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Space Science

Can We Travel To That Exciting New Exoplanet? 662

An anonymous reader writes "The news last week that exoplanet Gliese 581g may be in the 'Goldilocks zone' and could therefore hold liquid water and alien life got everyone all excited, with good reason. A potentially habitable planet — and only 20 light years away! But to put things in perspective, here are a couple of estimates on what it would take to travel to Gliese 581g. One scientist puts the travel time at 180,000 years based on current space flight technology, while another explains that it could be quite quick if we build a matter-antimatter drive, and can figure out how to bring along 530 times as much mass in fuel as is contained in the ship and cargo itself."
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Can We Travel To That Exciting New Exoplanet?

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  • Reality check (Score:5, Insightful)

    by elrous0 ( 869638 ) * on Tuesday October 05, 2010 @02:16PM (#33797156)

    Dave Goldberg, coauthor of A User's Guide to the Universe, took a more optimistic approach. In a blog post, he assumed an average travel speed of 92 percent of the speed of light

    That is one HELL of an assumption. Considering that the fastest space vehicles [] ever created took 3 months to travel a mere 8 light *minutes* (somewhere around one-16000th the speed of light), the assumption that we will ever reach even a significant fraction of the speed of light with a vehicle created anytime in the conceivable future is a bit of an overstretch to say the *least*. At the speed of the Helios probes, that journey to this planet would take over 300,000 years, BTW. So even McConville's 180,000 year estimate is a bit optimistic.

    And that's not even throwing in the navigation difficulties (that's going to require some epically precise calculations), the damage such a long trip would inflict to the craft with radiation and micrometeorites, the need for braking when you get there, etc.

    Interstellar space is a big VAST empty that few people appreciate. When I was a kid, all the science fiction and popular misinformation made it sound like the next solar system started right at the edge of our own. It was only when I got older that I realized that our solar system is just a tiny dot in a huge sea of lonely empty. The scale of distances between solar systems is difficult for the human mind to even appreciate.

    • Re: (Score:3, Insightful)

      by Anonymous Coward

      It was supposed to be an optimistic estimate:

      That is very bad news. Let’s put things in perspective and imagine sending the international space station (m= 370 metric tons) to Gliese 581g. The whole trip would require something like:

      * E = 1.8 x 10^25 Joules

      Or approximately 5% of the sun’s energy output in a second. That sounds reasonable, until you realize that that tiny amount would take approximately:

      * 3 million years to collect on e

      • Re: (Score:3, Interesting)

        by elrous0 ( 869638 ) *
        The numbers are truly staggering. I remember my grade school teacher telling us that we would probably one day live to see spaceships traveling to other solar systems. I think now what a silly statement that was, but as a kid I was all "Yeah! Let's go!" All the Star Trek and Star Wars probably didn't help with the popular understanding either (not that they were meant to).
    • by dreamchaser ( 49529 ) on Tuesday October 05, 2010 @02:30PM (#33797384) Homepage Journal

      You are correct, but just a mere few hundred years ago the fastest we could move was a dozen or so miles in a day. I am optimistic that if we don't manage to destroy ourselves we'll find means of providing energy and types of propulsion that would seem like magic to us today (kudos to A.C. Clarke for the reference).

      • by jandrese ( 485 ) <> on Tuesday October 05, 2010 @02:36PM (#33797496) Homepage Journal
        I don't think you understand the magnitude of the problem. These are fundamental physical limits of mass and energy we're talking about. Literally the only chance we have of getting to another solar system is to discover an entirely new branch of physics that somehow makes interstellar travel feasible. Probably the best bet is to copy it from visiting aliens, if any ever bother to visit.
        • I understand it quite well, and I'm humble enough in my understanding to acknowledge that if we survive another 1000 years we might solve said problem.

          • Re: (Score:3, Insightful)

            And maybe we won't. Ever wonder why we've never visited by aliens? (And I mean an actual visit, with hand-shaking or gun-shooting, not some drunken redneck staring at weather balloons or lights.)

            Maybe it's because the gap across stars is too large to cross, and there's simply no science to bridge the distance. Take Star Trek for example. Completely unrealistic. That one scientist says, "...develop a matter-antimatter drive, and can figure out how to bring along 530 times as much mass in fuel as is conta

            • by huckamania ( 533052 ) on Tuesday October 05, 2010 @03:39PM (#33798488) Journal

              There is no gap between stars. By the time you get close to exiting our solar system, you will already be closer to a neighboring star then you will be to Sol.

