[HN Gopher] Shields up: New ideas might make active shielding vi...
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Shields up: New ideas might make active shielding viable
Author : ben_w
Score : 164 points
Date : 2024-03-12 09:10 UTC (13 hours ago)
(HTM) web link (arstechnica.com)
(TXT) w3m dump (arstechnica.com)
| pfdietz wrote:
| Or, just make the vehicle being sent to Mars sufficiently large.
| Shielding mass needed goes as r^2; vehicle mass and volume as
| r^3. Just storing the cargo and propellant on the outside of the
| vehicle and the crew in the center should suffice for a
| sufficiently large vehicle.
| WJW wrote:
| Of course, cost goes up linearly with mass and thus cubed with
| `r`. Mars missions are expensive enough as it is without making
| the launch vehicle much bigger than required for the mission.
| hiddencost wrote:
| Manufacture in space.
| jusssi wrote:
| Even though Earth orbit is 2/3 the way there, the rocket
| equation still applies.
| dylan604 wrote:
| So? Do it in multiple phases just like we've done for the
| ISS. Isn't that one of the points of SpaceX building
| cheap/reusable rockets that can be launched quickly? Even
| Star Trek did this.
| pfdietz wrote:
| If going to Mars is worth doing, it's worth doing at scale.
| Considerations of "it's too expensive" mean one should work
| to make it cheaper, typically by reducing launch cost. It
| looks like we'll have launch costs of a < $10/lb to LEO
| before anyone seriously goes to Mars.
|
| Just say no to flags-and-footprints (and SLS); say yes to
| large scale Mars activities.
| irjustin wrote:
| > If going to Mars is worth doing, it's worth doing at
| scale
|
| This has too much chicken-egg problem built into it.
| ben_w wrote:
| Fortunately, Musk has a specific goal of "dying on Mars,
| just not on impact", and might be rich enough to make it
| happen.
| ramon156 wrote:
| If that's how they made decisions NASA would already be
| broke in the first 3 years
| pfdietz wrote:
| NASA isn't leading this parade anymore.
| posix86 wrote:
| I guess that's where politics comes into play. The reason
| NASA etc. are trying to push costs down isn't necessairily
| because it wouldn't be worth it if it was more expensive,
| it's just that projects that are cheaper have a higher
| chance of getting funded.
|
| Also, the value of going to Mars is still highly
| speculative. Once we reach it with low-cost, smaller
| missions, it's going to be less speculative, and the
| risk/reward profile of sending huge spacecrafts will make
| them more viable.
| myrmidon wrote:
| > If going to Mars is worth doing, it's worth doing at
| scale
|
| I don't think this is true.
|
| If the main value is getting credit for putting the first
| human there, and doing a few experiments on soil samples or
| somesuch, then it definitely wouldn't be worth scaling
| things up, the same way its not worth doing missions to the
| deep sea, Antarctica or the Moon at scale...
| hersko wrote:
| > the main value is getting credit for putting the first
| human there, and doing a few experiments on soil samples
| or somesuch...
|
| This is old thinking. I take the goal of self sustainable
| society on Mars very seriously. Will it happen in our
| lifetime? Probably not, but it is the goal we should be
| working towards.
| pc86 wrote:
| Why?
|
| I'm not being snarky (at least not intentionally). But
| you're saying a thing that is at the very least a
| superpower-level goal, if not a _civilization_ -level
| goal, that is very clearly not a current priority,
| should. What's more you're saying it in a way as if it's
| completely self-evident that we should change our global
| priorities to focus on this without the slightest
| evidence supporting that assertion.
| somenameforme wrote:
| Well where do you see humanity in the future? In a
| realistic but also optimistic future? To me all of these
| futures involves us being a multiplanetary species, and
| starting to expand out into the cosmos more broadly. It's
| not only the only way we'll ever become a post-scarcity
| species, but also the only way we can secure our own
| survival as a species. There have been countless mass
| extinction events on Earth, and we're well overdue for
| another one, and it will come.
|
| You're also probably grossly overestimating the cost. The
| SpaceX Starship program has been privately funded on a
| budget of ~$2 billion a year including all costs -
| research and development, construction, launches, etc.
| And once built it's expected to revolutionize space
| (again) sending launch costs to less than $10 million per
| flight, and price per pound to space into the low
| dollars! And once we can start transiting massive amounts
| of cargo to Mars, at a very affordable cost, colonization
| is very much within the domain of possibilities.
|
| I would not contrast prices against NASA. NASA is largely
| used as a tool for pork and graft by Congress, that
| occasionally launches something. Their latest ship, the
| SLS [1], is _literally_ reusing Space Shuttle era tech. I
| mean literally - the SLS is reusing refurbished Space
| Shuttle RS-25D engines, solid rocket boosters, and more.
| Managing to spend tens of billions of dollars over 13
| years (and counting) to develop this is the special sort
| of talent you can only get from a company like Boeing.
