# What method would an average human use to move in one-tenth of earth's gravity with no prior training?

You are standing near a wall in an enclosed space of 50m(L) x 50m(W) x 3m(H) at floor level with 0.1G gravity and earth normal atmoshere. You are of average height and mass. You are suffering from mild space sickness. You are wearing a cloth one piece outfit and soft-soled shoes. You have only minutes of prior microgravity experience in a much smaller space. There a few largish obstacles scattered about at 10m intervals and no convenient handholds.

How would you navigate to a human sized doorway in the center of an adjacent wall.

• If I smash some obstacles and make a pair of shivs, can I stab the walls to create temporary handholds? After all the cursing and vomiting and missed attempts, I'm gonna wind up stabbing something (or someone) anyway. Honestly, this seems like either a puzzle or a plot point more than world-building. – user535733 Jun 6 '20 at 2:57
• No, you are NOT of 'average size and weight'. You MIGHT be 'of average size and MASS.' In 0.1 G, you would hardly 'weigh' anything, but you would still have 'average' inertia. It still takes the same force to stop forward momentum as it would in normal gravity, and would still hurt just as badly. – Justin Thyme the Second Jun 6 '20 at 3:14
• A jet gun or an air thruster that you can aim in any direction. – LazyReader Jun 6 '20 at 3:47
• Time to splat: sqrt(2*3)=close to 3s... Gamer: "framerate drops like hell! not cool" – user6760 Jun 6 '20 at 9:52
• Have a brief look at the human lunar gravity experiments done before the apollo missions. For example: youtube.com/watch?v=U1CUhz0U-Gc This was 1963 so is probably "the most untrained you can get" – sdfgeoff Jun 6 '20 at 11:14

We have already seen what happens in a similar situation--in lunar gravity we find it very natural to do a hopping motion like we saw the astronauts do--that wasn't trained, that's just what they did. The Mythbusters reproduced this--in a lunar-simulating airplane they found the astronaut's hopping felt natural and was easier than walking.

I do not think that going from .16g to .1g would change this, thus I would expect the hopping, then jump to the exit on the other side.

Now, if you truly mean microgravity (say, on board the ISS), someone who was told what to do would push off gently. Completely untrained they would likely jump and get hurt.

• The confusion between 0.1G and 01.% of G – Justin Thyme the Second Jun 9 '20 at 23:47

You can gently propel yourself forward using small foot movements and hand movements. You will bounce from floor to ceiling - hence the need for hand movements.

Your movements will need to be reasonably gentle or you could easily build up too much momentum to stop without hurting yourself.

Controlling your direction of motion would be a little awkward for someone with no experience, but you would do it well enough to get close to the door. Once close you again use gentle movements to get you to the door.

As pointed out by another answer you can also swim slowly in air, so if you find yourself drifting in mid air you can use that technique to get close to walls, floor, ceilings or obstacle again and use the hand-foot method after that.

A more experienced (or over confident) person could use a more aggressive application of speed and momentum to essentially push themselves rapidly at obstacles and make faster progress. This risks potential harm if they misjudge, but would be faster in an urgent emergency. However once at the door you again have to slow down which is non-trivial.

If you have earth normal atmosphere, pressure, and density, it would not take long to realize that you can swim through the air bu pushing air with your hands. It would be slow, bot steady. And using outstretched arms to start a spin, then pulling them into the body, would allow some maneuverability using conservation of momentum, again by pushing against the air density.

If there were air ducts, causing an air flow, you could also sail this air flow.

• Good idea for true microgravity (i.e: LEO), but I'm not certain that this work well enough in 0.1G to be immediately noticeable. – Greg Jun 8 '20 at 1:32
• @ Greg Then just very slow walking would work. – Justin Thyme the Second Jun 8 '20 at 1:47
• That was my initial thought, but given the evidence of the Apollo video's (0.16G) I had my doubts. – Greg Jun 9 '20 at 16:09
• @Greg So the answer hinges, in effect, on how much 'up' and 'down' is effectively produced by one-tenth gravity, and if the OP's 0.1 g actually means one-tenth gravity or one-thousandths gravity. That is, 0.1% of 1% g. – Justin Thyme the Second Jun 9 '20 at 16:48

One particular tool, albeit no longer in use. A hand held maneuver unit or air gun. This device fired jets of compressed air, in microgravity conditions, early Gemini astronauts for maneuvering at various angles.

• Hmmm. If there were a compressed nitrous oxide whipped cream dispenser handy... or even a compressed butane cartridge. Container of shaving cream? Messy, but a can of spray paint, or WD40? Given the paucity of reaction mass in the can vs a human mass, it would be slow going, slow acceleration ...but still...maybe... the velocity of the expelled mass would make up for it...against the air pressure and density...better chance in a vacuum... – Justin Thyme the Second Jun 10 '20 at 0:02

Push off with legs from the wall.

Then a long straight glide to next vertical wall, reorientation, and another push.

As though I were in a swimming pool, in the depicted scenario I push off with my legs against the wall and drift through the air. But my aim was off and I wind up to the left of the exit. I reorient myself in the air so as to land legs first. My reorienting does not go so well either and I turn more than planned. When I push off I wind up hitting the cylinder so far to the side I do not have a good angle to get the exit.

I push off again hoping for the cube which has a good flat side. I miss by a mile, but the cylinder is good enough. I push off again aiming for the cube and this time I get it.

My push from the cube is on target and I get to the exit.

Probably I would bounce off stuff in the room many more times than that. But each time, the energy I impart is only what my spindly legs are capable of delivering, and it is no great thing to stop myself with arms or legs when there is something solid in the way. I reorient and push off again.

I might take off my shoes and do this barefoot - I think my sticky bare feet might have better purchase than the shoes. When I hit a vertical surface I have some fake weight for a second or two by virtue of my momentum and I can use this time to reorient with feet on the wall.

I put the shoes in my shirt and tuck it in; don't want to drop them!

• You still have the same MASS, which means you still have the same inertia. Pushing off too hard will give you so much momentum that you will probably break bones, or at least get badly bruised, when you hit the immovable wall. When we run fast, we depend on the friction with the ground, from gravity, to slow us down when we get close to the other wall. This situation would be like the puck in air hockey, slamming full force into every wall, bouncing off still going full tilt, full conservation of momentum. It would be the best banking pool shot ever. – Justin Thyme the Second Jun 9 '20 at 23:53
• @JustinThymetheSecond - when you push off as hard as you can from the ground with your (awesome) vertical leap, after you dunk the ball how much momentum do you land with. Exactly what your (awesome) legs gave you, minus a tiny tithe to Entropy. If your legs can give it, they can receive it back when you hit. But I do like the puck image. – Willk Jun 10 '20 at 3:07
• Here's the thing. When you make that awesome leap, you land back on your LEGS. What happens if you land on your ARMS? And when you kick off, the acceleration is applied over time. When you hit something, the deceleration is much shorter. Also if you made the same leap from a cliff, and landed in the valley below, you have gained momentum from gravity. That would be like glancing off a wall by kicking, and each kick adding to your momentum. However, my point was that generally people think incorrectly that their momentum would be related to their WEIGHT, not their MASS. – Justin Thyme the Second Jun 10 '20 at 13:30