You are not logged in.
Well,
drilling is needed to reach deeper layers of the sediments to look into the history of the planet, but to harvest the obviously existing sources of water for in situ use, it is only necessary to scratch the overlaying sands off the permafrost sites to reach the water ice.(like the PHOENIX tools) Put a bubble or dome over the site, get the air inside warmed up by the sun, and bring the air like a waterhose at high temperature in close contact at the regolith/water mix. Then crack the upcoming gases of CO2 and H2O in the bubble by controlling the cooling, and separate water and Co2. Such a rack could be moved by a trekking vehicle.
Just an idea, not very much founded by my limited knowledge of any of these technologies.
Could that be made working??
Offline
Well,
drilling is needed to reach deeper layers of the sediments to look into the history of the planet, but to harvest the obviously existing sources of water for in situ use, it is only necessary to scratch the overlaying sands off the permafrost sites to reach the water ice.(like the PHOENIX tools) Put a bubble or dome over the site, get the air inside warmed up by the sun, and bring the air like a waterhose at high temperature in close contact at the regolith/water mix. Then crack the upcoming gases of CO2 and H2O in the bubble by controlling the cooling, and separate water and Co2. Such a rack could be moved by a trekking vehicle.Just an idea, not very much founded by my limited knowledge of any of these technologies.
Could that be made working??
Actually, you don't need to drill to reach deeper layers of sediments, they are exposed by topography. You drill to test buried targets, or to sample material unaffected by syrface processes.
Your idea could work, in principle. The issue would be the rate it would work at. It could probably be tsted in a small pressure chamber.
Offline
The EXOMARS Rover (2014) has tools for drilling down 2m, forming a core, crush it and analyze for the buried targets. They say, it is deep enough because of the layers put over in the last 3.5 GYears over those material will keep it unaffected by surface processes (radiation).
The ground penetrating radar will help in selecting the right spot, just a pinpoint in the skin of the planet.
Going deeper to 10m it will be difficult to stabilize the hole.
Offline
One other idea to consider: you have to be able to drill to blast. It's done in "shot holes", not necessarily large ones, although ANFO requires a 9-inch hole. Major construction (as in a real base) always requires blasting to be truly inexpensive. It has for centuries here.
So, we simply have to learn how to drill in low gravity environments. Anything we could get working on the moon would work on Mars at over twice the gravity. Nice to have it so close by, as a playground where we can learn how to do such things, ain't it?
The real trouble will be drilling in essentially zero-gee on the NEO's, later on asteroids and comets.
I'm not even sure a stake would hold in unconsolidated rubble piles like that. Stakes hold by friction as much as anything. Friction develops from the normal overburden "pressure" (weight above per unit area below). On an NEO, that's negligible.
So, is there any friction on an NEO to hold a stake? That (surprisingly enough) is actually a very good question.
GW
Last edited by GW Johnson (2012-03-15 09:58:21)
GW Johnson
McGregor, Texas
"There is nothing as expensive as a dead crew, especially one dead from a bad management decision"
Offline
In the case of a stake, I thought that friction would develop from the horizontal force on the soil or regolith from the stake, e.g., when it pushes it out of the way. This would work even in zero g. It sounds like you're suggesting that the friction from the stakes comes from their weight, which is not true.
If your NEO is small enough, you can just tie a rope all the way around it and use that to hold your drill down. If your NEO is bigger than a few km around, though, things definitely get more tricky. I think stakes are a viable option for larger asteroids so long as the material of which the asteroids are made is strong enough that they will stay down.
I wonder if it would be possible to have an element of the drill itself which would fix it to the soil. Any thoughts on this?
-Josh
Offline
For a stake here, there is a force normal to the stake, some fraction of which (via the friction coefficient) becomes friction parallel to the stake. This also acts in other directions, complicated by the other forces involved in deflecting material out of the way as the stake rotates through the ground. All of the forces are generated by the overburden pressure: the weight of material above any particular plane you want to analyze. A very crude approximation is density times depth, although solids really do not behave like liquids. There is no overburden pressure at the surface, and no friction or lateral resistance to "plowing". Deeper, there is overburden pressure, friction, and plowing resistance, because of gravity.
