24 Apr 12
2 edits
Originally posted by WoodPushIt's feasible but I would have to be convinced if I were the venture capitalist sticking millions or billions into such a project. For instance, if we found an asteroid that had a high concentration of platinum or palladium, a few tons of that stuff back on earth would go a long way to pay for such a project but iron?
Is it really as lucrative as implied here? Space travel isn't exactly cheap. Is it even feasible?
http://news.yahoo.com/asteroid-mining-venture-backed-google-execs-james-cameron-011205183.html
Iron is star poop. The last of the line for fusion, you can't get any more energy out of iron either with fission or fusion so it comes out by the megaton from stars and coats everything in its path so there would of course be millions of asteroids half iron but unless you could figure a way to get it down to earth ala meterorite or something it would be worthless from a mining point of view.
Rare Earths, platinum, palladium, indium, that kind of stuff could be well worth it from asteroid mining but it would have to be proven a given asteroid had high concentrations of that stuff before any kind of mining equipment was sent there. So the first order of business would be analysis probes sent to at first the big guys, Vesta and so forth.
You could probably see from IR and UV and other techniques the hints of the major stuff we would want just in a fly by if you had the right tools on the craft. Otherwise you are talking explorers, humans, who of course have not even gone past the moon yet much less gone to Vesta or any other asteroid.
On the other hand, we may find nice deposits on the moon, which is a lot closer and lends itself to magnetic powered ramp launches to sling stuff from the moon to Earth, such devices could be powered by solar energy, where there is an infinite supply of on the moon, no atmosphere to block solar and no hailstorms, except for the occasional meteorite, a few acres for solar on the moon at 20% would get you megawatts of energy for a rail gun launcher, couple of klicks long in a vaccum, it would easily be able to escape moon's gravity.
The same thing could be built on an asteroid but the solar flux there would be maybe only 10 percent of what we have here so there would need to be a lot more area collected. On the other hand, the escape velocity of an asteroid is puny even by Lunar standards so the energy required would also be lower so it could work out. No fuel needed to get the stuff back to Earth.
BTW, just for example, if you had a system of 100% usage of energy, to accelerate 555 pounds at one G would take 32 horsepower. Of course we can't get anywhere near 100% but suppose it was 50% efficient for a rail gun on the moon, since there is no atmosphere, that would mean something like 60 Hp to get say 500 pounds off the moon. Just for grins, call it 50 kw for 500 pounds after all the friction, electrical and other losses taken into account so 200 Kw per ton, not a bad deal energy wise!
200 megawatts would sling 1000 tons off the moon, and it doesn't have to be all at once, it could come from 1000 launches of one ton each and you have to have a collection mechanism in orbit around the Earth but the engineering has already been worked out for such a project. Magnetic catchers (assuming the boules coming in from the moon are aimed precisely) would slow them down, like a rail gun in reverse and the neat thing about that is you get free energy.
Slinging stuff off the moon in a vacuum like that with its relatively low energy requirements as apposed to using rockets, which are extremely inefficient energy-wise is a win win situation.
Because the stuff is launched at only lunar escape velocity, some six times less than Earth's, when it comes into the Earths gravitational field, it starts building up kinetic energy, it was calculated to be pound for pound, kilo gram for kilogram, 6 times the energy density of gasoline, which is about 47 Mj/kg. So the magnetic catcher takes that 500 pound plug, say, and slows it down from about 25,000 mph to orbital velocity and the catcher is a giant generator at that point, the kinetic energy of the 500 pound slug going 25,000 mph minus 18,000 mph= 7000 mph, is very significant and the catcher is designed to handle that amount of energy and stop the slug dead in its tracks.
Then the satellite that has that catcher gets free energy for its own use and could even beam excess energy down to Earth.
Here is a great vision: a space elevator, if and when we can get that technology working, could be used in conjunction with the magnetic catcher, take the now zero velocity relative to orbital velocity, use that extra energy to go back to earth and use the elevator to transport the slugs from the moon to earth. All with no energy inputs needed anywhere except the solar panels on the moon.
Great concept, eh!
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25 Apr 12
Originally posted by sonhouseThe problem with mining on the moon is that you are stuck down a gravity well and the platinum
It's feasible but I would have to be convinced if I were the venture capitalist sticking millions or billions into such a project. For instance, if we found an asteroid that had a high concentration of platinum or palladium, a few tons of that stuff back on earth would go a long way to pay for such a project but iron?
Iron is star poop. The last of the l ...[text shortened]... o energy inputs needed anywhere except the solar panels on the moon.
