December 08, 2014
Some People Ready For One Way Trip To Mars

The Dutch non-profit Mars One wants to sends 4 people on a one-way trip to Mars. They've had no shortage of volunteers.The goal: 2025.

2025 is much too soon. Consider what is needed to settle Mars. Then think about when that tech will be available.

First, much better robots. A very small human team can't have that many skills. Worse, the humans can't live off the land the way settlers crossing oceans on Earth have done in centuries passed. Mars settlement requires ways to carry the skills. Robots seem the best way to bring a lot of skills. The robots should go first and build structures. The robots should be highly flexible, capable of a large range of construction and maintenance activities. They need fuel cells or batteries far better than can be bought today or likely to be available in 2025. They should be extremely durable too. The robots of 2035 seem more likely top fit the bill. The robots of 2025 won't be there yet.

Second, a Mars base needs a really good energy source. Fossil fuels are out. So are hydro and wind energy. That leaves lots of solar panels and nukes. Which one is more viable? Anyone know? Which would last longer? Curiously, the Mars day is almost 24 hours. Batteries to store solar power would need to equal about a half day's energy usage.

But the robots and power systems both suffer from a really big problem: How to make more to scale up output when babies are born? Ship more from Earth? Seems necessary anyway because equipment will wear out. Better send a lot extra gear. Extra computers too.

The third thing a Mars settlement needs: really advanced biotech. The biotech is needed to grow textiles for clothing, structural material (imagine airtight containers grown from genetically engineered organisms), drugs, and food. The organisms genetically engineered to serve humans on Mars seem the most able to scale out of the major technologies that would need to be sent to Mars.

I think a Moon colony would make the most sense as a place to try out tech needed for a Mars colony. Major technology failures on Mars will kill you. But if your tech and equipment fail on the Moon you can get new shipments sent relatively quickly or take a rocket back home.

A Moon colony would need a very durable lifter rocket for evacuations as well as an escape module up in orbit around the Moon to shift to for the ride back to Earth.

How to prepare for the Moon and Mars? With a remote base on Earth. But it is too soon to try. Most of the needed technology will be developed for many other purposes. We need to wait for robots to enter our homes and take over much more work before we can take them to the Moon or Mars. We need to wait for biotech capable of developing much more powerful plants for pharmaceuticals and textiles. A program to go to Mars can only have a small impact on the rate of development of these technologies.

Update: I am not willing to dismiss the practicality of solar power on Mars. First, solar insolation reaching Mars is only 42% of that on Earth's outer atmosphere with a smaller difference on the surface due to the much thicker Earth atmosphere. On Earth's surface the level of insolation varies much more than the difference between Mars and Earth average. In Europe alone insolation varies by abuot a factor of 3. Similarly, the difference between Seattle and Phoenix yearly solar irradiation is about a factor of 2. Even more dramatically, some places in Upper Peninsula Michigan and Western New York State get less than a quarter of the solar energy hitting northwestern Mexico.

Solar power on Mars is a question of the cost of transporting the panels (or a small panel-making factory) to Mars. If a small nuclear plant was transported to Mars to power a solar panel factory and a battery factory then nuclear power could get the settlement started and the nuke could run the early settlement with solar to expand power production and to replace the nuke once its uranium depleted.

So it seems to me that what a Martian settlement would need is a design for a very small solar panel making factory and battery making factory. Plus, it would probably need a large enough shipment of some rare earth metals to use to make panels and batteries for many years. Could batteries be made from the minerals available in Mars soil?

Share |      Randall Parker, 2014 December 08 08:21 PM 


Comments
Wolf-Dog said at December 8, 2014 9:54 PM:

In order to colonize Mars, which receives limited sunlight compared to Earth, we need to improve nuclear reactors. If thorium molten salt reactors can be made operational in a few decades, the robots will thrive. Robots need a lot of electricity to mine and colonize other planets. With energy, many things can be done. With nuclear reactors even space propulsion would be much faster and a lot more cargo can be carried.

Brett Bellmore said at December 9, 2014 5:39 AM:

Yes, it's not difficult to chose between solar, which is much more limited at Mars' distance from the sun, and only available part of the time, and nuclear, which runs 24/7, doesn't care how far it is from the Sun, and also provides needed heat.

On earth, one person's share of energy use is roughly 600,000 KWH per year. Assuming life on Mars might require ten times that, each colonist could bring along 20kg of Thorium in their luggage, and be covered for their entire life. It does not appear to me that nuclear fuel would be anything like the greatest expense of the colonization mission.

