Microgravity is brutal to the human body. Astronauts lose bone density, muscle mass, vision changes and aerobic fitness after months in space, and the current workaround — daily exercise on treadmills and resistance machines — is a stopgap, not a cure. Artificial gravity, the kind of force you feel when a spaceship spins or accelerates, might fix that. But the question remains: can we ever build it?
The short answer from Torin Clark, an associate professor of aerospace engineering at the University of Colorado Boulder, is blunt. “There’s really no reason it couldn’t happen,” he told Live Science. “From a technical perspective, this is something that could happen in the very near future.”
The Spin Option
The classic idea is a giant ring, like the one in Kubrick’s 1968 film “2001: A Space Odyssey.” Passengers live and work inside a rotating habitat, and the radius of the ring means the ship doesn’t have to spin very fast to produce Earth-like gravity. But that simplicity ends at the assembly line.
“You can’t get all the parts up there in the same spacecraft — you need multiple spacecraft and to assemble everything,” Clark said. “So, of course, you can see what a big endeavor this is.”
The alternative is a short-radius centrifuge, a tube about 6 to 10 feet wide that spins to simulate gravity. Passengers sit or stand inside, with their heads closest to the center of rotation. It’s small enough to fit in a single spacecraft, but it’s an exercise device, not a living space. Users go in for a session, then get out.
“It’s kind of like an exercise device,” Clark said. “In the ISS, you have a treadmill, you have this resistive exercise machine, so you go there for 30 minutes to do your exercise, and then you get out.”
The Engine Option
There’s also the linear-acceleration approach. Fire thrusters in one direction, and the force pushes passengers back into their seats, feet toward the floor. Reverse the thrust, and the ship slows down while keeping the gravity roughly constant.
“But then you need something like an engine that is able to accelerate all the time,” Clark said. “And propulsion-wise, I think we’re not there yet.”
The Budget Cycle
The idea has been circling NASA for decades. The Centrifuge Accommodation Module was a planned 8.2-foot-wide centrifuge for the International Space Station, designed to test artificial gravity on orbit. The project was canceled in 2005 for budgetary reasons.
Ana Diaz Artiles, an associate professor of aerospace engineering at Texas A&M University, has watched the funding pendulum swing. “[Artificial gravity] is one of those things — like all of a sudden, it’s super popular, and then all of the scientists at NASA and everybody … have a lot of funding to understand how to actually implement this, and then it just dies,” she told Live Science. “And then it comes back, and dies, and comes back. I’ve been going through a couple of these cycles in the time that I’ve been doing this.”
The Training Fix
Motion sickness is the biggest practical hurdle for short-radius centrifuges. The Coriolis cross-coupled illusion — a sensation of tilting or tumbling that happens when you tilt your head off-axis while rotating — causes motion sickness. But Clark and his team have found a workaround: incremental exposure.
“If you very slowly, incrementally increase the spin rate … and do that not just over one session but over multiple sessions across multiple days, as far as we could tell, anyone can be made to incrementally acclimate to the rotating environment [of] up to 20 to 30 rotations per minute,” Clark said.
Clark estimates that 30 minutes a day in a centrifuge prevented some loss of muscle function in studies of people on head-down tilt bed rest, the standard research method for simulating spaceflight deconditioning. But the exact numbers are still open.
“Thirty minutes a day … maybe is not enough,” Clark said. “Maybe an hour or even two hours a day, and maybe at higher G levels, would be beneficial.”
Diaz Artiles puts it more bluntly. “I think people are interested in this concept, but we just don’t have a good answer.”
What Remains Unknown
The core unknowns are simple: how much gravity, how long, how often. Long periods in microgravity can lead to bone and muscle loss, loss of aerobic fitness, blood clots, and visual issues from fluid shifts in the eyes. Artificial gravity might prevent those effects, but exactly how much gravity is necessary remains an open question.
The studies are expensive and time-consuming. Funding cycles come and go. The technology exists in pieces — propulsion isn’t ready for sustained acceleration, but incremental exposure training works. The political will has waxed and waned for decades.
The question of whether artificial gravity can work is settled. The question of whether it will is not.
Key Facts Box
– Centrifuge Accommodation Module: 8.2-foot-wide (2.5 meters)
– Cancelled: 2005, budgetary reasons
– Short-radius centrifuge: 6 to 10 feet (1.8 to 3 m)
– Spin rate tolerance: up to 20 to 30 rotations per minute
– Bed-rest study finding: 30 minutes a day in a centrifuge prevented some muscle loss
– Head-down tilt bed rest: standard research method for simulating spaceflight deconditioning
Clark’s optimism is grounded in what engineers can actually build. The centrifuge that was canceled in 2005 was a planned module, not a pipe dream. The training protocol against motion sickness is proven in the lab. The question of whether artificial gravity can work is settled. The question of whether it will is not.
The funding cycle will likely repeat. But each time it swings back, the knowledge accumulates. Incremental exposure works. The engines aren’t quite ready yet. The politics are fickle. The physics is not the obstacle.
Source material: “Could we ever create artificial gravity on a spaceship?,” Live Science.
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