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The early explorers set out on the high seas in wooden boats with cloth sails. They were brave people facing difficult conditions. The next century will see a similar wave of brave people willing to face difficulties to go see in space what no other human has seen or experienced. With proper planning, adequate funding, and modern technology, however, the conditions may not be all that difficult. In fact, they would definitely be considered luxurious by the crews of the Niña, Pinta, and Santa Maria. And it all has to do with an industry that doesn’t even exist yet—asteroid mining.
Near Earth objects or NEOs are usually asteroids, sometimes comets, that come close to Earth at some point in their orbits around the Sun. These are some of the most likely candidates for extraterrestrial mining. There is no gravity penalty with asteroids like there is for Mars and the Moon so design, equipment, and fuel costs are much lower. Although the technology is almost up for it, there are a couple of things to be resolved before mining the asteroids becomes a real thing.
A power source is required that won’t fizzle out towards the asteroid’s farthest point from Earth, which may be even further out than the asteroid belt. NASA could have a solution with technology called KRUSTY (Kilopower Reactor Using Sterling Technology) that puts out between 1 and 10 Kilowatts. I doubt that NASA is tired of the Simpsons jokes yet, so keep 'em coming. While most of the power needs of mining drones would be satisfied by a field of solar panels installed on the surface of the asteroid or hanging in orbit, it would not hurt to have a back-up generator should something go wrong. The drones will be powered by large lithium ion batteries like those in a Tesla and automatically seek a recharge near depletion like a Roomba.
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| KRUSTY nuclear power plant - courtesy NASA |
Also, someone needs to come up with an AI capable of running a space mission on its own. Once that's done and likely asteroid choices vetted, it won’t be long before AI driven, solar powered mining drones with a nuclear backup touch down on an asteroid as it makes a flyby of Earth and start mining it for water, metals, silicon, or whatever substance of value that can be hauled back to Earth orbit on the next closest pass.
If the drones are careful about how they excavate this chunk of space rock, the owners will not only be making money from the mine, but by renting out a perfectly safe and comfortable Solar System shuttle as well. It will serve as a scientific expedition base as easily as a planetary system cruise ship or some combo thereof.
What makes this craft so safe and comfortable? Besides the normal stuff like food, water, and air, there are two big current problems for human habitation of space—radiation and the lack of gravity. Radiation is a big bugaboo. Cosmic radiation can throw an iron nuclei at you that packs the power of a baseball thrown at 40 mph. Concentrating that much power in such a small area causes physical damage and ionizing radiation with mutagenic effects on human tissue. It could damage your eyesight and your genes. Also, we are not sure why, the lack of gravity in space is not that great for humans. It makes bones porous and muscles weak. It can also affect vision and balance. An asteroid-based shuttle does away with both of these problems. Here is how it will be done.
We will use asteroid 1996 FG3 as an example for this thought exercise. Asteroid 1996 FG3 has a diameter of 1.7 kilometers or 5,600 feet. It is a chondrite asteroid and rotates once every 3.6 hours and weighs more than a trillion pounds. It crosses Earth's orbit reaching just inside the orbit of Venus on its trip toward the Sun. Outward bound, it comes close to the orbit of Mars without crossing before heading back in. It takes 395 days to complete its journey so your trip will normally take at least a year.
The mining robots will form a cylindrical shape from the interior of the asteroid as they remove material to be processed. The axis of this cylinder will coincide with the rotational axis of the asteroid. But there is a problem. Even if the internal cavity is quite large, say 3,400 feet in diameter, standing on the inside of that big cylindrical cavity the artificial gravity would be a paltry .002 standard Earth gravity at its current rate of rotation. However much it would help your dunk shot, it would not work to keep you healthy.
If artificial gravity were to be created for cavities inside, the asteroid would have to be spun up to about 1.25 rpm or 20 times faster than what it is now. Even using the mass driver propulsion system I’ve proposed in A Heavy Metal, Cannibalistic, Asteroid Propulsion System producing 155,000 pounds of thrust, it would take a hundred years to get the asteroid up to speed. How can this be solved?
