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> Shorter periods of exposure to space radiation and microgravity could help mitigate its effects on the human body.

Of course once astronauts are on mars they will still be exposed to radiation, until some sort of shielding can be built.

Which would be an obscene undertaking, and involves moving lots of raw and refined materials to mars.

Which means hopefully the price of this rocket to get stuff off of earth is dirt cheap, because moving squishy humans to Mars, no matter the speed, is not the limiting factor! (Getting humans to Mars and keeping them alive there is!)

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As far as I know the plan has always been to use the martian regolith and water as primary radiation shielding -- same as the moon.

Here is a recent (2022) paper[1] on the concept, but you can easily find scholarly work on this going back many decades...

[1] https://www.sciencedirect.com/science/article/abs/pii/S00320...

https://en.wikipedia.org/wiki/Martian_lava_tube have also been proposed as pre-existing possible shelters.

https://en.wikipedia.org/wiki/Caves_of_Mars_Project#/media/F... "HiRISE image of Mars hole 'Jeanne', about 150 meters (492 feet) across and at least 178 meters (584 feet) deep."

Most of the materials could surely be found on Mars. A shelter built out of sandbags would be a low tech solution that would get you a large part of the way there.

Further, Mars itself shields you from half the radiation (at night), the Martian atmosphere shields you from a little more, and Mars is further away from the Sun on average than an Earth-Mars spaceship.

Radiation during transit really does seem like a bigger issue.

There are also cosmic rays. They come from every direction, so even at night.

An experiment measured that kind of radiation about 20 years ago https://en.wikipedia.org/wiki/Mars_Radiation_Environment_Exp...

The planet still shields you from half of those.

>> obscene undertaking, and involves moving lots of raw and refined materials to mars.

Or they can dig a hole and/or pile mars dirt on top of their living structures. Some materials are better than others at absorbing radiation but, as a general rule, mass/depth of the protection counts more than composition.

It's not an intractable problem, just send a robot bulldozer and excavator a few years beforehand. The real problem with a Mars colony is the economics for making it anything more than a small scientific outpost / political stunt. Forget the upfront cost of the habitat/etc, how do you actually create a self sustaining Martian economy? I've never heard a realistic answer for this.

It is an interesting problem of energy. How would a robot bulldozer or excavator be powered? They require more power than a rower.

Solar still works on Mars as does fission. Plenty of stuff about this online if you look.

Sure, but solar is not great for digging underground. So now you need a solar station and wires connected to it, and that already complicates things significantly and massively increases the chance of failure.

small nuclear power plant would be the first thing sent to mars, or many arrays of solar cells. then pods of batteries, then construction materials, then equipment, then humans.

realistically, the assembly could be done remotely, and you would want at least two habitable shielded pods with a very large excess of food/oxygen/supplies stored by the time humans arrived.

This might seem impossible, but i don't think it's particularly difficult, the only major hurdle would be the budget. The rocket vessel will make a good living pod, the small nuclear reactor was studied by the US Gov in the 50s, so that shouldn't be a problem, except maybe cooling, but again that should be a solvable problem.

They don't require more than a rover if you accept them doing their work far slower than their normal earth equivalents. Hence sending them years in advance to dig out a some holes that would only take a few days for excavators on Earth.

While speed is a factor as well, you still need a lot more energy consumption to move a mass of rock&dust some distance away than to move a small rover. This immediately follows from the formula for work and the gravitational force.

Given enough time, you can dig out a house foundation with a spoon, power is not an issue here. The less power you have available the slower you work. If your robots wear out, you send more.

The real problem is finding enough time and money to waste on such a fruitless endeavor. If that can't be managed it nullifies the entire problem of digging a hole on Mars since a Mars base is nothing but a waste of time and money. Wasting time and money is table stakes.

If we can spend $100 billion on blowing people up, we can certainly afford a Mars colony.

As terrible as it is, blowing people up at least serves a purpose (an evil, mean-spirited, ego-driven purpose). A colony on Mars is entirely pointless. It would be like spending $100 billion on a performance art project.

That's easy to claim, but it's not so easy to actually convince a government of this.