|
| So colonization will be costly, but it's nothing like a
| civilizational goal. It's just that our civilization only
| has governments mostly interested in fighting and
| dominating one another, just as has been the case for the
| entirety of human civilization. So we never really get to
| see what we could actually achieve if we tried. But
| what's finally changed is that these sort of grand
| achievements no longer require governments. Costs are
| plummeting at the same time private capital has
| skyrocketed. So the future looks brighter than ever!
|
| [1] - https://en.wikipedia.org/wiki/Space_Launch_System
| thfuran wrote:
| There's no such thing as post-scarcity. The observable
| universe is finite.
| ben_w wrote:
| You could reasonably define "post-scarcity" as "we've got
| more supply than we need".
|
| In this regard, you can define scarcity and post-scarcity
| independently for every consumed resource.
|
| We've been post-scarcity for oxygen since before we
| evolved; post-scarcity for water in most of the settled
| world; and now? Now we're post-scarcity for biros,
| photocopier paper, USB cables and wall-warts, and
| tchotchkes.
|
| The only reason we're not post-scarcity for intellectual
| property is that we've created rules to induce artificial
| scarcity.
| thfuran wrote:
| >We've been post-scarcity for oxygen since before we
| evolved
|
| Have we? Our supply has been getting tainted with
| worrying levels of trace contaminants. If we had 100x as
| much atmosphere, maybe that wouldn't be an issue yet.
|
| >post-scarcity for water in most of the settled world
|
| https://www.unesco.org/en/articles/imminent-risk-global-
| wate...
| ben_w wrote:
| > Have we?
|
| Yes.
|
| > Our supply has been getting tainted with worrying
| levels of trace contaminants.
|
| Note that I wrote "oxygen" not "clean air". You're not
| _literally asphyxiating_ , you're not even close.
|
| > https://www.unesco.org/en/articles/imminent-risk-
| global-wate...
|
| """Globally, 2 billion people (26% of the population) do
| not have safe drinking water and 3.6 billion (46%) lack
| access to safely managed sanitation,"""
|
| As you quoted me, _most_ of the settled world. _Most_. As
| in, more than 50%.
| ben_w wrote:
| If we don't, all of this will have been for nothing:
| https://www.youtube.com/watch?v=gU41J86Rrg8
| pfdietz wrote:
| Let me turn it around, then: if it's not worth doing Mars
| at scale, it's not worth doing it at all.
| thfuran wrote:
| Is there anything you own at least one of but fewer than
| ten thousand of? You should get rid of it immediately.
| pfdietz wrote:
| I'm pretty sure generalizing "going to Mars" to "anything
| whatsoever" is a bit of a non sequitur.
| thfuran wrote:
| If you don't think it's a general property of things
| worth doing, what in particular about going to Mars means
| it's only worth doing at scale? It's a frankly bizarre
| claim that you've so far made totally unsupported.
| pfdietz wrote:
| Obviously I meant there are specific aspects of going to
| Mars that justify the statement, even if I didn't list
| them. I am not required to laboriously explain the
| justification behind any statement I make. We could
| discuss this further if you like. Your assumption that I
| had no such aspects and meant that as a universal rule is
| clearly not listening to me in good faith.
| thfuran wrote:
| It's definitely not obvious if you spout off something
| that sounds like a platitude without elaboration that you
| actually only mean something very specific (let alone
| what specifically you mean), and while you're correct
| that you're not actually obligated to do so, you should
| provide some explanation if you have any interest in
| communicating effectively. Failing to do so is likely to
| lead to misunderstandings. But you've repeatedly missed
| opportunities to explain your position, even dodging
| explicit requests for clarification. That seems more like
| bad faith than just not reading your mind correctly.
| andrewflnr wrote:
| Personally I feel the main value of going to Mars is
| figuring out if it has or ever had life. That kind of
| search will benefit from scale. More tools to do more
| experiments, range farther from home base, maybe multiple
| landing teams. We could find ways to use an arbitrarily
| large payload. I guess that's not exactly what GP had in
| mind, though.
| AYBABTME wrote:
| Which is why minimizing the mass portion budgeted toward
| shielding makes sense. If you're going to send 10 smaller
| ships or 1 large one, you better send the 1 large one.
| yetihehe wrote:
| But one 10x large ship is 10^2 more expensive.
| ben_w wrote:
| 10x radius is (10^2)x mass, I'm fairly sure they were
| suggesting 10x mass.
| Asraelite wrote:
| You mean 10^3? I don't know where the previous commenter
| got 10^2 from.
| ben_w wrote:
| Shielding is only ever needed on the surface, not the
| volume, and has a fixed thickness for any given quality,
| hence ^2 not ^3.
|
| https://en.wikipedia.org/wiki/Square-cube_law
| Asraelite wrote:
| Mb, thought it was referring to the cost of the ship
| overall.