Mars has had hydrothermal processes in the past, this should have produced ore bodies, including for Uranium and Thorium. Finding them won't be that difficult, but given what a small proportion of the mass budget nuclear fuel would be, neither would it be urgent.

Wolf-Dog said at December 10, 2014 6:26 AM:


Here is a wonderful science-fiction book, "The Martian", about survival on Mars, written by the Silicon Valley programmer Andy Weir, who did a lot of research before writing the book, with unusual attention to technical details. Weir even wrote a computer program to calculate the orbit of Mars to find out how much fuel and food the astronauts will need on Mars. In this story an astronaut is accidentally left for dead on Mars, and just like Robinson Crusoe, he learns how to survive there:

www.amazon.com/Martian-Novel-Andy-Weir/dp/0553418025/
http://en.wikipedia.org/wiki/The_Martian_%28Weir_novel%29

The book is so good that Ridley Scott is making a movie version of it:

http://www.imdb.com/title/tt3659388/

This is the complete audio book version that is posted at YouTube:

https://www.youtube.com/watch?v=3TiyohYgako


Meanwhile, Elon Musk is determined to send humans to Mars within 15 years:

Steve said at December 10, 2014 2:57 PM:

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http://commoncts.blogspot.com/2014/12/viral-video-angel-rice-all-star-games-5.html

Ronald Brak said at December 11, 2014 12:39 AM:

Solar PV will be used. Pu238 used in RTGs is expensive and anything else requires more mass and so is expensive. Nuclear reactors tend to have both a lot of mass which is a cost problem and moving parts which is a reliability problem. Reducing moving parts tends to reduce efficiency and so increases mass and thus cost. Mass and reliability issues mean a small starter mars base won't have a nuclear reactor and as the base expands solar capacity can be added incrementally which is difficult to do with reactors. Concentrators made from local materials can increase the instensity of sunlight falling on high efficiency solar cells brought from earth dozens or hundreds of times and it will be easer to make solar PV on mars than nuclear reactors. If silicon solar cells are desired there is plenty of silicon dioxide which may be reduced with CO produced from atmospheric CO2. Doping agents are not rare and exploiting local phosphorous will be important for human life on mars. If for some reason extracting local boron is too difficult the quantities that would need to be imported are small with silicon PV requiring perhaps one boron atom per 10,000 silcon atoms.

Brett Bellmore said at December 11, 2014 2:53 AM:

Sheer rationalization: By the time you've dragged it to Mars, EVERYTHING is expensive. So, you want to rely on expensive PV that only produce power part of time, have to be periodically cleaned, and especially after the occasional dust storm? Instead of nuclear generators you can just set down behind a berm, and ignore while getting on with everything else you need to do.

Maybe after a few generations, with storage problems solved, colonists would be able to use indigenously manufactured solar panels. But colonists tend to be pragmatic, and that wouldn't be a terribly pragmatic decision. PV don't have a great EROEI at our distance from the Sun, they suck at Mars distance. And they'll have a lot of work to do, they don't have any reason to make manufacturing solar panels their culture's main occupation.

Bill said at December 11, 2014 10:49 AM:

Come on...if you want to be honest, admit that solar doesn't even work on earth yet.

Tom Billings said at December 11, 2014 11:20 AM:

"Come on...if you want to be honest, admit that solar doesn't even work on earth yet."

Yes, Bill, ...but it *does* work in Space! It has worked for 57 years in the inner solar system!

It will work better once we abandon solid state solar cells and admit that dynamic turbine-generator solar power systems are more efficient and easier to build from native materials on Mars, or in Mars orbit on Phobos and Deimos, than is any solid-state electronics. Once those are built in Mars orbit, move many of them, one at a time, to geostationary orbits above the planet, and beam down continuous microwave-electrical power to rectifying antenna farms built cheaply on the surface, with no need to store electricity beyond vehicles.

Brett Bellmore said at December 12, 2014 2:48 AM:

"Yes, Bill, ...but it *does* work in Space! It has worked for 57 years in the inner solar system!"

So do RTGs, and they don't care if you happen to end up in a shadow. If Rosetta had been nuclear powered, we'd almost certainly still be getting data right now.

Some day I think this era will be viewed as a time of madness, when humanity collectively lost its nerve for a while, and set aside its best tools.

