Gravity in science fiction movies

[wrobel]

In science fiction movies (Interstellar for example) people organize a rotation of a spacecraft to provide an artificial gravity by means of a centrifugal force. Besides the centrifugal force there is a Coriolis force as well. This force influences the blood flow in vessels for example. Can it make an astronaut feel bad? What do you think? :)

 

[Filip Larsen]

Can it make an astronaut feel bad?

Short answer: yes.
You can perhaps take a peek at a recent study to get a feeling for the numbers involved: https://www.nature.com/articles/s41526-020-00112-w

Edit: for overview of many issues you may also want to peek at NASA STD-3001, where section 6.5.2 of volume 2 shows the "current" limits as

 

[Baluncore]

Can it make an astronaut feel bad? What do you think? :)

If you are standing on the inside of the outer wall of a centrifugal spacecraft, facing the direction of travel, head towards the centre, then the fluid in your ears will be rotating as you are constantly falling backwards, but you will feel stable after a while. If you then turn to face backwards, you will almost certainly fall over, and will feel very bad.

 

[sbrothy]

In science fiction movies (Interstellar for example) people organize a rotation of a spacecraft to provide an artificial gravity by means of a centrifugal force. Besides the centrifugal force there is a Coriolis force as well. This force influences the blood flow in vessels for example. Can it make an astronaut feel bad? What do you think? :)

Microgravity may also cause problems. Also, in many movies spaceships tend to bank even though there’s no atmosphere.

If you are standing on the inside of the outer wall of a centrifugal spacecraft, facing the direction of travel, head towards the centre, then the fluid in your ears will be rotating as you are constantly falling backwards, but you will feel stable after a while. If you then turn to face backwards, you will almost certainly fall over, and will feel very bad.

It’s the Coriolis effect in centrifugal gravity, right?

 

[Filip Larsen]

Microgravity may also cause problems.

What kind of problems?

Microgravity is in large part due to the tiny accelerations that occur in a rigid structure in (low) planetary orbits for local positions away from the orbit path through center of mass. On a large space station microgravity will result in free-floating objects drifting around or away, but I as far as I know microgravity as such, i.e. compared to local total weighlessness, has no effect on astronauts.

 

[Borek]

Microgravity is in large part due to the tiny accelerations that occur in a rigid structure in (low) planetary orbits for local positions away from the orbit path through center of mass.

There was an article (in Scientific American perhaps?) about how to create artificial microgravity in satellites by using a long, stiff beam to move the center of gravity away from the main part of the satellite. Could help settle any dust particles inside (if needed for any reason).

 

[Rive]

Coriolis force ... Can it make an astronaut feel bad? What do you think? :)

As I recall, there was several studies about the expected effects (not just coriolis, but many other) at different ring diameters and the minimal recommended diameter (since many effects depends on the ratio of radius difference between feet and head).

 

[sbrothy]

I remember reading (Atomic Rockets?) it was akin to seasickness. Most people got used to it, a few never. Let me see if I can find the ref...

EDIT: I remember reading that study also. Or a study at any rate.

EDIT2: Tough luck finding out too late that you're one of the unlucky few! Have a nice trip!

 

[sbrothy]

Crazy title and a little over the top:

EXCRETION OF 17-HYDROXYCORTICOSTEROIDS, CATECHOL AMINES, AND UROPEPSIN IN THE URINE OF NORMAL PERSONS AND DEAF SUBJECTS WITH BILATERAL VESTIBULAR DEFECTS FOLLOWING ACROBATIC FLIGHT STRESS JOINT RESEARCH

How 11 Deaf Men Helped Shape NASA’s Human Spaceflight Program

While the test subjects played cards and enjoyed one another’s company, the researchers themselves were so overcome with sea sickness that the experiment had to be canceled.

...more to come...

EDIT: Interesting argument here: The Case for Disabled Astronauts

 

[BWV]

, but I as far as I know microgravity as such, i.e. compared to local total weighlessness, has no effect on astronauts.

There is a large body of research on the negative health impact of prolonged exposure to microgravity - including bone loss, muscle loss, vision problems, inability to heal wounds - the list is large enough to put doubt on the viability of long-term human settlement on Mars or the Moon

https://pmc.ncbi.nlm.nih.gov/articles/PMC9818606/

 

[Filip Larsen]

There is a large body of research on the negative health impact of prolonged exposure to microgravity

Indeed, that is why I specifically said effects of microgravity relative to the effects when in total weighlessness, that is, the known and suspected effects of being in a microgravity enviroment are due to lack of large acceleration. When talking astronauts health, the term microgravity is generally thought to include effect of zero weight (that is astronauts will suffer the consquences no matter if they are in a zero-g or micro-g environment), whereas microgravity in experiments and similar contexts often is meant to exclude zero weight. For instance in crystal growth experiments and similar where as-close-to-zero acceleration is desired, microgravity is usually taken to mean the presence of gravity gradients and vibration modes occuring from the experiment being attached to a large (station) structure instead of being free floating.