| ethbr1 wrote:
| Unless you source the mass from something that's already
| orbiting, like the moon.
|
| Since we're mostly talking water, any moon water doesn't have
| to pay the rocket tax to launch from Earth surface.
|
| And for a recurring trip, it'd make way more sense to keep a
| larger transit ship continually in either orbit or transit,
| with smaller barebones Earth/Mars cargo/crew transfer craft
| at either end.
| PaulHoule wrote:
| It is hard to pencil out lunar materials being cheap,
| except maybe for use on the moon. If we're at the point
| where we are capable of in-situ utilization we probably
| have some kind of Starship-class rocket. The worst part of
| the "rocket tax" is not that you have to burn a lot of fuel
| or screw around with stages and refueling, but rather that
| you (1) throw the rocket away after one use or (2) it is a
| Great American Boondoggle like the Space Shuttle.
|
| I do like the picture though of a lunar mass driver that
| sends up regolith, metal, or something like that to a
| catcher at, say, the L1 point.
| Asraelite wrote:
| A better option would be near-Earth asteroids. These
| require significantly less fuel to get to than the Moon and
| many are rich in ice. If you got really really lucky, you
| could even find one with an orbit similar to the Hohmann
| transfer path required to get to Mars and visit the
| asteroid en route. That way you don't even need to expend
| much fuel to transport the water to Mars; it's almost free.
|
| For a return trip you could use Phobos and Deimos for
| material. They are also extremely easy to land on.
| ben_w wrote:
| "Sufficiently large" is very large indeed. And that's why an
| Aldrin cycler is a good idea.
|
| (I assume Musk will announce one that looks like a famous 80s
| Sci Fi thing soon after Starship actually manages a round trip
| to Mars).
| bjelkeman-again wrote:
| Aldrin cycler: https://en.wikipedia.org/wiki/Mars_cycler
| pfdietz wrote:
| If we can get down to $10/lb, then for the price of a single
| SLS launch we can put the mass of a battleship into space.
|
| People need to stop thinking small.
| ben_w wrote:
| FWIW, my idea of a perfectly reasonable piece of space
| infrastructure in the multi-planet era has a mass of around
| 10^11 kilograms. Fortunately, the infrastructure itself can
| bootstrap in a way that reduced the launch costs to, it is
| claimed, 9 kWh/kg: https://web.archive.org/web/201203061753
| 03/http://www.paulbi...
| WJW wrote:
| Note: this is only for charged particles such as happen in solar
| flares, and only in space. Your personal shield against bullets
| and the like is still impossible, sadly.
| adrianN wrote:
| A few tons of superconductors work very well against bullets.
| Terr_ wrote:
| That's true even without power at room temperature. :P
| willis936 wrote:
| Who's making a 600 T magnet that weighs only a few tons?
|
| https://physics.stackexchange.com/questions/115011/how-
| much-...
| hobofan wrote:
| I think at that point you probably have to worry about the
| effect such a strong magnet will have on the brain and
| nervous system, so probably not the best fit for personal
| protection.
| skhr0680 wrote:
| I'm no rocket scientist, but I feel that statement holds
| true for bullets too
| bee_rider wrote:
| The bullets are the problem they are trying to use the
| shield to solve. If the shield also kills the user, that
| sort of renders the whole thing moot, right?
|
| Not to agree with the actual idea that the magnet _is_
| necessarily dangerous, haven't looked that up...
| taway_6PplYu5 wrote:
| "He was turned to steel In a great magnetic field"
| Scarblac wrote:
| You don't need 600 T, just a few tons of superconductor
| should be enough to stop most bullets. No need run any
| charge through them, just place them so that most of it is
| between you and the bullet.
| theultdev wrote:
| > just place them so that most of it is between you and
| the bullet.
|
| Easier said than done
| willis936 wrote:
| lol this is true.
|
| The 6 order of magnitude resonant eddy current induction
| looks like the more interesting solution. I could see
| this being done with a giant beamforming array that would
| be more practical than a giant steady state magnet. It
| would be pretty cool to melt a supersonic projectile
| midflight with eddy currents.
| bee_rider wrote:
| In sci-fi, shields seem to basically evaporate bullets. A
| shield that melts bullets could be a very cool sci-fi
| visual; the ship would still need some conventional armor
| (you still have molten metal flying at you), but it would
| splat against the armor. Plus it would provide a nice
| visual for a fresh fleet vs the battle-splattered one
| that's seen combat.
| tzs wrote:
| That's for stopping the bullet. All I need from a personal
| bullet shield is to deflect it enough to miss me.
| perlgeek wrote:
| not against silver bullets :-)
| theultdev wrote:
| or more practically, titanium bullets.
|
| the lead in them may be a problem though.
| myrmidon wrote:
| A strong magnetic field would affect all (eletrically
| conducting) bullets, they need not be ferromagnetic. This
| would work _better_ on silver bullets than steel, actually
| (because of better conductivity).
