How We Will Get Asteroid Material Back To Earth

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. 

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. 

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Moon being bombed by asteroids - courtesy NASA

The energy of the Sun near Earth is about 1368 watts/meter squared. The Falcon Heavy will be able to lift a directional mirror into space with a variable focus length of about 50 feet to thousands of miles. Its 332 square meters could focus 455,000 watts onto a spot the size of a baseball, vaporizing whatever has the poor fortune to be there at the time. 

Paper bags take 5 X the water to make and 7 X the fuel to transport than plastic bags 

Why would someone want such a machine? To mine asteroids. To mine the moon. To melt lunar regolith and asteroid material into shapes to build habitats in space or on the Moon. To power crucibles making steel and aluminum and other metals in space. To vaporize space debris that has become a hazard. Such power is handy in space, but there is a dark side. 

Asteroid being mined with solar mirror - courtesy Dan Brown on flickr

What if someone wanted to use such a mirror to do damage to a particular country or city for military purposes? One could set fire to or melt just about anything on the Earth or Moon with such a machine - cities, missile silos, air fields, ships, cities, individual buildings. No satellite in orbit would be safe. It could destroy the International Space Station. Keep the keys to the space mirror in a safe place.

There is a lot of money invested in the idea of moving an asteroid near to the Earth and mining it for metals and minerals. The acceptable location for such a huge mass of metal would be one of the lunar Lagrange points L4 or L5 where it would rest in a stable orbit about the Earth. Getting it there is the trick. It would require a robotic space tug. 

It costs $4000 to recycle ton of plastic bags worth $500 on open market. 

What if someone deliberately sabotaged the space tug’s guidance system and sent a kilometer diameter chunk of iron hurtling toward the Earth? The damage could be incalculable. From treasure trove for the future of mankind to the fall of civilization for some poor region of Earth, perhaps the whole planet. Or someone could attach such a tug to a smaller asteroid and program it to come fast out of the sun. Undetectable until it is too late. 

Asteroid being moved by space tug - courtesy Korite on flickr

These examples are besides what may be already in orbit or planned to go into orbit. This includes EMP (electromagnetic pulse) bombs and “rods of god”. Since 1967 it has been illegal to park atomic weapons in orbit, but that may not stop the likes of North Korea. To get around the orbital nuclear bomb ban, the U.S. has come up with a simple rod of tungsten dropped from orbit. The one foot diameter by twenty feet long cylinder of metal reaches ten times the speed of sound by the time it hits and mimics a small nuclear device in its devastation. It penetrates hundreds of feet into the ground, destroying underground bunkers and silos - something a nuclear weapon cannot do. 

That is not the only kinetic weapon available. Combine several NASA HiPEP ion thrusters with a TOPAZ style nuclear reactor, a guidance system, and a few tons of xenon (all properly armored against cosmic radiation); and you have a weapon that travels for light years and builds up a velocity that is an appreciable fraction of the speed of light. Besides targeting other planets for destruction, the truly paranoid might put such a device, perhaps several, in a long elliptical orbit around Earth, coming close to Earth on a periodic basis. In a form of mutually assured destruction, a country under attack could threaten to have one of these hit the Earth instead of continue its normal orbit. The affect would be similar to a super volcano eruption. Actual destruction might cover a continent. The weather effects could destroy the rest of civilization over the next few years.

It takes 7 trucks to move the same number of paper bags as one truck moving plastic bags. 

Another thing about having control of weapons in space is that it would allow an interdiction of anyone else coming into space for commercial or exploratory purposes. The entity in control of such weapons would be the arbiter of who comes and goes in space, who gets the benefits, who prospers and who doesn't. This is a very powerful position. This is the kind of lopsided power that starts wars.  

On June 18, 2018, President Trump directed the Pentagon to create a new division of the military - the Space Force. “My administration is reclaiming America’s heritage as the world’s greatest space-faring nation. The essence of the American character is to explore new horizons and to tame new frontiers. But our destiny, beyond the Earth, is not only a matter of national identity, but a matter of national security,” he announced. “[I]t is not enough to merely have an American presence in space. We must have American dominance in space.”

It seems the President may have been ill-informed about the advisability of a new branch of the military devoted only to space. The reason is that dominance of space means true dominance of the Earth. Other countries know this. The military has always valued high ground and space is the highest. That makes the President’s statement, “We must have American dominance in space,” one of the most nakedly aggressive of any leader of a nation on Earth regarding the frontiers of space. If any other large nations are taking him seriously, they will be making plans to counter aggressive actions taken in the last frontier.

