
A material way to make Mars habitable - SciNecromancer
https://www.seas.harvard.edu/news/2019/07/material-way-to-make-mars-habitable
======
bayesian_horse
Does it protect against other radiation than UV? Does it also seal a gaseous
atmosphere at a usable pressure?

In the novel/TV series "The Expanse", Martians live underground in tunnels,
because above ground it takes more material and energy to build air-tight
buildings which also protect from radiation. And they still have adverse
effects from the lower gravity.

One of the most fascinating aspects of that series is that there are three
Human "subpopulations", two of which would have trouble to exist on Earth,
physiologically.

~~~
alex_duf
Also the marines train at 1G just in case they have to fight on Earth which
makes an interesting detail

~~~
bayesian_horse
Yes, and Bobby Draper (a Martian marine) still can't deal with it when she
finally does go to earth. In the novel she admits to herself that the Idea of
Martian marines fighting on Earth is ridiculous.

~~~
0xDEFC0DE
I always figured if they actually had to do that, there'd be combat drugs
handed out like candy and it wouldn't be that big of an issue.

~~~
kbenson
I think that might only help if fighting was on the scale of hours to single
digit days (and at the extreme end of that, there might be long lasting
repercussions).

That's of course assuming all the possible repercussions of being born and
growing to adulthood in lower gravity that we don't yet currently know of have
been accounted for and counteracted. I'm doubtful that training in higher
gravity once an adult can negate the major negative effects of growing under
lower gravity (which might include weaker bones), and so also doubt that a
drug causing an even shorter term change can negate the negatives also.

~~~
solotronics
I don't think Mars and Earth would go to war because of the mutually assured
destruction (kinetic weapons such as asteroids). More likely they would fight
proxy wars for resources / control of moons etc. This is similar to how the
US/USSR on Earth struggled for supremacy.

~~~
bayesian_horse
Spoiler alert: In "The Expanse" all of the above happens...

Another reason why ground-level fighting on Earth is stupid for the Martians
is that Earth has like 20 Billion inhabitants at that point, and Mars has
"only" 5 Billion, and of course a lot less marines.

Though I have to say that most Sci-Fi universes, the Expanse being no
exception, are overly optimistic about population growth, and they must have
shipped at least hundreds of Millions of colonists to Mars to achieve the
stated population. Earth alone will probably not reach above 11 Billion
Humans.

------
SeanDav
I found the Mars Trilogy (Red Mars, Green Mars, Blue Mars) by Kim Stanley
Robinson a very interesting, although of course, fictional account of the
terraforming of Mars.

~~~
wcoenen
I started Red Mars. I love the setting and engineering but couldn't get
through all the political intrigue.

~~~
cududa
That’s pretty funny - I’m the exact opposite. I couldn’t stand his poetic
waxing over 3 pages describing the same looking red gorges over and over and
over again, but enjoyed the politics

~~~
tutuca
I loved that it mixes both very well. It's a really accomplished writer.

------
arethuza
Didn't Kim Stanley Robinson's Mars trilogy include tent cities on Mars that
used transparent aerogels for insulation?

[NB Those books seriously made me _want_ to go to Mars when I read them - mind
you I'd be a Red rather than a Green]

~~~
jwilliams
Aerogels are mentioned in both Red and Green Mars - Mostly as pillars for the
tents, but KSR mentions "airgels" (spelling in my copy) as an insulation layer
in the tent material too.

~~~
Retric
That seems odd. With the large pressure difference support pillars seem
unnecessary for tents. Why did they need such exotic support pillars?

~~~
jwilliams
In the book "tents" euphemistically refers to tenting that encloses small
towns. Also the tent fabric was a multi-layered thing (one layer was to absorb
some radiation). Imagine this is why supports were seen as necessary.

------
ta1234567890
There is no timeline or time estimates on the article about how long this
would take.

However, if the goal is the survival of the human species, I think we would be
much better off by exploring the inside of our own planet first. I bet we
could figure out how to safely live underground and harness the power of the
Earth's core a lot faster than it will take us to make Mars habitable.

Earth is a gigantic spaceship traveling through space, and we are on the
outside. Why not go inside the spaceship?

~~~
tshannon
While I agree with you for the most part, the technology developed to dig down
and live underground would mostly only be applicable to digging down further.

The frontier is in space, and every technological step we take towards that
frontier is a step we can use to keep moving outwards.

That being said there's no reason both can't be attempted. One does not
preclude the other.

~~~
ta1234567890
We might not need to dig at all if we can figure out how to navigate
lava/magma (lava submarine?).