|
| (This is obviously not practical)
| f4c39012 wrote:
| fortunately software engineers know there is no silver
| bullet
| scotty79 wrote:
| Not really. Bullet would just orient itself to minimize eddy
| currents. People would start using thin disc shape bullets
| that would slide through the magnetic field without much
| trouble after orienting themselves in the best direction.
|
| https://youtu.be/g0amdIcZt5I?t=735
| willcipriano wrote:
| > thin disc shape bullets
|
| Very powerful fans blowing in the direction of the flat
| side
| wkat4242 wrote:
| A few tons of steel is cheaper and also works very well
| against bullets
| roamerz wrote:
| Probably would be more efficient to vaporize a bullet with a
| directed energy weapon than to stop it with a magnet.
| RedShift1 wrote:
| My disappointment is immeasurable and my day is ruined.
| theultdev wrote:
| Well this may work for future phasers, and ceramic/steel plates
| work well for bullets.
|
| Emit the shield from the plate armor and you'll get protection
| from both.
|
| Bonus points for chainmail or kevlar suits for knives / shots
| on non-vital areas.
|
| Extra bonus points for gelatin to avoid broken ribs / stopping
| power from bullets.
|
| Basically a spartan suit...
| generic92034 wrote:
| If you are going that far you might as well think about
| sending a surrogate [1] instead. :)
|
| [1]: See https://en.wikipedia.org/wiki/Surrogates
| theultdev wrote:
| Porque no los dos?
|
| You can jam the remote control for "surrogates".
|
| You could do local AI to workaround that, but then
| ya'know... skynet...
|
| Also distance may be a problem, especially if we're talking
| space warfare.
|
| And surrogates would probably look more like the robot dogs
| or air/ship drones we currently have though, with some
| human-like ones sprinkled in.
|
| Put a remote control operator in a spartan suit to pilot
| drones nearby!
| g19fanatic wrote:
| One of the benefits of using "human like" surrogates is
| the compatibility of hardware. Lets say its a spartan
| type design, if a human needed to be on the front lines
| for that space warfare to manage things then taking the
| hardware from a surrogate make all the other things in
| war easier (fabrication, supply, support, etc...).
| theultdev wrote:
| Oh and a (shielded) micro nuclear reactor for power!
|
| Now how to solve the heating problem...
| VagabundoP wrote:
| Nano Black Hole to sink all that extra heat.
| thfuran wrote:
| A small blackhole is basically just a very compact
| nuclear bomb.
| ben_w wrote:
| Not one you could carry. One with an initial mass of
| 606,000 metric tons would have an initial power output of
| 160 petawatts, most of which was so high energy you'd
| have to worry about proton-antiproton creation on every
| atom those photons interact with, and it would still have
| a 3.5-year lifespan.
|
| The lower the mass, the worse it gets.
|
| https://benwheatley.github.io/blog/2022/05/14-17.06.59.ht
| ml
| thallium205 wrote:
| And solar flare based weapons systems.
| DrBazza wrote:
| Everything in space is about distance - want to stop an
| asteroid walloping the Earth? Nudge it when it is a few million
| [time or distance] unit away, and it will miss the earth. You
| could imagine a future spacecraft might have a leading arrowtip
| also with a field, many miles in front of it to deflect dust
| and so on.
| euroderf wrote:
| A ship moving at a double-digit percentage of light speed,
| with an ablative pilot craft ahead of it.
| regularfry wrote:
| Moving at significant proportions of c makes a very brief
| light show of pretty much any ablative solid,
| unfortunately.
|
| It's worth doing the maths on, for instance, how much ice
| at 4K you would need to dissipate the energy released by
| running into a 5g pebble at 0.2c. It's... not a small
| volume.
| donkers wrote:
| Your comment made me try this out on wolfram alpha.
| Kinetic energy of 1 gram with velocity of 0.1 C is 452.78
| gigajoules. Energy of the Hiroshima bomb is 6.3x10^13
| joules. It would take 139.14 grams of matter at a
| velocity of 0.1 C to have the kinetic energy equivalent
| to the energy released by the bomb. So wow, yes, stopping
| even a small amount of stuff at those speeds is no joke.
| grork wrote:
| Gonna save this post for some arbitrary point in the future to
| pull out as a point against 'impossible'. Might have to gift it
| to my descendants to make sure it's available for long
| enough... /s
| Night_Thastus wrote:
| _Currently_ impossible.
|
| We have no idea what technology will exist in say, 300 years.
| b33j0r wrote:
| In physics of the impossible (in 2008, I know a lot of our
| opinions of the author have shifted) Michio Kaku makes a
| pretty good case that force fields are the least likely
| phenomenon to exist.
|
| There's just not a field that hangs out in space and forms a
| repulsive boundary to matter as its interaction, besides
| matter.