Ronald Brak said at December 12, 2014 6:10 AM:

Brett, today satellite solar arrays can produce 180 peak watts of electrical power per kilogram in earth orbit. This comes to an average of about 15 watts on the surface of mars. A kilogram of plutonium 238 will produce under 38 watts of electrical power in an RTG. Plutonium 238 apparently costs around $8 million dollars a kilogram. If it costs one million dollars to land a kilogram of payload on mars then nine times as many kilos of solar panels can be landed on mars for the same cost as one kilogram of plutonium 238. Concentration of sunlight using local materials can potentially increase the output of solar PV over 100 times. This is not possible with RTGs. If the cost of landing a kilogram of payload on mars drops to only $100,000 a kilogram then 81 kilograms of solar PV could be landed on mars for every kilogram of plutonium 238. The cost of plutonium 238 may come down but it is unlikely to ever be cheap. One figure I have is that it takes a reactor one gigawatt-year to produce 15 kilograms.

Ronald Brak said at December 12, 2014 6:21 AM:

Bill, we have evidence of solar power working on both mars and earth. The solar powered rover Opportunity is one example on mars and is still functioning after over 10 years on the red planet. On earth rooftop solar provides the cheapest source of electricity available to Australian households and many businesses. Here in the state of South Australia about 6% of all electricity use is generated by rooftop solar and and around noon today it was providing over 20% of the state's total electricity use. Our rooftop solar capacity is still expanding. In Dubai utility scale solar has been bid in at six US cents a kilowatt-hour. And solar PV is extensively used for off grid applications across the world.

Brett Bellmore said at December 12, 2014 9:41 AM:

And, still, Rosetta would be functioning today if it had been powered by an RTG. Bit of a false economy there, no? All those years waiting for it to arrive, and then, a bit of shadow, and RIP.

I didn't advocate Plutonium 238 for a Mars Colony. I advocated Thorium. A radioisotope power supply makes sense for a small probe that has to function many years without maintainence, especially if you don't want it to die if it falls into shadow. For a really high power project, an actual nuclear reactor would be more appropriate.

dscott said at December 12, 2014 11:06 AM:

Fossil fuels are out.

Fossil fuels are definitely in since any fuel with carbon in it is considered a fossil fuel! A rather sweeping statement when methane is continuously detected in the Martian atmosphere where there shouldn't be any. Meaning methane is a potentially viable source of local energy. As Robert Zubrin outlined in his Mars Direct plan to manufacture methane for rocket fuel for return flights. http://www.geoffreylandis.com/propellant.html

The idea that any successful colony would be run purely on electrical energy is sheer nonsense from an engineering perspective. 100% electricity is an ideologue's pipe dream. Furthermore, the creation of a RTG from local radioactive materials should be a high priority as this would overcome the weight issue of supplying heat and electrical power. The decay of RTG material would include hydrogen which can be used for making water and methane.

Your colony can't work because your vision is way too small.

Brett Bellmore said at December 12, 2014 2:00 PM:

Methane is not a potential source of significant energy on Mars. It is present in the Martian atmosphere, but only at trace levels, and isn't a fuel unless you have an oxidizer available. And the Martian atmosphere is conspicuously lacking in oxygen.

Zubrin proposed manufacturing methane AND oxygen from indigenous materials, using, yes, nuclear power.

Its continued presence does suggest the possibility that there is still life hiding out on Mars somewhere under the surface, though.

Ronald Brak said at December 14, 2014 5:30 AM:

Brett, a small reactor sent to mars is still almost certainly going to need to be thermoelectric. And while efficiencies can be higher than for RTGs due to the higher operating temperature we're probably still looking at least 50 kilograms per kilowatt of electrical output. Looking at what's available now I see that 300 watts a kilogram solar PV is currently available for satellites. When used as fixed panels on mars they are going to have an average output of about 1.25 kilowatts per 50 kilograms and that's before concentration, and before tracking if that's used. As I mentioned earlier, concentration of sunlight can increase the output over 100 times. There is no way to boost the output of a nuclear reactor with simple local manufacturing. While nuclear sources of power have advantages, I doubt they would outweigh the mass advantage of solar. However, this does not mean I am saying early robots and/or settlers would not make some use of RTGs, as the Curiosity rover currently does.

Brett Bellmore said at December 14, 2014 3:31 PM:

"I see that 300 watts a kilogram solar PV is currently available for satellites."

