by Todd Jackson
A couple days ago, I wrote an essay concerning a solution to the doldrums NASA lately suffers, according to an appropriately distinguished panel of scientist observers. For reasons enumerated in that essay, I’ve concluded that NASA, contracting with SpaceX, Bigelow Aerospace, and other private space firms, ought to place the highest priority on achieving 1 Earth gravity – or rather, its equivalent – in a space habitat.
If NASA is looking for a mission which is compelling, and, necessarily, inexpensive, it could not do better than to attach a Bigelow habitat to a tether and rotate it about an axis, with cameras inside to record the astronauts, not floating about but experiencing the same gravity as viewers on Earth.
Afterward, I felt it a bit vague. It’s a lot of explaining why, rather little explaining what. So, here are 7 points toward making this concept more specific. First, concerning where:
1) It will have to be decided how far from Earth this ought to be. There are the LaGrange points, clustering around the Moon:
“For the Sun-Earth-Moon system, the Sun’s mass is so dominant that it can be treated as a fixed object and the Earth-Moon system treated as a two-body system from the point of view of a reference frame orbiting the Sun with that system. 18th century mathematicians Leonhard Euler and Joseph-Louis Lagrange discovered that there were five special points in this rotating reference frame where a gravitational equilibrium could be maintained. That is, an object placed at any one of these five points in the rotating frame would stay there, with the effective forces with respect to this frame canceling. Such an object would then orbit the Sun, maintaining the same relative position with respect to the Earth-Moon system. These five points were named Lagrange points and numbered from L1 to L5.”
There would be a tendency to want to keep it near Earth, perhaps within a quick Dragon flight of the ISS.
My own thinking is “If you’re inside, and somehow an asteroid sheers the tether – fantastically unlikely as that would be – and at that moment the habitat’s direction in its rotation was such that now it was being whipped toward Earth, how long do you want to have before reentry? Fifteen minutes? Or a day or so? Likewise with cratering on the Moon.
I could be overworrying this point.
My immediate preference is for L1, conferring that stability which LaGrange points confer, yet being just a bit closer to Earth in case of emergency, and all while being, among the L points, least likely to smack into the Moon in case something happens to the tether.
As I put on my Space Ranger hat, I can’t help but notice that L1 is the truest “high ground” in cislunar space, being commandingly “above” any likely Earth orbit, and also above the Moon, and any likely Lunar orbit.
2) A brief “artificial gravity made simple”: it isn’t actually “artificial gravity,” as it’s often called. It’s “gravitational acceleration.”
As we stand still here on Earth, our tendency is to believe just that, that we’re standing still. We are in fact moving in several directions simultaneously to get picky about it, but for the time being what is most important is that we are falling toward the Earth’s center. The fact that we are always falling is counterintuitive for a moment, until you think about what would happen if the ground you stand on turned into a sinkhole, or if the building in which you sit collapsed. You would fall, coming to rest only when the ground asserted itself to break your fall. Each of us is falling, with our fall broken by the surface of the Earth.
With “gravitational rotation,” you are being centrifugally thrown out in the direction of deep space. What breaks your fall is the floor you stand upon, which is the outer wall of the spacecraft as it rotates around its axis. Understanding this is prerequisite to understanding just what this craft ought to be.
3) The higher the ceiling, the better. I would like to see a full baseball stadium fit inside. Closely corresponding to this, the longer the tether, the better. What is needed is to avoid a rotational speed of 2rpm or greater, this being the motion sickness threshold. At 2 rpm the tether has to be 223.4m if 1g is to be produced. Those are the rules. The challenge is the unavoidable truth that everything being used has to be hauled up from Earth. That’s an obvious limiting factor, though mitigated by using Bigelow Aerospace’s expandable craft. This craft would have two other desirable traits: it would be capable of its own powered spaceflight, and it would be modular, allowing the entire station to grow over time and missions. My only nagging desire, while we’re dreaming, would be for a BA 330 that can dock to another not just at either front or back end, but along at least one length. This allows the growth of the station in all directions, potentially creating a single immense volume.
For this sort of work, which would have to be both inside the station and outside, spacewalking, you need NASA astronauts.
4) My favorite prototype for this project – to be accomplished in the first mission if there’s money, in ten and over twenty years if not -would be the Biosphere project.
The project isn’t often, or fondly, remembered. This might be unfair, though there were certainly problems over the course of the two Biosphere missions in the ’90s. The first lasted two years. The second ended prematurely but because the “Biospherians” ended up squabbling about money, and left. About that all I’ll say is that this has never happened during any NASA mission, and we are hopeful NASA can keep that streak intact through one more Project. The Biosphere itself suffered perilously large fluctuations in CO2, some of which turned to be reacting to the concrete in the walls. There was a drop in oxygen levels; oxygen had to be pumped in from outside.. That’s fine; if, once expanded we need to cheat a little about oxygen or carbon dioxide, that can be an ordinary resupply problem. Just another mission two-thirds of the way to the Moon.
5) Soon, we want the station to have its own magnetosphere. As I discussed in the earlier essay, we should test the radiation shielding capabilities of mini-magnetosphere technology, which, should it turn out as successful as I suspect (in my eager, amateur’s way) prepare a magnetosphere generator to be stationed between the station and the Sun.
6) There is no problem claiming this station, or any station however large, as American. The UN Outer Space Treaty, which Lyndon Johnson signed, reads, intimidatingly,
Outer space, including the moon and other celestial bodies, is not subject to national appropriation by claim of sovereignty, by means of use or occupation, or by any other means.
This renders nettlesome any aspiration by any nation to claim territory onthe Moon or Mars as its own territory.
No such problem would attend a space station – let’s now call it a space colony – whose national sovereignty, as desired, is suggested in many places, but stated firmly in Article VIII:
“A State Party to the Treaty on whose registry an object launched into outer space is carried shall retain jurisdiction and control over such object, and over any personnel thereof, while in outer space or on a celestial body. Ownership of objects launched into outer space, including objects landed or constructed on a celestial body, and of their component parts, is not affected by their presence in outer space or on a celestial body or by their return to the Earth.”
Legally, our whirling Biosphere is akin, not to the Moon, but to an Apollo capsule.
The implication of this is that neither the United States nor any other nation ought consider itself bound to or limited by the surface of the Earth.
7) As this technology makes its way into the private sector – and who’s to say it won’t be initiated as a private research venture, anyway? – this could also lead to the beginning of altogether new nations. The crew of any such space station would have the power to just drift off anywhere in the solar system it wished. It could just wander off the grid altogether, alone or with a small cluster of other stations, not to be heard from again. As detailed by Gerard K. O’Neill in his The High Frontier (1977) we have here the beginnings of the means by which the human race can expand to populations well over 20,000 times present, which suggests over one trillion before it starts to feel crowded. He writes in terms of 26,000 years of growth, keep in mind that the whole of recorded history goes back about seven thousand years. Most people’s lives would be in communities of maybe 5000, 10,000; there would simply be so many of these communities that they’d resemble bees or fireflies swarming, with the swarm thickest near Earth, but distributed throughout the solar system. Essentially, we will have become almost a fundamental part of the universe, like a new kind of substance.
Of course, any such growth in our population would be at the same time a growth of Earth herself. People might say “The Earth” to refer to the planet, but when they say simply “Earth” they’ll mean something quite different, and larger. Unlike any other planet, Earth will have begun multiplying herself, with us as her instrument.
Ought to make up a little for all our pollution.