6 ms·

Doesn't sound very "viable" to me. From my reading, they are claiming that (a) magnetic shielding is impracticable for weight reasons; and (b) heavy electrostat

Doesn't sound very "viable" to me. From my reading, they are claiming that (a) magnetic shielding is impracticable for weight reasons; and (b) heavy electrostatic shielding can't currently achieve even half the protection required for a Mars mission. TFA is unclear about what they mean by a "Mars mission". The amount of exposure an astronaut would face would depend on the duration of the mission, and a (say) two-day holiday on Mars doesn't make a lot of sense, if the one-way trip takes several months. I think TFA's most-useful observation is a throwaway: "but you could probably get away with just picking old men for the job." Yes - just choose astronauts that aren't expected to live very long anyway. As a bonus, that makes it less important to figure out how to get them back. I suspect my slip is probably showing: I'm very much a sceptic of long-distance manned space travel. It's definitely a job for robots.

ben_w 3y ago
> TFA is unclear about what they mean by a "Mars mission". The amount of exposure an astronaut would face would depend on the duration of the mission, and a (say) two-day holiday on Mars doesn't make a lot of sense, if the one-way trip takes several months. Usually[0] such calculations are based on orbital windows, so approximately 15 months round trip time for a short stay and 34-month trip if you're trying to minimise fuel requirements. To get down to just 8 months would require on-orbit staging, which is basically putting supply caches in orbit, but even that's talking about 2 weeks on the ground. But what matters is the time spent in space, not on the ground — once you're on the surface of Mars, things get a lot easier, as you've got a planet between you and the sun half the time, plenty of terrain to hide behind if you need to be out of line-of-sight, about 17g/cm^2 of atmosphere[1] between you and the sun even when it's at zenith, and the possibility of digging a hole to hide in. [0] exception: someone is proposing a fancy new engine, perhaps a fusion torch drive or something. [1] https://www.wolframalpha.com/input?i=2.5x10%5E16+kg+%2F+area+mars https://www.wolframalpha.com/input?i=2.5x10%5E16+kg+%2F+area...
- denton-scratch 3y ago
  > once you're on the surface of Mars, things get a lot easier Yes, thanks for pointing that out to me. But TFA notes that (a) the Earth's atmosphere, and (b) the Earth's magnetic field, contribute nearly all of our shielding from both solar and cosmic radiation. Living in a cave on Mars might shield you from solar flares; but it will provide quite limited protection from gamma rays. Mars has a much weaker magnetic field than Earth (Wikipedia says there's no evidence of any magnetic field at all).
  - ben_w 3y ago
    Indeed. Long term colonisation plans (if you can call them that at this point) generally come with "here's how to we make an artificial magnetosphere" — people do have solutions, though none of them are appropriate for just one mission on just one ship.
digging 3y ago
> I'm very much a sceptic of long-distance manned space travel. It's definitely a job for robots Do you mean in the near term or forever? I agree that we shouldn't be expecting to send humans to Mars in the next few decades at least but I would find it absurd to say that we should never expect it to be viable.
- feoren 3y ago
  Near-term, it's a job for robots. Very long term, the distinction between humans and robots is going to break down. Although unlike GP, I don't consider a few months' hop over to Mars to be "long distance" space travel. I'm talking about visiting other stars: clearly a job for robots.
- denton-scratch 3y ago
  > I would find it absurd to say that we should never expect it to be viable. Well, never say never. Obviously, a manned trip to Mars is just a bunch of technical challenges, and technical challenges can be overcome. The planned Orion spaceship, powered by a stream of H-bombs, the size of a hotel, and built from ordinary steel, has long struck me as the most realistic prospect for long-distance space-travel (they said that if you want, you could bring an ordinary barber's chair or dentist's chair on board). I can't see a Generation Ship working at all. Space travel requires personal commitment; my children can't be expected to have the same attitudes as me. Politics would destroy a Generation Ship. So I think the outer limit on space-travel is the distance you can travel before you die. That depends on velocity, but once you get into velocities comparable to c, the amounts of energy required are staggering. Getting protons moving at a fraction of c has required a huge international effort. Getting a human moving at those speeds seems simply infeasible. So I conclude that it's unreasonable to plan on travel beyond the solar system.
  - digging 3y ago
    > I can't see a Generation Ship working at all. Hm, that's fine, but it's taking the conversation in a different direction. > Politics would destroy a Generation Ship. Social constructions are also a form of technology and politics is also a technical challenge. I don't think generation ships are impossible on social grounds.