Before you get angry with me: I'm not saying this is the way it ought to be, but it's the way it is.

> how do you actually create a self sustaining Martian economy? I've never heard a realistic answer for this.

What would a realistic answer even look like? I imagine that since nothing like jump-starting an economy ex nihilo on a cold, desert planet has been done before, any proposal at all would sound wildly unrealistic.

Tourism? That's the only thing that even approaches realistic that I can think of.

I guess my question wasn't so much "What is a realistic solution?" but more "Would we even recognize a realistic solution if it were presented to us?"

The enterprise of starting a colony on Mars is so unprecedented that any economic solution sounds nuts.

I think the only realistic answer at this point is "We need more information".

The problem with the Martian tourism is the huge amount of time it takes - around 3 year round trip with current conventional rockets; this proposed nuclear rocket would cut travel time to 2 months one way, but you are still looking at a 4 month minimum just in travel time. A billionaire who could afford a Martian vacation would likely struggle to take the time out of their schedule for one. This is why I think lunar tourism is much more viable: a vacation on the Moon need only take 2 weeks (a week of travel time and a week there; and nuclear propulsion could cut the travel time substantially)

It takes 2 months in near-ideal winds to cross the Atlantic by (non-modern ultralight) sail, yet that sort of travel was done pretty regularly for business.

When steam engines decreased that time to 16 days, 200-passenger ships crossing Atlantic purely for tourism were very popular.

It once was a tradition for the English upper classes to send their young sons on a "grand tour" of the Continent, which would last for many months, sometimes even a year or two.

So, yes, some billionaire paying for their kid to spend 12-18 months on a Mars trip is a possibility. Or maybe even for themselves if they retire, or as a sabbatical.

However, I think the much greater time and expense is going to make Martian tourism a much smaller market than lunar tourism.

I think in the medium term, the Moon is a much more feasible destination for humans than Mars is. It is much easier for an ultra-wealthy person to take a few weeks out of their schedule for a trip to the Moon, than months or years for a trip to Mars. Since it is only a bit over a light-second away, they could even quite feasibly work remotely from there – the delay is small enough that real-time audio and video calls are possible. Mars is 3–22 light minutes, which forces all communication to be asynchronous.

"The Mars colony would produce [service/good] to generate income sufficient to pay for the colony's upkeep / expansion."

Let's assume the colony itself is built by some idealist willing a trillion dollars to the project or something. Now that you have a base on Mars, how do the inhabitants pay to keep it going? Self sufficiency is too far fetched at this stage so they need regular supply shipments from Earth, so they need income of Earth currency.

Ok, you've described the problem again, but I'm trying to understand what a realistic answer would look like.

Let's say for instance that some answer were "handicrafts built from local, Martian materials" along with "YouTube channel revenue". Sounds unrealistic to me, but maybe people would be willing to pay $1M for a little puppet made on Mars, and they could ship them out by the ton. The economics on this are unusual.

I don't know. I honestly think Martian colonization just will not happen until we have a global, peaceful, prosperous civilization. Then it would just be funded by the global government in a similar way and for similar reasons as the antarctic stations.

> Now that you have a base on Mars, how do the inhabitants pay to keep it going? Self sufficiency is too far fetched at this stage so they need regular supply shipments from Earth, so they need income of Earth currency.

Emotional blackmail: “If Congress doesn’t pass the Martian colony funding bill, Americans on Mars will die”

National competition: “China’s Mars colony is bigger than ours”

Religion: “God wants us to send money to Mars” (that may sound bizarre, but religion motivates humans to spend fortunes on all sorts of strange things, maybe at some point one or more religions will latch on to Mars)

Building an underground chamber doesn’t seem like an impossible undertaking. Alternatively, maybe mars already has caves and tunnels.

There are tunnels that appear to have been created by volcano lava. Lava tubes.

It takes a lot of energy to displace sand/dirt/rocks to build anything underground. Human-powered shovels require a lot of food and water, and machinery requires combustion and a lot of hydrocarbons.

> machinery requires combustion

solar power / RTGs could power such effort. Digging shelters could be done by unmanned missions before the manned missions would arrive.

