I know the surface gravity of Mars is 38% of that on Earth. Would it be possible, in theory, to develop means of equalizing the surface gravity to that of the Earth, so that humans could live there? Would it be possible to increase Mars' atmospheric pressure so people wouldn't need a pressure suit? What about oxygen? My novel takes place in a terraformed Mars, I'll need to have an explanation for these things.
In theory with an artificial magneto-sphere, you could give Mars an atmosphere. Though to it might be trickier to add gravity. A Martian day is only a little longer than an Earth day, so increasing the rotation rate will throw that out of sink. Maybe adding mass (somewhere) in a a high enough volume without increasing the size of the planet could in theory add gravity. So neither is just as simple as just planting a few trees and a few massive atmospheric generators is going to fix. It would take an enormous amount of energy to even give the planet a magneto-sphere to even hold in any form of atmosphere (and consequently pressure). Though it is possible, the entire process would take several hundred years (or even 1000s) before one could hope to walk outside without any form of breathing apparatus or enviro-suit. Also it is bloody cold, so you would have to warm it all up once you get the atmosphere in place. (That is why we Sci-fi writers just kinda BS it, to avoid all the intense tech babble). Cause while interesting to some, Terraforming a planet is not as exciting as you think.
How would smashing the surface of a planet with a rock help? It doesn't... You would lose some mass since mars already doesn't have much of an atmosphere, so debris would be launched into space. That would be about it. It would just pretty much make a crater, and that might be 'helpful' if you needed one for something... Otherwise I don't see how it really could help, other than save a few months years in drilling or blasting for mining purposes.
There's nothing you can do (with our current understanding) to adjust the gravity of a planet save adding a lot of mass, but the atmosphere is another matter. I would recommend that you read Kim Stanley Robinson's Mars Trilogy, as it's pretty much the current definitive work on terraforming Mars, but what he does in a nutshell is: A) Develop lichens and armored succulents (like cactuses) that can survive on the surface and convert CO2 to oxygen B) Drill a series of "moholes" down through the planet's crust to release some of the heat from the core into the atmosphere C) Set up greenhouse gas factories that release heat-trapping gases into the atmosphere D) Build dawn and dusk mirrors that orbit the planet and reflect extra sunlight down to the surface E) Most important to your idea, crash comets into the planet. Not rocky asteroids, but water-rich comets. He blows them up on entry to the atmosphere to avoid the chaos caused by, well, comet strikes, but when they burn up, they release water vapor into the air, thickening it, and the bits that get separated into hydrogen and oxygen serve to oxygenate things. There are some other strategies he uses like DNA manipulation to provide people the ability to breathe in an atmosphere that is higher in CO2 than we were evolved for, but those are the main points. I found the books to be excellent and can't recommend them highly enough, but I like all the geeky areology and terraforming discussion that goes on in them. YMMV.
There's nothing stopping people from living on a world with that gravity anyway. People who grow up there would probably be taller with longer limbs, and will probably be physically weaker such that they might find Earth gravity debilitating (I remember a Clarke novel where the protagonist is a native of Titan and has to walk around in weighted clothing to get used to how much he'll weight on Earth). Yes, it would. You'd need to either release gas already present on Mars (through burrowing into the crust, melting the ice caps, etc) or introduce it from outside. That could be accomplished by importing gas from other places in the solar system (Venus, Jupiter, Titan, or even Earth), synthesising them, or by landing an asteroid with the right stuff in it. One thing to note is that since Mars has less sunlight than Earth, you'd need more greenhouse gases for the atmosphere to retain heat. And in the early stages, the pressure will be greater in the lower regions where gas can concentrate--so lowland areas like the Noctis canyons will probably be the first places where people can walk around unaided, and highlands will be inhospitable for much further into the terraforming process. Dropping a large asteroid will raise the temperature (if the atmosphere is thick enough to burn it up in descent), and could also be a source of useful elements for building or for the atmosphere or biosphere. If it's icy, it's also a convenient way to get water on the surface.
The only way to change the gravitational pull of the planet is to add mass. An asteroid large enough to make any kind of worthwhile difference would render the planet uninhabitable for millions of years. An asteroid of that size would impact with such force as to melt the original planet. I actually have a similar situation in my current story, but the planet (a moon, actually) is completely artificial, built by an alien race long turned to dust. The gravity is just about Mars-normal, but the moon is much smaller than our moon, which should give a gravity much less than 17% of Earth normal. Issue resolved by having a core made of stabilized, shielded neutronium, brought to you courtesy of Clarke's 3rd Law.
Um, how's about go low-tech, and kill a couple of Mars issues with a single (simple) solution? Full metal jacket, well mostly, lined with enough lead to soak up some of the radiation there and bring the wearer nearer to their earth body weight...? Principle's like divers I guess (or me in a jacuzzi), they wear a weight belt right?
Actually, in the Mars Trilogy, when they initially land they have to wear "lightweight" pressure suits that mostly provide heating and prevent the skin from getting sucked off. Not full moon suits, but KSR has the weight of the suit under Martian gravity bring the users' weight up to about Earth normal. However, since a lot of that is in the air tanks, the characters speak of having a heavy yet hollow feeling. Wouldn't need that indoors though. As @Azuresun mentioned from the Clarke story, when the young Martian natives visit Earth, they have to go through a massive exercise program to prepare themselves for the trip.
This is also a big part of The Expanse novels. Belters, who live all their lives in microgravity, are little more than limp noodles on Earth, unable to function. Martians (humans raised on Mars) find Earth torturous at first and have to go through a serious acclimatization process. The fact that human procreation is pretty much not viable in microgravity is given the old Sci-Fi sweep under the rug, though.