With all of this death and destruction possible from outer space, it should be obvious that the exploration and exploitation of space should be done in joint ventures with as many countries participating as possible. This will cut down on paranoia about what any one country may be up to in space and prevent physical confrontations on Earth surrounding this subject and possibly prevent the use of space as the ultimate militarily strategic high ground. 

Other articles you may enjoy:

Oumuamua: Alien Probe or Asteroid? It Could Be Both

Cryptocurrency Is Going Into Space

Going Back To the Moon Is Not Just for Governments Anymore

Why It Is a Certainty We Will Become a Space-Based Civilization

Asteroid Mining - How to Pick the Right Asteroid

Recycling Asteroids For Fun and Profit

Taking the 06-03-25 Asteroid Shuttle to Mars - An Alternative to Planned Mars Missions

A Heavy Metal, Cannibalistic Asteroid Propulsion System

Sticking the Landing On Your Billion Dollar Asteroid

Artificial Intelligence and Asteroid Mining Will Be a (Necessary) Match Made In the Heavens

The Weapon of Mass Destruction Nobody Is Talking About

How We Can Diminish the Possibility of Water Wars

There's An Asteroid Out There With All of Our Names On It

What Will Be the Most Common Currency In a Future Space-Based Society?

Workers In Space Will Live In Igloos

How We Will Get Asteroid Material Back To Earth

Very Large Scale 3D Printing In Space

Energy and Space; Tweedle Dee and Tweedle Dum

China’s Strategy for the Future Is Scary Smart

We Will Live on the Moon: the How and Why

The Space Mirror Hack

by Glen Hendrix

Call me soft-hearted or a weeny-butt; I never fried ants with a magnifying glass when I was a kid. I did set pieces of paper on fire and burn my initials into a chunk of wood. What heady times those were. Those deeds were accomplished with a 2 ½” diameter magnifying glass at the bottom of a light-sapping 100,000-feet atmospheric well. Now imagine a magnifying glass 140 feet in diameter and sunlight that is twice as strong. That is what you have with an Orbital Adjustable Mirror.

The Orbital Adjustable Mirror is described in my science fiction novel Transmat World but is doable science. In the book the mirrors were first deployed to reflect sunlight to prevent the world from heating up due to an increase in greenhouse gasses. This has been proposed before by Lowell Wood, a senior staff scientist at Lawrence LIvermore National Laboratory. He states that reflecting 1% of sunlight striking the Earth’s surface would be enough to stabilize our climate, requiring a reflector of 600,000 square miles. The OAM is nowhere near that size but many of them were used in the book, taking advantage of the Space Elevators to get them into orbit cheaply. The OAM shown in the drawing is actually sized for the cargo bay of a Space Shuttle, a technology we know we are capable of even if it is not currently employed. It is a load that could easily be handled by Falcon Heavy to be launched this year.

Space Elevator illustration provided by Bruce Irving (FlyingSinger) under the creative commons license.
 
The OAM consists of two disc-shaped membranes approximately 8 thousandths of an inch thick. They are 140 feet in diameter and keep their shape via an inner-tube-shaped inflated tube 6 feet in diameter. One of the membranes is transparent and and the other is mirrored on the inside surface. Gas is introduced between these membranes to expand them, deforming them into spherical surfaces capable of focusing the sun’s rays on a small surface. The focal length ranges from several hundred feet to thousands of miles. Small thrusters around the outer surface of the tubular frame adjust the mirrors direction and its orbit. A small unit containing gas cylinders, computers, and solar panels attached by a flexible umbilical provides the essentials for directing and focusing the mirror. Even smaller, semi-autonomous robots roam the cavities of the framing tube and in between the membranes looking for and repairing small punctures.

Unlike the mirror proposed by Mr. Wood, the OAM does a lot more than prevent global warming. Once they have performed their climate-saving act, the mirrors can then be employed in their second job - creating space habitats. In the book the mirrors are focused on a mass of lunar regolith in orbit around the Moon. I propose that the mirrors be used to transform the asteroids captured and herded into orbit around Earth by the smart film I mention in an earlier post. If you will remember, smart film wraps the rock in a membrane that can change its albedo selectively over its surface to herd the meteor or asteroid using reflected or absorbed sunlight. The mirrors can be adjusted to focus on these captured chunks of material, melting them to extract metals or minerals. There is another reason to melt this detritus we’ve collected from the Solar System. Once they are melted, they form a spherical mass of molten material that can then be blown like pieces of glass into habitats. In future posts I will discuss further the fabrication of space habitations using the Orbital Adjustable Mirror.