Generating artificial gravity inside rotating space habitats has been a dream of science fiction since the earliest pioneers of astronautics. However, rotating to produce artificial gravity poses a serious challenge; Humans experience discomfort and motion sickness when exposed to rotation rates greater than a few RPM. To produce artificial gravity near 1g at rotation rates of 1-2 RPM, a kilometer-scale structure is needed.
Zachary Manchester of Carnegie Mellon University has received a phase 1 NASA NIAC grant for this study.
Long-duration spaceflight poses serious challenges for the human body, including muscle atrophy, bone loss, eyesight degradation, and immunosuppression. Many of these effects are linked to a lack of gravity. To address this challenge, researchers will leverage recent advances in mechanical metamaterials to design lightweight deployable structures with unprecedented expansion ratios of 150x or more. Such a structure could be launched inside a single Falcon Heavy rocket fairing and then be deployed autonomously to a final size of a kilometer or more on orbit without requiring complex on-orbit assembly or fabrication. The study will analyze a mission concept analogous to the Lunar Gateway, in which a kilometer-scale deployable structure forms the backbone of a large rotating space station.
SOURCES- NASA NIAC
Written by Brian Wang, Nextbigfuture.com
Brian Wang is a Futurist Thought Leader and a popular Science blogger with 1 million readers per month. His blog Nextbigfuture.com is ranked #1 Science News Blog. It covers many disruptive technology and trends including Space, Robotics, Artificial Intelligence, Medicine, Anti-aging Biotechnology, and Nanotechnology.
Known for identifying cutting edge technologies, he is currently a Co-Founder of a startup and fundraiser for high potential early-stage companies. He is the Head of Research for Allocations for deep technology investments and an Angel Investor at Space Angels.
A frequent speaker at corporations, he has been a TEDx speaker, a Singularity University speaker and guest at numerous interviews for radio and podcasts. He is open to public speaking and advising engagements.
I think the quickest route to a test is to orbit two Starships outfitted as though they were going to Mars, refuel one to make it appropriately heavier, and do the bolo test with them.
1. Gets you the partial gravity test, both Moon and Mars gravity, with plenty of room for test subjects and equipment.
2. Gets you long duration testing of the Mars vehicle as a habitat, including propellant storage.
3. Test vehicles can still be used afterwards for the Mars mission.
The tether and center docking could be launched separately, or just a tether could be carried along as payload, and brought out through an airlock for installation. Since this is meant to be a long duration test on a vehicle that would not see resupply for, potentially, an entire synodic period, it shouldn't actually be necessary to dock with it while it's rotating. The crew should be brought aboard and then spin it up, then spin it down again at the conclusion of the test.
This minimizes costs that are specific to just this test, and maximizes reuse of equipment. And I suspect this is how Starships would travel to Mars anyway, so that the passengers would have plenty of time to get used to Martian gravity.
I agree that aluminum can bolo with docking in the center is critical and should be funded. NASA NIAC is not the place for it. They need a basic advancing of foundational and non-complex technology. People inside NASA and key politicians who were influenced by Boeing had suppressed things like fuel transfer for decades. This has been broken now and fuel transfer is critical for the SpaceX lunar lander.
Orbital Assembly is working towards this kind of rotating stations. They have $1 million or so in funding.
https://orbitalassembly.com/
Probably 150x volume. That would be about right.
Personally? Starship should be flying by next year, and is intended to go to Mars.
So take two Starships, equipped exactly as though they were going to Mars, except for some extra medical monitoring equipment. Launch them into orbit, and refuel one for long term cryogenics testing. Connect them with a tether, and spin them up.
The fueled one will be at Lunar gravity, the unfueled one at Martian gravity, if you do it right.
Now you've got long duration testing at both accelerations, AND a shakeout cruise for the Mars mission Starship. The only thing missing is the reduction in sunlight as you get further from the Sun, and I suppose that could be simulated somehow.
Afterwards? You've still got two perfectly good Starships equipped for the Mars trip.
Understood. But it still remains that understanding the long term effects of partial gravity is a critical thing, which all our future plans in space hinge upon.
Why not spend the money on a similar grant for designing an 'aluminum can' bolo system, that could be launched in the next couple of years, and actually work?
It is only a tiny NASA NIAC grant.
Phase I (FY21)
$125,000 for a nine-month study
12 to 18 awards per year
Phase II (FY21)
$500,000 for a two-year study
Six to eight awards per year
$2 million for a two-year study
One award per year
Obviously you'd do it in LEO, below the Van Allen belts, where the radiation environment is fairly mild. So that's not really an issue.
That the material wouldn't hold air, and so doesn't actually have any use for a rotating habitat, that's an issue.
That the structure would be a big empty pretend habitat without enough structural strength left over to do anything with, not an actual usable habitat, that's an issue.
That the technique in question doesn't really solve a real problem, but instead is just an excuse to work with some fun technology, that's an issue.
But the radiation? Not really a big issue.
This should not require "Mechanical metamaterials" with unprecedented properties to do. All it actually requires is a couple of aluminum cans and a kilometer or two of tether. In fact, if you didn't throw away the fairings, you could easily set it up to test two different accelerations at the same time, with a three body system. And the whole thing still could launch on a Falcon.
Or, sometime in, likely 2023? Launch two Starships kitted out for a trip to Mars, and some tether material, and set up a bolo in LEO, so Musk can confirm they're fit for the job and test his long duration cryo propellant storage. That would be better because you do need the cans to have thrusters.
They're not developing the metamaterial structure to answer the questions about rotating gravity. They're doing it because metamaterials are interesting, and they can burn some of the funds that ought to be spent answering those questions ASAP having fun researching them, and never getting around to launching hardware, leaving the questions unanswered.
This is the typical NASA, cost plus model: Faced with a job, don't do it the most expedient way that gets the job done: Do it at ten or a hundred times the price in an overly complex way that generates lots of interesting make-work while not actually getting the job done.
No question about it, you come up with some neat tech that way. But you don't get the job done!
I've grown to hate that approach to space with a passion.
Radiation would be the least of the problems for humans if, as it appears, this isn't intended to hold air pressure!
Of course, they could mount pressurized pods within it, if it is strong enough to hold enough weight.
Personally, I'd go smaller, stronger, and aim for Lunar or Mars gravity at about the same RPMs. We already know what Earth gravity and zero-G do, it'd be nice to know what those do.
Not sure what they have in mind for the "metamaterials" that could expand 150x. The example shown looks like it might expand 5x at most. Maybe they will have 30 parallel layers that expand and swivel to form linear strands?
Radiation Shielding? To have such low density structure means your squishy human
bodies will be absorbing all of those fast particles
Hope they also spec a version for Starship. Falcon Heavy fairing is 5.2m by 13.1m, Starship is 9m by 18m.