So, what happens if there is virtually no gravity? There is virtually no overburden pressure, thus no normal force to derive friction or plowing forces from. Hmmmm....
Thought experiment: what happens if you jump off a tall building with a bag of sand and push on the sand bag while in free fall? Now, what happens if there is no bag around the sand? Two completely different outcomes. The difference is the tensile forces of the bag containing the sand, not anything to do with the sand itself.
What I learned at the asteroid defense meeting in Spain in 2009 is that a lot of these small bodies are very unconsolidated piles of rock dust, sand, gravel, cobbles, and boulders, all very angular in shape. The dry ones seem to have zero cohesiveness, like the bag of sand without the bag. The wet ones (the "icy" bodies") seem to have some structural cohesiveness, most likely due to the ice content. Basically, these wet ones are a natural form of the "icecrete" we have been discussing in another thread. (There's been another asteroid defense conference this last year in Budapest, but I didn't go.)
That last about cohesion brings up one more thought experiment: jump off that building with a wet, frozen sand bag. Bag or not, you really can push on it in free fall. What holds it together is not friction, but it is a force that resists very effectively. Cohesion. Also known as structural strength (the names tension, compression, shear, and bending come to mind).
Last few thought experiments: can you drive a stake into a sandbag while in free fall, and will it hold any force if you can? Hmmmm..... Do this with dry sand in a bag, and with dry sand not in a bag, then with frozen wet sand in a bag, and with frozen wet sand not in a bag. Hmmmm. Very interesting. Cohesion is necessary to exert any significant forces on these bodies.
So, how to we get some cohesion on the dry ones?
Use a hollow stake, drive it in with rocket thrust perhaps, then flood the body with water (perhaps as steam) and let that freeze the constituents "in place". Could that hold any significant force? Maybe. If so, then we just dreamed up our first application for the "icecrete" concept on NEO's: a way to touch down and actually stay there for a while, hanging on for dear life, as it were.
Good questions, no?
Hmmmm, rope around the NEO. Interesting. If the body is cohesive to begin with, it might work. Pull tension on the rope, it presses on the surface, thus generating friction, which resists slipping around the body.
But what if the NEO is one of the dry, unconsolidated (zero cohesion) rubble piles. If you pull tension on the rope, wouldn't it just cut into the body? What happens in the thought experiment, if you try to lasso a falling dry sand bag, without the bag?
Now wet the surface down and let it freeze where you want to place the rope. Hmmm. It just might work, unless the rope pressure forces exceed the crushing strength of the "icecrete" you laid down. Very interesting indeed!
I like thought experiments. Very intriguing thing to try. They often raise more questions than answers, though.
GW
GW Johnson
McGregor, Texas
"There is nothing as expensive as a dead crew, especially one dead from a bad management decision"
Offline
GW, that is true. But I would imagine that there would be at least some level of cohesiveness, else the object would not be able to stay together at all. These forces are probably pretty insignificant usually, but it might still be possible to take advantage of them with a big enough stake. More practically, if your asteroid is M-type or has metallic components magnets will very likely suffice to hold on.
With regards to roping a NEO, I think that the"bag of sand" analogy might be a little misleading in this case, but only because the object we'll be dealing with will be so much bigger. In that sense, it's okay if your rope penetrates a bit into the asteroid. Turning the rope into more of a cloth might prove even better, in that the cloth will spread the force out much more evenly.
For water, I definitely like that idea, especially the use of water vapor. That technique may be relatively energy intensive because in order to get the vapor to spread more widely, it will be beneficial to heat it. Depends how strong of a bond you want, I guess. Keeping a spacecraft on the ground is less demanding than holding down a drill, I would think.
