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Liquid Oxygen from Lunar Rocks
SIInudeity writes "A South African chemical engineer has come up with a way to produce liquid oxygen from lunar rock. Oosthuizen is a co-inventor of the Ilmenox process, named after the process' ability to produce oxygen from the lunar mineral ilmenite. The process extracts oxygen from moonrock, which are metal-oxides that may contain up to 30 or 40% oxygen. By means of electro-chemical equipment, which has now been patented, the oxygen and the metal in the moonrock are split."
Moon Base here we come!
And that other Zappa kid too.
It's a shame that he patented this now. I doubt he'll ever see it used during the patent period.
Glossed over in the /. summary is the fact that the output of this process is not JUST LO2, but also titanium (and presumably aluminum) metal, as well.
So not only do you get air to breath, you get materials with which to build your base.
Set up a base running this process, add a Lunar beanstalk to L1, and you have a cheap source of material for building items in Earth orbit.
I wonder if adding a spinner (i.e. a cable in orbit, the ends of which do not terminate on any celestial body but instead are allowed to rotate freely) could be used to reduce the delta-V even furthur - use the lunar beanstalk to launch to earth orbit, rendezvousing with the spinner to get the delta-V to enter LEO, and storing the energy in the spinner to launch items later.
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Assuming a moon base is set up to mine the metal and oxygen for futher development and exploration, what happens when we start running out of moon to mine?
Who owns the resources produced?
Anyway, all we need now is a way to increase the mass of the moon by about 6x, so the moon has a gravity similar to Earth's. Then it can hold an atmosphere, and we'll be able to make better use of it, like turn it into a huge vacation destination or something.
You are not alone. This is not normal. None of this is normal.
This is good in at least we won't need to ship the O2, but where are we going to find the other little necessities of life (and most rocket fuel)?
*whup* "Get along, little electrons. Heeyah!"
One problem with rotating skyhooks is that anything that's long enough to keep accelerations comfortable for people passes through the inner Van Allen belt too much. You're either going to be limited to cargo, or have to think of a different scheme. (Not that it hasn't been done already.)
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So they've managed to split the metal out, but don't have the oxygen as straight O2 yet? The article is a bit short on details on this. If so, it's not going to be useful until he figures out how to get O2 (or H2O) through chemical reactions with whatever he's got now.
--Ender
Loose things are easy to lose. You're getting your hair cut. They're going there to see their aunt.
Could this new invention/process be the argument that finally makes people realize the usefulness of such an intermediate step before we race off to the red planet? Besides the ability to produce their own breathable air from lunar rocks for sustained occupancy, the base could double as a fueling station, producing liquid oxygen for the ISS for breathing, fuel, etc. It might even become practical to use such a base as the staging location for the actual Mars mission. It would be much easier to do in-space assembly of a Mars super-ship with a low-gravity (as opposed to the microgravity of orbit) "Factory" available on the moon, shuttling pieces to the ship in lunar orbit.
We've had the technology to setup a permanent presence on the moon for some time, I want to see it happen just for the cool factor, but I think there's plenty of scientific and exploration reasons. Maybe now that the moon can be used to actually produce something we will take advantage of that. Here's hoping.
-- I'm not a pessimist, I'm a realist. It's not my fault that life sucks so much. --
There's lotsa Helium on the moon. If Mr Fusion gets underway, then they can mine Helium 3 and breathe the 'waste helium' with their O2.
Of course, I don't believe in: Economically useful fusion, Economical manned space travel, any need to colonize the moon or solar system when Antactica is empty and so much more hospitible.
Therefore moon bases are just a pipe dream for zit-faced slashdotters to masturbate to.
The idea of using the spinner is for cargo only - low energy transfers from lunar surface to LEO.
By using a spinner, you can save the energy from an incoming cargo as rotational kinetic energy in the spinner, rather than pissing it off as heat in an aerobraking maneuver.
You can then use the rotational energy to launch other items back out of Earth's gravity well.
The biggest arguement against using the moon as a base of operations is the delta-V required to get to the lunar surface from earth. But delta-V is only expensive when you have to expend non-reusable reaction mass (and the energy to drive it). When you use skyhooks of various forms (spinnners, beanstocks, etc.) your reaction mass is reusable (the reaction mass is the skyhook), and you can frequently reuse the energy from an incoming cargo - greatly reducing the costs.
True, a manned craft is still expensive as you don't want to follow the slower, lower energy paths - but if you can reduce the mass of the manned craft by shipping nonliving support mass (food and fuel) via slow orbits you can reduce the cost of the manned ship to a managable level.
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I would like someone to look at that more closely - there are some well known age-old methods already around for chemically extracting oxygen from oxides & other minerals..
Maybe when we go to the moon, we should leave all the patents on earth!
"You lied to me! There is a Swansea!"
It's not actually necessary to combust anything to get a rocket going. Rockets work by ejecting mass and using the reaction force to accelerate. As long as you have something to eject (the O2 in this case), and a means to propel it from yourself, you're fine.
