We didn’t even know asteroids existed until 1801, when Giuseppe Piazza came across Ceres by accident while making a star map. Now we know there’s millions. Only about 20,000 are considered near Earth asteroids with about 860 of those over a kilometer in diameter.
Their orbits around the Sun have them crossing paths with Mars, Earth, Venus and sometimes Mercury before returning to the asteroid belt. They circle in and out, around and around for millions of years in the same orbit.
Stretched out in your one-piece Nike All-Conditions suit on an aerogel blanket on the surface of an asteroid, you would be afforded a panoramic view of the Solar System sliding by. Sounds like fantasy but it could be closer to the truth than you think. Once asteroid mining begins, so might begin the luxury asteroid shuttle age.
A good, reliable artificial intelligence that can deal with new situations much as a human is all that’s needed for asteroid mining to become a reality. That and a lot of money, a few finer points of outer space legalities to be hashed out, and good prospecting reports on some particular asteroid.
AI controlled drones will converge on the chosen asteroid, set up shop, and begin to remove ore, refine it, and store it. The next time the asteroid swings relatively close to Earth, one of them hauls the processed material back to Earth orbit. At some point, the void left by that mined material beckons us to get creative. Building living quarters inside a near Earth asteroid is the most logical thing to do if you want safe, stable, cheap transportation between Earth orbit and Mars, Venus, the asteroid belt and beyond.
What makes this concept so safe and comfortable? Besides the normal stuff like food, water, and air, there are two big 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 the health of 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 carbonaceous asteroid rotating 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 typical round trip will normally take at least a year.
The mining robots will be programmed to excavate a cylindrical shape from the interior of the asteroid as they remove material to be processed. The central 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 useful artificial gravity were to be created for this cavity, the asteroid would have to be spun up to about 1.25 rpm or 20 times faster than what it is now. Even using large rocket engines and lots of fuel, it might take many years to spin this rock up to a healthy gravity. Even if you managed that, the structural stability of the asteroid might not be up to snuff, and it flies apart. What do we do?
We fabricate a cylinder that fits inside the cylindrical space in the asteroid and rotates on a spindle at the center. It is hundreds of times lighter than the asteroid, therefore much easier to spin. To maintain the structural integrity of the asteroid (and because it’s easier) let’s make the cylindrical space 2,200 feet in diameter and the cylinder 2,000 feet in diameter, giving a hundred feet clearance all around. Spinning the cylinder at 1.6 rpm would provide 87% of normal gravity. A 200 pound person would weigh 174 pounds standing on the outside wall of the cylinder.
We cut down the length of the cylinder because if it’s too long engineers would have the same problem supporting it the middle as they would on Earth. Since this is an expeditionary vehicle and not a space colony, we will pare the design down to a minimum. The minimum looks, unsurprisingly, like a large centrifuge — which it is. It has two diametrically opposed, tubular arms a thousand feet long. These arms serve as elevator housings and support for living quarters along their length.
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 gravity ranges from .23 g in the inner pod to .87 g in the outer. There is a lot of water on some asteroids, especially the carbonaceous. Water is removed from the mined material and stored as ice. The water is broken down with electricity into oxygen and hydrogen to run the rocket shown turning the habitat about its axle.
This is the only situation where the exhaust from a rocket can be recycled. The burning of hydrogen and oxygen in the rocket converts it back to water in a vapor form. It freezes in the cold vacuum and collects like snow in the cylindrical void until collected and turned back into rocket fuel or water for plants, bathing, drinking, etc.
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 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 1.6 rotations per minute of the habitat. They shed their suits, and climb “down” one arm or the other to different levels.
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.
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 asteroid.
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.
As a converted asteroid nears Mars during its orbit, 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 asteroid shuttles will be excellent for preparing expeditions to the outer planets and their moons, the Kuiper Belt, and even the Oort Cloud. Stocking outposts for such ventures with fuel and supplies is easier with such a conveyance.
The human race is at this fantastical pivot point in history. We are poised to begin an expansion into space and, at the same time, witnessing our planet being ravaged by unforeseen (or ignored) climate changes involving the very industrial/technology base that allows us to venture into the great unknown. Let’s 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 by Glen Hendrix: