Space structure material

[Robotbeat]

Mars has literally trillions of tons of hematite crystals lying around on the martian surface (the blueberries in the rover pics). Once we get some industry going there, martian steel will be the most useful and affordable structural product.

Forget that, iron meteorites are littering the surface of Mars! Based on the rovers' findings, I'd guesstimate roughly 1 ton of free metal every 1 or 2 square kilometers. Within 100km radius of a base, there could be roughly 50,000 tons of free metal!

True that. No need for any convoluted exercises with basalt or spinning nanotubes out of CO2. Just install some nuke plants and start melting stuff down.

OK - Let's see a design for a system to harvest, say 3,000 tons of free metal, bringing it back to the smelter. And sending the kids out to pile the iron rocks into fence rows is disallowed. Just to make this more of a challenge, we are addressing the first 3,000 tons, starting with ton number one.

Electric pickup truck plus a couple astronauts and a winch. Remember, a 300 kg meteorite would only weigh 100 kg-f on Mars. I bet you could gather a few tons every day. May need to distribute solar powered recharge stations to extend the range of the rovers. Spectroscopic surveys from orbit or from balloon or something could identify iron meteorites.

[aero]

Mars has literally trillions of tons of hematite crystals lying around on the martian surface (the blueberries in the rover pics). Once we get some industry going there, martian steel will be the most useful and affordable structural product.

Forget that, iron meteorites are littering the surface of Mars! Based on the rovers' findings, I'd guesstimate roughly 1 ton of free metal every 1 or 2 square kilometers. Within 100km radius of a base, there could be roughly 50,000 tons of free metal!

True that. No need for any convoluted exercises with basalt or spinning nanotubes out of CO2. Just install some nuke plants and start melting stuff down.

OK - Let's see a design for a system to harvest, say 3,000 tons of free metal, bringing it back to the smelter. And sending the kids out to pile the iron rocks into fence rows is disallowed. Just to make this more of a challenge, we are addressing the first 3,000 tons, starting with ton number one.

Electric pickup truck plus a couple astronauts and a winch. Remember, a 300 kg meteorite would only weigh 100 kg-f on Mars. I bet you could gather a few tons every day. May need to distribute solar powered recharge stations to extend the range of the rovers. Spectroscopic surveys from orbit or from balloon or something could identify iron meteorites.

OK, so you have 4 iron rocks, 250 kg each and a 1 ton sized electric pick-up truck. Drive back to the smelter. How big is the smelter, what is it made of, what is its capacity? Do you need to break up the iron rocks, or just put them in the smelter? Soft iron is not so good for structure, is it? What do we need in order to convert them to good structural steel members? What do we define as "Good enough" for Mars structures?

And do you think the colonists might get tired by the time they've gathered 3000 tons? But then, that's just a number. How much do they really need to start with?

[Robotbeat]

I'd imagine that the colonists would be building mini mills designed to melt the iron, perhaps add carbon (produced in-situ, of course!) if necessary for improved material properties, and cast directly into sheets and beams. I'm sure such mini mills (micro mills would probably be a better term) would have relatively small batch sizes to keep their mass low.

The sheets and beams could then be welded together to form pressure vessels for base expansion. The nice thing about Mars is it's practically a soft vacuum, so electron beam welding can work better than at Earth pressure.

[aero]

I'd imagine that the colonists would be building mini mills designed to melt the iron, perhaps add carbon (produced in-situ, of course!) if necessary for improved material properties, and cast directly into sheets and beams. I'm sure such mini mills (micro mills would probably be a better term) would have relatively small batch sizes to keep their mass low.

The sheets and beams could then be welded together to form pressure vessels for base expansion. The nice thing about Mars is it's practically a soft vacuum, so electron beam welding can work better than at Earth pressure.

My point in raising these questions is to figure out what we will need to take along when we go to Mars. So far, I have one electron beam welder. Or do we plan to make that on site from native materials?