Great concept, eh!
group rare earth metals that you really want to get at are in exactly the same place on the moon
as they are on the earth.
Stuck in the core. (excepting those deposited by meteorite impacts)
The advantage of small asteroids is that they never became molten and stratified with the heavy
stuff sinking down into the core.
As the article said one metal rich 500m asteroid contains more rare earth metals than we have mined
in our entire history here on earth.
And small asteroids like that are close by, easy to get to (relatively speaking) and small enough to
be relocated into earth orbit.
A single asteroid that size contains trillions of dollars worth of minerals. That's trillion with a t.
So what if it takes a few billion or even a few tens of billions to fund the mining operation if you're making
a conservative trillion dollars per asteroid you mine.
The really cool option is to process in orbit, drop the valuable stuff down to earth, and then use the majority
of the asteroid (made of stuff readily available and cheep on the earth) to build more space ships/stations/and
habitats in orbit, essentially meaning that from that point on pretty much the only stuff you have to lift into
space is biomatter. (people, and plant/animal life for terraforming biospheres)
A space elevator is the real grease for getting this going because it not only makes lifting stuff into space that much
cheaper but it also means you don't have to ferry thousands (millions) of tonnes of ore via space shuttles that
have to withstand re-entry. And means you don't dump all that heat into the atmosphere.
And don't screw up and drop what is effectively a multi hundred tonne asteroid on anyone's head (with kiloton
yield energy range).
25 Apr 12
Originally posted by googlefudgeAll well and true but with a base on the moon first, it is thought there is mountains of ice inside permanently shaded craters on the moon, good enough for a base or colony. With a permanent supply of solar energy used to power a rail gun propulsion system, you don't need to expend rocket fuel to get to those asteroids. If you mined them in space you still have to get the minerals to Earth. Those guys are pretty much dreaming at this stage of the game. You have to get off Earth, we have no base on the moon, to get to some of the asteroids is a bit easier than going to the moon but there is a hitch, space radiation. If they expect to do it right they better have a decent propulsion system that can give a constant acceleration of at least 0.05 G otherwise you spend months in space near a volatile sun that regularly spews highly energetic stuff into space and if it runs into a slow craft on its way to an asteroid and that craft is manned, they can kiss their health goodby, it might be a one way trip for them.
The problem with mining on the moon is that you are stuck down a gravity well and the platinum
group rare earth metals that you really want to get at are in exactly the same place on the moon
as they are on the earth.
Stuck in the core. (excepting those deposited by meteorite impacts)
The advantage of small asteroids is that they never became m ...[text shortened]... ively a multi hundred tonne asteroid on anyone's head (with kiloton
yield energy range).
There needs to be a powerful ion rocket with either massive solar cells or some kind of nuclear power supply, megawatts of power that gives steady acceleration, otherwise they might get fried on the way to the asteroid. That means they can't go out between Mars and Jupiter where there are literally thousands of them if they only have present day chemical rockets.
Remember, the Apollo cost about 25 billion in 1970 dollars. I imagine that would be more like 100 billion today.
Of course private companies can do it cheaper than NASA, especially now 40 years on with improvements in technology and such but they would only be able to intercept near Earth asteroids because of time constraints on the human body running around in space for months at a time.
The astronauts on the ISS have a leg up on radiation because they are within the Earths force field, the magnetic field of the Earth. If the space station was a couple thousand km higher, they would be SOL if they stayed there for any length of time, they could be hit by solar storms that would deposit deadly radiation on them. Not 100% of the time of course but they come and go unpredictably so unless you can get to someplace inside a month you have a good chance of being fried. Space is not a place for humans. Not that I would refuse such a trip myself but it is not a benign environment.
The new designs for powerful ion rockets can do the job assuming someone actually builds one and gets it into space.
You would not have to spend months in space for near earth asteroids however but the number is rather low and you wouldn't know what you had till you got there and dug into it.
So obviously, the only viable option is for near earth asteroids but a base on the moon first would be a big step in getting there. The moon has only 1/6th of Earth's gravity so it is not that deep a well and once there with a colony able to build rail guns, the solar system would be theirs and asteroids too.
First we have to get back into space and not with little puny things we see for the tourist trade either.
25 Apr 12
Originally posted by WoodPushSpace missions are notorious for going way over budget projections. I suspect that it would end up being a money losing venture.
Is it really as lucrative as implied here? Space travel isn't exactly cheap. Is it even feasible?
http://news.yahoo.com/asteroid-mining-venture-backed-google-execs-james-cameron-011205183.html
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25 Apr 12
The trouble with rail guns is that to launch people they would have to be astronomically huge.
