Can a spacecraft be gravity controlled someday?

[steveda19]

Right now. The technology on gravity control hasn't been invented yet. Astronauts are still floating in space. I hope one day they can invent gravity control inside a spacecraft.

 

[Trekker4747]

By "gravity controlled" do you mean having artificial gravity? Because otherwise a spacecraft is already "gravity controlled" by nature of how we move spacecraft.

As far as artificial gravity that's a tricky one since we still don't even know what gravity is or why it is. Sure, we can measure it, predict it, and we know how it behaves but we're still not sure what exactly or causes it, why it's caused or generated. Beyond "something to do with mass."

In most sci-fi depictions of artificial gravity it's implied there's something in the deck's structure generating gravity to provide a normal environment. But how is it being generated? Why does its influence only extend "up" from the deck and then no higher than the deck's ceiling? Shouldn't the person on the next deck up experience twice the gravity since he's got the gravity on his deck and the gravity from the deck below him?

Why doesn't the gravity generator extend "down" to the deck below? Gravity, as we know it, pulls things from all directions towards a center of mass.

So short of a "magical MacGuffin that we can influence to move only upwards and only by 10-12 feet or so (or a deck height)" it's not likely we'll have "gravity control" any time in the foreseeable future. It's more likely any gravity generated for long-term space missions will be artificially generated by rotating the ship, or some part or module of it, fast enough to simulate a 1G environment on the inside surface from the centrifugal force.

 

[MacLeod]

Well from a technical point of view we now how to simulate gravity on a spaceship, you'll have seen the method in films like 2010 and shows like B5, where part of the ship rotates.

http://en.wikipedia.org/wiki/Artificial_gravity

 

[Metryq]

Many years ago I visited a traveling "VR" (virtual reality) exhibit. One of the attractions was a game that used centrifugal force to simulate the transient accelerations in a fighter plane or race car. The rig was a carnival-style boom with a spherical passenger pod at either end. (One pod had the fighter plane game, the other the race car.)

The gamer sat normally. As the boom accelerated to top speed, the pod tilted forward so that the gamer was then facing the ground. The change in orientation was noticeable, despite the lack of windows in the pod. Whirling about "eyes down," as real fighter pilots call it (seat pressure against one's butt), the videogame began.

Transient accelerations (hard turns in the jet or race car) caused the pod to gimbal left or right, up or down, so that the line of centrifugal force pushed in the correct direction. For example, stomping the accelerator in the race car gimbaled the pod "eyes out" so that the gamer was pressed into the back of the seat.

Despite the heavier-than-normal feeling in the "eyes down" orientation, the simulation was very convincing.

 

[{ Emilia }]

Well from a technical point of view we now how to simulate gravity on a spaceship, you'll have seen the method in films like 2010 and shows like B5, where part of the ship rotates.

http://en.wikipedia.org/wiki/Artificial_gravity

I think we also need to stress that there's absolutely no reason for a potential spaceship to produce Earth-like gravity. Even just a little gravity generated through a rotating element would probably make things a lot easier.
It might help alleviate negative health effects and make work on the spaceship less messy.

 

[Lakenheath 72]

I think it will be a requirement if humans do travel past the Moon. Our bodies degenerate in zero-gravity. I have read about studies where it is discovered that the body ages in zero-gravity and that astronauts suffer from a wide range of maladies.

Astronauts in space for weeks to months can run into trouble. Calcium in bones secretes out through urine. As the bones weaken, astronauts are more susceptible to breaking them if they slip and fall, just like people with osteoporosis. Muscles also lose mass.

Astronauts typically exercise two hours a day in space to counteract these effects, but it still takes months of rehabilitation to adjust on Earth after a typical six-month space mission. More recently, doctors have discovered eye pressure changes in orbit. NASA has tracked vision changes in astronauts that were on the space station, but nothing so serious as to cause concern.

http://www.space.com/23017-weightlessness.html

If we aren't able to build a gravity controlled spacecraft, then the humans who go on expeditions into deep space will either be the descendants of people who adapted to life in space or will be breed for that purpose.

 

[MacLeod]

I suspect that these types of spacecraft would have to be assembled in space. But as with anything it might be done in stages, i.e. a new space station might have a section which rotates to stimulate gravity, before we try it on a spaceship.

 

[Asbo Zaprudder]

Other than using rotating sections, simply keeping the spacecraft under constant acceleration would suffice. Not that we can do that yet -- it would probably require a fusion or M/AM drive to sustain enough thrust for long periods of time -- but the technology required seems much more achievable from our current level of understanding than does generating artificial gravitational fields.

 

[YellowSubmarine]

I am a bigger fan of the building personal hover jets. Instead of accelerating the whole spacecraft to get some sense of gravity, accelerate all astronauts "upwards" as primary means of travel within the spacecraft. Accelerate, stop, accelerate, stop. Major downside would be that it would feel like standing on your head when you're stopping, but the fact that you'd probably go crazy would make up for it. You will feel weightful, it will keep your bone mass if you're constantly flying around, and it will cost less fuel. Also think of the possibilities – punching through the shell of your inflatable spacecraft when you forgot to decelerate – priceless.