See ion engines for example, which eject tiny particles at tremendous speed to get going. No combustion involved, just electrical acceleration of ionized particles.
So a rocket engine could be built with solely a heat source and an inert propellant that expands when heated. For example, a nuclear reactor could heat liquid O2, which would escape under high pressure through a rocket nozzle.
I'd guess that liquid O2 would expand hugely when heated from -183 degrees celsius (its boiling point) to, say, 500 degrees. A significant amount of thrust could probably be produced this way.
I don't remember how to calculate the specific impulse such an engine could produce, maybe someone else does?
Wenn ist das Nunstruck git und Slotermeyer? Ja!... Beiherhund das Oder die Flipperwaldt gersput!
So by the time we start using the moon as a base for traveling to Mars, the patents will have expired and we can use the tech for free. Thanks! (Sometimes researching years ahead of the need doesn't pay off.)
Let's go Hurricanes!!! 2006 Stanley Cup Champions!!!
living on the moon, and an occasional bath. To tell the truth, I wasn't considering rocket propellant. I was considering living.
Oh, and to get a high specific impulse, you want your propellant gas to have as low a molecular weight as possible, which is one of the reasons that H2 is used as a rocket fuel. The O2 is just there to heat it up, so to speak.
*whup* "Get along, little electrons. Heeyah!"
I would suspect there is less helium than hydrogen on the moon. The hydrogen will at least combine with other elements and stay put in the form of minerals.
*whup* "Get along, little electrons. Heeyah!"
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I know it's nitpicky, but it's spelled "rendezvous". I only point it out because on the moon, we are excellent spellers.
Since when is pure oxygen lethal? It was used on the Apollo missions, it is used in hyperbaric chambers (at more than atmospheric pressure, I might add), and it is used by military pilots flying high-altitude aircraft to remove the nitrogen from their blood before they fly.
The only thing dangerous about pure oxygen is the fire risk - if that is why you consider it "lethal", then perhaps you might want to check the fuel tank on your car.
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It's not much, but the Moon has 100 ppm nitrogen and 50 ppm hydrogen. I think whether or not water ice is available on the Moon is also an open question.
Anyways, it's quite possible that not -everything- would be available in situ. However, having available oxygen helps quite a bit in terms of required mass. Heck, about 90% of water's molecular weight is oxygen. For other things you can just import and recycle them.
It's brilliant! As long as our subject races don't have any Mac-compatible computers, it can't fail!
...I was actually using that word alot lately (brushing up my English).
That would explain it, as Rendez-Vous is French. Rendez (To return, ) Vous (2nd-person formal).
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you could collect hydrogen from the solar wind using a stationary Bussard collector. not a lot - maybe a few kg per month of operation for a large collector.
If you consider 3 G as the acceptable limit for people, a skyhook with its end stationary at the lowest point and the center of mass moving at 16,000 MPH (allowing for altitude and some excess velocity) would need to extend 1738 km from the center of mass. Re-entry interface for the Space Shuttle is considered to be 400,000 feet; if the lowest point is 120 km (~394,000 feet), by the time it gets to 100 miles the tip of the skyhook would only be moving upward at about 3450 MPH and forward at roughly 380 MPH. These are very low speeds compared to the orbits of satellites, and it would be going in and out roughly endwise compared to the earth; the drag would be correspondingly small.
I expect this to fall out of our anti-missile technology. A guidance system which can "hit a bullet with a bullet" will be able to plot an intercept to a highly cooperative grapnel moving at a much lower speed, and nothing says that you can't carry fuel for a few seconds of thrust at 3 G to perform the attachment at zero relative speed.Sustainability and energy independence essay
100 km 8.0e-7 kg/m^3
120 km 5.0e-8 kg/m^3
150 km 3.0e-9 kg/m^3
Et cetera. I found this a bit odd, so I decided to confirm with the Standard Atmosphere table in the CRC Handbook of Tables for Engineering Science, 2nd ed. This book yielded these figures from table 7-3:
100 km 5.0e-7 kg/m^3
200 km 3.3e-10 kg/m^3
400 km 6.5e-12 kg/m^3
Table 7-5 lists temperatures, molecular weights and pressures rather than densities, but we can calculate density from rho = mw*P/RT. I get similar figures for the 600K exospheric temperature table (calculated using oocalc):
120 km 380.0 K 26.77 g/mol 2.30E-005 mb 1.95E-008 kg/m^3
140 km 483.9 K 25.40 g/mol 5.92E-006 mb 3.74E-009 kg/m^3
160 km 535.0 K 23.90 g/mol 2.00E-006 mb 1.07E-009 kg/m^3
180 km 561.1 K 22.32 g/mol 7.80E-007 mb 3.73E-010 kg/m^3
200 km 574.1 K 20.79 g/mol 3.36E-007 mb 1.46E-010 kg/m^3
250 km 593.7 K 17.85 g/mol 5.53E-008 mb 2.00E-011 kg/m^3
300 km 598.4 K 16.06 g/mol 1.19E-008 mb 3.84E-012 kg/m^3
400 km 599.9 K 11.30 g/mol 9.91E-010 mb 2.25E-013 kg/m^3
Second, you assume that the skyhook would go down to 100 km. I did not say this, I said 120 km (roughly the altitude that SS1 actually reached); this knocks 1.5 orders of magnitude off the maximum air density as well as cutting the speed of the segment below 400 km. If this remains a problem, the pickup could be moved up to 150 km and knock another 1.2 orders of magnitude off the density and another good fraction of the airspeed.