Because people are rather limited in the number of g's they can withstand.
Also to slow down at the other end you still need rockets and fuel and the stronger you build
the spacecraft and thus the more g's it can withstand the more fuel and propellent it needs to
slow down again. And then it still needs enough juice to tow an asteroid.
So given that you either are doing this with unmanned robotic ships and don't really care how slowly
they go, or you are using a nuclear torch drive anyway, the rail guns on the moon bit seems like a
waste of time and effort.
The way I would do it is to send multiple small robotic space craft to capture and tow the first small asteroid,
using solar/nuc battery powered ion drives on a NEO, probably a sub 100m asteroid.
Then once I have it neatly inserted in earth orbit I send up manned shuttles to mine it and to construct
a nice big torch ship using a nuclear steam drive which I then use to collect more asteroids.
Thus I never have to send people out of earth's orbit in ships that are too slow or don't have enough
shielding and I don't have to take the risk of launching a nuclear pile into orbit.
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25 Apr 12
Originally posted by Metal BrainAgain, there are thousands of trillion dollar asteroids out there.
Space missions are notorious for going way over budget projections. I suspect that it would end up being a money losing venture.
And that's just the mineral value, before you factor in the value of the habitats and space
stations you build in orbit.
As long as you can afford whatever the initial start up costs turn out to be, and you can actually
do asteroid mining, it would be almost impossible to not make money doing it.
26 Apr 12
Originally posted by googlefudgeI am not convinced that manned shuttles are needed at all. I think robotics are far enough advanced (or will be by the time the mining takes place) that they will be more efficient than using humans.
Then once I have it neatly inserted in earth orbit I send up manned shuttles to mine it and to construct
a nice big torch ship using a nuclear steam drive which I then use to collect more asteroids.
Besides, I suspect that the mining operations would consist of either some basic refining process, followed by sending the results back to earth, or, more likely, simply chopping up the asteroid into workable chunks then parachuting them down to earth. Of course the danger is getting it wrong and dropping an asteroid on earth that is big enough to cause a disaster.
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26 Apr 12
Originally posted by twhiteheadThe trouble with not refining the asteroid materiel in space is that you 'parachute' down a
I am not convinced that manned shuttles are needed at all. I think robotics are far enough advanced (or will be by the time the mining takes place) that they will be more efficient than using humans.
Besides, I suspect that the mining operations would consist of either some basic refining process, followed by sending the results back to earth, or, more l ...[text shortened]... er is getting it wrong and dropping an asteroid on earth that is big enough to cause a disaster.
load of materiel that is not particularly valuable here on earth.
This materiel massively outweighs the stuff you actually want and every ton you shift costs
you in fuel needed to de-orbit it and in weight of heatshielding.
And I agree that the mining process would be mostly automated but it will for the foreseeable future
still need human supervision and the trouble with trying to do it from the earth is that there is
some signal delay but more importantly you have to keep switching from one radio station to another
as you go around the earth.
NASA can't currently even maintain permanent video links with the ISS. They have periodic blackouts
when the station goes over areas where there aren't antennas that support high bandwidth
communications.
So I think that some humans would be wanted in space to oversee the operations and in the event something
breaks or goes wrong to manually fix it. Doing the kind of stuff we have not yet figured out how to automate.
26 Apr 12
Originally posted by googlefudgeThe thing we were talking about using rail guns is launching finished minerals, concentrated ores and the like which don't give a rats bum about acceleration, 1 g, 1000 g, same thing to that stuff. For people the rails would have to be kilometers long of course, one possible alternative could be a space elevator on the moon.
The trouble with rail guns is that to launch people they would have to be astronomically huge.
Because people are rather limited in the number of g's they can withstand.
Also to slow down at the other end you still need rockets and fuel and the stronger you build
the spacecraft and thus the more g's it can withstand the more fuel and propellent i ...[text shortened]... ough
shielding and I don't have to take the risk of launching a nuclear pile into orbit.
That depends on how far out you can go and not start getting gravitational interactions with Earth gravity, although the strength requirement for the cable would be greatly reduced, probably by the same amount as the difference in gravity between the Earth and Luna, and on the moon there would be no atmosphere to muck things up with design.
The main question to answer there is with the moon rotating at only once per 28 days, how far out does a space elevator have to be to not run into earthy gravity?
I think I already did that calc but years ago, would have to do it again. I seem to remember it would not work but may be mistaken. If there were no Earth planets next to the moon, even a 28 day rotation period would not stop an elevator design but with our rather large mass next door, could be some problems interacting with Earth.
