Because they are feeling, continuously, what we feel for all of (an incredibly long) two or three seconds while undergoing freefall on an amusement park ride, right? That visceral sensation of anxiety-provoking, butt-clenching weightlessness, that is. I’ve never been able to get through a serious rollercoaster, freefall ride, or even the easily underestimated “swinging ship” ride without screaming my fool head off. I don’t think I could ever come to embrace the feeling of freefall, regardless of context, purpose, rewards, or training available.
NASA astronaut-selection and -training procedures aside, how do the astronauts manage to function at all, maintain a normal-enough blood pressure, or fall asleep? Is the first step in astronaut selection to take the candidates to a theme park and weed out all of the screamers? :dubious:
The butt-clenching feeling in the pit of your stomach is from the acceleration of the free-fall. Once you reach terminal velocity, that sensation goes away. Of course, you may still be freaking the hell out because you’re hurtling towards your doom.
Astronauts in orbit are “falling” around the earth at a mostly constant velocity, so it’s as if they’re not moving at all. The sensation is basically that they’re floating, like floating in water, except in air.
What friedo said. The Earth is rotating very quickly and hurtling through space at speed, but you’re not screaming your head off right now, are you? That’s because the Earth has a (well, an almost) constant velocity. So do the astronauts.
I bet taking off on the space shuttle feels a little bit like a really horrible theme park ride, though.
Well, that explains a lot – but what caused the nausea experienced by many astronauts, such as Frank Borman? Was that just regular motion sickness, unrelated to the brief-duration “pit of the stomach” feeling?
Yeah, that’s “space sickness.” Getting used to the weightlessness and completely different ways of moving is very disorienting for some astronauts and they end up blowing chunks. They get used to it after a while though.
Same thing that causes motion sickness on the ocean when it’s cloudy. You’re receiving mixed messages from the various motions you’re feeling, and the lack of horizon your brain expects to dovetail all those sensations.
Astronaut motion sickness is much worse during acceleration - like in the vomit comet when the airplane is actually diving for a minute or so - but not so perfectly that you have truly zero acceleration.
Of course, not everybody “gets used to it”. Some people are sick the whole time they’re in zero-gravity. All the original astronauts were pilots who were preselected for their immunity to nausea and disorientation during violent manuevers. Today’s shuttle astronauts aren’t screened so tightly, but you do have to have a certain amount of physical and mental toughness before they allow you to go up. And everyone has some time in the “vomet comet”, a special airplane used for zero-g training. So you might get sick, but you go about your work anyway.
I’m sorry, but this sounds entirely wrong. The sensation of floating in water is absolutely no different from the sensation of standing on the ground or falling at terminal velocity – all involve “having weight,” the equal and opposite forces of gravity driving you down and pressure forcing you up. Your middle-ear fluids are supported by your skull tissues, your internal organs are supported by muscle and bone; the mechanical consequences of being held stationary or at a constant velocity in a gravitational field are familiar and necessary for comfort, and both orbit and free-fall are terrifying (or exhilarating) because those consequences are missing. Asronauts are NOT falling at constant velocity – they are accelerating freely, and with sufficient “sideways velocity” to avoid getting any closer to the center of gravity.
I think the big distinction between the free fall ride at Six Flags and being in weightlessness is the frame of reference. At the amusement park you can see the ground rushing towards you. Very anxiety provoking. In the Shuttle everything around you is relatively stationary so you might have unusual perceptions of up and down, etc and space sickness, but you don’t necessarily have the anxiety associated with the amusement park ride.
This is almost entirely wrong. The butt-clenching feeling is due to the lack of acceleration of free-fall, and is exactly what astronauts experience. When you reach terminal velocity, you start accelerating again, just like normal, but that’s completely irrelevant for astronauts, who don’t reach terminal velocity.
The answer to the OP is just that they get used to it. If there truly exist individuals who can’t get used to it (I don’t know whether this occurs or not; have you ever been in freefall for hours or days straight?), I would presume that they’re screened out at some point in the extensive astronaut training process.
Huh? This flies in the face of virtually everything I’ve ever heard in the subject. Could you elaborate?
Let’s say I’m in a really powerful car that blasts off. As long as it is accelerating, I feel pretty much like I’m in a rollercoaster. Once it reaches maximum speed, I might as well be sitting still.
Doesn’t “terminal velocity” mean something like “the maximum velocity that a falling body reaches”? If not, what does it mean, and if so, what do you mean when you say that acceleration starts at terminal velocity? How can you say that a free-fall theme park ride doesn’t accelerate?
I mean, I’m sure you’re right, but I definitely don’t understand it.
No, that’s completely wrong. The astronauts are in a constant state of falling - they just miss the earth. What happens is they (and their bodies) just get used to it, but some people get very sick indeed. (Appeal to authority, my dad used to be a NASA physician and did his PhD on zero-G medicine.)
When a car is accelerating, you don’t feel the same way that you do on the long drop in a roller coaster. Or at least, it’s not the same beyond the level of “my insides feel funny”. Usually, you’re accelerating at 9.8 m/s[sup]2[/sup] (don’t believe me? Check an accelerometer). When you’re in a car that’s getting up to speed (or one that’s braking, for that matter), you’re accelerating at more than 9.8 m/s[sup]2[/sup]. When you’re dropping, you’re accelerating at less than 9.8 m/s[sup]2[/sup]. Accelerating at any value other than normal feels funny, but it feels funny in different ways.
This part, at least, is correct (mostly, at least). If you’re moving in a straight line at constant speed, you might as well be standing still. This could be a car on the highway, or it could be a skydiver at terminal velocity. But the straight line part is important, too: If the car goes around a turn, you get exactly the same feeling as when it speeds up or slows down (just in a different direction).
Because something is pushing you. When you’re in freefall, nothing is pushing you: space is warping around you and drawing you in without any “acceleration” you can feel.
When you reach terminal velocity, you are being “pushed” by the air below you to the same extent, more or less, you would be if you were laying on the ground.
And a third of them still got sick and puked during the trip.
Although there is a relationship between motion sickness, sea sickness, and space sickness, it is possible to suffer from just one and not the other two.
WAG: the first two involve not only conflicting information, but changes in acceleration in various directions. In space, you get conflicting information but with fewer inputs of changing acceleration.
About the only advantage pilots would have, and this would only apply to pilots who have been trained to fly on instruments alone, is that they’ve had some training and practice in ignoring what their body is saying in such situations and trusting what their eyes or various instruments are saying in regards to their orientation and so forth. It’s that conflicting information thing again. Most people don’t vomit while learning to fly on instruments, but a certain percentage do, and some dizziness and disorientation is common during the process of learning how to do the task.
As several “right stuff” astronauts have demonstrated, however, that does not guarantee immunity to barfing in space.
Or the way that I have always understood it - orbital free fall involves falling down towards the earth at an acceleration of approx 9.8m/sec2 bt with just the right forward speed to prevent you actually hitting it. Too fast, you fly off into space, too slow and you eventually become a meteor. Just right, you go round and round and round, falling all the time.
Or at least, that’s what I gathered from reading Asimov books…