zoeysmithe 3y ago
Its incredible to me that educated adults are taking long-distance manned space travel seriously. Its comically absurd and Dr. Strangelovian that people are floating "Send old people who will probably die soon" as a viable fix. This is a job for robots and especially with new AI advances. Trying to fit the biology evolution created for Earth for non-Earth places is a classic square peg problem. I've always sort of mused that the 'gray alien' body is some sort of collective mythical idea of a space-engineered body. That is to say, if you want biological beings to casually work on other planets and moons, our Mark I primate bodies aren't good enough. Ethically, breeding 'space body children' should be a no-go for any civilization that values ethics and consent. So that just leaves us robots, which not only makes scientific sense but ethical sense. Even the "old man" solution is unethical. We cannot know which one of these men might live to 100 if not bathed in radiation. Estimates on average age don't apply to the individual, so sending a 70 year old who will "die anyway in his 80s" is still very problematic. Fun fact, William Shatner is 92, so the famous Captain Kirk actor is one of those long lived individuals. Imagine sending him to Mars in 2004 at 72 because "he'll die soon anyway," but instead he's starting to look like someone who is going to live well into his mid or late 90s. Its probably worth mentioning that when humanity does figure out a cheap and safe flight to places like Mars, Venus, moons of Jupiter, etc and figures out the engineering and bioengineering, we'll probably either be at our extinction event before then or AI will be at the level where we'd be just as much machine as human, or entirely replace by self-aware robots. So its a bit like those old film strips where they launch a manned cannon ball to the moon or an airship to go to Venus. The society, tech, and culture, etc of the time just wasn't far-seeing enough to understand the complexity of these issues and the changes needed to address them. We never danced around the moon's surface in Victorian gowns, used a sextant to navigate our spaceship, or brought a contingent of slaves to Mars. Modern thinkers are making similar mistakes as these naive old stories. Migration to the stars is just not going to be done in these bodies nor with this technology.
- adrianN 3y ago
  You’d find thousands of volunteers of any age for a manned mission to Mars, even if it were one way. I don’t think it’s unethical to let informed people risk their life
dylan604 3y ago
>I think TFA's most-useful observation is a throwaway: "but you could probably get away with just picking old men for the job." Yes - just choose astronauts that aren't expected to live very long anyway. As a bonus, that makes it less important to figure out how to get them back. Why is this deemed as such a negative that people won't be coming back? Is it strictly fear of negative PR? I get that if an unscheduled rapid disassembly happens, that people get upset. However, if it is a part of the original plan that the first people will not be coming back, but instead become permanent resident aliens on Mars, then why is the negative PR being attached? People left their land to never return but settle and establish new places to live through out history, yet no negative PR was associated. Why now about Mars?
- virgildotcodes 3y ago
  There’s something very alien about dying on an inhospitable, dead, cold world millions of miles away from all that humanity has ever known. I find it hard to believe that we’d be able to find a sizable group of people who wanted this to be their fate and who were actually otherwise qualified for the mission. Imagine the nightmare scenario of someone changing their mind partway through the mission. Talk about a disaster (PR and otherwise) that could be significant enough to chill the entire push for manned missions beyond the moon.
  - dylan604 3y ago
    > I find it hard to believe that we’d be able to find a sizable group of people who wanted this How do you think the Americas were settled by Europeans? These people decided that whatever their fate, it would be worth making the attempt. That's just the most recent, but history is clearly full of a group of people deciding that the horizon demanded to be investigated. Otherwise, we'd all just be massed together in what ever the current belief on where humans started is at the moment. The call of the wild, the sense of adventure, exploration, or whatever you want to call it is part of human nature. > Imagine the nightmare scenario of someone changing their mind partway through the mission Yeah? And? So? You think people moving from Europe to the colonies didn't get cold feet? Hell, as times get hard, it's only natural to wonder WTF you made this decision. Those people will probably be culled from the herd so to speak. It's only a PR disaster because people like you sound like without the sense of adventure and too meek to do anything other than leave their house for work. Just because someone else is much more bold than you does not mean that you should prevent them from doing it because you might feel uncomfortable upon hearing about something.

