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Humans Will Sail To The Stars

oddsheep points to an "article on BBC news from the AAAS Expo in Boston about how researchers are discussing spreading the human race across the galaxy in solar sailing ships. Not a new idea of course but the social implications discussed are great: what the hell do the volunteer colonists (and their descendants) do for the hundreds of years it would take to get anywhere? Cue "Are we nearly there yet?" from the back seats ad infinitum and the longest game of 'I Spy' in history..."

40 of 385 comments (clear)

  1. I Spy a star by autopr0n · · Score: 4, Funny

    the longest game of 'I Spy' in history..

    "I Spy.... A star."

    "Hey, thats what I was going to say!"

    I think it would be a pretty short game, personaly.

    --
    autopr0n is like, down and stuff.
    1. Re:I Spy a star by Kwikymart · · Score: 4, Funny

      For the first couple of months of the trip, I would imagine this would be a reoccuring version:

      "I spy with my little eye, something that is gaseous!"

      Uranus?

      --

      Buying a Dell computer is equivalent to dropping the soap in a prison shower.
    2. Re:I Spy a star by gilroy · · Score: 4, Funny
      Or, adapted from Babylon 5:


      I spy, with my little eye, something starting with the letter S... Stars


      I spy, with my little eye, something starting with the letter M... More Stars


      I spy, with my little eye, something starting with the letter E... Even More Stars



      ... and that's when I shot him, Your Honor. :) :)

  2. How Solar Sails Work by tiltowait · · Score: 4, Informative

    Good overview here.

  3. forward history by Speare · · Score: 5, Interesting

    It would seem that the people on the ship would have a lot stronger sense of forward history. Say, generation two of ten, for a long voyage, they'd understand the critical nature of conservation, preservation, and making sure that their children's lives aren't for naught.

    There are many science fiction stories about "people born on the way," in ark-like ships of this sort.

    What strikes me is the sense of drama and tragedy if the on-ship culture panics or corrupts itself before it reaches the goal. Does anyone know of any stories that focus on that? Where generation eight of ten finds that they need to scrap the historic goal, due to some miscalculation or some unforeseen hardships, or merely a decadent generation five?

    --
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    1. Re:forward history by Vuarnet · · Score: 4, Informative

      What strikes me is the sense of drama and tragedy if the on-ship culture panics or corrupts itself before it reaches the goal. Does anyone know of any stories that focus on that? Where generation eight of ten finds that they need to scrap the historic goal, due to some miscalculation or some unforeseen hardships, or merely a decadent generation five?

      I can think of a few:

      - Robert A. Heinlein's Universe short story.

      - Michael Cassut's The Longer voyage (which, interestingly enough, deals with a spaceship voyage gone wrong even before it even sets out from orbit).

      - Ian R. McLeod's "Starship Day".

      - Robert Reed's "Chrysalis".

      There's a lot more, but those are the ones I remember right now.

      --
      Tongue-tied and twisted, just an earth-bound misfit, I
      Learning to fly, Pink Floyd.
    2. Re:forward history by Fweeky · · Score: 3, Informative
      Greg Bear's Eon trilogy (Eon -> Eternity -> Legacy) has the descendents of such a vessel find something rather more interesting to do than just sitting waiting to get to their destination.

      David Brin and Gregory Benford's Heart of the Comet has a group of people try to colonise a comet to bring it back to Earth to mine it, but find their original goal becomes increasingly more remote.

    3. Re:forward history by benwaggoner · · Score: 3, Interesting

      Larry Niven's "A Gift from Earth" posits a variation of it. The ship contained a small, multi-generational crew, and a much larger number of cyro-frozen colonists.

      When the ship finally gets to the (unexpectly sucky) planet, the crew decides they've gotten the short end of the stick, and decide to rule the planet with the colonists are their vassels. So they thaw them out one by one, tell them what the new order is, and chuck them off that habital plateaus which are the only places to live on the planet.

      The book takes place after several generations of this, and also involves psychic powers, a revolutionary movement, sleep inducers, organ cloning, what it's like to live on a planet with a tiny habitable area, and a bunch of other cool stuff. And what happens when you light up a colony ship's fusion drive on a planetary surface. About my favorite book ever from when I was 11.