|
| The EM field kinda, but no one means big magnets when they
| think of a practical force field (if so, "QED," they already
| exist) :p
| BobaFloutist wrote:
| Shear-thickening gas? Is that anything?
| simne wrote:
| Plasma could affect bullets and fragments (for example from
| mines). Just like current dynamic armor, which is just boxes
| with explosive material, and it's explosion deflect cumulative
| stream and fragments.
|
| Imagine something like multiple-nozzle rocket engine.
|
| Sure, existing proof of concept realizations are ugly, but with
| time they will become better.
| hiddencost wrote:
| The end is very funny. Mars trip costs 1200 mSv, NASA cap is
| 1000. Should we just send old men to Mars? Oops, they dropped the
| cap to 600, we need this tech now.
| grapescheesee wrote:
| What is the non governement standard/target going to be set at?
| Do private companies need to adhere to the 'new' NASA limit?
| marcosdumay wrote:
| Regulations will appear. There are already regulations about
| radiation exposure that will be immediately extended into
| space travel if no regulatory body acts quickly enough.
|
| A short search gave me this number, apparently for the US:
|
| > 20 mSv a year, averaged over defined periods of 5 years
| with no single year >50 mSv
|
| This basically prohibits paid-for space labor.
| kwhitefoot wrote:
| Surely in such unusual circumstances any limits must be set
| as part of a cost benefit analysis from the point of view of
| the person concerned. One person might be rationally willing
| to risk higher exposure in the pursuit of knowledge.
| denton-scratch wrote:
| > Mars trip costs 1200 mSv, NASA cap is 1000
|
| The NASA cap is a specific lifetime radiation dose; the Mars
| trip cost is an estimate of some kind, but they don't specify
| the duration of the mission. Is 1200 mSv the estimate for the
| outbound journey, or for both legs, or for both legs plus a
| 1-year stay on a Mars base?
|
| I'm 68, and I've already had cancer; I probably match the "old
| man" criterion. But I won't be volunteering to travel through a
| hostile environment, to visit - a hostile environment. For
| pity's sake, use robots.
| kwhitefoot wrote:
| > use robots.
|
| Why not use people who are willing to take the risk?
| denton-scratch wrote:
| It's _much_ more difficult and expensive to get a human
| encased in a robot to Mars, than to just get the robot
| there, without the human. The attitude of the human is
| largely irrelevant (although if you are going to send a
| human, it seems advisable to not send a suicidal nutter).
| vlovich123 wrote:
| There's a difference between a suicidal nutter and
| someone who wants to do it because they're thrill seeking
| and to make the history books as the first person on
| mars.
|
| Also, there's a huge qualitative difference between a
| human on Mars and a robot on Mars in terms of what it
| means for humans back on Earth. It's an achievement
| people will take pride in, can help unify people, &
| inspires the imagination of the next generation in a way
| that robots won't.
| krunck wrote:
| I thought 1000mSv seemed low.
|
| I recently had a lung perfusion scan where I inhaled a saline
| vapor with technetium in it and I was the x-ray source for the
| imaging. When I got home I measured 43mSv/hr. I must be pretty
| close to the NASA limit. Too bad I'm not an astronaut though.
|
| Would having a medical scan cause an astronaut to have a
| reduced usable lifetime?
| ooterness wrote:
| Neat concepts, but these aren't going to fly any time soon.
| Quotes from the article:
|
| "Take these solenoid designs. Your spaceship basically becomes an
| MRI tube."
|
| "At the end of the day, though, we are still talking about using
| a roughly 40-ton shield to protect a module that weighs maybe 8
| tons. It doesn't add up. No space agency is currently considering
| putting a magnetic shield on a rocket because today we don't have
| a good solution."
| was_a_dev wrote:
| Did you miss the final section on the electrostatic shield?
| ooterness wrote:
| You mean the one that only exists in a simulation?
| mrcsd wrote:
| > Based on their simulations, Fry and Madzunkov built
| small-scale models of their electrostatic shields and
| tested them in a particle beam at Brookhaven National
| Laboratory with good results--they showed that the ASPP
| software was fairly accurate in its predictions. "We are at
| the stage where we need to start looking at building larger
| demonstrators. Stojan and I proposed putting a device on a
| lunar surface as a technology demonstration for the plasma
| mitigation method. Sometimes, you've just got to focus on
| applications that perhaps you don't want to do first," said
| Fry.
|
| It is only a small scale model, but your comment really
| doesn't warrant such certainty about simulation only.
| denton-scratch wrote:
| 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 wrote:
| > 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...
| denton-scratch wrote:
| > 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 wrote:
| 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 wrote:
| > 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 wrote:
| 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 wrote:
| > 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 wrote:
| > 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.
| denton-scratch wrote:
| > politics is also a technical challenge
|
| That's a remarkable claim, in view of the fact that
| political problems don't seem to be diminishing in the
| face of technical advances over 2,000 years. I don't
| think I've even heard of a technical formulation of
| political differences.