              The idea that we will build a ship to go to another star on a direct route is a child's fantasy, much like terraforming Mars. We need to figure out how to live in space. Once we have figured that out, we can go anywhere or nowhere. The resources in space that are close to the Earth dwarf the resources that exist on this planet.

              What we need to be working on is automated fabricators and such. Propulsion is over-rated. Just start seeding the path with resources from our automated fabs and then when we do want to go somewhere, we can take our time and not have to bring everything with us.

              Gene Roddenberry had it right. We need a wagon train to the stars.

              • Re: (Score:3, Interesting)

                by astar ( 203020 )

                I liked your take on the gap to the stars. The usual argument goes more along the lines if we get to the next star system and colonize, then make some reasonable assumptions on how easy is would be to recurse and maybe we own the galaxy in 10meg years.

                As far as space vs planet, your point has virtue for those who are silly, but you know darn well that we will do both. Who leaves habitat unused? Even the Sahara, which is really sort of an example of the failure so far of whatever ,life oriented deity yo

          • Re: (Score:3, Funny)

            by 0xdeadbeef ( 28836 )

            I understand it quite well, and I'm humble enough in my understanding to acknowledge that if we survive another 1000 years we might solve said problem.

            What an odd way of saying "my ignorance allows for a greater degree of wishful thinking".

        • by elrous0 ( 869638 ) *

          Probably the best bet is to copy it from visiting aliens, if any ever bother to visit.

          I guess it would be nice to probe THEM for a change. And we could always use a baited field to lure them out. I suggest a trailer park filled with meth-addled hillbillies.

        • by IndustrialComplex ( 975015 ) on Tuesday October 05, 2010 @02:41PM (#33797586)

          Probably the best bet is to copy it from visiting aliens, if any ever bother to visit.

          Meanwhile in a neighboring star system,

          "Probably the best bet is to copy it from visiting aliens, if any ever bother to visit."

        • Re: (Score:3, Interesting)

          "I don't think you understand the magnitude of the problem." Banks told Cook, "There are fundamental physical limits to the amount of food we can take and the amount of money available to either of us."

          Cook wasn't really listening, just looking through the window, already enamouring the feel of the audacious idea. Seeing his friend take but little to no appreciation from his words of warning, Banks continued.

          "Literally, the only chance we have of finding another continent is to build an entirely new ship th

        • Re: (Score:3, Interesting)

          by dpilot ( 134227 )

          Then there's the other way...

          Well before we have a fraction of the technology necessary to ship our "ugly bags of mostly water" to another star, we'll likely have hit Kurzweil's Singularity, and most notably the ability to extract and run a Turing image. Even if the computer necessary to run that Turing image is the size of a human body, its "life support" will be electricity and temperature control, the hardware can be slowed down during the boring parts of the journey, it can likely stand higher accelera

    • by dkleinsc ( 563838 ) on Tuesday October 05, 2010 @02:32PM (#33797422) Homepage

      Short version: "Space is big. Really big. You just won't believe how vastly, hugely, mindbogglingly big it is. I mean, you may think it's a long way down the road to the chemist's, but that's just peanuts to space."

    • Re:Reality check (Score:5, Informative)

      by MarcQuadra ( 129430 ) on Tuesday October 05, 2010 @02:35PM (#33797478)

      Right? The diameter of our solar system (Pluto's orbit) is about 80 AU. 80 AU is 0.0012 light years. This planet is 20 LY away. That means that it's about 1600 times as far as Pluto.

      Remember, you need to bring along just as much fuel to slow down as you did to speed up. This is going to be a long, expensive, boring ride.

      • Re:Reality check (Score:4, Insightful)

        by frostfreek ( 647009 ) on Tuesday October 05, 2010 @02:41PM (#33797594)
        I think you missed a digit there; more like 16000 times.
      • by Surt ( 22457 )

        That's not true. There's a lot of interstellar hydrogen out there, you can use that as decelerant if you want. Acceleration and deceleration are often assumed symmetric, but that's not required, and given the distribution of resources not even the most effective way to do things.