      Works great as an anti-apartied metaphor, although I didn't pick up on that parallel at the time. It was an evocative expression of the horrors in living in a totalitarian state, and of running one. Much more politically sensible than most of Niven's later collaborations with Pournelle.

      It's one of the early entries the Known Space series. 100% Kzin free, as I remember.

  4. Hilarious Quotation by SmileyBen · · Score: 4, Funny

    The Guardian also has an article. It includes the hilarious quotation 'Some very
    clever people have been chipping away at the problem, and now we think it could be possible without breaking the laws of physics' - I presume as opposed to how people used to think it was possible only *with* breaking the laws of physics...

  5. Centuries-long voyages? by Vuarnet · · Score: 5, Interesting

    Heh. I wouldn't be very concerned about the boredom level of the colonists... I mean, if we were going to build such a big spaceship, it wouldn't be much of an extra cost to give them:

    a) A digital collection of the complete works of art of Humanity (you know, something to read in the way), and

    b) A laser-link or something similar to give them fresh news (inasmuch as 50 or 60 years old news can be considered "fresh").

    What I would be concerned is to how to convince their descendants to continue the work started by their parents. No matter how sophisticated the ship's systems may be, there's always gonna be the need for knowledgeable people to keep them in shape, or as backups, or something.

    "But I really want to be a... ballerina!",
    "Shut up, John, you'll be a cooling system engineer just like your father was, and his father before him, and so on".

    Of course, we could end up with something similar to Robert Heinlein's "Universe", where the descendants are so remote from the original colonists that they don't even know they're on a spaceship.

    --
    Tongue-tied and twisted, just an earth-bound misfit, I
    Learning to fly, Pink Floyd.
    1. Re:Centuries-long voyages? by the+phantom · · Score: 3, Interesting
      "But I really want to be a... ballerina!",
      "Shut up, John, you'll be a cooling system engineer just like your father was, and his father before him, and so on".

      This thought intriges(sp?) me. As the only perspective I have to offer on this subject is the Anthropological one, here's a go:

      Much of what we take for granted is a matter of being presented to us by our enculturation into American (or British, or Russian, of !Kung) upbrining. People grow up to be lawers in large part because they are taught that it is important to make money and that lawers make lots of money. Or they are taught that being a lawer is a prestigious occupation. Or they learn that lawers can be of great help to people and that helping people is desireable.

      However, a member of the !Kung would not feel that being a lawer is desireable. Certainly, there has been contact with lawers, but can a lawer kill a giraffe (or any form of game)? What good would a lawer be to the !Kung. Therefore, !Kung children are not taught about becoming lawers. They may hear about them in fairy tales, but they will not be taught to want to be lawers.

      By the same token, children on a generation ship would likely be taught how to be engineers, specialists in gardening in space, or doctors. Different professions would no doubt have different levels of prestige, but if children are never taught that they could have been lawers, the thought is unlikely to occur.

      I know that I am not doing a very good job of explaining myself, but take a moment to stand back from your own culture. Examine why it is that you believe what you believe. Do you worship a god or gods? What profession do you feel is desireable or prestigious? What do you feel makes an atractive mate? What do you consider art? And most importantly, how have these ideals been shaped by your upbringing; by your parents beliefs; your teachers, friends, and relatives beliefs?

      Now, if possible, isolate yourself from that upbringing and imagine a universe defined by the inside of a multi-generational colony ship. You would likely be taught that the preservation of the colony is supreme. Your entire ethical and moral systems would revolve around this ideal.

      Therefore, I don't think that the children of the children of the children of the first people to board the ship would have any problems continuing on their mission. They are likely to actually be more comfortable in the ship than thei parents, as they would grow up in the environment of the ship, never knowing a sunny day or a spring breeze. The question is: would they want to disembark when they reach their destination?
  6. wear and tear by sudasana · · Score: 3, Insightful

    Wouldn't asteroids and space dust pose a threat to the solar sails? On a long enough journey, the combined damage of thousands of tiny impacts could tear the sails to pieces.

    --
    --- Foam weapons, real sparring: buyjin.com/diamondsword
  7. Another approach by quantaman · · Score: 5, Insightful

    I still think the easiest way to spread the human race to other stars in a Van Neuman machine. It's a self-replicating machine that when it finds a good planet will first terraform it that clone humans to live on it (I may be confusing it with something else but I think I got the basics right). This would not only be drastically cheaper and more practical it holds much more potential for the spread of the human race. It also avoids finding a way to keep a bunch of people occupied for several decades.

