Pressurized Rover + Crater = 1 Earth gravity

Tom Kalbfus · 2017-01-19 23:18:55

We first need a fast rover.

This rover looks big enough, we need to soup up the engine so it can go 70 miles per hour however. this rover looks big enough to live in. and now we need a crater.

A crater shaped like this would do nicely, the third requirement is that this crater be 200 meters in diameter. Now we pave the walls of this crater to make it nice and smooth. We drive the rover into the crater, line it up along the wall inside the crater, and then we step on the gas pedal, accelerating to 70 miles per hour and driving on the wall of the crater at a slope. Once the rover reaches 70 miles per hour and is driving along the lip of the crater, it will circle the crater 3 times per minute and generate a g-force equal to 1 Earth gravity. Now we employ self-driving car technology, the driver puts the rover on automatic and it continues to circle along the inside of the crater. The driver walks towards the back of the rover to join his family at the dinner table, or maybe he'll jog on the treadmill, do some push ups on the floor, or just sit on the couch and watch some movies on the video screen. This is his time off, the Sun has already set on Mars, there is work to do tomorrow on he surface, but for now, he can relax in the comfort of his own mobile home under a full Earth gravity.

GW Johnson · 2017-01-20 14:06:50

Why propose an energy-intensive solution for a situation where energy will be at a premium? Drag times speed is power required, even at 100% propulsive efficiency (so it's a lower bound). Air drag is not significant, but tire drag is, at something like 1-2% of the vehicle weight on hard pavement, 10 times that on soft ground.

2% of say 10 tons x 38% is about 170 lb on hard pavement, 1700 lb if soft dirt. 170 lb x 70 mph / 375 = 32 HP on hard pavement, 320 HP if soft dirt. Where will those KWe come from? How will you create the hard pavement, if you do? Your vehicle has to double as a road grader, whether you choose hard pavement or soft dirt.

And what happens if you're asleep when a tire blows out, and the vehicle rolls over in a crash? Are you gonna build it heavy enough to survive that? And thereby drive the power requirement up even more?

There's a lot of real practical things to worry about, when you propose things like this. Not paying attention to them kills crews, not just credibility.

GW

Last edited by GW Johnson (2017-01-20 14:08:36)

Tom Kalbfus · 2017-01-21 01:02:10

Don't tell me you've never been in a truck doing 70 miles per hour! As for power, how about a nice electrical motor, and a power cord on a spindle? The truck in question is moving around in a circle a fixed distance from the center of the crater. That kind of makes it easy to locate the power source in the center of the crater, you could have banks of solar cells or a nuclear reactor generating electricity, have a cable delivering the electricity to the truck, and have no need for batteries!

Last edited by Tom Kalbfus (2017-01-21 01:07:14)

SpaceNut · 2017-01-21 12:41:01

Put it on a rail track system and there are no tire blowouts, use rails to provide power and keep on looping.....

RobertDyck · 2017-01-21 14:20:27

If you want to live on Mars, get used to Mars gravity. If you want to live on the Moon, get used to lunar gravity. If you can't live without Earth gravity, then stay on Earth.

GW Johnson · 2017-01-21 15:15:55

I never said it wouldn't work, Tom, I said it was an energy cost to a mission that will be strapped for energy, and it also presents some crash risks. Plus it ties up a rover better used for other things. The effect is called a "banked curve". I've designed them, and I've taught high school and college kids how to design them. I've seen some highways mis-designed by idiots that evidently still don't understand them, though. Silly bastards should've taken my courses.

We won't actually know until we actually start staying for extended periods in these places, because the partial gee experiments were never done with the spinning space stations we never built. But I suspect that people exposed to even partial gee will stay healthier for longer periods than people exposed to zero gee. It's only a theory, but that theory says that even a little bit helps.

You don't need to stay full-gee fit while on Mars or the moon, as long as you do not see the problems seen at 6 months to year at zero gee. You don't even need to prepare for the trip home, if 1 gee of artificial gravity is provided in the space vehicle that takes you home. A 6 to 9 month ride at one gee will restore all the fitness you need, even up to and including a 15 gee emergency-bailout direct entry at Earth.

Fail to build your space vehicles to provide artificial gravity, and now you incur all sorts of needs to compensate and restore fitness. All of which are heavy, expensive, and usually power hungry.

Why not avoid it all, and just spin the damned space vehicles? If you're one-gee fit during the months of the ride, there's no gee challenge you cannot meet, at either end of the ride. Simple as that.

Musk doesn't seem to be planning on doing that, but I personally think that's a mistake.

GW

Last edited by GW Johnson (2017-01-21 15:18:31)

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#1 2017-01-19 23:18:55

Pressurized Rover + Crater = 1 Earth gravity

#2 2017-01-20 14:06:50

Re: Pressurized Rover + Crater = 1 Earth gravity

#3 2017-01-21 01:02:10

Re: Pressurized Rover + Crater = 1 Earth gravity

#4 2017-01-21 12:41:01

Re: Pressurized Rover + Crater = 1 Earth gravity

#5 2017-01-21 14:20:27

Re: Pressurized Rover + Crater = 1 Earth gravity

#6 2017-01-21 15:15:55

Re: Pressurized Rover + Crater = 1 Earth gravity

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