Mars water surprise in Curiosity rover soil samples | Hacker News Reader

Mars water surprise in Curiosity rover soil samples

bbc.co.uk

301 pointsdoublerebel44 comments

"If you think about a cubic foot of this dirt and you just heat it a little bit - a few hundred degrees - you'll actually get off about two pints of water - like two water bottles you'd take to the gym," Dr Leshin explained.

This is huge for Mars exploration by humans.

1. We can send unmanned expeditions to stockpile large tanks of water.

2. This would allow us to literally 3D print structures on the surface and allow us to significantly decrease the amount of materials we need to transport to the surface in order to build a habitat.

Edit: 3. And ALICE rocket fuel could be created using this water and the aluminum found in the Martian soil.

Water doubles as a source of propellant. A human Mars trip may now only need to carry a one way load of propellant.

Since people have been hopeful about finding water there for a while, are there any good estimates for how much exploration mission costs would be reduced by if water were found?

One of the central costs of a round trip to Mars is the fuel for the return flight. With enough water at Mars we can manufacture all the methane/oxygen rocket fuel we need on site.

The Mars Direct mission architecture and the NASA Johnson Space Center's Design Reference Mission derived from Mars Direct both assume we send hydrogen from Earth to manufacture rocket fuel for the return trip at Mars, combining it with atmospheric carbon dioxide into methane and oxygen, and saving 95% of the mass of the fuel versus bringing it all from Earth. They are estimated at $20-30 billion and $50 billion respectively (spread over ten to twenty years), compared with the earlier $450 billion price tag of the Space Exploration Initiative announced by President Bush 1, which was based on bringing all our fuel for the round trip with us from Earth. Not even having to send hydrogen from Earth would cut the cost further.

Methane/oxygen rockets have been rare outside of Russia, but Pratt & Whitney demonstrated a working model of a modded RL10 rocket engine running on methane/oxygen.

More to the point in the context of Mars missions, SpaceX is switching to methane/oxygen for their new Raptor engine.

Are there benefits to methane/oxygen outside what you referenced?

Liquid hydrogen has what Elon Musk calls the pain-in-the-ass factor. It requires much higher volume tank at much lower temperature, adding lots of mass to the rocket, and it's impossible to effectively seal. RP-1 kerosene has the inconvenience of requiring your planet to have been covered with life a hundred million years ago. So, methane is the liquid fuel of choice for future martians.

Methane, while less dense (thus requiring bigger tanks) has a higher specific energy than kerosene, and thus has a higher ISP (rocket efficiency). Methane is also less sooty and should have better cooling as its a "mild cryogenic" like liquid oxygen.

Basically, it's between LH2 (hydrogen: high ISP, very low density, very very cold) and RP-1 (kerosene: lower ISP, high density, room temp) and may be a good compromise.

And its derivable on Mars. Downside is there's very little flight heritage for a methane engine, so most of this is theoretical.

EDIT: Paper: http://thehuwaldtfamily.org/jtrl/research/Propulsion/Rocket%...

We can also electrolyze the water into oxygen and hydrogen for oxygen to breathe, and mix the hydrogen with carbon dioxide from the air to make methane, and use the methane and oxygen (or hydrogen and oxygen) for rocket fuel.

In situ return journey propellant production has been a key element of Robert Zubrin's "Mars Direct" proposal: http://en.wikipedia.org/wiki/Mars_Direct

ALICE is Aluminum+Water Ice in case anybody is wondering. You basically make a slurry of very fine Aluminum powder and water, then freeze it. Very cool stuff.

Aluminium Nano-thermites like ALICE are certainly cool, and certainly scary. Could you make a explosive more powerful than small atomic bombs?

http://en.wikipedia.org/wiki/Nano-thermite

My physics is rusty, but I don't think any chemical reaction can approach the energy yield of fission or fusion.

They also suggest that one of the main components is perchlorate -- which, if turned into lithium perchlorate can be used for oxygen generation, and if turned into ammonium perchlorate can be used for solid rocket fuel.

The perchlorate hypothesis seems to be getting a lot of confirming evidence:

http://www.sciencedaily.com/releases/2013/09/130926143246.ht...

While the science dailies are pitching the perchlorate finding as a "setback" (because it complicates the search for organic molecules), it's indeed promising for fuel usage.

Transporting material to Mars isn't going to be an issue with SpaceX's reusable rockets. Though 3D printing structures is a good idea and option to consider. And preemptively capturing water for use is smart.

>2. This would allow us to literally 3D print structures on the surface and allow us to significantly decrease the amount of materials we need to transport to the surface in order to build a habitat.

Could you explain the connection here? What does water have to do with 3D-printing?

I think he is using 3D printing synonymously with on-site fabrication of components. Not quite the same, but similar.

Or he means literally 3D-print structures using water, which will freeze in the Martian atmosphere to form water ice - which is actually a pretty great structural material if used appropriately.

Unfortunately, exposed ice will sublimate pretty quickly. You could possibly use it as a bulk structural material when covered, and certainly for radiation shielding.

You can also use water for holding your pressurized structures together: bolt some pipes to your structure, bury them, pour liquid water through the pipes and into the soil, let it freeze, and you've got anchors made of ice.

