 |
| Tesla Roadster in space - courtesy wikipedia |
We won't be hauling it down with a Tesla Roadster.
An asteroid one kilometer in diameter is parked at the Lagrange point L5 of the Earth/Moon gravitational system. The asteroid orbits the Earth at the same distance as the Moon - 238,900 miles. If a line were drawing through the center of the Earth to the Moon and the center of Earth to the asteroid there would be about a 45 degree angle between those lines. It is in a safe, stable orbit that does not require regular expenditures of fuel to keep it there. This safe, stable location was the deal between the United Nations and the company retrieving the giant space rock; actually more metal than rock. 16217 Ryugu contains iron, nickel, cobalt, water, nitrogen, hydrogen, and ammonia.
Plastic bags are made from ethane, a part of natural gas burned as waste before they started making plastic bags.
Outer space construction has not yet hit its stride so some cheap way is needed to get these metals to the surface of Earth where they can be sold. Here is how it could be done.
If chunks of metal were cut off of Ryugu and simply dropped to Earth, it would be a mess. Chunks big enough not to vaporize completely upon reentry could do major damage. The velocity when it reached Earth would be nearly 200,000 miles per hour and create an explosion equivalent to 100,000 tons of TNT. So, for practicality, we need to get this stuff closer to Earth and reduce that velocity.
 |
| Flaming mass making reentry - courtesy Neil Bleving |
A deal is brokered between the powers that be on Earth and the asteroid mining company so that a million ton chunk of iron can be brought into a medium Earth orbit about 2,000 miles up with careful planning and monitoring. Along with it comes several space tugs and lots of water (from the asteroid) as fuel (electrolysis - oxygen, hydrogen) to keep it in orbit. Engines are anchored to the big asteroid chunk and will automatically kick in to prevent a deterioration in orbit.
Any amount of heat one requires in outer space is available. One simply needs the right size mirror configured to apply that heat to an appropriately sized area on command. With this heat the stoney portions of an asteroid and, perhaps, lunar regolith can be melted and turned into ceramic. Metals can be melted down by these same mirrors.
Concentrating mirrors cut off a 300 ton chunk of iron and begin to melt it down.
Concurrently, stoney portions of the asteroid are melted to form ceramic. While the ceramic is molten, pre-heated (to prevent explosive expansion) nitrogen is introduced into the ceramic melt to produce a foamed ceramic material. This material will be formed into the shape of a lifting body similar to that of the Space Shuttle but about half the size. As the hot nitrogen entrained in the ceramic cools it forms a partial vacuum, making the material much less conductive to heat.
It takes 7 trucks to move the same number of paper bags as one truck moving plastic bags.
The blob of iron melt is rammed into the ceramic mold. High temperature spargers inserted through the wall of the mold inject the iron with nitrogen as well, making a foamed metal having one tenth the weight of iron while still retaining much of its strength.
Once out of the mold, a foamed-ceramic mat is attached to the bottom of the foamed metal lifting body. and a steering module is inserted into the cavity molded in the rear to accept it. This is a heat-resistant rudder and elevators on vertical and horizontal stabilizers controlled by an onboard GPS and autopilot. Built in space with only the electronics and motor coming from Earth, those parts are used again while the rest is recycled.
A railgun is built on the mass of the asteroid chunk and points at a tangent point to Earth about 100 miles above the surface. The lifting body is attached through grooves molded into it and launched towards Earth at 20,000 miles per hour retrograde to orbital velocity. When the lifting body reaches the upper atmosphere, it is going much slower in relation to the Earth, allowing a safe, guided landing on a shallow lake where it is recovered.
The bubbled metal might be worth many times its solid value, making the whole operation profitable. Many types of metallurgy may be possible in a vacuum and weightlessness that aren’t feasible on Earth. We could be talking about metals such as high temperature inconels that are very expensive. I designed a coil in a furnace, the prototype for making BPA free plastic bottles, where a 6 inch schedule 40 (1/4” thick wall) piece of pipe cost $1200 per linear foot.
For smaller packages of very valuable metals like platinum or palladium, NASA may have just the thing. They have developed a folding heat shield. A small reentry vessel with a hundred pounds of palladium has a heat shield that folds out to a much larger size than the vessel itself, creating a shield off of which most of the frictional heat is sloughed away around the side of the vessel on its reentry path to an elevation and speed at which it can deploy a parachute. Be there to pick it up before someone else gets it because that's 1.6 million dollars we're talking about.
For smaller packages of very valuable metals like platinum or palladium, NASA may have just the thing. They have developed a folding heat shield. A small reentry vessel with a hundred pounds of palladium has a heat shield that folds out to a much larger size than the vessel itself, creating a shield off of which most of the frictional heat is sloughed away around the side of the vessel on its reentry path to an elevation and speed at which it can deploy a parachute. Be there to pick it up before someone else gets it because that's 1.6 million dollars we're talking about.
 |
| courtesy NASA |
These are the possibilities once we start thinking about how to maximize the payback for such a massive undertaking as capturing an asteroid. Of course, the real payoff for the asteroid miner will be when construction off world begins, increasing the value of their asteroid many times. Unexpected returns will be the technological advances necessary to get this done that will eventually work their way into our everyday lives.
Other articles you may enjoy:
Other articles you may enjoy:
No comments:
Post a Comment