      • Re: (Score:3, Informative)

        Emphasis on the "boring" part. Sci-Fi movies have conditioned us to think that space travel would be "start the journey, press the 'hyper-warp-jump' button, watch a light show out the windows for a minute or so and we're there." Instead, unless we discover some radical new way of traveling through space, it'll be "Start the journey, wait anywhere from a thousand to a hundred thousand years and we're* there." (*Where "we're there", really means "our descendents, born aboard the spaceship, are there even t

    • Re: (Score:3, Interesting)

      by ari_j ( 90255 )
      The Helios probes didn't exactly take 3 months to travel 8 light minutes. I'm not sure where you're getting the numbers, but most likely they mean that the probes took 3 months to get from perihelion to aphelion. The article you linked to on Wikipedia claims their speed record to be 0.000234c, which is over 1/5000th the speed of light, around 3 times the speed you quoted. That's only 100,000 years to go 20 light years. Still impractical.

      The real question is the delta-v required to make the trip, incl
      • by ari_j ( 90255 )
        Oops. Perihelion/aphelion reversed, but of course the time between them is the same in either direction. :)
  • Well hell, if we develop wormhole technology, we can open a gateway, visit Gliese 581g, and be back home in time to watch the next episode of Fringe. Can I be quoted in the Discoblog too?

  • by CompressedAir ( 682597 ) on Tuesday October 05, 2010 @02:19PM (#33797196)
    Project Orion [] could get us there.
    • by Xtense ( 1075847 ) <> on Tuesday October 05, 2010 @02:30PM (#33797392) Homepage

      The theoretical speed for a momentum-limited, 100m orion craft would be 3,3% of the speed of light, so... no. No it wouldn't.

      • Hopefully you can recognize the assumptions in your statement.

      • Re: (Score:3, Interesting)

        by David Jao ( 2759 )

        The theoretical speed for a momentum-limited, 100m orion craft would be 3,3% of the speed of light, so... no. No it wouldn't.

        You missed the point completely. 3.3% of the speed of light isn't enough to get there within our lifetimes, but it's a lot faster than the estimate of "180,000 years based on current space flight technology" quoted in the summary.

        And make no mistake, Project Orion is completely feasible with present-day technology. The only reason why people avoid mentioning it is because it contains the dirty word "nuclear".

    • by MozeeToby ( 1163751 ) on Tuesday October 05, 2010 @02:33PM (#33797432)

      I'd really love to see some college actually do a study on if it would be possible or not. It's hard to say without real research just how much and what kind of resources an ark ship would need over those kinds of timescales. What's the theoretical rate of atmosphere loss? How efficiently can waste be recycled and put back into the ecosystem?

      Using a sperm bank to dramatically increase genetic diversity would significantly reduce the minimum size of the crew, an all woman crew would further reduce the size but would probably cause all new problems. A vegan diet reduces the need to support non-human animal mass, but adds a requirement to be able to synthesize some vitamins and proteins. Enough redundant manufacturing to produce spare parts for everything, including the manufacturing facilities. IMO, it looks hard but not impossible with today's technologies.

  • Let's make sure first that it has, you know, oxygen, and not one of those 95% carbon dyoxide air content some younger planet lacking vegetation may have. Or one of those fancypants sulfuric acid atmospheres that melts your lungs.
  • Damn you, Enrico Fermi, and your infernal paradox []. Damn damn damn!

  • by tverbeek ( 457094 ) on Tuesday October 05, 2010 @02:22PM (#33797254) Homepage

    How long would it take at warp 6, Ensign Chekov?

  • by Overzeetop ( 214511 ) on Tuesday October 05, 2010 @02:22PM (#33797256) Journal

    Just convince some corporation that it has unobtainium.


    Well - he'll have had 3000 years to enjoy his income at that point!

  • by Braintrust ( 449843 ) on Tuesday October 05, 2010 @02:28PM (#33797356)

    Technological limitations aside, this is the first time in several hundred years that we have had a further shore to sail to... a place where no man has gone before, as the saying goes.

    That has to count for something.

    For me this is the most profound discovery in the history of us. Without hyperbole. The only thing I can see superseding it is, of course, the confirmation of life itself out there.

    I think we need a further shore... and I'm glad I lived to see a new one.

    • by dasherjan ( 1485895 ) on Tuesday October 05, 2010 @02:42PM (#33797618)

      We already have plenty of shores to explore in the solar system. They're just not as sexy as another earth type place. ;-)

    • Re: (Score:3, Insightful)

      Mars, Callisto, Ganymede, Europa, Titan, Pluto, Mercury, Iapetus, Miranda, Charon, Eris and a bunch of other "further shores" I have forgotten the names of that are just a tad closer to home.