    --
    I stole this Sig
    1. Re:Another approach by Bodrius · · Score: 5, Interesting

      A consequence of human intelligence is that it encourages individual selfish behavior. Extending the domains of the human race suddenly takes a very very low priority, well under personal and tribal survival, personal ambitions, plain convenience and indulging our laziness.

      What do we care if the Van Neumann machine is a more efficient AND effective method of colonizing the universe?

      The humans on those planets will not be "us". They will never have had direct contact with Earth, and probably would be quite different from what we consider human unless we provide very strict controls... and hope they work 300 years and some light-years away with no intervention.

      Why do we care about interestellar travel at all? It's not really to spread mankind through the universe; we already have seen how much enthusiasm we have even for a measly solar system.

      We care because WE WANT TO BE THERE. Personally, if possible. Symbolically, at least, through direct descendants that we can see growing and becoming "us". At the very, very least, we want to give ourselves the illusion that we're part of the trip by climbing on a ship and going away.

      The Van Neuman machine has all the romanticism of the postal service, therefore people won't care, therefore no decent resources will be assigned to such a project. It may be the intelligent solution; so was automated exploration of the solar system.

      No, what we're currently doing does not count as systematic exploration of the solar system anymore than your high-school chemistry lab is doing serious research.

      --
      Freedom is the freedom to say 2+2=4, everything else follows...
  8. communicate by smashin234 · · Score: 5, Funny

    I like how they talk about earth english and space english. We already have ebonics english, British English, and the English that my foreign professors have that is completly different then the english I speak. We could always use another English...

    I say if you want to go to another solar system, go for it. I would rather stay here and respond to slashdot articles.

  9. Re:what they do by mar1no · · Score: 4, Funny

    Here's an brilliant idea! They should load the ship with robots and upon the arrival of their destination the robots can begin the mixing of eggs and sperm (i dont know this process as i am not familiar with the artificial breeding methods of humans) and then the robots can parent the babies and the babies will be robots when they grow up and then we can have an INTERGALACTIC ARMY OF HUMAN ROBOTS! HEAHEHEAHEHA

    --
    "you sonofabitch i didn't know!"
  10. Sorry to burst your bubble here ... by Rolo+Tomasi · · Score: 3, Insightful
    ... but first of all, this will only work really close to the sun, maybe within the five inner planets, as the wind pressure decreases with the inverse square of the distance to the sun. Second, it won't work with humans on board, because to protect people from the solar wind itself (electrons, protons and neutrons, so highly ionizing and not good for your health) and cosmic radiation, you need thick layers of absorbant material (water or rock), which would make the craft too heavy to be adequately accelerated by the solar wind.

    So, it's maybe a good idea for low-cost space probes, but it won't work for manned spacecraft.

    And I think before worrying about linguistic problems (space English and Earth English, WTF?), we should first find a way for humans to even survive for an extended period of time on our front porch, i.e. interplanetary space.

    --
    Did you know you can fertilize your lawn with used motor oil?
  11. Hibernation by Daemonik · · Score: 4, Insightful

    Hopefully we would have developed some form of hibernation before we tried to set out on such an endevor. Trying to keep a boat load of colonists occupied and safe on a multi-generational voyage would be trying at best.

    Not to mention the problem of what to do if your intendid destination proves unsuitable for habitation. Like they're going to go back to a planet they've never been on and a culture they've never been exposed to?

    The best system would involve cryogenically frozen embryos and artifical wombs with a small crew in hibernation. Due to the absolute zero temperatures of deep space, little energy would have to be expended on keeping the embryos frozen for the trip as well.

    Robotic probes would detect if an approaching system could sustain life or decide to move on to it's next potential target. If it was on the iffy side, the crew could be woken to make the judgement call.

    In the end however, until we can develope some form of FTL propulsion, most people are not going to be satisfied with the 'casting seeds' approach to extra-solar colonization because of the dubious chances of return on investment and the enormously long travel times. Everyone on Earth involved with such a project would be long dead before any kind of information could come back from these expeditions.

