Instead of sending one rocket, you send two. You link them with steel cables. Then you rotate them around to generate the required gravity.
From
Mars Direct: A Simple, Robust, and Cost Effective Architecture for the Space Exploration Initiative, by Robert Zubrin, February 1991
DOI:10.2514/6.1991-329
A relatively cheap (for space) setup to get some good actual measurements.
Nevermind together, if the cable snaps they won't be going to the original destination.
https://en.wikipedia.org/wiki/Advanced_Resistive_Exercise_De...
More generally - I often wear socks and slippers around the house while otherwise half dressed, because my toes get cold. Warm feet is a luxury.
For example in a barbell squat, your shoulders lift the bar, but your legs lift that weight plus your bodyweight. In space, bodyweight is not a factor so your legs only have the same load as the shoulders. So upper body / shoulder might end up being the limiting factor, not giving the legs the same amount of load they would under gravity.
Your great grand kids might eventually cope.
Muscle mass is so vital for long term health. 70-year-olds confined to bed rest for just two weeks have been observed to lose significant muscle mass that they most likely will never get back.
Obviously most astronauts are younger than 70. But they're also losing a lot more muscle mass and bone density.
A spinning drum is probably the best method short of artificial gravity, but it has a couple problems. A rotating reference frame creates some pretty non-intuitive effects (https://www.youtube.com/watch?v=bJ_seXo-Enc). Research is ongoing about just how fast a human can be spun for a long duration, although data is hard to come by. We also don't know how low of a gravity a human can stay healthy in without intervention like serious exercise. If it turns out that you need 1G, that involves a much larger spinning drum than a G/3 (Mars) or G/6 (Moon) environment. The problem is that we really have no way to simulate those environments for a human.
So you'd have Mars G for time on the surface anyway.
And besides: a few astronauts have already done long duration microgravity, returned to Earth & lived to tell.
It's a valid hypothesis. Humanity would need to have an entire engineered biosphere to replace the biome living in our guts, our eyes, our . . everywhere. And anywhere we find that's close enough to Earth to live in, will have . . something else . . almost certainly[1] already there.
Kim Stanley Robinson isn't an easy read if you're on the other side of the political spectrum, but Aurora is comparatively free of his standard preachiness, at least in my ears. I actually disagree with his primary thesis of Aurora, and the novel suffers from some fundamental problems as a story, but the point is still salient. Humans will have to build their own Earth, wherever they end up, either out there or back here. I have a funny feeling we won't learn to treasure our own planet until we find out how much work it is to live on another.
[1] Particularly given the extraordinarily early date of the first Terran lifeforms. It doesn't seem to take too much to get the ball rolling, unless the panspermia theories actually turn out to hold some water.
*No* place is going to be "close enough" to Earth to live in: the closest star system is 4 light-years away, and will take tens of thousands of years to travel to with anything remotely like current technology. The only way we're going to find another planet "close enough to Earth to live in" is if we invent a real, working, practical FTL drive. That's not terribly likely. Well, there is one other possibility: some glowing blue alien substance called "protomolecule" is discovered in our solar system and somehow (through a long, twisting plot arc) takes over an asteroid with 100k people, assimilates their biological matter, crashes on Venus, then travels to the outer system and builds a Ring Gate. Anyway...
Basically, we're stuck with this planet, the not-at-all-like-Earth worlds near it, and the other resources of this system.
The only real way we're going to create a viable, Earth-like colony is to build an O'Neal Cylinder.
Aurora uses the generation ship model of transport, which . . does not go ideally. Many problems unforeseen for hundreds of years of travel in the utter empty (you hope desperately that it is empty). It's also a fast but not relativistic ship, .07C, at exorbitant energy costs. Hope you like the moon / mercury covered in purple lasers. Relativistic lower-mass vessels with the same technology, I guess, but the impact threat goes through the roof, and it's not a settlement ship. A better way to make the Aurora-style project is a small ship with frozen embryos that get birthed insitu by machines of loving grace. Then you can go faster, smaller.
But it's all talk talk. We're technically capable of doing these things, but I'm not sure we're socially capable of even lunar settlement at this stage of our history. Let alone Mars, the outer system. The Expanse was, in its own way, optimistic about our future. They just had to get medieval to get Earth's gas balance (and probably phosphorous! and who knows what else) back in the normal range.
Heh heh you know it's funny but if we took the solar system as it exists right now, a floating settlement higher up in the Venutian cloud layers would be closest[1] to fitting that bill, in terms of kgs of crap you need to carry around outside with you. Just, yknow, not anyone's typical idea of a "settlement".
[1] And yet so very damn far away.
Huh? As I recall, there were some lines in the show stating that Earth's population was significantly higher than it is now.
And, in fact, Earth could easily handle a much larger human population than it has now. The problem is, it can't handle a larger population (or even the same as now) if they all want to live like suburbanite Americans driving 6000-pound SUVs and living in McMansions. If everyone (except the farmers) lived in megacities that looked just like Tokyo, we wouldn't have the climate-warming problem we have now.
>I'm not sure we're socially capable of even lunar settlement at this stage of our history
I think we are, but not as a unified planetary population. One wealthy country, or better yet a bloc of allied wealthy nations, could do it if they really wanted to.
>a floating settlement higher up in the Venutian cloud layers would be closest to fitting that bill
I've thought about this before, and my conclusion is that this kind of colony just makes no sense. It's technically feasible, but the question is: why? What purpose would such a colony serve? A moon colony makes sense: you can do lots of stuff on the moon, like mining or astronomy or low-g manufacturing. What the heck are you going to do in a Venusian cloud city that makes it worthwhile for people from Earth to fund your colony? All colonies in history have required funding (and a lot of it), and that meant that investors were expecting a return somehow. There's no economic incentive to build cloud cities on Venus so people can sit around and play video games or whatever; there's absolutely no resources on Venus that are valuable or accessible.
I really think that it would be technically easier to just build a bunch of O'Neal cylinders here near Earth orbit, than to build ships capable of colonizing a distant planet.
That is not the only way, extending lifespan would work as well
Most sci-fi just doesn't think of this stuff because the idea of a ship traveling for 100s of thousands, or even millions of years, is almost too much to consider for us. Making a ship that takes a few months or years to get somewhere is much easier for us to think about, because we've done such things before, so sci-fi always either invents FTL drive, or just conveniently ignores it and hopes the audience is too ignorant of the vast distances between stars to notice (which they usually are).
Optimistic! I have a feeling we won't learn to treasure our own planet until we fail to reach another. The problems here are simply too massive for us to coordinate spreading to other places.