I don't think this comment fully appreciates the density of hydrocarbon-based energy sources.

No, a RTG-powered bulldozer isn't going to be clearing caves and trenches on Mars, ever.

rtgs can be used to aid solar in charging batteries, the digging process can take a long time, if you space it correctly you would be able to get that energy from solar etc

No, you cannot. You are still dramatically underestimating the density of hydrocarbon energy. Solar, electric, batteries, etc do not even remotely come close.

This line of thinking also dramatically underestimates the energy requirement to excavate dirt and rock...

Then, figure it's on another planet with dust storms that have already killed solar-powered rovers, etc.

> You are still dramatically underestimating the density of hydrocarbon energy. Solar, electric, batteries, etc do not even remotely come close.

I never mentioned hydrocarbon energy. You keep bringing it up for some reason.

> Solar, electric, batteries, etc do not even remotely come close.

I don't need them to come close. I need them to do the job, and they do it

> This line of thinking also dramatically underestimates the energy requirement to excavate dirt and rock...

here are some electric, battery powered excavators:

- https://www.volvoce.com/europe/en/products/electric-machines...

- https://www.wackerneuson.cz/en/zero-emission/electric-excava...

- https://www.komatsu.jp/en/newsroom/2023/20230721

- https://www.jcb.com/en-us/products/compact-excavators/19c-1e

- https://www.bobcat.com/na/en/equipment/excavators/compact-ex...

- https://www.volvoce.com/europe/en/products/electric-machines...

- https://www.hitachicm.com/eu/en/onsite/article/Introduction_...

- https://www.casece.com/en/europe/products/excavators/d-serie...

- https://www.kubota.com/news/2023/20231218.html

There are excavators both small and big so yes you can definetely excavate using electricity alone.

> dust storms that have already killed solar-powered rovers

Looking at list here https://en.wikipedia.org/wiki/Mars_rover I guess you talk about Zhurong and Opportunity? Both of these seems like success story given that they survived way longer than they were expected to..

Just wanted to add to your list, electric dozers have been on the market for some time. Even more impressive given the weight.

https://www.cat.com/en_US/products/new/equipment/dozers/medi...

And how do we get a 51,333 lb bulldozer to Mars?

Not to mention this bulldozer still burns hydrocarbons. It uses electric drive for it's tracks - and the electricity is generated by hydrocarbons!

a gallon of gas produces about 33 kWh. A meter of solar panels (which has a similar weight without glass) produces about 1000 kWh / year. (It's about the same on Earth and Mars since a Mars year is almost twice as long)

This isn't a helpful metric though - even if we had a vast grid of solar on Mars - how is the power going to be stored? Batteries? How do you get them there? Who plugs it all in? Who maintains if when it fails?

Excavating earth and rock in the volume being proposed (to build underground dwelling spaces) is not trivial...

Why store it? Dig when the sun is shining and idle when it isn't.

Your other concerns are power source agnostic.

All of the other issues still exist. How do you setup a solar farm on a remote planet without any humans being involved (the OP was discussing tunneling before any humans arrived). Who plugs it all in? Who dusts it off after a storm? How long are the cables that power this excavator? What happens if they get tangled or damaged?

It's just a non-starter of an idea...

Mining on Earth is already electrifying and going remotely piloted and a little bit autonomous [1].

[1] https://www.smh.com.au/business/companies/no-one-behind-the-...

Tunnel boring machines often use electric motors, often in the thousands of kW range.

The ones the boring company uses are battery powered (using containers full of batteries). The batteries are swapped out periodically and charged overnight.

Seems like a use-case for a "controlled" thermonuclear demolition project.

Submarines run on nuclear. Wouldn't nuclear be the natural choice on mars?

Those are big, and heavy. https://www.oregon.gov/energy/safety-resiliency/Pages/Naval-...

> The submarine reactor compartments that have been taken to Hanford are about 33 feet high and 40 feet in length. They weigh between 1,130 and 1,680 tons. Eventually, the Navy may deactivate its Ohio class submarines in the same manner. Those compartments would be much larger and heavier.

Submarines don't have to get them into orbit.