Third, you assumed a very large width for the skyhook. The tensile strength of both standard grade carbon fiber and Spectra is about 3.5 gigapascals, and a 3.3 ton vehicle accelerating at 3 G would weigh roughly 100 kN; at a 100% safety factor the cross-sectional area required would be only 0.57 cm^2, or a circular cross-section about 0.85 cm across. There's another half order of magnitude for you, assuming that you don't elongate the cross-section and align it with the direction of motion to cut drag further.
Fourth, the skyhook only dips into the atmosphere for a small part of each rotation, and only when it is at perigee while it goes through vertical alignment. Keeping it in an elliptical orbit and avoiding the atmosphere when not required would further reduce the average drag.
In conclusion, you should revisit your calculations using better data and more realistic assumptions.
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Okay, suppose you have 0.28 N of average drag. At a speed of 7050 m/sec (about 16,000 MPH) the required reboost power is... less than 2 KW. (In actuality it's much less. The draggy parts are at low altitude and moving at low speed, so the F dot v is considerably smaller than the center-of-mass velocity would suggest.)
The solar array on Deep Space One was capable of about 2300 watts. If you have a significant excess of up-traffic over down-traffic, you'll need tends or hundreds of KW to replace the lost energy and angular momentum. I can't see a couple KW of power demands for drag makeup being an issue. (Of course, if you're trans-shipping stuff to the Moon and back, you could always launch chunks of iron on the down path and play catch-and-drop with the skyhook to replace the losses to the upward traffic, with a little extra mass thrown in for lagniappe.)
The point about a braided tether being bigger than a solid one is well taken, but you probably don't need to spread it out in two dimensions; one will do, and that one can be aligned in the direction of motion. Nor do you need huge coatings; a sputtered layer of gold will do for UV and conductivity, and heating would be insignificant. (How much heat would you generate with 2 KW of drag?) There are a lot of icky technical issues that you'd have to deal with, but do you really thinkk there are any showstoppers in the basic physics? I don't.
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Damping torsional vibrations is relatively easy; you've got a magnetic field you can torque against, and passive coils will damp out rotation just fine (they're used to de-spin some passively-stabilized LEO satellites). East-west vibrations can be damped using current through the tether (additional plasma contactors will be required to allow the current to vary in different segments). Not sure how you'd handle north-south vibrations, but I have neither given it thought nor done research.
If you need to provide make-up thrust of 1 N through the segment between 120 km and 400 km, which is moving at an average forward velocity of ~1400 m/sec (figuring 10 m/sec/km), that is 1400 watts plus losses. Compared to the tens or hundreds of KW you'll need to reboost in compensation for net upward traffic, drag comp is nothing.
If you are referring to the TSS, it failed because of poor design and defective electrical isolation between the tether proper and the reel mechanism. This was relatively easy to foresee and prevent, but nobody did the work.... A skyhook in free space wouldn't have those particular issues. It would, however, be a great place to use the properties of conductive buckytubes.1e-5 tesla field times 1400 m/sec is 14 millivolts per meter; over the 280 km segment that dips below 400 km, that's only about 4 kV. I doubt that this is going to be a big headache, especially if the tether is segmented and charge pumps used to keep each segment at close to the ambient voltage level (each charge pump would be in an insulated segment). For each difficulty there are probably several ways to address it; we should be flying a few so that we can get engineering experience.
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A long, massy tether has the advantage that it has to be tapered and the amplitude of any wave will be attenuated as the thickness of the tether increases; waves will also be partially reflected at discontinuities such as joints between segments. Really, what are the difficulties here?
- Avoiding resonant excitation of vibrational modes, e.g. by the 2/rotation tidal forces.
- Snubbing shocks from sudden changes in load can be done passively (elastomeric dampers) or actively (piezoelectric elements in the load path). Magnitude of shocks can be limited by e.g. using magnetic grapnels for picking up loads and limiting the maximum force to values which will not overload the tether.
Trapped gas isn't going to be an issue with a skyhook which has nothing nearby to arc to. Magnetic propulsion can't fail; ISS has serious issues with the open conductors on some of its solar panels and F=IxB isn't about to be repealed. Last, a serious effort isn't going to founder on trivial budget considerations like two (three?) of your examples.Sustainability and energy independence essay