Astronaut Scott Kelly on the devastating effects of a year in space | Hacker News Reader

Astronaut Scott Kelly on the devastating effects of a year in space

theage.com.au

27 pointsALee12 comments

I think a real takeaway from this article is that long distance space travel will not be truly realistic until we have a way to simulate earth’s gravity on a ship. There are numerous approaches to this as any hard sci-fi novel will tell you, but how far away exactly are we from creating something like this in real life?

Is it that difficult to have the ship cabin rotate?

I’m only an armchair physicist but from reading the Wikipedia article on artificial gravity the main blockers to having this happen appear to be the amount of power/fuel required to sustain gravity and the size of the spacecraft. Under the centripetal model it seems that the bigger you make the craft the less that is required for gravity, but then you have the problem of getting a giant spacecraft off earth. It seems like one of those problems we have a theoretical solution for but the cost/technical limitations make it pretty infeasible currently.

Maybe the first realistic implementation will be something along the lines of only having the sleeper berth with gravity and everywhere else is weightless.

The rotational radius has to be pretty large to be practical, but the spaceship itself doesn't need to be particularly large. This is because you can attach to a counterweight with a cable and spin the whole system about a point somewhere along the cable. So you're really only restricted by how long you can practically make the cable.

Is a small fast-spinning not equivalent to a big slow-spinning spaceship? And since there is no friction, once accelerated, it wouldn’t need any more fuel.

I wouldn’t be surprised if humankind is the evolutionary predecessor to a new kind of life form that is god-like. We already see the biological manipulation of humans, and the fusion of human and machine. When enhanced humans outperform normal humans, enhanced humans will proliferate. The pressure to outperform will not stop there, so ever more enhanced humans will exist. There will be a point where those enhanced beings are able to design new beings from the ground up. What if there will be some kind of division of labor, but more broadly, i.e. beings manufactured for certain tasks or environments? Space travelers with hibernation capabilities, beings bread for certain atmospheric compositions, temperatures etc.

> small fast-spinning not equivalent to a big slow-spinning spaceship

The smaller the radius of the spin the larger the differential in gravity and motion between your head and feet. This wreaks all kinds of havoc on the vestibular system which leads to short-term issues (think motion sickness like on a boat) which some people don't have issues with issues, some grow accustomed to, or some treat with drugs (generally some combination of the three) and much longer-term issues that we really don't fully understand but can begin to affect cognition and physical well-being beyond the obvious motion-sickness-like events.

The Zubrin book mentioned goes into a lot of this and suggests a novel solution of providing a tiny amount of gravity, basically enough that liquids pour, at the end of a very long tether such that there is minimal difference in gravity between your head and feet and minimal speed so you don't sense motion. This can, theoretically, allow for much easier and more productive exercise as well.

I highly recommend reading _The Case for Mars_; it is an excellent technical volume that explains in a lot of detail exactly why our current space program faltered after Apollo and how to get us focused again. The chemistry bits were a bit too complex for me, but are very easy to skip.

At least one version of Robert Zubrin's Mars Direct[1] plan calls for attaching the crew module to the booster stage with a tether and then spinning them to provide artificial gravity. This diagram is a good visual explanation: https://spectrum.ieee.org/ns/slideshows/06W_Slide_GoToMars2/... [2].

[1] https://en.wikipedia.org/wiki/Mars_Direct

[2] Slide 4 from https://spectrum.ieee.org/slideshow/aerospace/space-flight/s...

The real takeaway is that he was up there far longer than needed to get to Mars, and he’s fine. The first travelers to Mars will just tough it out. Eventually we will likely have spinning Aldrin Cyclers providing artificial gravity and strong radiation shielding, but don’t need them for our first trips.

Magellan didn’t have a cure for scurvy, safe ships, or maps, but he still agrred to lead an expedition that cost him and 80% of his crewmen their lives but opened the world for exploration. If those explorations had waited until ship and medical technologies advanced to provided modern day levels of safety, westerners only now would be reaching the Philippines.

I agree. Yet, the first stage of problem solving is identifying the problem. Thanks to Scott Kelly, some problems were identified, and now it's possible to test possible solutions. If Magellan knew about the problems posed by scurvy a couple of years before he set sail I'm sure he would've preferred to figure out some ways to avoid that problem instead of risking losing 80% of his crew.

I think an important open question is how much gravity is enough. Will Mars's 0.38g be enough for colonists? How about the Moon's 0.165g? These are critical questions we need to answer to know how practical it will be to have colonies on those worlds. The only choice my be to breed humans for those conditions. Homo ares and Homo luna.

Venus is such a tragedy. Surface gravity of 0.9g, probably quite livable, but the surface is Hell.

yes, this is like the biggest oversight for me - it's well known that 0.38g will affect people differently than 1g.

Imagine people that have been born and spent most of their life on Mars and at some point will meet people who were born on Earth - what a strange encounter that will be.

A guinea pig speaks! "It's not all fun and games being a guinea pig." Great story, I'm looking forward to reading the book this is excerpted from.

Granted that this is a first person account, still, this is what heroism looks like. Thank you for your service, Captain Kelly.

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