In case you're serious, nobody is suggesting launching a water-cooled reactor to Mars. Between the idiot ends of the power-source spectrum bounded by, on one end, a U.S. Navy PWR and, on the other end, Martian Aramco, we have the reasonable options of solar power, batteries, RTGs and fission-powered Stirling engines [1][2].

[1] https://www.nasa.gov/directorates/stmd/tech-demo-missions-pr...

[2] https://www.nasa.gov/tdm/fission-surface-power/

I think solar's the far more likely option, yes. Cheap, light, low-maintenance. Maybe fuel cells for night.

RTGs aren't gonna power a good-sized base; they're a few hundred watts at best.

edit: I very much hope Kilopower pans out.

What is wrong with launching a water-cooled reactor to Mars? Or more likely launching the materials needed to build it. The active components of a reactor are quite tiny -- most of the bulk is in the shielding, which won't be necessary on an already radioactive planet like Mars.

> What is wrong with launching a water-cooled reactor to Mars?

Water is heavy and difficult to replace if lost for whatever reason.

There is water on Mars, why not use it?

> There is water on Mars, why not use it?

It's expensive. Every gram takes tremendous resources and energy to extract. It would be like using antimatter for a small-town fireworks show.

If the nuclear reactor was the only thing that needs water, yeah. But if we're at the point of installing a nuclear reactor on Mars, I guess we would also be actively mining and processing water in large quantities.

> if we're at the point of installing a nuclear reactor on Mars, I guess we would also be actively mining and processing water in large quantities

A reactor should be among the first things we put down, ahead of the arrival of humans. And even if we’re processing lots of water, it would be a long time before it’s so abundant that sequestering (and irradiating) such a large amount of it is cheaper than other methods.

Mars isn’t radioactive. A reactor would still need shielding.

Only if you intend to stand near it while it's running. Not trying to be glib, just pointing out that at least initially, there might not be any humans near. Admittedly, radiation might be a bother for high density electronics (CPUs, RAM, etc), but maybe it'd be cheaper to shield the bot-brains. Bots could rely on the power for a few years and when the humans get there, if nothing else you could drop all the rods in and let the rad flux die down.

I know, I wouldn't want that in my back yard either, but Mars is exactly nobody's back yard at present. Bootstrapping a (necessarily!) technological civilisation on another planet is not an un-risky business.

Barring significant progress in robotics we'll still need humans to maintain the thing.

> we'll still need humans to maintain the thing

Sure, but you're not going to need major shielding for the first few hundred reactors on the planet. Putting the stuff that requires maintenance away from the reactor will be enough for a few decades. (Put simply, the aspiring interplanetary powers who insist on heavily shielding their reactors aren't going to be releavant on the ground. You can launch a second reactor for the cost of one's shielding.)

Dirt works fine for shielding, when you live on a planet whose soil is already toxic to life. And yes Mars is radioactive, because it has no magnetosphere. Especially when there is a solar flare.

Mars is regularly irradiated by solar radiation. This is very different from being radioactive.

> Mars is regularly irradiated by solar radiation. This is very different from being radioactive

Yup. Mars is radioactive to the degree empty space is.

Not really. Being regularly irradiated makes you low-level radioactive.

After all the pedantry is out of the way, the point is that humans on Mars already have to deal with radioactivity, which makes using nuclear power a no-brainer.

Submarines are encircled by water, that is very good at absorbing heat. Nuclear power stations are also invariably close to a large source of water.

There is no such thing on Mars, and that significantly increases the mass and size of your radiators, making it uncompetitive with solar for example, unless the waste heat is needed for something else.

I still think that this would explain Musk's dalliance with tunnel boring machines.

The easiest solution is to set up shop in a cooled volcano tube

"hopefully the price of this rocket to get stuff off of earth is dirt cheap"

This is not a launch technology.

Not with that attitude!

Attitude isn’t going to help when the thrust to weight ratio is less than one.

*altitude

Got to have the correct attitude to gain altitude. (Attitude has a second meaning in respect of spacecraft.)

>> Of course once astronauts are on mars they will still be exposed to radiation, until some sort of shielding can be built.

Send tunnel boring machines. There a company making electric ones.

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