|
| Of course, an 'iron fist' is a sort of technical solution
| to political problems; and the classical model of a ship
| has a captain who commands total obedience. But even
| ships with authoritarian captains have suffered mutinies;
| arguably, an authoritarian captain makes a mutiny more
| likely.
|
| Are you suggesting that technology can solve political
| problems by psychological manipulation? If that's the
| deal, then I'll lead the mutiny.
| digging wrote:
| > Are you suggesting that technology can solve political
| problems by psychological manipulation?
|
| Not at all.
|
| > That's a remarkable claim
|
| I don't think so. I think it's self-evident.
|
| You're not born knowing how to interact with others
| socially; it is learned. There is not one single
| technique for persuasion, but many rhetorical techniques.
| Therefore it follows that any given individual can learn
| to become more skillful and effective at social
| interaction, broadly. (I'm _not_ specifically talking
| about manipulating or convincing others to do something
| they don 't want.) It also follows that people can learn
| new social interaction techniques from each other and
| build on their skills by sharing. This is a form of
| technology; social structures and language are tools.
|
| Social structures come in a range of complexities and
| types. Governments come in a range of complexities and
| types. Communication techniques, languages, ideas, etc.
| All can be built upon, adapted, and improved in
| effectiveness, as evidenced by the structures we've built
| upon the structures our ancestors have invented. For
| example, how do our legal codes compare to the Code of
| Hammurabi? Is it possible that Hammurabi could have
| spontaneously invented anything like the modern US penal
| system without building upon millennia of innovation?
|
| And if we do agree that social interactions and
| structures can be improved upon, then the _most_
| remarkable claim would be to say that we must have
| already discovered all the techniques and their limits,
| and cannot learn new techniques for cooperation in new
| environments, without any evidence.
| denton-scratch wrote:
| > You're not born knowing how to interact with others
| socially; it is learned.
|
| I disagree. As I've grown older, it has startled me to
| observe the degree to which personality is innate, or
| inherited. I used to believe we were born tabula rasa,
| but since raising children and burying my parents, I see
| that my earlier opinions were absurd.
|
| Do you have children?
| digging wrote:
| What social skills are infants born with?
| denton-scratch wrote:
| Well, obviously not many! They haven't learned to
| communicate, which is a bit fundamental to having social
| skills.
|
| But they end up with personalities that were NOT trained
| into them. I don't know what is 'nature' and what is
| 'nurture', but I do know that kids arrive with their own
| personality, even if you can't yet discern it in the
| newborn infant.
|
| Do you have kids?
| zoeysmithe wrote:
| 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 wrote:
| 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
| zoeysmithe wrote:
| We'd find thousands of "volunteers" for blood sports, but
| we disallow them. Letting misguided people, the poor, the
| unwell, etc sign up for capitalist-backed suicide ventures
| is extremely unethical.
|
| Once allowed, the corrupting influence of money would take
| over. People would be guilted into this by family for
| sponserships and such.
|
| Not that long ago a woman received a huge forehead tattoo
| for an online casino as a PR stunt. They paid hew a few
| thousand for this stunt. She said she needed the money for
| her kids.
|
| I don't think you're fully understanding how many desperate
| people out there would sign up for this or be forced into
| this against their will under the dishonest guise of
| "volunteering."
|
| Look at the near revolt of the early space programs for
| example both Soviet and Western, with astronauts and
| engineers demanding safety measures and more personal
| control of the spacecraft after high profile "dog eat dog"
| philosophy failures that killed and injured many. We've
| already been through this. It doesn't work.
|
| Lastly, a lot of engineers might walk away from the job for
| ethical concerns because they dont want to build suicide
| machines. Look at how MD's refuse to be part of state
| executions in the USA, thus leaving a cottage industry of a
| fairly incompetent execution industry. Your best people
| would walk away from SpaceX, Boeing, etc if tasked with
| making suicide machines for vulnerable people. People have
| ethics and not all subscribe to bottom-tier "dog eat dog"
| capitalism "volunteerism," but instead are educated to know
| what that means and how that's historically abused our most
| vulnerable.
| adrianN wrote:
| We have for example test pilots who take high risks for
| their job without the slippery slope problems you
| describe so I don't think that doing something similar
| for a Mars mission is impossible.
| zoeysmithe wrote:
| I think there's a fundamental difference in what people
| and society allow between these two scenarios:
|
| 1. There are jobs that are risky.
|
| 2. When your air runs out at Mars take this suicide pill
| because we're not funding a round trip.
|
| The latter is a huge deviation from what is acceptable.
| kwhitefoot wrote:
| > a huge deviation from what is acceptable.