    In the days of instant messaging, cell phone calls to anyone on the planet and relatively fast air travel to any destination, we are fundamentally incapable of grasping and backing the idea of a multigenerational investment of this scope with our current cultural outlook.

  12. I can see it now... by UTPinky · · Score: 3, Funny

    "Mommy, Tommy threw my shoe out the window."

    "If you two don't stop it right now, I'm just going to have to turn this spaceship around right now! Do you want me to have to do that?!?"

    --
    I'm only paranoid because everyone is against me...
  13. Why get off once you're there? by TheFrood · · Score: 5, Interesting

    After the colonists spend a few centuries or millenia traveling to another star system, their society will have adapted to life in space. They'll have become emotionally acclimated to living in a confined habitat surrounded by vacuum, and they'll have learned the technical skills necessary for survival there. Hell, they'll probably be agoraphobic.

    So why bother going back down and living on a planet again? Any other star system will have enough comets, meteors, and other matter to provide plenty of resources for the colonists to live. Why go back down to a planet to live in a gravity well and have to deal with all those scary wide-open spaces?

    TheFrood

    --
    If you say "I'll probably get modded down for this..." then I will mod you down.
  14. Re:What to do?! by agentZ · · Score: 3, Funny

    Yes, but this group might not want to sit around playing Civilization together, lest they reveal their strategy for taking over the new world too soon...

  15. It would take 160 colonists for a viable colony by jACL · · Score: 3, Interesting

    ...or at least 80, according to an article at New Scientist.

    However, there could be a slight problem with inbreeding. From the article:

    "The decrease in genetic variation is actually quite small and less than found in some successful small populations on Earth," he says. "It would not be a significant factor as long as the space travellers come home or interact with other humans at the end of the 200 year period."

    --
    "It remains to be seen if the human brain is powerful enough to solve the problems it has created." Dr. Richard Wallace
    1. Re:It would take 160 colonists for a viable colony by Catbeller · · Score: 4, Insightful

      Besides, they could carry ova and sperm from hundreds of thousands of people with them. Not a problem.

  16. Overpopulation? by ocie · · Score: 4, Funny

    In the words of Dr. Strangelove:

    "Naturally, they would breed prodigiously, eh? There would be much time, and little to do."

    --
    JET Program: see Japan, meet intere
  17. So we build... by Amarok.Org · · Score: 5, Funny

    three ships. We put all the laborers on one, all the intellectuals on another, and...

    (If you don't get it, don't moderate it)

    --
    -- "Other than that, how was the play Mrs. Lincoln?"
  18. Unrealistic by GCP · · Score: 5, Insightful

    Technology is advancing so quickly that people would realize that any group that launched such a voyage would be passed by a faster group within a few years.

    That thought is likely to limit our voyages at any given time to a radius that can be reached in probably about a decade or less with current technology.

    In the meantime, they'll be pushing the limits harder with unmanned probes that can endure tremendous accelerations.

    And until such probes provide proof that there is an inhabitable world at the end of the journey, I find it extremely unlikely that anyone will put together a space city and launch themselves into the unknown for an unknown number of centuries toward an end that's more likely to be a massive destructive event (either external or internal) than an accidental discovery of Earth II.

    --
    "Those who have never entered upon scientific pursuits know not a tithe of the poetry by which they are surrounded."
  19. I'd go by Deanasc · · Score: 3, Insightful
    Subject say's it all but to expound further...

    I would be willing to give up quite a lot to go even 1/4 of the way to another world.

    They'll probably solve the suspended animation problem by then. In that case I'd get to go on the whole trip.

    In fact I hope they solve the suspended animation problem soon as I'm sick of listening to the kids go at it in the back seat.

    --
    I've hit Karma 50 and gotten a Score:5, Troll... I win!
  20. Re:What to do?! by Bodrius · · Score: 3, Funny

    How about hacking the spaceship's computer?

    Sure, it might be risky. But there would be few things more satisfactory than pulling a hack to, say, get the computer to announce "Arrival" 200 years early.

    --
    Freedom is the freedom to say 2+2=4, everything else follows...
  21. I know what I would do by Waffle+Iron · · Score: 4, Funny
    If I was born on one of these ships, I'd dedicate my whole life to inventing a warp drive so I could get the hell out of that tin can.