I guess we'll just have to put up an air tight tent in the Utah high desert, and using fabricated Mars iron rocks, make some structural steel inside the tent. And keep records of everything we have to bring in.

[jryodabobs]

My point in raising these questions is to figure out what we will need to take along when we go to Mars. So far, I have one electron beam welder. Or do we plan to make that on site from native materials?

I guess we'll just have to put up an air tight tent in the Utah high desert, and using fabricated Mars iron rocks, make some structural steel inside the tent. And keep records of everything we have to bring in.

Don't forget the extrusion capability for the poly-something material that would make up the rest of the structure. Need the raw materials plus the forge and support things. Seems like a test run as mentioned is a real smart idea. Don't need to test something like that on the Moon for a first cut at what is really needed.

[Robotbeat]

You don't necessarily want to make your electron welder on Mars, but it should (like everything else) be able to be made with Martian materials plus a limited and catalogued number of "vitamins" from Earth. It should definitely be completely serviceable on Mars with plenty of spare parts and vitamins, even if you can't produce everything with ISRU materials.

Rep Rap 3d printers, by the way, has made significant progress. Folks have started fabricating PCBs for the 3d printer's electronics using the 3d printer.

Bring a lathe along with. All of its turned parts can be fabricated using itself, and its cast parts can be sand cast, which you should be able to do using Martian sand and clay, and the pattern can be printed with a 3d printer (the thermoplastic used for the 3d printer can be produced via something similar to the Fischer–Tropsch process or simply be a vitamin and recycled numerous times).

...

I've tried to collect most of these ideas into a diagram. Unfortunately, the plastics part of the diagram is a little less detailed. But if you can make hot glue sticks (or something like that for sealing things) and thick thermoplastic filament for the 3d printer, you're ahead.

Electrical wire is in short supply, but steel wire may be a useable substitute which could be extruded at the steel mill.

Also, grease may need to be produced via Fischer-Tropsch if you have a lot of machinery.

If you can make greenhouses and pressure vessels and seals, you can expand your base.

A good "vitamin" could be very, very thin solar arrays which can be deployed manually. Also, just reflective mylar film would probably be rather handy for increasing light on plants and for thermal control while also be very lightweight. It may take a very long time before it'd be worth manufacturing those sorts of things on Mars, if you have a stockpile of a few tons of them.

EDIT: If you have enough greenhouse space, biological sources of plastics may be easier and use less power than using Fischer-Tropsch. Here's an example of how feedstocks like fatty acids and sugar could be used to make acrylic: http://www.sciencedaily.com/releases/2008/11/081113085155.htm

Bioreactors may end up being smaller than the full industrial equipment necessary to turn CO2, H2O, N2, and sunlight into usable plastics. Cellophane is made from cellulose, for instance, and PLA is a thermoplastic made from corn (and often used in hobby 3d printers). Rubber, of course, originally comes from the Rubber Tree.

But it means you need a lot of greenhouse space to grow these things in.

[A_M_Swallow]

If you are building greenhouses you will need to make glass.  There is plenty of silicon oxide on the Moon.  Glass and fibre glass can also be used as sealants and glue.  There may be a source of silicon on Mars.

[mlorrey]

Forget that, iron meteorites are littering the surface of Mars! Based on the rovers' findings, I'd guesstimate roughly 1 ton of free metal every 1 or 2 square kilometers. Within 100km radius of a base, there could be roughly 50,000 tons of free metal!

True that. No need for any convoluted exercises with basalt or spinning nanotubes out of CO2. Just install some nuke plants and start melting stuff down.

Basalt? Nanotubes? If you're talking about material for an elevator or tether, iron is ridiculous.

http://en.wikipedia.org/wiki/Ultimate_tensile_strength#Typical_tensile_strengths

Martian iron might be good for local use. But Mars' gravity well and atmosphere precludes Martian iron as an export to anywhere but Mars' neighborhood, in my opinion.

Mars gravity well is less than 40% of Earth's. Mass fractions are such that SSTO RLV is rather easy on Mars, and given that the peak of Mons Olympus extends above Mars atmosphere, a mass driver up the side of the mountain built from martian steel would be a very affordable means of putting large quantities of materials into space.