We build a cylinder inside this cavity that is much lighter. With a cylinder spinning inside the asteroid, the gravity can be controlled by the speed of rotation. Assuming the dimensions already given, a cylinder 3,400 feet in diameter spinning at 1.25 rpm would provide .91 normal gravity. A 200 pound person would weigh 182 pounds if that person was standing on the outside wall of that cylinder.
Such a large cylinder may have many levels from the center to the outer wall. If each level was a hundred feet from floor to ceiling, there would still be 17 levels. Gravity at the innermost level (100 feet from the center) would be .05 Earth normal while level 10 (1,000 feet from the center) would be .53 or half Earth normal.
To save time and resources, the cylinder will be made a lot smaller and the rotation sped up to compensate. For instance, a 2,000 foot diameter cylinder spun at 1.65 rpm to provides .93 Earth gravity at the outermost level. But we’re not talking about enough room for a space colony … yet. We are only planning for a few dozen people. Plus, if the cylinder is over 100 feet long, serious structural issues begin to pop up at the outer level, the same ones that bedevil an engineer on Earth trying to span a 100 feet with proper safety margins. The above design can be pared down to its simplest configuration—a glorified centrifuge.
This centrifuge would consist of two arms of equal length attached to a central hub. The arms would serve as the vertical access tube to the different elevations and as the main structural support countering centrifugal forces.
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| Drawing by Glen Hendrix. Click to enlarge. |
This first illustration shows a minimalist layout for the habitat inside the asteroid. The hub of the habitat contains electromagnetic bearings that provide frictionless rotation of the habitat. The illustration shows six levels but that could vary. Whatever the final configuration, the arms have to be identical and the internal loading must be monitored by AI to prevent unbalanced loads.
The long, curved outer tubes on the arms will be considered the “basements” as they are the farthest thing “down” and they have the highest gravity at .93 g, a little less than Earth normal. The next level “up” would be .79 g and the next, .65 g. The short tubes closest to the center will be the “attics”. They only have an artificial gravity of .23 g, less than 1/4 of Earth’s gravity. The basement and the next level up will be the primary levels for residence since this will convey the greatest protection against the deleterious effects of low gravity. The rest will serve as labs, storage, and special applications.
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| Drawing by Glen Hendrix. Click to enlarge. |
1996 FG3 is a chondrite asteroid made up of anhydrous silicates, hydrated clays, organic polymers, magnetites, sulfides, and maybe some nucleic and amino acids. The Murchison meteorite proved the extent of organic materials in space when 70 different amino acids were found using high resolution spectroscopic tools. There is the possibility of millions of unique organic compounds in that same meteorite. It is possible these will also show up in asteroids like 1996 FG2.
The asteroid has water, which is important. Water will be extracted during the mining process and stored as ice. This water will power the rotation of this habitable centrifuge. Rocket motors burning hydrogen and oxygen will bring the habitat up to speed with occasional boosts to keep it there. The hydrogen and oxygen come from water mined from the asteroid. This will be the only instance where rocket exhaust in space can be reclaimed and reused. The rocket exhaust will turn to water which will turn to ice which will accumulate in the inner cavity housing the habitat. Special drones will vacuum the ice crystals up periodically for recycling.
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| Drawing by Glen Hendrix. Click to enlarge. |
Once the habitat is up to speed, it’s time for the voyagers to move in. A deep space tug has brought them from Earth’s orbit to 1996 FG3 as it makes one of its passes near to Earth. The tug parks in a bay excavated for it by the mining drones. This gives it protection from radiation coming from most directions. The illustration labeled “Detail 3” shows the tug in its protective bay. The space-suited future inhabitants go from the tug to the access tunnel dug into the rock of the asteroid. This leads to the airlock for the habitat. Through this they gain entry to pressurized living space and transition from 3.6 rotations per hour of the asteroid to the 1.65 rotations per minute of the habitat. They shed their suits, and climb “down” one arm or the other to different levels.