 

[Filip Larsen]

Crazy title and a little over the top

Briefly scanning that 1963 report seems to indicate they were investigating "heavy" vestibular (inner ear) effects. It is fairly well-known that the human vestibular system is rather sensitive to cross-axis couplings in a rotating system (cf. with coriolis forces) and may even adapt fairly quickly to certain rotational motion "in the wrong way", i.e. leaving pilot with the wrong sense of rotation afterwards (e.g. enabling graveyard spirals).

By the way, those wikipedia topic pages also has a nice one on the coriolis effects that the OP asked for.

 

[Ken Fabian]

If you are standing on the inside of the outer wall of a centrifugal spacecraft, facing the direction of travel, head towards the centre, then the fluid in your ears will be rotating as you are constantly falling backwards, but you will feel stable after a while. If you then turn to face backwards, you will almost certainly fall over, and will feel very bad.

The vestibular effects look quite serious and a persistent mismatch between what eyes see and what the inner ears sense can be nauseating and disorienting. (I recall [don't have a link offhand] a study using a room rotating around a vertical axis - the inner ear senses rotation in that direction the same as it senses head over feet tumbling - and even experienced pilots suffered. If I recall correctly people didn't acclimatize, the effects got harder to put up with over time).

It sounds a lot like the too much alcohol effect, only it won't go away. That seems more problematic than bodily sensations and changing forces from coriolis and compensating for them.

I would expect acclimatizing isn't going to work when simply turning your head changes what the inner ears sense; the sensations don't stay constant enough to get used to unless you stay still.

Large diameters and rotation rates below the threshold for vestibular sensations seem advisable.

 

[Filip Larsen]

Large diameters and rotation rates below the threshold for vestibular sensations seem advisable.

Indeed.

Earlier in this thread I couldn't find the old (1999) overview paper [1] I usually refer to on this, but finally managed to dig it out. It has this nice diagram based on various limits:

[1] https://www.artificial-gravity.com/JBIS-52-7-Hall.pdf

 

[256bits]

viability of long-term human settlement on Mars or the Moon

We have ample evidence of human effects at prolonged 1g and 0 g.
For a short term, astronauts experienced gravity of the moon - Apollo mission - which as far as I know did not seem to be a problem. Extrapolation to the long term would not be good science.

 

[BWV]

We have ample evidence of human effects at prolonged 1g and 0 g.
For a short term, astronauts experienced gravity of the moon - Apollo mission - which as far as I know did not seem to be a problem. Extrapolation to the long term would not be good science.

pregnancy is the real quandary - we don’t know the impact of microgravity on a developing fetus and it’s unethical to attempt

 

[Ken Fabian]

We have ample evidence of human effects at prolonged 1g and 0 g.
For a short term, astronauts experienced gravity of the moon - Apollo mission - which as far as I know did not seem to be a problem. Extrapolation to the long term would not be good science.

Not sure that subjecting impregnated chimps or other primates to it as a proxy and is good and ethical science either, but I have a deep distaste for cruelty, to animals as well as humans, that is not universally shared.

But I also don't see 'colonising' moon or Mars for the usually cited reasons as a worthwhile goal - I don't think the term itself properly describes what is proposed; it sounds more like large scale experiment in long term human survival and planned economy creation in extreme and remote environments using live human subjects. And not much like 'era of colonisation' examples at all - which relied on abundance of readily exploitable resources (including prior inhabitants) and viable, profitable cross-oceans trading using ordinary, cost effective technologies already in widespread use. I think if humans ever establish settlements in space they are more likely to be exploiting asteroid resources, with rotating habitats than attempting to live on Mars.

The cylinder or wheel station - or 'dumbbell' or 'bola' (which I think would be better styles to attempt first) - is fundamentally different to actual low gravity.

It is fairly well-known that the human vestibular system is rather sensitive to cross-axis couplings in a rotating system (cf. with coriolis forces) and may even adapt fairly quickly to certain rotational motion "in the wrong way", i.e. leaving pilot with the wrong sense of rotation afterwards (e.g. enabling graveyard spirals).

Seems like the acclimatizing itself is a serious problem - the way doing twirls awhile makes it feel like you are twirling when you stop. For the (too fast rotating) wheel station dweller it should be a milder version but it will happen every time you turn your head after keeping it still awhile.

Can people acclimatize to the disorientation from repeated transitory acclimatizing that breaks down over and over? Being aboard boats has constantly shifting motions and people do acclimatize... yet can barely walk when first returning to land. If it makes you sick will you eventually get over it if you have to endure it for months or years?