-Josh
Offline
Josh -
It's possible we ought to start a steel-making thread. I know how it's done here, and posted that in another thread here in this topic (I forget which one). I dunno how it would have to be done on Mars in 6-7 mbar CO2 atmosphere. But, ultimately it would have to be done, and on a significant scale, if we are ever to plant multiple bases there.
This would be to support general construction of buildings and facilities, and any steel-rail railroads. The scale of it would resemble late 19th-century steel-making plants. That's the scale of construction we're talking about: big buildings and hundreds of miles of track, plus railcars and locomotives.
GW
GW Johnson
McGregor, Texas
"There is nothing as expensive as a dead crew, especially one dead from a bad management decision"
Offline
Are there any estimates how long equipment like drills and robotics etc can last on the surface of Mars? How would dust and particulates as well as radiation impact duration of use? Also what is the best way to get the equipment to the surface controlled crash or rocket thrusters? Thanks.
Offline
Just with my visual work, Mars has always been tough. It seems like it would be relatively easy when it is close. With a lot of eye-brain training on the object over a couple weeks, more things do show up, but not as much as I would like. It is still a fun object to go after. Bill Steen
Removed offensive content
Last edited by SpaceNut (2017-12-17 08:36:39)
Offline
Mining tech heads for the stars as IMDEX backs lunar rover project
https://www.techbusinessnews.com.au/new … r-project/
Super strong material produced with Martian rock, titanium alloy
https://www.mining.com/super-strong-mat … ium-alloy/
Researchers at Washington State University report that a small amount of simulated crushed Martian rock mixed with a titanium alloy made a robust and high-performance material in a 3D-printing process that could one day be used on the red planet to make tools or rocket parts.
In a paper published in the International Journal of Applied Ceramic Technology, the scientists explain that the parts were made with as little as 5% up to 100% Martian regolith, a black powdery substance meant to mimic the rocky, inorganic material found on the surface of Mars.
Sign Up for the Suppliers DigestWhile the parts with 5% Martian regolith were strong, the 100% regolith parts proved brittle and cracked easily. Still, the researchers believe that even high-Martian content materials would be useful in making coatings to protect equipment from rust or radiation damage.
“In space, 3D printing is something that has to happen if we want to think of a manned mission because we really cannot carry everything from here,” Amit Bandyopadhyay, corresponding author of the study, said in a media statement. “And if we forgot something, we cannot come back to get it.”
Bringing materials into space can be extremely expensive. The authors noted it costs about $54,000 for the NASA space shuttle to put just one kilogram of payload into earth’s orbit.
Bandyopadhyay first demonstrated the feasibility of the idea of producing materials in space or on celestial bodies in 2011 when his team used 3D printing to manufacture parts from lunar regolith, simulated crushed moon rock, for NASA. Since then, space agencies have embraced the technology, and International Space Station has its own 3D printers to manufacture needed materials on site and for experiments.
For this study, the WSU researcher, together with graduate students Ali Afrouzian and Kellen Traxel used a powder-based 3D printer to mix the simulated Martian rock dust with a titanium alloy, a metal often used in space exploration for its strength and heat-resistant properties.
As part of the process, a high-powered laser heated the materials to over 2,000 degrees Celsius. Then, the melted mix of Martian regolith-ceramic and metal material flowed onto a moving platform that allowed the researchers to create different sizes and shapes. After the material cooled down, the researchers tested it for strength and durability.
The ceramic material made from 100% Martian rock dust cracked as it cooled, but it could still make good coatings for radiation shields as cracks do not matter in that context. On the other hand, just a little Martian dust, the mixture with 5% regolith, not only did not crack or bubble but also exhibited better properties than the titanium alloy alone, which meant it could be used to make lighter-weight pieces that could still bear heavy loads.
Space station experiment suggests Mars rovers will need to dig deep to find life
https://www.space.com/mars-biomarkers-d … experiment
Extraterrestrial Excavation: Digging Holes On Other Worlds
https://hackaday.com/2019/03/27/extrate … er-worlds/
Offline