Try doing the numbers.

[mlorrey]

Mars has literally trillions of tons of hematite crystals lying around on the martian surface (the blueberries in the rover pics). Once we get some industry going there, martian steel will be the most useful and affordable structural product.

Forget that, iron meteorites are littering the surface of Mars! Based on the rovers' findings, I'd guesstimate roughly 1 ton of free metal every 1 or 2 square kilometers. Within 100km radius of a base, there could be roughly 50,000 tons of free metal!

True that. No need for any convoluted exercises with basalt or spinning nanotubes out of CO2. Just install some nuke plants and start melting stuff down.

OK - Let's see a design for a system to harvest, say 3,000 tons of free metal, bringing it back to the smelter. And sending the kids out to pile the iron rocks into fence rows is disallowed. Just to make this more of a challenge, we are addressing the first 3,000 tons, starting with ton number one.

I've got an idea for a crawler with a wide harvesting head that has robot arms with electromagnets as hands, sensing iron on the surface, picking it up, and placing it on a conveyor that drops it into a hopper on a trailer. Call it a Martian Combine.

A second crawler comes and replaces the trailers as they get filled, returning full ones to the smelter.

The system maps the location of meteorites too large for the combine harvesting arms to be scooped up by a larger scoop loader.

Should be able to handle several tons of material per trailer.

[mlorrey]

I'd imagine that the colonists would be building mini mills designed to melt the iron, perhaps add carbon (produced in-situ, of course!) if necessary for improved material properties, and cast directly into sheets and beams. I'm sure such mini mills (micro mills would probably be a better term) would have relatively small batch sizes to keep their mass low.

The sheets and beams could then be welded together to form pressure vessels for base expansion. The nice thing about Mars is it's practically a soft vacuum, so electron beam welding can work better than at Earth pressure.

My point in raising these questions is to figure out what we will need to take along when we go to Mars. So far, I have one electron beam welder. Or do we plan to make that on site from native materials?

I guess we'll just have to put up an air tight tent in the Utah high desert, and using fabricated Mars iron rocks, make some structural steel inside the tent. And keep records of everything we have to bring in.

Electron beam welder, lathe, milling machine, grinder, polisher, threader, hydraulic press. Wire extruder. Induction smelter with LOX injection (for Bessemer process).

I think chips are small enough that it is better to ship them from Earth for now, along with a number of other complex electronic components.

Machines to build:

Metal roller
Steel extruder
various hammer and press forgers. (for instance, a hammer forging machine for gun barrels and high pressure pipes is very different than a press forge to forge alloy wheels)
Cable winder
steel wire loom

eh, virtually every industrial machine for producing metal, ceramic, abrasive, or chemical product needs building from the first set of machine tools you send.

The people you send need to be geologists, mining engineers, industrial, mechanical, civil, chemical, and nuclear engineers, as well as master machinists, robotics mechanics.

[Robotbeat]

mlorrey, a lot of those things you listed are cheaper ways of doing the same thing a lathe or a CNC mill (for instance) can do.

The idea right now ought to be to establish the minimum set of tools which are able to produce almost everything you might need while also being able to repair and even rebuild themselves (or build additional copies of themselves), with some limited vitamins (like computer chips, for instance). Ideally, you should be able to get by with no vitamins, but vitamins have the opportunity to greatly enhance everything else with relatively little logistical difficulty (if they are small).

Power production is probably the most significant vitamin. It can greatly enhance everything else and is very difficult to reproduce reliably with only Martian materials (but not impossible).

But anyways...

The simplest structural material is just plain regolith. Put it in plastic bags and it makes a good radiation/micrometeor/thermal barrier. 100kg of bags should be able to hold about 100 tons of regolith.

[jryodabobs]

Thanks, folks. Lots of good ideas and information have shown up. I've generated the attached list to summarize the key things mentioned. If additions or changes are needed, have at it.