We all know the pictures of the astronauts on the ISS floating around. We also suspect that a lack of gravity is bad for the body as the muscles go weak and such.
Why don’t spaceships just rotate to cause the effect of artificial gravity through centrifugal forces?
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…
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.
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.
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.
on point 3, long distance communication invariably uses highly directional antennas, which means these need to be aimed precisely, which means special automated gimballed antenna set that would drop signal anyway probably
also you definitely don’t want to deal with rotating gas seal that is also under pressure and fail-deadly, these already wear out quickly with sporadic use on earth. if there are two sections, one spinning and one not, both would have to be sealed
That was worth every second it took to read.
For number 3 and the slip ring. I have always thought, just make the stuff on the end self sufficient. Essentially make two spacecraft. One to run all the experiments in zero ish g. And the other to be like living quarters. You can even make them suit up to commute. But you would need one heck of a long arm to make the 2 palatable. Maybe 3 craft, two way the hell out there attached to some crazy long tethers. One in the middle. Then some kind of speed sled thing to get a person from the outside in or something. Probably need to worry about balancing out the change of weight due to the sled (and person) moving from outside in and such.
according to the hohmann transfer orbit
you only do one burst at the beginning of the journey, then drift for 6 months before entering the atmosphere of the target planet to slow down.
So there’s 6 months where you don’t need to fire any engine. My plan is to first do the acceleration burn, then install solar panels on the outside of the ship (attach them via some kind of cord and cable) they fly outward due to centrifugal force so they get constant sun exposure, and then put the ship into rotation. So you don’t need to do any work on the outside anymore, until you’re shortly before landing, then you stop rotation, get in the solar panels, enter the atmosphere, do landing burn, and land.
Humans have flown a total of ten manned missions that involved a Hohmann transfer: Apollo 8, Apollo 10-17, and Artemis 2. All ten flew to the Moon. On a typical Apollo mission, the outward bound coast leg is about 72 hours, between TLI and LOI, during which time they had to do the release-turn around-dock-extract maneuver with the lunar module and do at least one course correction.
We’ve been wasting tax payer dollars for more than half a century now designing and redesigning manned Mars missions that aren’t ever going to fly. Some of the various “artist’s conceptions” over the decades have included various centrifugal gravity solutions, be it the wagon wheel type or the bolas type or whatever. I don’t believe any actual hardware has even begun construction. Before you start worrying about that, you’ve got to 1. have a society healthy enough to fly manned deep space missions, and 2. figure out how to shield the crew from radiation first. Neither of which we have figured out at the moment.