|
| The question is acceptable to whom. There are pastimes
| that are risky such as rock climbing, Formula 1 racing,
| and many others. Would you ban those too? If not then you
| must accept that there are degrees of risk that are
| acceptable to some and not to others. Assuming that the
| decision is genuinely made without any kind of coercion
| why should society dictate what risks people can take?
|
| As has been pointed out elsewhere on this topic the poor
| and ill educated won't be offered these opportunities
| anyway so that kind of implicit coercion does not apply.
| denton-scratch wrote:
| > you must accept that there are degrees of risk that are
| acceptable to some and not to others
|
| Someone who accepts the 'risk' of certain death on the
| mission doesn't seem to me to be the sort of person you
| want as your companion on a dangerous voyage. And if
| you're planning to found a colony, you want all sorts;
| not just nerds, scientists and technicians.
| MrYellowP wrote:
| > Someone who accepts the 'risk' of certain death on the
| mission doesn't seem to me to be the sort of person you
| want as your companion on a dangerous voyage.
|
| That is EXACTLY the person I want around, because I know
| they can be relied on even in dangerous situations. You,
| on the other hand, who thinks that someone who does not
| fear death would be a bad companion on such a mission,
| would likely piss himself in face of actual danger.
|
| Someone who's afraid of death on a suicide mission is a
| danger to the mission and, thus, to myself. When you want
| to found a colony, you need strong men and smart men,
| best when each man covers both.
|
| You definitely _just_ want nerds, scientists, doctors and
| technicians, because they get the shit done.
|
| This isn't a hollywood movie.
| aerostable_slug wrote:
| Our most vulnerable populations wouldn't be of any
| interest as crew members of a spacecraft. They're the
| ones who wouldn't get to go at all.
|
| The point of a crew wouldn't be to demonstrate human
| safety, but rather to do things automation can't
| currently do (e.g. improvise solutions based on a deep
| and broad background of general knowledge + specific
| training coupled with high basic intellect, in austere
| environments under great personal stress). People like
| that don't get their foreheads tattooed for money.
| thfuran wrote:
| >Not that long ago a woman received a huge forehead
| tattoo for an online casino as a PR stunt. They paid hew
| a few thousand for this stunt. She said she needed the
| money for her kids.
|
| Would her kids have been better off if she couldn't get
| that money?
| jjslocum3 wrote:
| <Its incredible to me that educated adults are taking long-
| distance manned space travel seriously>
|
| Comical and Strangelovian perhaps, but also the only hope for
| humankind. How many years until the expanding sun's corona
| envelops the earth? Assuming we make it that long without
| first destroying ourselves or meeting an unfriendly asteroid,
| you can bet that all of humanity will be behind the effort.
| So while it's not on this week's scrum board, it's definitely
| a high-priority TODO.
| denton-scratch wrote:
| > but also the only hope for humankind
|
| You make it sound as if humankind is doomed if we don't do
| it. But we're doomed anyway; no species on Earth has
| survived more than a coupla hundred thousand years without
| evolving into something else.
|
| I think there's a desperate desire to live forever, behind
| some of the speculation about long-distance manned space-
| travel. Hey, guys, it's like this: you ain't gonna live
| forever. You won't be able to orbit Alpha Centauri, let
| alone colonize the galaxy.
|
| 100 years ago, we weren't at all sure that the Milky Way
| wasn't the same as the Universe. As we learn of faraway
| places, naturally we dream of visiting them; but now we
| know for sure that there are places we can see, that
| definitely can't be visited. We'll get over these dreams
| eventually, and maybe realize that we have to take due care
| of our home planet, and try to avoid killing one another in
| wars. Those are the great threats to 'hope', and the idea
| of survival through space-travel is a distraction for
| people who aren't prepared to face that fact.
| BobaFloutist wrote:
| > How many years until the expanding sun's corona envelops
| the earth?
|
| So, so, so many years. We've gotten as far as we have in
| something like 200,000 years, with most of our
| technological advancement happening in the last...I don't
| know, let's be generous and call it 10,000.
|
| It takes probably what, two hundred years for technology to
| become nearly unrecognizably advanced these days?
|
| We have around 7 and a half _billion_ years before the sun
| wipes us out. Trying to get people on Mars with current
| technology has its arguments, but that we 'll run out of
| time if we put it off anymore isn't one of them.
| dylan604 wrote:
| >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 wrote:
| 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 wrote:
| > 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.
| nemomarx wrote:
| in those cases, people expected to live there, settle and
| have children, etc
|
| Which seems very unrealistic for the first stage trip to
| Mars? you'd need several waves to even have enough
| material there to be livable for more than a year. No one
| moves to the south pole without a plan to go back, for
| instance.
| dylan604 wrote:
| > in those cases, people expected to live there, settle
| and have children, etc
|
| exactly. These people are choosing to go to Mars without
| expecting to come back. If they die of old age or
| catastrophic failure doesn't matter. They willingly had
| no intent of coming back. So the cheeky comments about
| only send "old" to Mars is not totally out of line. Just
| remove the age constraint, and make it people willing to
| take a one way trip. There are people right now willing
| to do it.
