Ask Lemmy

Basically, the spinning diameter has to be really long so the spinning doesn't make you puke long-term (Coriolis force is a bitch). There were NASA tests and studies about it, which range between a 100 and a 1000 meter diameter.
So, the ship has to be built for it from the design phase, be it with a rotating ring or a tether approach. Which we didn't have yet a usecase for (for only a few days or months):

• For a future Mars mission, would slow acceleration and deceleration be more viable.
• Only real fitting usecase is a orbital space station with permanent crew.

Here is a great video on spin gravity. It covers an important detail that another comment mentions but most over look. Spinning fast enough to create gravity-like centrifugal force causes real dizziness at small diameters. 5 or 6 rpm is about the maximum we can stand.

Because the constant rotation complicates things a lot.

Specifically talking about the International Space Station, its main mission is a microgravity laboratory. We put it up there so we can learn about microgravity. Why go through all the expense of putting it up there and then spinning it to make gravity when we get it for free down here on the surface?

As for other craft? We have yet to develop manned spacecraft that can do the duration where it would be worth doing. Even the longer Apollo missions were in space for a whopping two weeks and 2/3 of the crew still landed, got out and stretched their legs. It hasn't been worth the engineering hassle to do it.

And it is an engineering hassle, because...

1. The ship has to be designed to handle it. It's under additional stresses, so it's got to be built tougher to handle it. That's added weight, and just typing that sentence made at least three rocket scientists cringe to death.

2. Humans actually aren't great at living in a spin gravity environment. The smaller the radius of the spin, the worse it gets. For one thing, in a centrifuge, there's a pretty steep gradient in centrifugal/centripetal/pedantic force, the farther toward the rim you are the greater the gravity. For very small distances that can be significant enough to cause problems on its own. But also, spinning humans isn't good for their vestibular systems. Each of your inner ears has three semi-circular canals filled with fluid, and little hairs that can detect the movement of that fluid. This allows you to sense rotation around three axes, kind of like a gyroscope sensor. This evolved in an environment that rotates a 1 rotation per day, functionally stationary. Spin a human at several RPM and that constant rotation is enough to start throwing off balance, causing nausea etc. So the bigger the radius of the spin, and the slower, the better. That takes more weight, and there go three more rocket scientists.

3. It makes the spacecraft a pain to handle. You need to be able to orient spacecraft in space to point engines, windows, instruments, docking adapters etc. in various stable directions. A constant roll complicates that. "point in this direction and fire the engines" becomes a pain because, say you're constantly rolling, and you need to change the direction your long axis points. What thrusters do you fire in what combination to steer the ship? Or do you stop the roll, maneuver/use your telescope/dock/whatever, then start rolling again? So now you've got to deal with gravity starting and stopping variously throughout the journey. Or, do you design the ship to have sections that do roll and sections that don't? First, look up "gyroscopic precession" on Wikipedia. Second, wiring, plumbing etc. is a pain in the ass to handle via slip ring, let alone crew access. Third, that adds weight, which...I should probably stop saying that, rocket scientists aren't cheap to train and that's nine we've killed just in this list.

In conclusion, look what you made me do.

We haven't done anything worthy of the effort to build a ship that's capable yet, basically.

The ISS is primarily designed to research the effects of microgravity and other space environment issues. Hard to study zero g manufacturing when your station has artificial gravity.

Small ships would have to rotate really fast to make 1G, and it’s not worth the trouble if nobody lives there permanently.

It helps reduce the problems mentioned if you lessen the target goal. We don't need 1 G of force just like we don't need a full 1 atm or pressure or 80% of nitrogen mix in the air to breathe. Less gravity force, less RPMs for the same diameter.

But scale is still the better option, making something a few kilometers wide and with only 0.7 G means less stress, less effects from the rotation, etc. That's still in the category of megastructures though, so while not impossible to build, not going to happen at our current level.

Currently because math. The amount of mass and length required to simulate gravity is to expensive to get into space.

The answers here are very scientific, but I always wondered if having a magnetic shoe sole could fake gravity? Is there a ‘floor’ to stand on in these ships?

the one in space odyssey did.

You would need a pretty large radius to generate stable rotational gravity. If the radius is too small, the speed of rotation would make standing or walking nearly impossible. The larger the radius, the more imperceptible the rotational effects would be.

For clarity: I don't know for certain. I am not involved in the community, not an engineer.

Opinion: It's incredibly difficult to do. A spinning station needs to be designed to do such a thing. It needs to be balanced and have thrusters positioned in such a way to both spin up and maintain the rotation as it goes. The ISS has been built and expanded over decades by tons of new science modules over time as new breakthroughs happened.

Spinning objects can behave in strange ways and having a regularly shifting center of mass can be a challenge by itself, and that's before you start planning for yet uncertain experiments to bring aboard.

In addition to this, it would be an ENORMOUS challenge to dock with a station that is spinning, and the added danger to do this (or increased fuel consumption of spinning down and then spinning back up) just isn't worth it. The alternative of maintaining a central core that is static relative to the spin wastes power and creates a massive risk (more moving parts, especially those which might create friction against metal aren't easy to maintain in space).

Also, a small spinning station is much harder than a massive spinning station because it would have extremely noticeable differences from normal gravity to the people on board. Your head and feet would likely be moving at noticeably different speeds, which by itself is disorienting, but moving either towards or away from the direction of the spin would feel different (dropping an object would mean it falls away from the direction of spin).

Lastly, maintenance would mean that every single EVA either wastes a tremendous amount of fuel to spin down/up again, or risking flinging a person into space every time they exit.

Realistically, on a much larger station, artificial gravity via spinning might be a fantastic idea, especially for longer-term living aboard, but for the ISS, given its history, its goals, and especially where it's at, it's just not a great idea.