eli5: why can’t we create artificial gravity on space crafts by accelerating at 9.8 m/s
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You can’t accelerate forever. The energy required to maintain a constant acceleration is exponential. Even if you could accelerate constantly there is a speed limit in the universe. There would be a point when you would have to just stop accelerating (or rather you would reach relativistic speeds and I don’t know how that works). Besides, having to be constantly accelerating is not very practical for a spacecraft that presumably needs to move from place to place or just stop for a while
Edit: I am assuming you meant accelerating on a straight line at 9,8m/s*s. Constant centripetal acceleration on a circular motion is very much feasible in theory
Technically, while your accelerating, your temporarily artificial increasing the gravity of your feet on the ship. Once you stop accelerating, your left with the gravity of whatever the nearest celestial object is. At that point to create gravity you would have to spin the spacecraft around one the of axis to create gravity.
There are several theories that say we could emulate the effects of gravity by using rotation in such a fashion. Right now we don’t have the technology to do so effectively. We can’t make spaceships large enough with enough power to make that happen. But it is something that might happen in the future.
We can,
The issue is fuel requirements. Given our current tech, it’s not practical or cost effective to carry enough fuel to fuel an engine to sustain 9.8m/s.
We can and we should, but not with acceleration. Constant acceleration would take lots of fuel. Instead we could use centripetal force in a large space station, such as the one used in the movie 2001: A Space Odyssey (note: many other movies use this too). The only energy required is to keep the station in a spin.
Accelerating is expensive and requires a constant supply of fuel. A constant supply of fuel is currently impossible in space crafts.
I can’t think of a good analogy, but that’s the simplest answer at least.
we can, and in fact we sometimes do. When spacecraft rotate around a centerline or are designed with a spinning section it’s because they’re using the rotational acceleration acceleration around a given axis.
Think about the “gravitron” ride at amusement parks, fairs, and carnivals. If the rotational speed is correct you can stand up against the walls right? It’s the same principle.
The fuel required to sustain 9.8 m/s^2 of acceleration for any practical amount of time would make the rocket way too heavy to lift off. It may be more reasonable to rotate a structure at a constant angular velocity to create artificial gravity via centripetal acceleration.
There isn’t enough fuel to sustain that level of acceleration.
We currently have two kinds of engines.
The kind that burn hard but not for long.
And the kind that can burn for weeks, but not hard at all.
To get the change in velocity to go to the moon, the Apollo 17 mission only burned for 346 seconds using it’s liquid oxygen and liquid hydrogen engines.
Meanwhile the Dawn Probe’s ion engines would take 4 days to go from zero to 60 mph, but was burning for weeks.
That being said, if we somehow made an engine that could accelerate for 1 g for days on end, we could do it.
But for now it’s science fiction.
Read/watch “The Expanse” for an excellent example of this.
That series acknowledges that the engine that does it simply shouldn’t have worked.
The key is on the “accelerating” part. We would need infinite amounts of fuel to keep accelerating indefinitely, plus eventually the spaceship would eventually reach escape velocity so it would stop orbiting the earth or whatever it is that it was supposed to be orbiting and we’d lose it
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