Does that factor in the poor duty cycle, and necessity for batteries? A good phone battery might run to 2-300 W-H/Kg, and if you assume a Mars ground level panel gets a duty cycle of 30%, (That's a tracking panel, then.) you'll need to pair that 1 kg of solar panel with over 5 kg of battery to produce a *continuous* 100 watts. Making your 300 watts a kilogram solar PV panel into a 16 watt per kilogram 24/7 source. At which point the nuclear looks better on a weight basis, and you don't have to periodically dust it off to keep the power output from dropping. It just sits there without maintenance, plugging away for decades.

The math works out much better for PV if you're in space, and reliably exposed to sun, that I'll grant you. Neither of which the surface of a planet, (Or, obviously, a comet!) qualifies as. It also works out better for PV if you assume that you don't need electricity at night. But efficient utilization of infrastructure in a colony would pretty much mandate not leaving it idle 2/3 of the time.

If you can manufacture your high efficiency solar panels, AND the batteries, from indigenous materials, it might make sense to go solar on Mars, if you assume the colonists really have nothing better to do than manufacture solar panels and batteries.

Everything also changes if you assume we develop Von Neumann replicators, and THEY spend much of their time making the solar panels and batteries. That technology is, I think, the key to affordable space colonization, and I really think we could achieve it, given a good push. We have most of the pieces already.

Ronald Brak said at December 15, 2014 1:53 AM:

Brett, a one kilogram 300 watt panel should produce an average of over 25 watts on mars. That's an average of 50+ watts during the day and no watts at night. A one kilogram 300 watt-hour battery can produce 25 watts for 12 hours which is almost as long as night on mars. Assuming slightly more electricity is used during the day than the night one kilogram of batteries would suffice to "even out" the output of one kilogram of fixed 300 watt PV. But with concentration the output of PV can be increased 10 or 100 or more times and it should be possible to concentrate sunshine with local materials. This drops the mass of PV required by a tenth or a hundreth or more so can drop the mass of battery plus PV required to provide a steady 25 watts to below 1.1 kilograms. I assume that rather than rely on energy storage brought from earth the colony will soon manufacture its own.

Brett Bellmore said at December 15, 2014 3:01 AM:

Ronald, first, I think you're being remarkably optimistic in assuming a 50% duty cycle for a solar panel on a planetary surface. That's tracking with a vengeance, and you don't seem to be counting the cost of mounting and tracking, which will likely outweigh the panels. I think you're realistically going to get more of a 30% duty cycle, not 50%, and even that requires tracking of some sort.

Second, batteries are not, of course, 100% efficient. Though you could likely use the waste heat for heating, in as much as Mars is rather cold.

Third, you're not accounting for the notorious Martian dust storms. Here's your system, working fine in nice weather, and then suddenly the sky fills with dust, and your panel output drops, and doesn't go back up again until somebody goes out and dusts many acres of panels.

My position is, these people are going to have a LOT of things to do. Solar panels are just one more thing to do, the first generation colonists at least are likely to rely on nuclear, just because it cuts their "to do" list substantially.

Ronald Brak said at December 15, 2014 3:08 AM:

Randall, there is no reason why batteries can't be made out of minerals on mars, but possibly it would be easier at first to use fuel cells for home made storage. Hydrogen fuel cells are an old well known tech but there will be a very slow but steady loss of hydrogen from the system as hydrogen is basically impossible to completely contain. But if martian ice is being exploited, as I presume it will be, this loss may not be a problem. And a very simple form of energy storage is gavitational potential energy. One earth we use water for pumped storage but on mars rock or gravel or dust could be used. If a deep sample hole is bored near the base a steel weight made from a nickle-iron meteorite could be placed in it and used to store energy. Nickle-iron meteorites will probably be an important resource for the colony. Both mars and earth have atmospheres that can result in them being collected on the surface, but on earth they slowly rust away while on mars they can hang around for eons. And they're basically just lumps of stainless steel sitting around waiting to be used. And then there's heat pumps. They could be run off the fairly extreme temperature differentals that commonly occur between between the ground and the atmosphere but an option to increase their effectivenes would be to concentrate sunlight to heat a thermal mass (like a heap of rocks) and then run the heat exchager after sunset to provide power at night. And of course solar thermal heating could be used to warm thermal mass in the day so things stay warm at night, which is a simple form of energy storage. Oh, and compressed air storage could also be used. I suppose it could work directly off the thin martian atmosphere, but if that's not practical then two chamber storage could be used.

