1. Alex A.
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    Alex A. Member

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    More gravity on Mars

    Discussion in 'Research' started by Alex A., Aug 11, 2011.

    I've been researching logical ways to explain an earth-like amount of gravity on mars for my sci-fi book idea and I can't seem to find a good explanation to back up gravity other than "gravity was magically restored by gravity machines." Which is ridiculous. I want to put some logic behind my writing. So if anyone can help me with a way to restore gravity on mars, that would be great!

    So far I've seen: the use of magnetism for gravity, centrifugal force(would only work on huge space stations) and things of that nature.

    Magnetism seems the way to go but i need to know how to explain it a tad so the reader doesn't question it.
     
  2. PeterC
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    PeterC Active Member

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    Magnetism wouldn't mimic the gravitational force exactly. That might or might not be a problem for you. In particular, a person wearing magnetic boots might have to work harder to lift his or her feet from the ground but the magnetic field wouldn't change the forces on a person's body parts (for example).

    Are you sure centrifugal force wouldn't work? I could imagine a rotating building like a large merry-go-round. There would be some engineering challenges to build such a thing on a large scale but it probably wouldn't be crazy.
     
  3. Quezacotl
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    Quezacotl Contributing Member

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    Increase the mass of mars or triple the mass of the suits the people wear.
    Gravity on mars is about a third of earth's. Triple the mass of the person on mars.

    Assume the force of gravity is the same on mars and on earth.

    Mass(person) * Gravity(Earth) = Mass(person with suit) * Gravity (moon)
    Mass(person) * 9.8 m/s/s = mass(person with suit) * 3.711 m/s/s
    2.6 * mass(person) = mass(person with suit)

    Please don't say you want this to be high-tech.
     
  4. minstrel
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    minstrel Leader of the Insquirrelgency Staff Supporter Contributor

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    You can't really increase the mass of Mars because that would affect the orbits of it and the asteroids and practically everything else in the solar system, over millennia.

    Why, exactly, do you need Earth-like gravity on Mars?
     
  5. Quezacotl
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    Quezacotl Contributing Member

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    That's science. Make one breakthrough and a thousand million new problems appear.
     
  6. Cogito
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    Cogito Former Mod, Retired Supporter Contributor

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    Compress Mars to a smaller diameter. About 80% of its current diameter would do it at the same mass (mental calculation).

    A ridiculous solution, to be sure. I would have to echo minstrel's question: Why?
     
  7. flipflop
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    flipflop Senior Member

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    Increasing the gravitational force of mars would not affect the planets as much as that it would cause an increase in vibration from all the planets but the two moons of mars would actually have to be put in a faster orbit or higher orbit. In theory if there was a slow collision between mars and a body highly dense and approx twice the mass of mars it would cause an increase gravity if this was timed right it could throw both moons into a higher orbit via a slingshot method. A slow collision would result in a mars that would look a bit like the moon (skewed with a thin crust on one side). So in theory it could happen naturally. There are many problems with this - a nuclear winter being one, half the planet being molten the other half covered in tonnes of rock (thousands of tonnes), massive tectonic activity, shifted orbit around the sun, the core of mars would not be frozen anymore but would be molten. It is a current theory that explains the moons make up so is not completely fantasy you just need to sling a dense moon or something into mars. Timing would have to be precise though.

    here is the article on the colission of a large body with the moon for reference http://physicsworld.com/cws/article/news/46767
     
  8. Alex A.
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    Alex A. Member

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    well there is a colony on mars in my book and i want the people(who live in vaults essentially, in the sides of the mountains/dormant volcanoes) to be able to move freely in the colony like they would on earth.
    I need a chase scene and i want it to be fast paced(meaning regular human speed). On Mars, youd be running as fast as you do in your dreams(for me, when i run in my dreams, i move as fast a snail for some reason, 3x slower), so i need a regular or near regular amount of gravity for the colonists.

    A heavy suit is a nice idea, which would work if the people were outside on the surface of mars, but they are in the mountain/colony/ shanty town/ city so they would be in normal clothes (whatever the fashion sense is 200 years from now. I will take that suggestion though and it is much appreciated.

    centrifugal force wouldn't work for a planet because that means you would have to increase mars' rotation rate, and it isn't as easy as spinning a basketball on our fingers. but thank you for the suggestion.

    heavy magnetic boots does sound like a good one though

    thanks alot for the help guys, I really appreciate it. keep it coming, if possible.
     
