars, this isn’t possible.

Mars is an unknown land to us.

Here are some geology conditions from Earth that can become problems on Mars.

Hard abrasive rocks

No matter how strong cutters are, they will wear over time. If we’re dealing with hard abrasive rocks, the cutters will be damaged more quickly.

And who knows what type of rock we’ll find below Martian soil.

I doubt we’ll be lucky and only drill through soft soil. This means we’ll need to replace the cutters often.

Blocky rock, sand, and clay

These materials and shapes can cause a cutter to get stuck. To counter these types of materials, the drill crew does half strokes with half resets.

This allows the crew to pull back if there’s too much torque build-up. This slows the drilling work, but it beats trying to remove a giant drill from a stuck position.

Loose running ground made of a lot of clay

Drilling through this type of material can cause a collapse above the drill.

The ground above the tunnel can fall trapping the drill. Even more, a large cavity can form above the tunnel where the collapse happened.

This cavity can extend 40 plus feet high above the tunnel. Obviously it depends how far down we’re drilling.

Sometimes removing the fallen materials requires building a bypass tunnel. And to fix these types of problems, humans need to be present.

Underground water

On the bright side, almost all water on Mars exists as ice. And this ice is found near the poles.

One problem on Earth is the inflow of water in the tunneling area.

Water can flood a tunnel causing huge delays. Plus, it can damage parts of a TBM.

So, before drilling, we need to pump out all the water from the tunnel area as best as possible.

As I mentioned already, for our large drilling project, we designed in a couple of 5,000 plus HP pumps. Not only are these pumps large, but the infrastructure required is extensive.

#7 Infrastructure required to support the operation of a TBM

It’s not just the drill we need to take to Mars. There are many other parts needed:

  • Electrical equipment like transformers and nuclear reactors
  • Extra parts for the TBM
  • Cranes to lift the heavy equipment
  • Hydraulic jacking systems
  • Laser-guided equipment for guiding the drill
  • Pre-cast concrete segments for the tunnel outer wall

My point is, drilling is a huge effort. You need a lot of equipment. And a lot of people working closely together.

Important Note: Mars has little to no atmosphere as we learned. So, this makes landing heavy objects on Mars even more difficult.

On Earth, our atmosphere reduces the speed of something falling. On Mars, the atmosphere does nothing for you.

#8 Building the outer shell of a tunnel

As we bore through the ground, we need to install pre-cast concrete panels. These panels create the outer shell for the tunnel. They’re the support system for the tunnel.

But, a lot of the time the panels break or don’t properly get placed.

More important is the analysis before the drilling. A complete field investigation with geological analysis is required.

This will help with the design of the concrete segments. These concrete segments need to withstand all loads caused by tunneling on Mars:

  • Rocks
  • Water pressure
  • Earthquakes
  • Thrust forces from construction conditions
  • Usage from any type of traffic loads

On Earth, this analysis can take years. On Mars, we don’t have this luxury of time. Even worst, it’s all foreign land.

We don’t want to spend trillions of dollars. Then waste decades of time to end up with failed construction.

What’s more, the process of creating precast concrete panels is time-consuming. Plus, these panels are heavy.

#9 Required human team to support a TBM

A TBM normally has a team of 10 to 15 people supporting the drilling at any given time.

Machines alone can’t do the drilling on Mars. We need humans on Mars.

The drilling will need constant hands-on problem-solving.

While keeping in mind, the work is intense and difficult even here on Earth. The difficulties include:

  • 24-hour drilling
  • Extreme loud noise
  • Mountains of dust
  • Low visibility
  • Fatigue
  • Dangers of working with heavy equipment underground

On Earth, we take a lot of safety measures. Also, we have the best hospitals nearby.

But that luxury doesn’t exist on Mars.

Any help from Earth would take at least 6 to 8 months to arrive. This is on top of working in a foreign hostile environment.

Alternatives to digging manmade tunnels on Mars

We don’t have the tech to drill into Mars’ surface today using a TBM. We do, but it’s not practical in any way to get all our equipment there. And, then make everything operate.

Too many problems.

But, we don’t need to abandon the idea of living underground on Mars. Other options exist, such as:

  • Sealing off natural caves.
  • Digging into lava tubes to use as shelter. Lava flows create these amazing empty tunnels.

Of course, we need to first find these caves and lava tubes.

But when we do, this approach will reduce the amount of digging we need to do. What’s more, if we pressurize the cave or tubes, we can create a livable environment like on Earth.

Even more, we can warm the underground area up. Obviously much easier said than done, but nothing will be easy when it comes to living underground on Mars.

The goal of living underground on Mars

The challenges of terraforming Mars are huge. I’m not talking about landing several humans on the red planet.

Rather, full-blown colonization.

It’s very difficult to wrap your head around this mission. Partly because our tech isn’t there yet to pull this off.

Frankly, taking a TBM to Mars is a horrible idea today. I’m sure in the future we’ll have the ability to colonize Mars without huge tunnels.

Ironically though, humans started living in caves. Then after thousands of years of evolution, we’re planning to go back to cave living.

That’s where tech is taking us in the future.

What are your thoughts on living underground on Mars? What are the biggest challenges of terraforming mars that you foresee? Do you think we should drill our own tunnels?


Featured Image Photo Credit: European Space Agency

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