All that said, I suspect that the first energy storage creating device on mars might be a very clever box that mostly uses carbon, of which there is plenty in the atmosphere as well as rocks, to make a carbon based supercapacitor. We don't have anything like that available at the moment, but perhaps we will when the first robots or humans start to colonise mars.

Ronald Brak said at December 15, 2014 11:42 PM:

Brett, 300 watts of PV on mars produces an averge of at least 25 watts as a fixed panel.

There is about a one in three chance of a planetary dust storm over martian year. These can last over a month but generally occur when mars is closest to the sun and even on the worst days insolation is over a third of normal. So during a dust storm insolation would probably be on average halved. This is not good, but it is probably the sort of thing that can be handled by demand management.

And Brett, I have to point out that nobody is going to go out and remove dust from solar PV. Colonists would no more remove dust themselves than they would adjust the position of fuel rods in a nuclear reactor by hand. Humans in their current state cannot perform routine duties on the surface of mars. It would kill them. It would probably take time but the radiation environment on the surface of mars is such that unless the colonists wish to raise a crop of Kuatos they will limit their surface time to emergencies. Dust removal will be automated.

And given the extremely high cost of getting payload to mars, the "work" of the colony will revolve around eliminating the need to import mass from earth. Importing some high efficiency PV and then using perhaps some stainless steel from an iron-nickel meteorite to concentrate sunlight is an easy way to save on imported mass.

Ronald Brak said at December 15, 2014 11:45 PM:

Brett, 300 watts of PV on mars produces an averge of at least 25 watts as a fixed panel.

There is about a one in three chance of a planetary dust storm over martian year. These can last over a month but generally occur when mars is closest to the sun and even on the worst days insolation is over a third of normal. So during a dust storm insolation would probably be on average halved. This is not good, but it is probably the sort of thing that can be handled by demand management.

And Brett, I have to point out that nobody is going to go out and remove dust from solar PV. Colonists would no more remove dust themselves than they would adjust the position of fuel rods in a nuclear reactor by hand. Humans in their current state cannot perform routine duties on the surface of mars. It would kill them. It would probably take time but the radiation environment on the surface of mars is such that unless the colonists wish to raise a crop of Kuatos they will limit their surface time to emergencies. Dust removal will be automated.

And given the extremely high cost of getting payload to mars, the "work" of the colony will revolve around eliminating the need to import mass from earth. Importing some high efficiency PV and then using perhaps some stainless steel from an iron-nickel meteorite to concentrate sunlight is an easy way to save on imported mass.

Brett Bellmore said at December 16, 2014 3:08 AM:

You just seem to be obsessed with having to use PV, no matter how many disadvantages it has. Now the colonists are going to have to have an army of panel dusting robots. And engage in "demand management", which is doublespeak for "Just accept brownouts".

When they could have a comparably energy dense reactor which would just sit there unattended, churning out electricity 24/7, and get on with doing other things.

Ronald Brak said at December 16, 2014 5:39 AM:

Let's see Cassini RTG units were 57 kg for 300 watts of electricity when new, that comes to 5.26 watts a kilogram. Curiosity RTG gives 2.8 watts a kilogram. The Advanced Sterling Radioisotype generator which was cancelled was supposed to have double the energy density of RTGs so I guess that would make it about 11.5 watts a kilogram. The SNAP-1a thermoelectric nuclear reactor had a mass of about 91 kilograms and produced about 125 watts for about 1.4 watts a kilogram. A RORSAT thermoelectric nuclear reactor was 1,250 kilograms with an electrical output of about 2 kilowatts making for a total of about 1.6 watts or so per kilogram. Record lifespan 134 days. The TOPAZ-1 reactor was about 320 kilograms and depending on its efficiency may have delivered 500 watts of electrical energy for maybe 1.6 watts per kilogram. Record TOPAZ-1 operating time is one year.

Yeah, I guess I'm just being really unrealistic by looking at solar PV used in satellites today that would produce an average of at least 25 watts a kilogram on the surface of mars and pointing out how their output could be increased by 10 or 100 or more times through the use of local resources to concentrate sunlight and thinking that might be a better option.

Randall Parker said at December 19, 2014 6:30 PM:

Brett,

Nuclear: Plutonium is lightweight. But nuclear reactors are NOT lightweight. Ditto the steam turbines that are very difficult to build. Further more, nukes on Earth use lots of water for cooling. Where you going to get the water? Furthermore, nuclear plants require complex control systems, piping, lead shielding. You either take all that with you (for trillions of dollars) or you build up all these materials on Mars. How hard to find lead for shielding on Mars?