  9. psychotick
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    psychotick Contributing Member Contributor

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    Hi,

    My thought would be don't mess with the gravity at all. One third gravity is fine for running around in once you adapt to it. Don't forget people's muscles would atrophy a little as they adapted to having to push less weight. In time they would find things almost earthly.

    Cheers.
     
  10. minstrel
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    minstrel Leader of the Insquirrelgency Staff Supporter Contributor

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    Also, be aware that a heavy suit won't speed up your running. Acceleration due to gravity is not dependent (in the case we're discussing) on the mass of the person or the suit he's wearing. It's proportional to the mass of Mars and inversely proportional to the square of the distance from the center of Mars. (It's not as technical as it sounds.) But it means that increasing the weight of the suit won't make your chase scene more fast-paced. It's like Galileo dropping a heavy rock and a light rock from the leaning tower of Pisa and both hitting the ground at the same time. Something that weighs more doesn't fall faster (neglecting air resistance).

    end of physics lesson.
     
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  11. Quezacotl
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    Quezacotl Contributing Member

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    Fedurp, forgot that, how did I ace that test...nevermind the weighted suit, the force is equavilent, by the accelaration remains the same.

    That's tough, now.
    Another method: strenghten magnetic field headed from south to north pole and have a small device that always transmits a strong current heading east to west. Does not necessarily have to be ones boots or a suit.

    Hopefully I'm not screwing this up too.

    Right now, magical gravity machines seem more plausible than anything here.
     
  12. flipflop
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    flipflop Senior Member

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    mars doesn't have a magnetic pole....sorry :)
     
  13. psychotick
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    psychotick Contributing Member Contributor

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    Hi,

    Magnetics wouldn't work either. The fall off rate for magnetic field strength over distance is very different then that of gravity. I.e. it falls off very, very quickly. So say you magnetise the steel decking of your habitat, your boots would have a strong attraction from say a millimeter above the floor, but a far weaker one say two millimeters above the floor. Contrast this with gravitational field strength decay over distance where your attractive force (weight) is much the same at one millimeter above the floor and one mile above it.

    This translates to jerky movements as your magnetic boots are clamped to the floor in sudden thunks the moment they get very close to the floor, but the moment you lift your foot even an inch or two off it, there's almost no attraction at all.

    Heavy, massive suits come with a different problem. Say you weigh in on Earth at one hundred kilos. And you want to weigh the same on Mars. So you actually weigh thirty three kilos and have to make up the rest with a suit. So sixty seven kilos of suit, times three to allow for the weaker gravity of Mars means your suit weighs just on two hundred kilos Earth weight. So you stand on Mars in your two hundred kilo suit and weigh the same effectively, one hundred kilos. But your mass is three hundred kilos. So every time you try to move, starting walking, stopping, your legs have to counter the inertia of three hundred kilos even though your weight is only one hundred kilos. What that means is that it takes you more effort to get going and to stop or change direction.

    Theoretically, as gravitational force is inversely related to distance, and you had some sort of uber science, you could shrink Mars, so that it consisted of the same mass but had a smaller diameter. I.e. you'd make it denser. This wouldn't alter the effect of Mars' gravitational field on other objects within the solar system, except maybe for its two small moons, but would mean that on the surface you'd weigh more. But I have no idea at all how you'd do it - except maybe insert some sort of singularity / black hole into the planet's core. But even if you could do that the chances are that you'd simply destroy the planet.

    Cheers.
     
  14. Cain
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    Cain Member

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    Same mass = same gravity surely? Don't think the density really comes into it.
     
  15. Clumsywordsmith
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    Clumsywordsmith Active Member

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    Negative. Think about black holes. They're roughly the same mass as they were before being a sun, but compacted to such a tiny point that their gravity becomes strong enough to suck in even light. Physics was a long, long time ago for me... but something like this should explain:

    g = GM/r^2

    Where G is the gravitational constant, M the mass of whatever (in this case presumably the earth), and r is the radius of the earth (or mars, I guess). The tighter the radius, the bigger "g" gets.