"The frontier" is an arbitrary concept that we choose. We can choose another
one.

We have limited time and limited resources, whatever we use for one thing we
stop using for another. When the public mind is focusing on a big thing like
space, it is not focusing (and reallocating enough resources) to another big
thing like reaching the Earth's core.

~~~
throwaway5752
That is way outside of what is possible. The pressures and temperatures so far
beyond what material science can cope with - the outer core is "liquid" \- but
just 100 miles down it's well beyond the melting point of aluminum (2000 deg
F) and almost 1x10^6 psi. The outer core is 1800 miles down, 10,000 deg F, and
5x10^7 psi. Assuming you acquired unobtainium that would not collapse and/or
melt under those conditions, you'd need a insulators and power sources that
are probably also made of or powered by unobtainium.

I don't think it can be handwaved away, I think it's impossible outside of
fanciful science fiction.

~~~
ta1234567890
Today, colonizing Mars is also "way outside of what is possible". It's all a
matter of wanting to do it and then figuring out how to do it, one step at a
time.

I'm sure that with enough time and effort we can figure out how to reach the
Earth's core. Of course it will take a lot of creativity and lots of people
and resources to figure it out, but we can definitely do it.

Also the Earth is right here, we are on it right now. Mars is very, very far
away. We can iterate a lot faster here on Earth than anything we want to do on
Mars.

What do we gain by colonizing Mars?

We can probably gain the same, or more, and faster, trying to reach the
Earth's core first than trying to colonize Mars. In fact, reaching the Earth's
core might even make it easier/faster to colonize Mars by applying all the
knowledge and tech we would develop.

~~~
throwaway5752
No, Mars is pretty easy. Materials are there, solar works as an energy source
there, and it's just an extension of known tech. I bet if - for whatever
reason it became an existential issue - humanity could have habitable base
there inside of 10 years.

The deepest hole ever dug is not even to the mantle and is less than a foot
wide. We could all live in a (modestly) deep cave no problem, but navigating
lava is beyond the properties of any known material.

It's literally impossible to reach the core. No nanomaterials, no carbon
nanotubules, no fusion reactors, no superalloys. I am 100% confident saying
that human kind will never reach the center of the Earth.

~~~
ta1234567890
Like I said, we are here, we can iterate infinitely faster in figuring things
out here.

The only reason why the Earth's core might seem out of reach to you is because
of how little focus and resources have been put into it (compared to
colonizing Mars).

> I am 100% confident saying that human kind will never reach the center of
> the Earth

Well, that is your own personal opinion. And in my personal opinion, it sounds
very pessimistic.

We can definitely do it, and we might not even need to drill any holes. We
just need to get excited about it and go for it.

~~~
depressedpanda
I don't understand why you are so insistent on getting to the core?

On the topic of surviving extinction level events, it may very well be that
researching how to live deep down indefinitely is a much better way to spend
resources than researching how to survive Mars.

But for some reason you are arguing about going to the core -- which is so far
beyond our current technology level that we may as well consider it
scientifically impossible for now.

~~~
ta1234567890
> I don't understand why you are so insistent on getting to the core?

> \-- which is so far beyond our current technology level that we may as well
> consider it scientifically impossible for now.

That's exactly it. Going to space or Mars, were impossible dreams for hundreds
or thousands of years, now we have robots and satellites over there.

If we don't dream about going to the core, we will never get there. Big
challenges make us dream big and work hard to accomplish them.

Also, despite now seeming so hard, I bet there's tons of low hanging fruit
discoveries just waiting to happen. Have you seen a diagram of the inside of
Earth? It's just laughable, especially if you compare that to the level of
detail that we have of Earth's surface, or even the Martian surface.

------
mNovak
Cool concept, though solid sheets of silica aerogel are very difficult to
manufacture.. I wonder how well this concept holds up with leakage between
panels, or using the 'gravel' version of aerogel?

Also having handled aerogel in the past, it has a very rough surface texture.
I suspect it would quickly build up a layer of sand, negating the greenhouse
effect.

~~~
bayesian_horse
I guess there are a lot details not explained in the article and much of them
have come up in the research.

I would have liked a discussion over how this stuff could be produced on Mars,
because no self-respecting rocket engineer would allow transplanetary shipping
of a material largely composed of air.

~~~
russdill
The primary components of Mars's crust are silicon and oxygen. The components
of Silica Aerogel are .... silicon and oxygen.

~~~
bayesian_horse
Thank you, I didn't know that. Though the next question is how much energy you
need to part the silicon and the oxygen and bring them back together to form
the aerogel.