I think getting enough energy on Mars is very hard. How to build complete manufacturing chains to make the complex stuff there that we make here with many businesses in many countries cooperating? Mars is so much harder. Can't use trees for building material because, hey, there's not much atmosphere.

I think the people talking about a Mars colony in the foreseeable future are totally dreaming.

Dan said at December 19, 2014 9:24 PM:

Randall,

What about Venus? If Mars is too hard, do you think we could do Venus instead in the near term?

"NASA's Incredible, Futuristic, And Totally Real Plan To Establish A Human Colony On Venus"

http://www.businessinsider.com/colony-on-venus-2014-12

"NASA has plans to live on Venus. Seriously.

In fact, up in the clouds above its scorching surface, Venus is "probably the most Earth-like environment that's out there," Chris Jones of NASA told Evan Ackerman at IEEE Spectrum.

Forget Mars and its frigid temperatures and thin atmosphere when we can live like gods, afloat in the clouds of Venus.

Jones is part of the Space Mission Analysis Branch of NASA's Systems Analysis and Concepts Directorate at Langley Research Center in Virginia. The research group recently unveiled a detailed plan to eventually set up permanent residence on Venus. The mission is called the High Altitude Venus Operational Concept, or HAVOC."

Engineer-Poet said at December 19, 2014 10:14 PM:
How hard to find lead for shielding on Mars?

Lead shielding?  Most nuclear plants use concrete; it has enough hydrogen to eat neutrons and it absorbs gammas too.  Regolith would do on Mars or the moon.

I suspect the biggest problem with nuclear on Mars is finding an adequate heat sink.  There's tons of atmosphere to supply working fluid for a supercritical CO2 cycle, but its rarefied nature might make it difficult to dump heat to it.  If iron can be sifted from regolith with magnets as it can be on the moon, that pretty much solves that; you could make all the nickel-iron tubing you wanted, and make radiators of enormous size.

Ronald Brak said at December 20, 2014 2:20 AM:

EP, there are plenty of big chunks of nickel-iron just sitting on the surface of mars. On the moon impactors get smacked to bits but on earth and mars the atmosphere can slow them down enough so small to car sized chunks of nickel-iron can end up sitting on the surface intact. On earth they slowly rust away but on mars they hang around forever and are ready to be used as is if desired. The grain size is very large though. But iron could also be sifted from martian grit with magnets and I wonder if the action of the wind has concentrated it in places.

Randall Parker said at December 20, 2014 8:25 PM:

Dan,

The HAVOC idea for blimps with humans riding around in Venus upper atmosphere is a really cool idea and I hope NASA does it. I'd like to see them do a smaller automated version first with sensors to study Venus atmosphere and surface and to test out the technology. But HAVOC is not a way to build a self-sustaining presence. What's missing? Access to raw materials. They can't go down to the surface of Venus to get raw materials to use to expand a colony. So no way to build a really big dirigible civilization. The dependence on Earth would be very high.

Now, go capture an asteroid and put it in Venus orbit to construct a mining operation and then the picture changes. But what's the energy cost of doing that? I would guess enormous. But if it was done and the asteroid was used to build orbital light shields then Venus could be cooled. Then it would start to get interesting.

Dan said at December 20, 2014 8:35 PM:

Randall,

So at this point, would Venus be more feasible and a better option than Mars?

Engineer-Poet said at December 21, 2014 2:33 AM:

What stops people from dredging the surface of Venus from their aerostats?

Brett Bellmore said at December 21, 2014 6:10 AM:

The habitable altitude around Venus is about 30 miles. and many materials have support lengths considerably greater than that, so hanging equipment from aerostats down to the surface would be feasible. But most materials aren't terribly strong at the sort of temperature you find at Venus' surface, it would be a challenge to build a tether that would hang together. Not an insurmountable challenge, though, I think.

Engineer-Poet said at December 21, 2014 10:16 AM:

This might be handled using mining craft designed for low altitude only, from the 10 bar level downward.  With the pressures involved, dirigible envelopes would be fairly compact.  Steam would work just fine as a lifting gas, doubly so because extra lifting capacity could be held as compressed fluid.  Alloys like Inconel are more than capable of standing up to Venus temperatures.