ben_w 3y ago

> TFA is unclear about what they mean by a "Mars mission". The amount of exposure an astronaut would face would depend on the duration of the mission, and a (say) two-day holiday on Mars doesn't make a lot of sense, if the one-way trip takes several months. Usually[0] such calculations are based on orbital windows, so approximately 15 months round trip time for a short stay and 34-month trip if you're trying to minimise fuel requirements. To get down to just 8 months would require on-orbit staging, which is basically putting supply caches in orbit, but even that's talking about 2 weeks on the ground. But what matters is the time spent in space, not on the ground — once you're on the surface of Mars, things get a lot easier, as you've got a planet between you and the sun half the time, plenty of terrain to hide behind if you need to be out of line-of-sight, about 17g/cm^2 of atmosphere[1] between you and the sun even when it's at zenith, and the possibility of digging a hole to hide in. [0] exception: someone is proposing a fancy new engine, perhaps a fusion torch drive or something. [1] https://www.wolframalpha.com/input?i=2.5x10%5E16+kg+%2F+area+mars https://www.wolframalpha.com/input?i=2.5x10%5E16+kg+%2F+area...

denton-scratch 3y ago
> once you're on the surface of Mars, things get a lot easier Yes, thanks for pointing that out to me. But TFA notes that (a) the Earth's atmosphere, and (b) the Earth's magnetic field, contribute nearly all of our shielding from both solar and cosmic radiation. Living in a cave on Mars might shield you from solar flares; but it will provide quite limited protection from gamma rays. Mars has a much weaker magnetic field than Earth (Wikipedia says there's no evidence of any magnetic field at all).
- ben_w 3y ago
  Indeed. Long term colonisation plans (if you can call them that at this point) generally come with "here's how to we make an artificial magnetosphere" — people do have solutions, though none of them are appropriate for just one mission on just one ship.

digging 3y ago

> I'm very much a sceptic of long-distance manned space travel. It's definitely a job for robots Do you mean in the near term or forever? I agree that we shouldn't be expecting to send humans to Mars in the next few decades at least but I would find it absurd to say that we should never expect it to be viable.

feoren 3y ago
Near-term, it's a job for robots. Very long term, the distinction between humans and robots is going to break down. Although unlike GP, I don't consider a few months' hop over to Mars to be "long distance" space travel. I'm talking about visiting other stars: clearly a job for robots.
denton-scratch 3y ago
> I would find it absurd to say that we should never expect it to be viable. Well, never say never. Obviously, a manned trip to Mars is just a bunch of technical challenges, and technical challenges can be overcome. The planned Orion spaceship, powered by a stream of H-bombs, the size of a hotel, and built from ordinary steel, has long struck me as the most realistic prospect for long-distance space-travel (they said that if you want, you could bring an ordinary barber's chair or dentist's chair on board). I can't see a Generation Ship working at all. Space travel requires personal commitment; my children can't be expected to have the same attitudes as me. Politics would destroy a Generation Ship. So I think the outer limit on space-travel is the distance you can travel before you die. That depends on velocity, but once you get into velocities comparable to c, the amounts of energy required are staggering. Getting protons moving at a fraction of c has required a huge international effort. Getting a human moving at those speeds seems simply infeasible. So I conclude that it's unreasonable to plan on travel beyond the solar system.
- digging 3y ago
  > I can't see a Generation Ship working at all. Hm, that's fine, but it's taking the conversation in a different direction. > Politics would destroy a Generation Ship. Social constructions are also a form of technology and politics is also a technical challenge. I don't think generation ships are impossible on social grounds.