    Good luck crushing mars down to 80% of it's current size! To be honest, I think that humans would discover the means of faster than light/long distance space travel long before they figured out how to alter the gravity on mars. Besides, why would you want a completely earth-styled chase on mars? What's the point of having a story take place on mars if it's been rendered no different than earth? Make it interesting. Make someone jump over a four meter high wall. Make someone go plummeting down into a deep valley and survive. Make someone leap from the edge of a monstrous building. It'd be badass.
     
  16. jonathan hernandez13
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    jonathan hernandez13 Contributing Member Contributor

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    It would require technology that not only doesn't exist but is inconceivable. Adding that much mass to a planet requires godlike resources and maybe long spans of time. By the point any civilization has that kind of power colonizing and engineering planets would be peanuts to them.

    Magic maybe?
     
  17. art
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    art Contributing Member Contributor

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    About twenty years ago I killed a fly that had landed on my window. I did not swat him but rather sprayed with some deoderant or other - I think the coldness of the spray and the various toxicants did him in. Listen: this dead fly did not fall from the window but stayed there, for days, as if mummified, on the upright pane of glass. I concluded from this, being a scientific sort, that flies wear anti-gravity socks.

    When time allows, I'm going to learn the secret of these socks and then produce anti-gravity socks for humans. I think I'll make a pretty penny.

    And, since your story is set in the future, bear in mind that most folk will be then wearing my patented anti-gravity socks so the gravity on Mars will seem nothing out of the ordinary.
     
  18. Islander
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    Islander Contributing Member Contributor

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    Why exactly would people run slower in lower gravity?

    You fall slower in lower gravity. This, together with the difficulty of moving in bulky space suits, is why films of the moon expedition looks like they're in slow motion.

    When you're running fast, you're also pushing your feet more forcefully against the ground, which could cause you to take leaps in low gravity, which in turn would slow you down. The friction against the floor would also be lower, so you'd have to have shoes and/or floors with good friction. Are these the problems we're talking about? And would it be that bad in 1/3 of Earth's gravity?
     
  19. Alex A.
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    Well Art, I think you answered all our problems with that.

    I think having weak magnets hidden in the sole of a boot would be the best way, if i refine psychoticks explanation and make it so the movements aren't jerky. it would be like running through mud essentially, but your shoe wouldnt come off and your sock wouldnt get dirty. so i think i am gonna go with that because magnets in boots are cheaper, a business would make a killing off them, and it doesn't require a super device that gravitizes mars.

    thank you everyone for your ideas! Ill put you in my dedication page. If this gets off the ground
     
  20. Cogito
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    Cogito Former Mod, Retired Supporter Contributor

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    Same mass equals same gravity at the same distance. Distance is measured from the center of mass. Gravity falls off by the inverse square law, so a planet with the same mass but half the radius will have four times the surface gravity.

    There is also the solution proposed by the Q for a somewhat different problem: "It's simple. Just change the gravitational coefficient of the universe."
     
  21. minstrel
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    minstrel Leader of the Insquirrelgency Staff Supporter Contributor

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    Cogito is right.

    Alex A., you are really bending over backwards trying to increase the Martian gravity. Is it really that important to your story? You shouldn't have to twist the laws of physics to get your plot to work.

    Isn't there some way of making your story work while leaving the gravity of Mars exactly as it is?
     
  22. flipflop
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    flipflop Senior Member

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    personnally armageddon was a pretty good effort with the jet suits and jets on the vehicles try that

    you could have your car chases and running scenes but you could have them turning there packs off to leap large objects free running style
     
  23. Cogito
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    Cogito Former Mod, Retired Supporter Contributor

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    To amplify my point a bit more, why have it take place on Mars if it isn't going to be Mars?
     
  24. Alex A.
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    Alex A. Member

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    the Main character is from Mars so a couple of chapters takes place on Mars.

    Ive decided to go with weak magnetic soled shoes that will be attracted to the titanium floor so it will be like running through light muck.

    no bending over backwards. I wont go into explain alien inventions... just the human ones
     
  25. Steerpike
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    Steerpike Felis amatus Supporter Contributor

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    I don't think titanium is magnetic, however. Not sure those shoes will work...
     

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