It might even be possible to make such mining craft totally dumb; they'd descend by negative buoyancy, grab a bucket-full of whatever they landed on, release water from a reserve tank to expands the gas cells to provide positive lift again, and ascend to the point where a smart craft can grab them and take the cargo of regolith.  Condense the excess lifting steam, pump it back into the reserve tank and repeat.

Brett Bellmore said at December 21, 2014 1:23 PM:

I like that proposal, it does sound feasible. Might not even require a "reserve tank", just let the heat capacity of the water provide enough delay to reach the surface. Store it in a tank with a telescoping section, to expand as the water boils, no elastomers required, and on the bottom an impact actuated claw. Let it drop, and when it bobs back up to a more tolerable altitude, retrieve it to see what it picked up.

But ultimately something like a refrigerated caisson might be more effective, if decent ore bodies were found.

Randall Parker said at December 21, 2014 8:00 PM:

E-P,

Gas cells? I do not know what you mean. To inflate a blimp on the surface? I do not see how any blimp material can withstand the high temperature (mean temp 462 C on the surface), sulfuric acid clouds, and pressure.

Think about the weight and fuel involved. Whatever goes to the surface has to be strong enough to cut into and pull up soil. The soil would in no way be the ideal mining vein. You'd then have to have rocket thrust (or a blimp?) to blast off. Would the thrusting fuel get too hot and blow up before lift-off? Would Venusian atmosphere rush up into the rocket engine and wreck it?

So then your load (somehow) goes back up into the upper atmosphere and then run a smelter. Really? Hanging off a blimp? How is that going to work? The blimp would need to be massive and the cables down to the smelter quite long.

Since the atmosphere is 96% carbon dioxide there is one bright side: You can get all the carbon you need. So carbon blimp synthesis seems possible and then the inside of the blimps could be NO2 (3.5% nitrogen in atmosphere).

I think an asteroid mining operation in Venus orbit would be a better bet. Though if the energy costs of getting the asteroid into orbit are prohibitive then I'd back off that position. I also think atmospheric engineering is needed to cool the planet.

Dan,

Anything that doesn't give us leverage (really capital) that makes it possible to build up even more assets is a waste of time. I think an asteroid mining operation in Earth orbit (or at a Lagrange point) would be better as a stepping stone to develop more assets in space. Or a mining operation on the Moon. We need space assets that can create more space assets. No more stunts.

Randall Parker said at December 21, 2014 8:14 PM:

Guys,

With a surface mean temperature of 462C I do not see how the water is going to stay liquid all the way down. Suppose you extracted N2 out of the atmosphere and made it liquid (it boils at -195.8 C). Maybe it could work as a coolant to boil off, take heat with it, and keep the water frozen down to near the surface. Your surface visit would be bounded by how long it takes the water to boil. But I'm still unclear on how you'd use the steam. To expand a blimp to create buoyancy?

So consider what you have to work with in the atmosphere: carbon, nitrogen, oxygen, and pretty much only the hydrogen you bring with you (unless you've got a really high efficiency atmospheric H extractor). Plus some traces of chlorine, argon, helium, flourine and water vapor. What can you build that is a sustainable way to make trips to Venus's surface? Your vehicle has to be extremely durable or easily refurbished using materials you bring up. How do you make this work? The electronics in the vehicle also have to be extremely durable. This all seems very problematic.

I like an asteroid mining operation much better.

Engineer-Poet said at December 21, 2014 8:51 PM:
Gas cells? I do not know what you mean.

Assuming the mining 'bot is carried by a dirigible and not a balloon, the lifting gas will be held in cells.  These can be anything that flexes to accommodate volume change and keeps the lifting gas inside.  Metallized carbon fabric is a possibility.

Whatever goes to the surface has to be strong enough to cut into and pull up soil. The soil would in no way be the ideal mining vein.

That may not matter too much.  If you're material-poor, you can just scrape up whatever is down there and sort it out later.  As you note, the atmosphere has all the carbon you can possibly use; what you're after from the surface will probably be metals, silicon/silicates and minerals like potassium and phosphorus.  If you have to make the teeth of the drills/chisels out of diamond, it's not like you lack raw material.

I imagine some totally dumb mining machine that lands where it will (perhaps ballasted by dross from previous refining) and uses either a bucket or some kind of digging/scraping mechanism (perhaps powered by the steam boiling off the reserve lift tank and going into the lift cells) to fill its hold.  It dumps its ballast when the hold reaches its weight limit or the steam pressure runs down too far to operate the digger any more.  It then rises up to where a powered aerostat can catch it and unload it.  My eyeball scan of the steam tables suggests that the vapor pressure of water is considerably higher than the atmospheric pressure of Venus at Venus temperatures to a point well above the 10 bar level.