In theory, could you solve the atmosphere and pressure problem by creating giant domes with hermetically sealed interiors? Then you'd have the cities and places forming inside them while the outside remained wild and uncolonized?
Certainly. The idea could also be flexed to handle the radiation problem on Mars since there is no magnetosphere to protect our delicate little chromosomes. Domes would seem the most conservative method, though I would think that gigantic = fragile. Smaller domes, dedicated to agriculture and open space for humans to walk, with extensive underground networks. Instead of buildings going up, tunnels going down. Make use of the living rock, so to speak. Then you don't have to port all the materials with you, just dig.
Big craters are good sites for domed cities, since the dome is partially made for you. Also, valleys, caves and lava tubes in the big volcanoes can also be sealed off relatively easy. One other thing to bear in mind is that if there's enough space and ecosphere development for them to roam and breed, animals are going to get bigger as well as humans. Depending on how much time has passed and the state of Mars, you could have giant-size wildlife worthy of a Burroughs novel.
Others have suggested Robinson's "Mars Trilogy" for good reason. Read at least Red Mars if your goal is a terraforming plot, because your work will be immediately compared to this standard. The "comets" mentioned above were, I believe, lumps of methane ice harvested from Saturn's rings; going out to the Oort Cloud for comets would have been unreasonable, even given the centuries-long timescales that Robinson wrote about. He had them come in at low declination angles so they burned up (melted) in the upper atmosphere, adding greenhouse gasses to the atmosphere, which were great for the plants but still unfriendly to humans. That's where the (above-mentioned) plants came into play. Gravitational changes are out of play if you want your science to be even reasonably plausible. Also, consider that the mean air pressure on Mars is about 1% of what it is on Earth. However, at the bottom of the very deep and very large Marianas Trench, the pressure should be appreciably higher. It makes the Grand Canyon look like a scratch in the dirt. I've always thought that setting a story down there would be a good way to get a semi-believable terraforming story going. Cheers. JD
But if the humans and animals lived inside the domes, where the gravity and everything is equalized with the Earth's, they wouldn't get any bigger, correct? @J.D. Ray would a domed and pressurized environment be unbelievable?
Domes that equalize gravity are the same as magic, Star Trek gravity. A dome would only give you a bubble of air and maybe protection from radiation; it wouldn't do a thing for gravity.
I need some sort of artificial gravity to exist in my setting. The people inside the spaceships will need to move normally.
As @Wreybies said, domes only give you air pressure, not gravity. Unless you have "gravity plating" a la Star Trek, which his (currently) scientifically unsound (e.g. magic). Basically all TV shows save The Expanse use "gravity plating" or some similar techno-babble to make it easier to shoot the show here on Earth and concentrate on the story they're telling rather than the tech. If your spaceships need gravity, use acceleration/deceleration (The Expanse) or centripetal force (rotating habitats). Adding gravity to a planet the size of Mars is just fantasy.
Not at all. Very believable, and the tech that Robinson used in The Mars Trilogy. Realize that, given that the surface pressure of Mars is below one pound per square inch (I don't know what the metric equivalent is), and Earth-normal pressure (1 bar, or 1000 millibars) is 14.7 pounds per square inch, then bringing a habitat up to full pressure means that your tent material can weigh up to fourteen pounds per square inch without any internal supports. You don't need anywhere near that pressure for humans to survive (five p.s.i. is, I think, what space suits run at), but you do need to control the atmospheric makeup closely, and that's difficult in large environments. Also, realize that doubling the pressure doubles the amount of air you need, and making that much air is problematic. Another plot twist.
Not entirely true. To increase the surface gravity, you could, in theory, keep the same mass but decrease the distance from the ce ter of mass, i.e. shrink the planet to a smaller diameter. Of course that's much easier said than done. We have no technology, or even developable theories, to accomplish this. We'll probably come up with artificial gravity generators first.
"Gravity plating" is more scientifically plausible than shrinking an entire planet and maintaining its mass. If one really HAS to have Earth-normal gravity (I doubt they do, but it's their story), they should use "Bose-Einstein particle-doped metamaterials" as the basis for their technology. At least then they're on a believable path. But I think pursuing Earth-normal gravity is a cop-out.
Do they? Gravity can be simulated with part of the ship / station being a rotating ring, where centrifugal force presses people to the outer surface. Elsewhere, boots that seal to the "floor" can keep people oriented the same way (as well as keeping loose items contained or secured to something), or they can operate in zero-g in the same way that the ISS crew do now. As well as the aforementioned sources, Mobile Suit Gundam and its sequels worked without artificial gravity, in a way that felt very natural and convincing. Characters would anchor themselves to the floor, or would drift across space as needed. There were handles you could grab onto in a corridor, which would pull you to the end of it with very little effort.
It's techno-babble for the "technology" that enables a spaceship to provide gravity to its occupants without rotating. Look at Star Trek, Star Wars, or just about any sci-fi TV series or movie. Rarely do ships, space stations, or other space-based habitats rotate to provide gravity. But none of them mass enough to have gravity of any significant measure. So early on (Star Trek), everyone sort of "agreed" that the deck plates (floor sections) would have "gravity plating" to enable them to make gravity. Never mind that everyone on the floor below them would be pulled up or (at the very least) suspended in mid-air. The concept (woo-woo science) is akin to an electromagnet, which is why I suggested the Bose-Einstein thing (Google "Bose-Einstein condensate gravity" to see what I mean), which is at least on the same golf course as the sort of thing you're looking for. Deck plates made from handwavium produce gravity so people can walk around like normal. Like I said, I feel like it's a cop out. Having your characters deal with the gravity differences is WAY more interesting. If you don't want to read The Expanse series, read Orson Scott Card's "Ender's Game" (shorter).