    Most likely though, after sixty years of fruitless effort I would throw in the towel. I would spend the remainder of my time drunk in my cabin: a bitter, broken lonely man, shunned by my shipmates.

    Upon my death, friendless, my body would be unceremoniously dumped into the biomass recycler.

  22. What you're asking by Catbeller · · Score: 5, Insightful

    What you are asking for is impossible.

    You want people to stop being selfish, solve all the world's problems, and in general, become angels.

    Since this will never happen, your goal will insure that we will never pollute the universe with our evil selves.

    Here's a point: the very things that make us "evil", such as greed, lust, territoriality, warlike tendency, aggresssion -- all of that -- are precisely the qualities that make a species dominant over others in the evolutionary sense. And given that, if we do go to the stars, and meet others, I'd guarantee that those others will be selfish, paranoid, violent and warlike. A species without those traits would not have survived the test of time. If we go to the stars as Zen Buddhist monks, those colonists will be annihilated by the locals - even if the locals are bloody non-sapient crytals. Life is hungry and pitiless.

    As for a great future for humanity among the stars: by your logic, Europeans should never have left their continent. Instead, they should have stayed home and perfected their societies.

    Well, think of this. If there had been no Canada or United States, what do you think would have happened to world civilization after World War I or II? The Western Hemisphere was critical - CRITICAL - in defeating a thousand years of twisted nationalism, and in rebuilding the shattered nations in the aftermath. If Europeans had not left their homes and travelled to the New World, the Old World would have shattered into a new iron age, and would not have recovered for centuries -- if ever. New worlds create opportunity for those who would want to leave, and create resources that can be used to shore up those left behind, even heal them and advance them.

    The fallacy is the basic Zero-Sum game. The idea that there is a finite ulimate prize to human endeavor will concentrate human social toxins, and ultimately kill us all. We need the IDEA of new horizons, even if we don't have them yet.

    1. Re:What you're asking by wurp · · Score: 4, Insightful

      I disagree with your notion that the species that succeeds most is the one with the most selfish members. It's not a zero sum game, and groups that cooperate amongst themselves, and groups most capable of working out arrangements that balance trust versus mutual gain, succeed best. Groups of individually selfish, greedy bastards find themselves unable to form larger, more powerful entities, and they are wiped out by coordinated groups.

  23. Geeks as the perfect volunteers by Bodrius · · Score: 4, Funny

    The solution, of course, is to use Slashdot Geeks.

    Used, and perhaps even comforted by the lack of sunlight and fresh-air, the Slashdot Geek presents advantages over other subespecies of the human animal for such an endeavor.

    Its lack of social skills might be problematic, of course, but taking into account that most of them barely leave their rooms if given a network connection, human contact and its unfortunate consequences can be minimized.

    Co-existence will be limited to posts and flamewars, and provided sufficient sources of electronic boards, sophomoric pseudojournalism and porn all violence would be confined to the network.

    Ensuring reproduction of each generation, however, could present a bit of a challenge...

    --
    Freedom is the freedom to say 2+2=4, everything else follows...
  24. Backwards Nonsense by Beautyon · · Score: 5, Interesting

    Saying we will sail to the stars can be likened to the inventor of the zepplin saying that we will have mass crossings of the atlantic via deridgible.

    Not even the ultra skeptical Nasa believs this solar sail stuff, which is why they are working on the REAL way that people will colonize the stars, with next generation propulsion systems.

    These new systems are to chemical rockets as the sails of sea ships are to the jet; profoundly differnent and unpredicted by the "scientists" and sailors of old.

    --
    ATH0 Bitcoin: 1DnwFLXczVZV8kLJbMYoheUrpqHesjxrSi
  25. Prisms by Graymalkin · · Score: 4, Interesting

    You could never put several generations of humans on some form of interstellar ark and then have then continue as they had on Earth once they got there. A couple generations removed from the rest of human society would cause them to develope independantly from the rest of the human race both physically and socially. As an example many cultures cremate or bury their dead after performing some traditional rite. This is unrealistic in a self contained environment thus the dead would be recycled to eventually become food for the living. Lets say a voyage was launched tomorrow, how much do you think the culture on the ship would change in 20 years after several people died from various causes, natural and unnatural. A whole dogma might form around the mere act of eating, on an ark you would be eating the remains of your dead* on a daily basis. In a hostile environment (which deep space certainly qualifies as) the weak either die or become a burden on the rest of society. Unproductive members of society would be a waste of resources. Like samurai warriors or elder Eskimos ritual suicide would be a common and revered cultural dogma. Any culture being sent into the wilds of deep space would not have an analog back on Earth, in fact they would be almost an entirely new culture, a result of people adapting to a dangerous environment.