If you can manage to make highly refractory electronics (maybe on those diamonds), or sufficiently reliable cooling systems for the computers, sensors and servos, you can make smarter mining 'bots.  I'd prefer not to have those be the difference between life and death.

I think an asteroid mining operation in Venus orbit would be a better bet.

Then why go to Venus?  I mean, other than because it's there?

I also think atmospheric engineering is needed to cool the planet.

The latest on selective radiation surfaces which can radiatively cool to 7-9°C below ambient in direct sunlight suggests that this could be done.  A planet with an atmosphere full of self-cooling retroreflective aerostats might get chilly in a relative hurry.  Or, you could just put a sunshade at the Sun-Venus L1 point a la "2312".

Randall Parker said at December 21, 2014 11:39 PM:

E-P,

High pressure preventing water from boiling: Good point.

Why go to Venus: The asteroid mining operation could supply the raw materials needed to carry out a big climate engineering project.

What strikes me about all that CO2: It calls out for chloroplasts. Can we make incredibly long lasting unmanned dirigibles that exist to provide a habitat for microorganisms with chloroplasts? If we could and if we could get some hydrogen from somewhere then we could gradually convert the carbon hydrocarbons. But if not much H could be gotten maybe we could create a plant-driven system to build up pure carbon. Build more and more dirigibles (whose frames and bags could be made from carbon) and thereby create growing amounts of habitat for microorganisms that fix carbon out of the atmosphere while releasing O2 into the atmosphere.

If we can find a way to get materials up from Venus' surface then hydrogen might be the element in shortest supply.

Brett Bellmore said at December 22, 2014 3:14 AM:

Randall, a gas bag for the lower Venusian atmosphere could be a telescoping cylinder, or a bellows, it doesn't have to be conventionally flexible. That wouldn't work in our atmosphere, but aside from the temperature and heat, 90 atmospheres makes it much easier to build an aerostat, because your lifting gas gives so much lift per unit volume.

I do wonder if it shouldn't be possible to develop elastomers that work in that temperature range. We don't have such now, but that's probably because chemists do most of their work at STP, and any elastomer at Venusian surface temperatures would be a brittle glass at STP.

You're probably right about the asteroid mining, though. Working out how to mine the surface is just interesting.

Engineer-Poet said at December 22, 2014 6:38 AM:

Mining the surface is of interest because it's already there in massive volume.

It occurs to me that reflecting half the incoming sunlight from high in the atmosphere would change the Venus energy balance to something rather Earth-like, at least after the greenhouse effect was abated.  You'd need a whale of a lot of water to allow the CO2 to be taken up as carbonates.

Randall Parker said at December 24, 2014 12:33 PM:

Another problem with high atmosphere Venus blimp living: Venus lacks the magnetic field that creates a big protective zone around Earth. So astronauts living in blimps are going to get hit really hard by solar flares.

Engineering Venus to be suitable for humans seems really hard. We need massive sun shields in space. We need to bring in lots of hydrogen. We need to genetically engineer organisms to live in high atmosphere and do carbon fixation to convert more of the atmosphere to oxygen. But even if we succeed it will be too much oxygen and not enough nitrogen. So we need nitrogen too. Plus, we need an artificial magnetic field or even bigger shields against solar flares.

Engineer-Poet said at December 24, 2014 5:41 PM:
astronauts living in blimps are going to get hit really hard by solar flares.

Are they?  Habitats at the .5 bar level (roughly the cloud tops, IIRC) will have about 5 tons of shielding per square meter against normally-incident solar protons.  X-rays will not penetrate.  Protons will be scattered at much higher altitudes; Wikipedia states (without obvious attribution) that

The majority of the energy is extinguished in the extreme lower region of the ionosphere (around 5080 km in altitude).

In other words, dozens of km above the 0.5 bar level.  I wouldn't worry about this; a few dozen mSv/year is about an order of magnitude below the tolerance dose.

Lon Phillips said at December 27, 2014 9:15 PM:

http://quest.nasa.gov/aero/planetary/mars.html

Why rule out wind power? NASA said that average wind speed is 20 MPH. Seems enough to me.

Engineer-Poet said at December 28, 2014 8:50 AM:

Surface pressure on Mars is a few millibars.  Calculate ½ρv³ and get back to us.

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