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| Drawing by Glen Hendrix. Click to enlarge. |
As illustrated, this habitat has about 320,000 square feet of habitable space. That does not include areas for storage or utilities. If just half is used for 600 to 1200 square feet apartments, a hundred to two hundred people could have their own digs aboard this asteroid shuttle.
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| Drawing by Glen Hendrix. Click to enlarge. |
This design easily lends itself to expansion. From the minimal wedges of the original layout, it goes full circular. Also, the mining drones have excavated four more cavities for additional rotating habitats and added another access tunnel with docking bay at the other end of the asteroid. This space would allow about 26,000 people to inhabit the shuttle.
By this time, and we may be talking about a couple of centuries in the future, there is a mature economic system in space. There will still be a few tourists, but much of the habitat will be devoted to labs and manufacturing facilities making products in low gravity or vacuum that can't be made on Earth. There will be labs studying new organic compounds discovered on asteroids and comets. It could include a new repository of seeds that will replace the Svalbard Global Seed Vault in Norway. It will be safer from cosmic radiation and/or conflict and climate change on Earth. Likewise, a repository of the world's animals as embryos will come about and be stored on such an asteroid.
On its approach to Mars, it will become commonplace for one of the deep space tugs to rendezvous with the uppermost station of the Mars Space Elevator, allowing people to go to the surface of Mars to conduct business or science or just sightsee. Likewise, the approach to Venus allows travelers to make a connection with the orbital labs around Venus working to terraform the planet.
Other asteroids will be converted in a similar matter. Some will have orbits taking travelers to the outer edges of the asteroid belt, almost to Jupiter. These shuttles will be excellent for launching expeditions to the outer planets and their moons, the Kuiper Belt, and even the Oort Cloud. Outposts with fuel and supplies for these ventures can be more easily stocked with such a conveyance.
The human race is at this fantastical pivot point in history. At the same instant in time, historically speaking, we are poised to begin an expansion into space and to witness our planet ravaged by unforeseen (or ignored) circumstances involving the very industrial/technology base that allows us to venture into the great unknown. I sincerely hope we are up to the precarious balancing act from here forward that will allow us to keep our home planet livable while exploring others.
Other articles you may enjoy:
There May Be a Quadrillion Dollars Lying About on the Moon
By this time, and we may be talking about a couple of centuries in the future, there is a mature economic system in space. There will still be a few tourists, but much of the habitat will be devoted to labs and manufacturing facilities making products in low gravity or vacuum that can't be made on Earth. There will be labs studying new organic compounds discovered on asteroids and comets. It could include a new repository of seeds that will replace the Svalbard Global Seed Vault in Norway. It will be safer from cosmic radiation and/or conflict and climate change on Earth. Likewise, a repository of the world's animals as embryos will come about and be stored on such an asteroid.
On its approach to Mars, it will become commonplace for one of the deep space tugs to rendezvous with the uppermost station of the Mars Space Elevator, allowing people to go to the surface of Mars to conduct business or science or just sightsee. Likewise, the approach to Venus allows travelers to make a connection with the orbital labs around Venus working to terraform the planet.
Other asteroids will be converted in a similar matter. Some will have orbits taking travelers to the outer edges of the asteroid belt, almost to Jupiter. These shuttles will be excellent for launching expeditions to the outer planets and their moons, the Kuiper Belt, and even the Oort Cloud. Outposts with fuel and supplies for these ventures can be more easily stocked with such a conveyance.
The human race is at this fantastical pivot point in history. At the same instant in time, historically speaking, we are poised to begin an expansion into space and to witness our planet ravaged by unforeseen (or ignored) circumstances involving the very industrial/technology base that allows us to venture into the great unknown. I sincerely hope we are up to the precarious balancing act from here forward that will allow us to keep our home planet livable while exploring others.
Other articles you may enjoy:
Carbon Capture and Sequestration (CCS): The Existential Technology We Are Ignoring
There May Be a Quadrillion Dollars Lying About on the Moon