    Thus it is of my opinion that sending people to the stars without a warp drive does little to preserve a culture or way of life which when it comes down to it is the only real difference between any of us. Spaceborne cultures would not resemble anything we've seen here on Earth specifically because they weren't born there. If a decendant of some space colonist were to meet a human from Earth they would be as alien to them as anything else dispite the similarity of their DNA and maybe even the fact they share a common ancestor. It wouldn't matter what you did to prepare people for the rigors of a generations long journey into space they would become wholly alien to anyone back here.

    As for the technical feasibility of enormous solar sails propelling people to stars that is 99.99% bunk. The people envisioning such systems disclaim their theories by saying "if we could only find a way..." which usually requires something along the lines of changing the physical laws of nature. I'm sorry but even the magical properties of carbon nanotubes isn't going to solve any inherent problems in using a giant physical structure to capture photons. I groan every time I see this idea rehashed. The key factor in sails all of all sorts if the ratio between the sail surface area (for much force is can use for propulsion) to that of the overall mass of the craft (how much force it needs to get going). While a giant solar sail might work fine for sending a ship to Mars (albeit a small one), getting megatons of personnel and equipment outside the solar system is another matter entirely. The sail needed for a colony ship would be stupendously large which means increased mass and you guessed it needs more force to get it moving. The bigger they are the bigger they need to be to have the energy to get them going. Say the ship is heading to the other side of the galaxy and a solar sail ship is doing about 10% lightspeed by some means. Relative to the rest of the universe not doing 10% lightspeed the vessel would have to survive 600,000 years worth of cosmic travel without something going HCF. Even with relativistic time dialation which would only save you about 2,390 years ship relative off of the 600k that is still quite the feat. Humans not frozen, kept in some form of stasis, or otherwise inert would have evolved into a completely alien species by then. Shit it'd been only recently the last of the other monkeys in our genus died out. Wake me when we hit .99999999c that way it will only take me about 8.5 years ship relative to shoot out of the other side of the galaxy. That's one fast rocket monkey.

    --
    I'm a loner Dottie, a Rebel.
  26. Polynesian Models by Alien54 · · Score: 3, Insightful
    I recall that a year or so ago objects were discovered way out well past pluto, maybe even out to half a light year or more. (30,000 AU?)(ah, here's the link) With a number of these conveniently placed, travel to the stars could be done via these distant places, in a manner very much like Island hopping used by the Polynesians. The Kuiper Belt becomes a launching pad, training ground, etc. But this may not be the case.

    If convenient objects are just a quarter light year or so apart, then the journeys do not have to be so long.

    Just make sure to bring along a whole lot of cheese doodles. we'll be sending GW with you. (smile)

    Which brings up the question of who should we send as the the first people to travel?

    --
    "It is a greater offense to steal men's labor, than their clothes"
  27. Re:producing your own wind by the+Atomic+Rabbit · · Score: 5, Informative

    You're thinking about the Orion project, which was proposed in the 70s. It was quietly dropped, and I think it's safe to say that it will never come about, given humanity's disillusionment with nuclear bombs. Not to mention the impracticality of the design, compared to the alternatives.

  28. Re:Strange idea ... by Ivan+Raikov · · Score: 3, Funny

    It will take a little time before you like/love it and before you can work with the same efficiency (as before the change)...

    So what you're saying is that we should load a bunch of Windows users on a space sailship, give them Linux only computers, and by the time they have figured out how to surf for intergalactic porn, they'd have reached their final destination?

  29. Hmmm. Yet another clueless highly modded post. by RobertFisher · · Score: 4, Interesting
    Hmmm...

    It would appear that this poster didn't even take the time to read the article. In fact, the term "solar sail" is somewhat misleading, because the scientists quoted proposed using directed pulses of light from lasers to propel the interstellar craft. The 1/r^2 law is only true for isotropic radiation -- not for a directed laser beam, which can remain well-collimated over great distances.