The spacecraft can be spun as a circular tunnel and you could do constant acceleration races along the corridor. We can call the entire thing the Large Human Collider.

 

[Asbo Zaprudder]

Or just simply run round the inside like on Skylab (at 0:23):

[yt]https://www.youtube.com/watch?v=S_p7LiyOUx0[/yt]

or in this simulator (at 1:43):

[yt]https://www.youtube.com/watch?v=2EHwT33YCAw[/yt]

 

[Lakenheath 72]

Or like what was shown in 2001: A Space Odyssey, with the Discovery?

 

[MacLeod]

An advantage to rotating sections, is that you could rotate them at different speeds to siulate different levels of gravity.

 

[Metryq]

In the sci-fi novel ENDGAME ENIGMA James P. Hogan described a circular space station "faked" on Earth. The ring habitat was banked like a race track to balance out the vectors of centrifugal force and Earth normal gravity.

He later used the idea in two other novels where a ring habitat on a ship was segmented. The segments, connected by flexible tunnel joints, automatically tilted depending on whether or not the ship was under drive. The concept sounds plausible, but might produce some odd Coriolis-like effects.

MacLeod mentioned 2010 above. One of the technical gaffes in that movie is a scene where Dr. Floyd (Roy Scheider) and Dr. Curnow (John Lithgow) are slouched in poses suggesting they are under "gravity." Yet the rotating habitat had been halted since the Leonov was mounted to the back of Discovery.

And since we don't know how fictional artificial gravity systems work, it is difficult to nitpick them. However, numerous shows and movies have depicted power losses aboard ship that nevertheless maintain normal gravity (STAR TREK TOS "The Doomsday Machine" and FIREFLY "Out of Gas" to name just two). Perhaps these systems do not require power? (That is, unless you're aboard a Klingon ship in THE UNDISCOVERED COUNTRY.)

 

[YellowSubmarine]

An advantage to rotating sections, is that you could rotate them at different speeds to siulate different levels of gravity.

That gives you a lot of torque and friction. You'd need something excessive like fluid or magnetic bearings where the sections join, and those need to be pressurised connections. I don't know if isn't a better idea if you just climbed the ladders to the upper and lower levels when you needed different levels of gravity. That gives you the same effect.

Admittedly, it would also make your spacecraft more massive, which might be more expensive than the structural elements and energy supplies needed to maintain a limited number of sections rotating at specific speeds. And I always thought it would be kinda fun to step between these sections rotating in respect to one another. Way funnier than the supposed artificial gravity generator spot in Star Trek: Enterprise.

But then you can just tether four sections at different levels. Three of them might be your counter-weights of your 1G living quarters. An EVA will be necessary to visit your experiments, and you'd have weight during your EVA – which is a bit scary – but otherwise I think it is more practical.

 

[steveda19]

Like Star Trek & in Star Wars you don't see any floating around.

 

[Asbo Zaprudder]

Or like what was shown in 2001: A Space Odyssey, with the Discovery?

Yes, a rotating section is also seen in the space station that rotated as a whole. Other examples are Mission to Mars, B5, etc. The videos show how simply running around a curve in free fall can generate centripetal force (as I believe A C Clarke suggested to the Skylab astronauts). The problem with rotating sections is that the rest of the spacecraft tends to rotate the opposite way, unless thrust is provided to counteract the torque (eg, by using a tail rotor or tip jet in the case of a helicopter). Babylon 4 had counter-rotating sections, which made it seem more a more plausible design to me than B5.

ETA: Of course, running around your spacecraft is going to make it rotate in the opposite direction (albeit, probably minutely) so attitude correction using flywheels or thrusters might be required.

 

[publiusr]

I'm not a big fan of cables, but I am told that spinning a spacecraft can confuse one if you don't stay still.

Also, you need the craft to be as large as possible
http://www.popularmechanics.com/science/space/rockets/why-dont-we-have-artificial-gravity-15425569

Now I'm all for that.

If Musk's new rocket pans out--that might be do-able
http://nextbigfuture.com/2014/10/fifteen-spacex-raptor-engines-five.html
http://nextbigfuture.com/2014/10/near-future-for-vastly-increasing-space.html

As large as this structure would be, I would like to have even more up there in terms of fuel to push a ring station to become a cyler--so all you need is a Dragon atop a Falcon Heavy to use as a fast taxi to catch up with it--to keep a constant flow of astronauts.

SLS may play a role as well--what with an ATLAS SCORE type launch
http://www.astronautix.com/craft/stsation.htm
http://www.astronautix.com/craft/selation.htm

http://www.astronautix.com/craft/neptune.htm

 

[Into Darkness]

All you need to do is create a material that interacts with a higgs boson field a lot. Pretty easy really.

 

[Metryq]

Sorry, magical or imaginary solutions are not allowed in the science forum.

 

[YellowSubmarine]

It's true. Actual physics don't belong in the science forum – they are all lies. As a matter of fact, it's all gnomes.