~~~
jacobush
One nice thing which didn't automatically occur to me, is that a nuclear
fission reactor on Mars would be comparatively cheap to build. You don't need
any radiation shielding _at all_. Just walk away and turn it on. Have it
produce methane and oxygen or electricity or both.

~~~
bayesian_horse
That would require really good automation. I think most nuclear reactors still
require a lot of manual labor relatively close by.

But yes, some kind of fission or fusion reactor would be on a colonization
plan, if it is easier/cheaper than solar. One problem though would be getting
fissile material. You can probably find some on Mars or its moons or some
asteroids, but it would require lots of heavy industry to get enough of it for
reactors.

Bringing significant amounts of nuclear fuel from Earth would be really
unpopular, what with the risk of rockets blowing up. That risk or fear is also
what prohibits the use of nuclear propulsion for space travel...

~~~
jacobush
Yeah... politically it would be hard, I agree. But I don't think it would be a
show stopper technically to bring fissile material from earth. For one,
automated nuclear power plants are being designed for use on here on Earth.
The fissile material itself does not weigh very much. It's also not (very)
radioactive until you start the process.

The bulk mass of a (normal) reactor is shielding and cooling plumbing. You
don't need any shielding on Mars, and cooling could maybe (probably?) be some
kind of radiator/convector to the surrounding air. Maybe you could even crack
the CO2 with the heat directly?

Fusion needs a lot plumbing and containment. Fission is just basically a pile
of fissile material in proximity. Not very hard if you can skip on all the
protection.

~~~
stefco_
You still need a heat sink of some sort to extract usable energy from any
reactor, nuclear or otherwise; this is a universal property of engines [1].
Radiators are very inefficient for this and would be far heavier than the
equivalent water cooling method. Same for air-cooling (especially in mars's
thinner atmosphere). The cooling systems are not just there to prevent
meltdowns; you _need_ heat to flow, in _large_ quantities, from a hot place to
a cool place in order to extract energy.

You're right that, if you could find some useful endothermic reaction like
vaporizing CO2, you could use it as a heat sink. The problem is that
distributing heat to arbitrary places in the martian ground (remember, this
CO2 is not magically flowing to you) requires an even more complex heat
exchanger than that used by a simple earth-based reactor.

Not to mention that having no shielding would be hell for your robots;
radiation hardening of automated systems remains non-trivial. But the
fundamental thermodynamics strike me as harder.

Maybe there are niches where this would make sense, but the thermodynamics is
the elephant in the room.

[1]
[https://en.wikipedia.org/wiki/Thermal_efficiency](https://en.wikipedia.org/wiki/Thermal_efficiency)

~~~
jacobush
Actually, the CO2 is flowing, it's in the atmosphere. :) But maybe it's not
enough.

~~~
stefco_
Right, that's the point! The low pressure would make it very very inefficient,
and you would actually need a heat exchange system _far_ larger than earth
reactors. We use liquid cooling in our PCs because a smaller heat sink can
pump out more heat if it's going into liquid (for a fixed flow rate). This is
why liquid cooling for CPU/GPU setups is quiet and effective: the liquid flows
quietly and carries heat to a BIG, slow fan. Your fan and heat sink would be
even bigger/faster at Mars atmospheric densities just to cool your puny CPU.
Doing that at scale with no water cooling for your reactor would be absurdly
materials intensive.

That's all for a typical high-power reactor setup. You can, of course, have a
low-power setup with nuclear power. RTGs [1] use this approach, though they
mainly rely on decay heat rather than self-sustaining reactions, which is just
as well because they are also thermodynamically limited by the rate at which
they can radiate heat away.

One addendum I should have noted: the efficiency of a thermal engine on mars
would actually be perfectly reasonable for a small engine (it's nice and cold
there, perfect for high efficiencies). The issue is that you can't dump the
heat fast enough, so your heat sink will get hotter, trashing your efficiency
and reducing your cooling capacity (both of which exert downward pressure on
your final power output in a serious way).

[1]
[https://en.wikipedia.org/wiki/Radioisotope_thermoelectric_ge...](https://en.wikipedia.org/wiki/Radioisotope_thermoelectric_generator)

~~~
jacobush
I was thinking about cracking CO2 into methane and oxygen - in that case you
would need a high temperature. But I get the general drift - no good cooling.
Maybe on could be plunked into the ice cap. You would need a lot of plumbing
then though...

~~~
stefco_
Ah, yes, that would be one good place to put a lot of the energy (if you could
also get some water for the hydrogen).

------
anthony_doan
I wish we would focus on Venus. It have similar gravity to Earth's. There is
an excellent video about it
[https://www.youtube.com/watch?v=gJ5KV3rzuag](https://www.youtube.com/watch?v=gJ5KV3rzuag).