|
| It totally changes the agenda. If we can just plan on
| making long term remote isolated bases, then we just
| focus on that. But it takes the same amount of effort to
| survive on the surface for short stays that then require
| the extra effort of returning. So I'm saying we're
| wasting effort on the first stages including the return.
| Let the people willing to relocate do it, establish a
| foot hold so that the "weekenders" can come visit if
| that's something that is still felt as a need.
| denton-scratch wrote:
| > Let the people willing to relocate do it
|
| Well, sure. As long as they don't cause serious
| environmental and safety problems while they do it. But
| that's obviously a personal choice; it's absurd to expect
| the public finances to support the project. If they want
| to make money out of weekender tourists, then presumably
| they are making some kid of business plan; I'm fine with
| them losing all their money.
| chrisfosterelli wrote:
| I feel like your analogy conflates early explorers (who
| definitely intended to go home unless something went
| wrong) with early settlers (who did not). I feel like
| Mars is very much in the "explorer" phase more than the
| "early settlers" phase.
| kayodelycaon wrote:
| You're missing that those people didn't know what would
| happen and they had the hope of a better life at the end.
| Returning was always an option.
|
| It doesn't need to be rational. Humans are emotional
| beings and greatly affected about what they believe to be
| true.
|
| Stranded on another planet is a guaranteed death sentence
| and people know that. They have no hope of survival to
| cling to.
|
| You really can't equate the two.
|
| A better example would be a platoon of soldiers staying
| behind to delay the enemy so everyone else escape. They
| have deliberately made the decision to die for a cause.
| dylan604 wrote:
| I'm not missing the point at all. I think we're just
| willing talking past each other???
|
| We've been sending robot explorers for decades. If we're
| sending humans, we should no longer be considering them
| explorers. They're settlers. Framing it any differently
| is just a serious limitation of what we're trying to do.
| Send up the equipment they need in advance. If the
| colonies fail (with all that entails), study it to see
| why and prep for the next attempt. It eliminates all of
| this hand wringing, and simplifies things to the point of
| becoming achievable
| virgildotcodes wrote:
| > How do you think the Americas were settled by
| Europeans?
|
| These were families, who were setting out for the promise
| of a better life, to a world where they were promised
| fertile land and... a breathable atmosphere.
|
| Do you understand how that might be completely
| incomparable to traveling to a dead world, where life
| will invariably be much worse, and there is no chance to
| bring your family or build a future with them?
|
| There is no mystery, there is no unknown, there is no
| promise of riches or a better life, which is what
| explorers of the eras you're referring to were seeking.
|
| > 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.
|
| You're being so glib, think a little longer. Did those
| colonists have twitter? Could a disaster be
| instantaneously broadcast around the world and cause a
| simultaneous shift in global perception and government
| policy? Think about the Challenger disaster leading to
| the end of the shuttle program. Could you conceive how a
| major disaster on such a ludicrously expensive
| undertaking as a Mars mission might result in cuts to the
| program and potentially all future plans for manned space
| travel beyond the moon?
|
| >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.
|
| This is funny. Do you know the life I've lived? Are you
| confident that it's in alignment with your assumptions?
| chrisfosterelli wrote:
| Because people imagine most quintessential heros to dream of
| exploring but also dream of coming back to their friends and
| families at the end of it.
| transfire wrote:
| I think the take away is that the progress has been surprisingly
| good and, if it continues, the next generation of designs after
| the ones we currently have might be viable.
| h2odragon wrote:
| oo just in time to save the planet form all the satellite debris:
| https://spaceweatherarchive.com/2024/02/01/will-satellite-me...
| Perz1val wrote:
| What if we make the shielding once, put it in orbit and "borrow"
| it for each ride. Launching it from surface is expensive, between
| planets not so much. Even better, ship it in parts on the small
| reusable rockets that we already have. It's about time we start
| making stuff in space, welding a metal box seems like a good
| first project (also no shielding gas required)
| zzzeek wrote:
| at last a great example of positive cooperation between Earth and
| Romulans
| simne wrote:
| Nice try, but unfortunately article have few factual mistakes and
| bias.
|
| First, Earth shield is not just magnetic, but it is complex,
| magnetic + 100km of thin atmosphere, where most secondary
| particles just decay with time.
|
| Calculations said, for comparable shield, need approx 6 meters of
| just water. Sure, it is lot of weight, so other calculations
| said, interstellar ship (or even martial ship) could use tanks
| with liquid hydrogen as shield, as they should be huge (for
| martian ship they should be thousands of metric tons, for
| interstellar, magnitudes more).
|
| Second, very long text, but not said clear, that after
| cancellation of Shuttles, AMS-02 was modified, to use permanent
| magnet instead of superconductor.
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