    This idea is not at all new -- I recall reading essentially the same notion as a high school student in the mid-1980s in a book on solar sails. Some futuristic plans included building a massive bank of lasers on the far side of the moon. While we are still very far from realizing such dreams (as we will need the infrastructure in place to support such a lunar base first), I always thought that such ideas were intringuing, and provided a physically viable mode of transporting large payloads, to say, Mars, and the outer solar system.

    Lastly, I should also point out that it appears that this author doesn't even understand the basic physics of conventional solar sails. Solar sails use light pressure from the sun, not the solar wind itself. The pressure from the hot plasma streaming from the solar wind is orders of magnitude smaller than the light pressure. Light pressure is also tiny, but since your net velocity is proportional to the time exposed to the source of light, you can build up significant velocities over weeks or months. A great number of people extend the "sail" analogy a bit too far.

    Bob

    --
    Science, like Nature, must also be tamed, with a view turned towards its preservation.
  30. Asteroids, Interstellar Dust, Maser Sails by RobertFisher · · Score: 5, Interesting

    The chance of a collision with asteroids is very minute. There are actually very few significantly sized asteroids, and they are spread over an enormous volume of space, generally concentrated between Mars and Jupiter. If you don't believe me, just consider that any number of space missions have made it to the outer solar system by now. JPL has launched Pioneer 10, Pioneer 11, Voyager 1, Voyager 2, Galileo, Ulysses (on a gravity assist to get to the sun), and Cassini (now halfway between Jupiter and Saturn), and none were taken out of commission by an asteroid (though Galileo had unrelated problems).

    Dust and micrometeorites are a much bigger problem, especially since they are distributed throughout space, and the further your mission travels, the more material you will inevitably sweep up. There is an interesting solution here, though. Although the article refers to laser-pulsed sails (in the visible range), it is also possible to use masers (in the microwave range). Since a "good" reflector need only be smooth to within a wavelength of light, a maser sail would only have to be smooth to within a few mm or cm. Not only would this enable you to save greatly on the mass of the sail by using a conducting "spiderweb" sail, which would be mostly empty space, but the sail would also be greatly resiliant to many small dust impacts.

    Whether such a design is actually feasible for an actual mission is not immediately clear. However, the distribution of dust sizes in interstellar space is well-known to astronomers, so it would be very straightforwards to study the "damage" done to a sail, as a function of the speed of the vessel. (I'm sure someone has done this...)

    Bob

    --
    Science, like Nature, must also be tamed, with a view turned towards its preservation.
  31. Well, yeah, but, well, no... by Nindalf · · Score: 4, Interesting

    As you get nearer to the other star, you'll have to turn it around, and let it start decelerating.

    You've gotta decelerate if you don't want to just shoot through the other system.

    However, there are some tricks you can pull to slow yourself down faster than you get started, and thereby spend more time going faster and get there sooner. For example, you can use a big loop of superconducting wire to transfer your momentum to charged particles. Space isn't all that empty, and you can get drag in an imperfect vacuum if you try hard enough. You might even manage to scoop up propellant to finish braking maneuvers.

    Another trick: imagine two mirrored sails forming a right angle. Now imagine that light is coming from both sides equally. Aim the point of the wedge at the destination star, and the light from it will be redirected to the sides, while the light coming from the departure star will be reflected straight back, resulting in a net gain of momentum towards the destination star. With this system, you can get forward acceleration about up until the light from the destination is double the light from the departure point. You can up that by bringing the sails closer to parallel, but you lose area as you do that.

    Such a trick might not be worthwhile, of course, since light intensity drops off pretty quickly with distance. You'd get most of your boost early on. As a double-whammy, as your velocity increases, your driving light will red-shift, reducing its pressure, while your braking light will blue-shift, increasing its pressure.

    However, as the pressure reduces, you might be able to increase sail area by reprocessing structural support into sail surface.

    Maybe some nice people back home will let you leave a system of mirrors (or perhaps solar-pumped lasers?) to focus the sun's light on you as you go, and keep the pressure from dropping off. If you can do that, you can have almost constance acceleration for the trip, which is really nice for space travel. OTOH, how much do you want to trust the people of Earth not to redirect your system for their own transportation or power generation?

    It's a thoroughly interesting topic.