zoeysmithe 3y ago

Its incredible to me that educated adults are taking long-distance manned space travel seriously. Its comically absurd and Dr. Strangelovian that people are floating "Send old people who will probably die soon" as a viable fix. This is a job for robots and especially with new AI advances. Trying to fit the biology evolution created for Earth for non-Earth places is a classic square peg problem. I've always sort of mused that the 'gray alien' body is some sort of collective mythical idea of a space-engineered body. That is to say, if you want biological beings to casually work on other planets and moons, our Mark I primate bodies aren't good enough. Ethically, breeding 'space body children' should be a no-go for any civilization that values ethics and consent. So that just leaves us robots, which not only makes scientific sense but ethical sense. Even the "old man" solution is unethical. We cannot know which one of these men might live to 100 if not bathed in radiation. Estimates on average age don't apply to the individual, so sending a 70 year old who will "die anyway in his 80s" is still very problematic. Fun fact, William Shatner is 92, so the famous Captain Kirk actor is one of those long lived individuals. Imagine sending him to Mars in 2004 at 72 because "he'll die soon anyway," but instead he's starting to look like someone who is going to live well into his mid or late 90s. Its probably worth mentioning that when humanity does figure out a cheap and safe flight to places like Mars, Venus, moons of Jupiter, etc and figures out the engineering and bioengineering, we'll probably either be at our extinction event before then or AI will be at the level where we'd be just as much machine as human, or entirely replace by self-aware robots. So its a bit like those old film strips where they launch a manned cannon ball to the moon or an airship to go to Venus. The society, tech, and culture, etc of the time just wasn't far-seeing enough to understand the complexity of these issues and the changes needed to address them. We never danced around the moon's surface in Victorian gowns, used a sextant to navigate our spaceship, or brought a contingent of slaves to Mars. Modern thinkers are making similar mistakes as these naive old stories. Migration to the stars is just not going to be done in these bodies nor with this technology.

adrianN 3y ago
You’d find thousands of volunteers of any age for a manned mission to Mars, even if it were one way. I don’t think it’s unethical to let informed people risk their life

dylan604 3y ago

>I think TFA's most-useful observation is a throwaway: "but you could probably get away with just picking old men for the job." Yes - just choose astronauts that aren't expected to live very long anyway. As a bonus, that makes it less important to figure out how to get them back. Why is this deemed as such a negative that people won't be coming back? Is it strictly fear of negative PR? I get that if an unscheduled rapid disassembly happens, that people get upset. However, if it is a part of the original plan that the first people will not be coming back, but instead become permanent resident aliens on Mars, then why is the negative PR being attached? People left their land to never return but settle and establish new places to live through out history, yet no negative PR was associated. Why now about Mars?

virgildotcodes 3y ago
There’s something very alien about dying on an inhospitable, dead, cold world millions of miles away from all that humanity has ever known. I find it hard to believe that we’d be able to find a sizable group of people who wanted this to be their fate and who were actually otherwise qualified for the mission. Imagine the nightmare scenario of someone changing their mind partway through the mission. Talk about a disaster (PR and otherwise) that could be significant enough to chill the entire push for manned missions beyond the moon.
- dylan604 3y ago
  > I find it hard to believe that we’d be able to find a sizable group of people who wanted this How do you think the Americas were settled by Europeans? These people decided that whatever their fate, it would be worth making the attempt. That's just the most recent, but history is clearly full of a group of people deciding that the horizon demanded to be investigated. Otherwise, we'd all just be massed together in what ever the current belief on where humans started is at the moment. The call of the wild, the sense of adventure, exploration, or whatever you want to call it is part of human nature. > Imagine the nightmare scenario of someone changing their mind partway through the mission Yeah? And? So? You think people moving from Europe to the colonies didn't get cold feet? Hell, as times get hard, it's only natural to wonder WTF you made this decision. Those people will probably be culled from the herd so to speak. It's only a PR disaster because people like you sound like without the sense of adventure and too meek to do anything other than leave their house for work. Just because someone else is much more bold than you does not mean that you should prevent them from doing it because you might feel uncomfortable upon hearing about something.