~~~
Chickenality
The atmospheric pressure and temperature on Venus are far too high for it to
be habitable. Even if those problems were surmountable, there is no liquid
water, and the days are very very long.

~~~
gkfasdfasdf
> The atmospheric pressure and temperature on Venus are far too high for it to
> be habitable.

Which is why the video proposes floating cities. I agree with GP, Venus
deserves more consideration.

------
prennert
If an atmosphere were created one way or another on Mars, would it not be
stripped away again by solar winds? I thought the lack of a magnetic field is
the reason why Mars has so little atmosphere left.

~~~
bayesian_horse
A more problematic consequence of the lack of magnetic fields is that Mars is
not protected from cosmic radiation.

However, the "habitable" space under the aerogel may mainly be used for
agriculture or as a temporary working area for people in vacuum-proof suits.
One thin sheet of aerogel also sounds like a flimsy way of keeping atmospheric
pressure.

~~~
hyperpallium
Can we give Mars a magnetic field? Crash a million iron-rich asteriods on it,
and magnetize them?

Or do you really need a hot iron core?

~~~
pfdietz
One could run superconducting cables around the planet.

The mass required is prodigious, but the energy requirements would be
surprisingly small. The magnetic field of Earth above the surface stores about
100 megatons of magnetic energy; on Mars, and if the field were a bit weak,
the energy needed would be much less.

~~~
prewett
Were you thinking 100 MJ perhaps (which seems awfully low). Energy isn't
normally measured in tons. But if you were applying e = mc^2, then that would
be 8.988e21 MJ [1], which is a considerable amount of energy.

[1]
[https://www.omnicalculator.com/physics/emc2](https://www.omnicalculator.com/physics/emc2)

~~~
pfdietz
The energy stored in the part of the Earth's magnetic field above the surface
is about the same as the yield of a 100 megaton nuclear bomb. This is about
4e17 J, or about 13 gigawatt-years.

Mars is smaller, and so the volume of the magnetic field would be smaller, and
a lower field is probably enough. Since stored energy goes as B^2, maybe this
energy could be reduced by two orders of magnitude.

------
geogra4
Floating Cloud cities on Venus makes more sense. 1g, 1atm, habitable
temperature, endless CO2. We'd need Oxygen and Water but that's true on Mars
too.

[https://en.wikipedia.org/wiki/Colonization_of_Venus](https://en.wikipedia.org/wiki/Colonization_of_Venus)

~~~
prewett
Venus makes even less sense than Mars. At least on Mars once you get there is
no barrier to mining what you need. But on Venus you either have to haul all
your materials there, or be able to deal with the pressure of 93 atmospheres
at temperatures of 900 deg F just to mine stuff. Plus all that sulfuric acid,
which at 900 deg F is going to be highly reactive. [1]

Now your cloud city has to both float and be impervious to the sulfuric acid
in that atmosphere. The best material I could using [2] was coated on smooth,
uncorroded steel (making uncorroded steel on the surface is going to be a
trick with all that sulfuric acid, you'll need a clean room just to make your
steel). Steel isn't exactly the most floaty stuff, so I think it's going to be
a challenge to make your floating city surrounded by a steel coating. Glass is
also relatively impervious to acid, so you could surround your city with
glass, at least it would let the light in, but I think it will make the weight
problem even worse, because glass isn't all that strong.

Compare to Mars: dig underground for radiation protection, and let the inside
pressure provide the force to hold the shell in place.

[1]
[https://en.wikipedia.org/wiki/Atmosphere_of_Venus](https://en.wikipedia.org/wiki/Atmosphere_of_Venus)

[2] [http://www.sulphuric-
acid.com/TechManual/Materials/materials...](http://www.sulphuric-
acid.com/TechManual/Materials/materials_linings.htm)

------
simonebrunozzi
An even better title would have been "Aerogel could be the material to make
Mars habitable". And to be clear, I'm referring to the title on the article
itself, not how it has been submitted here on HN :)

~~~
bsmith
I think "material" as used in the existing title is a bit of a pithy joke
(maybe in the spirit of the journalistic tradition of crafting cheesy titles).
Your suggestion is certainly clearer, but maybe at the expense of being less
amusing.