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26 Apr 12
Originally posted by sonhouseIIR A space elevator on the moon would have to be tethered to a large object in the earth moon L1 Lagrangian point.
The thing we were talking about using rail guns is launching finished minerals, concentrated ores and the like which don't give a rats bum about acceleration, 1 g, 1000 g, same thing to that stuff. For people the rails would have to be kilometers long of course, one possible alternative could be a space elevator on the moon.
That depends on how far out ...[text shortened]... design but with our rather large mass next door, could be some problems interacting with Earth.
And there is an issue with high accelerations and resultant velocities with both rail and coil guns.
Heat dissipation.
Neither are 100% efficient (or really even close) and dump large amounts of energy (heat) into both the gun mechanism
and the projectile.
You try accelerating an object too hard to to high a top speed and it will be molten by the time it reaches the end of its run.
And hundreds if not thousands of KM is what you need for humans.
26 Apr 12
Originally posted by googlefudgeI guess one has to work out the figures. Its a question of how difficult refining is as opposed to the cost of dropping stuff down to earth. Does one really need heat shielding? Can't you slow the stuff down using parachutes? Or something along these lines:
The trouble with not refining the asteroid materiel in space is that you 'parachute' down a
load of materiel that is not particularly valuable here on earth.
This materiel massively outweighs the stuff you actually want and every ton you shift costs
you in fuel needed to de-orbit it and in weight of heatshielding.
http://www.newscientist.com/article/dn17641-inflatable-heat-shield-tested-in-space-for-first-time.html
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26 Apr 12
Originally posted by twhiteheadOk lets take a candidate N.E.O for mining 99942 Apophis which is due for several close
I guess one has to work out the figures. Its a question of how difficult refining is as opposed to the cost of dropping stuff down to earth. Does one really need heat shielding? Can't you slow the stuff down using parachutes? Or something along these lines:
http://www.newscientist.com/article/dn17641-inflatable-heat-shield-tested-in-space-for-first-time.html
approaches (was once thought to be a possible impact threat) and is about ~270m across.
It has an estimated mass of 2.7E10 Kg.
Or 27 million metric tonnes.
Lowering that materiel to earth requires slowing it down from (lets assume it was in low
earth orbit) Mach 25 to zero dissipating it's kinetic energy as heat.
In metric that's about 8200m/s. Giving us a total amount of Kinetic energy to dissipate of
about 9.1E17 Jules.
Which works out to about 217 Megatons of TNT. (1 Ton TNT 4.184E9 J)
The materiel the asteroid is made of can't take that kind of heat and will get largely vaporised.
Which is bad for business because you just lost a large part of your valuable minerals and also
just dumped a load of dust into the atmosphere which is now going to give us some bad winters.
So you need to add in the weight of the specially designed heat shields needed to dissipate that
kind of energy. Plus in all likelihood the weight of the engines you are using to de-orbit, you need
to be precise so air brakes are not really an option. And also whatever systems you're using
for soft landing this rather than just impacting it into the ground (well I suppose you could if
you could find a few thousand square miles of desert nobody was using)
So as you can see even with a really quite small asteroid (and the link was talking about a 500m
asteroid) you need a biblical amount of heat shielding to drop an asteroid down to earth.
And of course you are not going to be bringing this thing into low earth orbit, you are going to
have to park it in a high orbit that isn't going to degrade (and isn't fully occupied with satellites)
And so the velocity is going to be higher.
(and btw I am not suggesting you do it all in one go but the total energy is the same regardless
of how many small packages you send it down in)
So as you can see being able to leave the vast majority of the ice, iron, silicon ect up in orbit and
just drop down the valuable stuff is immensely preferable to trying to drop the entire thing.
And as I say all that remaining materiel you leave in space is immensely valuable for constructing more
space ships and space stations/habitats.
So I would say that all these factors heavily favour in space processing and just landing the
valuable stuff in easy to control shuttles. (assuming you haven't manned up and built a space elevator)
27 Apr 12
Originally posted by googlefudgeNo, I am not convinced. Just telling me how big the asteroid is tells me nothing.
So as you can see being able to leave the vast majority of the ice, iron, silicon ect up in orbit and
just drop down the valuable stuff is immensely preferable to trying to drop the entire thing.
What I want to know is if we chopped off one metric ton of the asteroid, could it be brought down to earth and what would it cost to do so? What percentage of that chunk would be valuable material and what would it be worth? What would refining it in space cost and what would bringing the refined material back cost?
Without at least approximate figures I don't think one can say which is the better option. It is not necessary to bring the whole asteroid back to earth, so the total size of the asteroid is not relevant.