Long stays in space have a major hitch. Medical studies on the effects of microgravity on astronauts after many months in low-Earth orbit (LEO) can’t get around one hard truth — humans aren’t cut out for life without gravity. Thus, artificial gravity habitats are now being discussed as a crucial component of long-duration near-Earth asteroid (NEA) mining missions.
Artificial gravity will be particularly important for years-long commercial missions where real-time telerobotics will need to be performed by crews housed in close proximity to the asteroid itself. Such gravity habitats would also be useful for years-long exploration of low-gravity bodies such as the Moon, Mars , or eventually even the moons of the outer planets.
William Kemp, a Washington, D.C.-area defense contractor, thinks he and business partner, Ted Maziejka, have come up with a design that offers a viable solution in such instances. It’s a 30-meter diameter cylindrical space station, capable of creating variable artificial gravity by spinning the cylinder about its long axis.
“If we want to stay in space longer than a year we’re going to have to have artificial gravity systems or else we’re going to sacrifice people in the process,” Kemp, Founder and CEO of United Space Structures in Falls Church, Va., told Forbes.
The idea is that artificial gravity is achieved through centrifugal force which requires spinning to create a downward pressure. A small 10-meter structure could, in theory, rotate fast enough for humans to feel gravity, but Kemp says astronauts using such a structure would have horrible inner ear problems as a result.
“If the spin velocity were too great, your sense of balance would be thrown off and you would soon be on your hands and knees violently ill,” said Kemp.
However, a small cylindrically-shaped 30-meter diameter station, of the sort that Kemp is proposing, would create 0.6 gravity; the minimum needed to keep humans safely in a gravitational environment for at least two years. Astronauts would live both inside the cylinder and within the structure’s semi-hemisphere.
Kemp says a 30-meter diameter cylindrical station would need a spin rate of 5.98 revolutions-per-minute and is the minimum useful size to create artificial gravity. A spin rate any faster would be too uncomfortable for the astronauts.
“The direction of the spinning cylinder is not important,” said Kemp. “The speed is based on the radius of the spinning object and the gravity you are attempting to achieve; the larger the radius; the slower the spin rate.”
The first step for United Space Structures’ foray into artificial gravity would be to test a 30-meter cylindrical prototype of the system in low-Earth orbit, says Kemp. Although such a 30-meter diameter station would house less than 30 people, he says it would also work well for a near-Earth asteroid mining operation in deep space.
As for potential partners to build these new gravity stations?
“We are talking to companies like Deep Space Industries that want to mine asteroids and other companies that want to mine the moon,” said Kemp. “We would like to use Space X’s launch platforms, but it’s all going to boil down to costs which is why we will initially use composite materials for the structure instead of metals.”
And despite projected leaps in space medicine over the next two decades, Kemp is absolutely convinced that there will still be a need for artificial gravity. As he notes, over time, microgravity reduces muscle and bone mass; squeezes the optic nerve creating vision issues; greatly diminishes an astronaut’s natural immune system; and may even hinder critical thinking.
But by no means would artificial gravity be a panacea.
In an artificial gravity environment, astronauts would still be aware that they were on a rotating surface, says Kemp. Walk with the spin, he says, and the effect would feel a bit like walking downhill because the floor is falling away. Walk opposite the spin, and it would be a bit like walking uphill because Kemp says the floor would be rising. And if walking perpendicular to the spin in either direction, he says, one would feel as if they were falling slightly sideways.