------
azernik
The full paper is freely available at
[https://www.nature.com/articles/s41550-019-0813-0](https://www.nature.com/articles/s41550-019-0813-0)

------
ryanmercer
Doesn't solve the fact that there just isn't enough material to heat (ice and
rock) to create enough of an atmosphere for decent pressure without importing
massive amounts via asteroids.

I'm all for manned exploration of Mars, I think the amount of science a team
of humans can do during the necessary mission times (while waiting for the
launch window for the quickest return) will be insane. Actually, the amount of
science humans could do in a WEEK would likely generate more data, and more
discoveries, than every probe and rover sent to Mars to date. I think the
extreme risks to the crew, which may remove any reasonable hope for a good
qualify of life upon return, and could result in fatal cancer, is absolutely
worth the sacrifice as long as the crew is 100% volunteers that have
adequately been explained the myriad of risks.

That said, as cool as it would be to colonize another planet, Mars just isn't
going to realistically be it. Not until we are well on our way to being a Type
II civilization (arguably we are still decades, at least, from being a Type I)
but constructing something like O'Neill cylinders is far more realistic, as
long as we can figure out asteroid mining (especially if we can automate it).

------
Aardwolf
How long before we'll put some organic material on it?

Currently it seems we're doing everything possible to avoid doing so... what's
needed to stop that? Ensured that we measured everything possible there is now
in its pristine condition?

Imho, put some organic stuff on it, e.g. some of the toughest lifeforms, it
may be the most useful thing humanity does :D

~~~
WhompingWindows
The problem is how do we know whether or not Mars already has life on it? If
we contaminate it with our own microbes, we may mistakenly claim Mars had its
own microbes to begin with.

~~~
phkahler
At some point we will need to say "who cares". You can't possibly prove the
non-existence of life on Mars. So at some point you need to stop looking and
get on with things. When is that point? I dont know. My opinion is we should
get humans there to have a look and then move forward - assuming they find
nothing.

------
iuguy
What if Mars is already inhabited? Do we preserve the existing life, or
reshape Mars to our own ends?

------
rmtech
This wouldn't be robust over the long term, which is the main advantage of
going down into a gravity well rather than colonizing asteroids and open
space.

Mars terraforming is hard and will require serious tech. At a minimum you
would need to crash asteroids/comets rich in water and nitrogen into it. So I
wouldn't really worry about the 7% atmospheric pressure limit, it's not going
to be a constraint that matters.

~~~
est31
Can you tell me about the long term problems that colonizing asteroids
entails? It feels to me that colonizing the surface of planets is very
wasteful: the entire core is rich of various elements which you could access
if you disassembled the planet (there is no other way than disassembling it).

------
logfromblammo
For reference purposes, a shell of [evacuated] silica aerogel exactly 3 cm
thick, around the entire planet, is about 4e12 m^3 and 4e12 kg.

That's 1/369th the mass of Deimos.

~~~
anchpop
Such a shell would not be stable and would crash into the planet almost
immediately without a huge control system to keep it in place

~~~
jonathlee
Of course you put supports under it. The point is the low amount of mass
required.

~~~
logfromblammo
You just have to build another shield volcano antipodal to Olympus Mons.~

------
BlueTemplar
Pff, aerogel greenhouses, that's soft !

I vote that we stick with the current plan, which, as you may remember, is to
send there Arnold Schwarzenegger with a full supply of blue pills, guns, and
highly breakable glass windows, so that he can activate the alien reactor that
will melt down the poles, change the sky color filters, and anoint him as the
Martian Governator !

~~~
stallmanite
I love it. No gerrymandering on Mars!

------
baybal2
I think covering the thing in a few layers of plastic domes will be much
easier

------
onemoresoop
This reminds me of the Arnold Schwarzenegger movie Total Recall.

~~~
BlueTemplar
;)

[https://news.ycombinator.com/item?id=20451289](https://news.ycombinator.com/item?id=20451289)

(As an interesting coincidence, I watched it yesterday - and for the first
time in several decades !)

------
LoSboccacc
but will environmentalist let us?

------
tempguy9999
How about we stop wrecking the terrestrial ecosystem then worry about making
other places habitable.

~~~
thejohnconway
Apart from the fact that humanity can think about more than one thing at a
time, thinking about this stuff will probably give us ideas for how to
(counter)terraform earth.

~~~
tempguy9999
I don't know about your 2nd point but to your first, I fear that though it's
true, it is not an _as well_ but an _instead_ ; we're thinking about other
things so as to block out what we face now.