Aye, true that. Well, cover it in mylar, and it was rads I was thinking of predominantly. You could potentially make something like http://en.wikipedia.org/wiki/Pykrete using martian topsoil.

Molding would be more suitable here. The time to 3D print a piece is a cubic function of volume, making it suboptimal for larger structures.

Even with that (ab)use of the term 3D printing, I don't see the connection of on-site fabrication and water.

ALICE is unlikely to be the best idea for rocket fuel produced on Mars. We already know that it is easy to produce propellant on Mars using the sabatier reaction and the Martian atmosphere as the primary ingredient (to produce liquid methane and O2). Not only is this a high grade rocket propellant but also the vast majority of the mass comes from the atmosphere. Of the mass of the propellant only 1/4 of it would be methane and of that only 1/4 would be Hydrogen (1/16th of the total mass). This makes it feasible to ship over the Hydrogen feedstock from Earth and generate the remaining 94% of the mass of propellant using Martian resources.

However, the easier it is to get water on Mars the easier it is to produce propellant in this way. However, we already know that substantial amounts of water ice underlie most of the Martian surface, materials that are as much as half water by mass only a meter or so below ground. This new information only means that it will take much less equipment to get at small quantities of water nearer the surface.

The primary reference behind this is the new Special Issue of the journal Science with several research papers on Curiosity data:

Curiosity at Gale Crater http://www.sciencemag.org/site/extra/curiosity/index.xhtml

INTRODUCTION: Analysis of Surface Materials by the Curiosity Mars Rover http://www.sciencemag.org/content/341/6153/1475

For a comparison, typical values for water content on Earth are in the 15 to 50% range for the inhabited world.

This is kind of an awkward way to present this data. They are talking about water content (which is by weight) and then translating to volumes which is not straight-forward in all cases.

I don't know how revolutionary this is. A cubic foot of soil is, in my experience, quite a bit larger than most laymen think and heating something a "couple hundred degrees" on a world with no established infrastructure (e.g. - there are no large scale solar panels or nuclear reactors set up on Mars) seems like quite a problem.

> A cubic foot of soil is, in my experience, quite a bit larger than most laymen think

Larger than a cubic foot?

I have questions about this. Can anyone help?

How do they know the water is everywhere? How do they know it's not just in the one place they dug and nowhere else?

Why hasn't the water evaporated? Isn't Mars almost a vacuum?

Why didn't the water evaporate from the soil after being dug up but before being put in the oven?

Could there be large underground frozen aquifers?

There is no water per say. It's just that the soil chemical composition is so that if you heat it a "few hundred degrees" a chemical reaction will produce water.

Are you sure? If that's true I totally misread the article. I'll go back band check

"How do they know the water is everywhere? How do they know it's not just in the one place they dug and nowhere else?"

Mars is believed to have a global soil layer, due to massive windblown dust storms. The area sampled is specifically chosen to be this dust and not local soil.

"Why hasn't the water evaporated? Isn't Mars almost a vacuum? Why didn't the water evaporate from the soil after being dug up but before being put in the oven?"

Air pressure is very low, though not close to vacuum. The water detected is probably bound in various chemical bonds, and is not ice, which indeed would sublimate quickly if exposed.

"Could there be large underground frozen aquifers?"

These are indeed conjectured. Large parts of Mars could be water glacier with a thin coating of dust.

Where do you get the energy to heat the soil?

Solar, or potentially nuclear.

It's nuclear. You can read about it here: http://en.wikipedia.org/wiki/Curiosity_(rover)#Specification...

SAM (Sample Analysis at Mars) then uses this energy to heat the soil and analyze it. I recommend everyone to read about the SAM, it's a fascinating instrument. Arguably the most complicated instrument we've (humans) ever built.

(If you're curious about the SAM, read this article: http://www.planetary.org/blogs/emily-lakdawalla/2012/curiosi...)

https://planetary.s3.amazonaws.com/assets/images/spacecraft/...

Nuts.

The irony - water everywhere yet the inhalation (or ingestion?) of space dust proves detrimental to the thyroid system. Wonder what else is in that crazy dust?

> . This striking block was dubbed Jake Matijevic, in honour of a recently deceased Nasa engineer.

They are naming rocks. They haven't even stepped foot on Mars yet and they are already going space mad.

And what's so special about getting a rock named after you? I'm sure there are enough rocks out there that everyone can have their own rock. Why not name a canyon or mountain after him?

There is a bureaucracy involved. To name a feature, you need approval from International Astronomical Union Working Gruop for Planetary System Nomenclature. No, I am not kidding.

http://planetarynames.wr.usgs.gov/

Ah yes, the IAUWGFPSN. You don't mess with those guys. I think they have Gary Coleman on staff. He's a real hard case. Ironically, he killed a man for using the word "ironic" incorrectly.

If you are working for months with a bunch of rocks (as the NASA rover team is), then you need a way to distinguish rocks from each other, and to accurately reference which exact rock you mean in both documents and conversation.

Names are more memorable than numbers, and names with some meaning to you are more memorable than random words - that's it.

Every time I read Curiosity stories, David Bowie starts playing in my head.

Hopefully the first man on mars will not be Major Tom

♫ Bowie's in Spaaace ♫

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