      But I agree on your other point, Gliese 581g is, possibly, a truly profound discovery. If improvements in remote sensing and telescopes reveal that this new world has an Oxygen rich atmosphere or other solid indications of life (radio?) then it will likely be the most profound and culturally altering discove
  • Radio (Score:4, Interesting)

    by mukund ( 163654 ) on Tuesday October 05, 2010 @02:28PM (#33797360) Homepage
    How about sending some targeted "Hello world" transmissions towards that object first? If they have any intelligent life and a SETI program in place, they may hear us and answer back.
  • Communicate first? (Score:5, Interesting)

    by earthloop ( 449575 ) on Tuesday October 05, 2010 @02:29PM (#33797372) Homepage

    Would it not make sense to communicate first? Radio at 20 light years is a 40 year round trip. You never know, somebody might answer with instructions on how to get there quicker.

    Hey! That's given me an idea for a great film. Is Jodie Foster available for the lead?

    • Re: (Score:3, Insightful)

      by boarder8925 ( 714555 )

      Would it not make sense to communicate first?

      Provided that if there is life out there, and if it's intelligent, said life can understand any of our languages, or would care to take the time to figure out what it meant.

  • Why do we need to go away when we still have to colonize about 80% of our planet?

    The fantasy to live on another planet is irrational.
    • Why do we need to go away when we still have to colonize about 80% of our planet?

      Answer: Click here []
    • Why do we need to go to America when we still have to colonize about 80% of Europe?

      Humanity explores that which seems unattainable. It's human nature.

  • by rotide ( 1015173 ) on Tuesday October 05, 2010 @02:33PM (#33797436)

    What I find exciting is the prospect of a lot of young minds trying to figure out how to get a probe there with the capability of communicating back (within a reasonable time frame) what it finds. And then the science, if it is a habitable planet, of trying to visit it.

    We need a new catalyst to spark imagination and an intense drive to succeed in the sciences.

    Even if it is impossible to venture there, the discoveries and new technologies that we _do_ develop that doesn't quite reach the goal, but is above anything we currently have... Exciting!

  • by Wonko the Sane ( 25252 ) on Tuesday October 05, 2010 @02:34PM (#33797458) Journal

    Everyone is forgetting about Project Orion [].

    The biggest design above is the "super" Orion design; at 8 million tons, it could easily be a city.[6] In interviews, the designers contemplated the large ship as a possible interstellar ark. This extreme design could be built with materials and techniques that could be obtained in 1958 or were anticipated to be available shortly after. The practical upper limit is likely to be higher with modern materials.


    Later studies indicate that the top cruise velocity that can theoretically be achieved by a thermonuclear Orion starship is about 8% to 10% of the speed of light (0.08-0.1c).[1] An atomic (fission) Orion can achieve perhaps 3%-5% of the speed of light. A nuclear pulse drive starship powered by matter-antimatter pulse units would be theoretically capable of obtaining a velocity between 50% to 80% of the speed of light.

    At 0.1c, Orion thermonuclear starships would require a flight time of at least 44 years to reach Alpha Centauri, not counting time needed to reach that speed (about 36 days at constant acceleration of 1g or 9.8 m/s2). At 0.1c, an Orion starship would require 100 years to travel 10 light years. The late astronomer Carl Sagan suggested that this would be an excellent use for current stockpiles of nuclear weapons.[10]

  • Nuclear propulsion. (Score:3, Interesting)

    by MaWeiTao ( 908546 ) on Tuesday October 05, 2010 @02:36PM (#33797498)

    For now a matter-antimatter drive might as well be a pipe dream. We don't have a way to create antimatter in any meaningful quantity. Using the current process it would take 2 billion years to produce 1 gram of anti-hydrogen. Then there's storage. Anti-hydrogen has been kept from destroying itself for 10 seconds. (Thanks, Wikipedia.)

    Before we start even talking about getting to other planets there are a few things we need to do. We need a space station far more robust than the ISS. One that allows manufacturing in space. Heavy-lift vehicles get all the materials we need into orbit. It's all assembled and launched from space. Needless to say, that's far easier said than done. But if we want to engage in real space exploration I think to start outside of Earth's gravity well. Too much energy is wasted just getting spacecraft into space and building them to survive launch and flight through the atmosphere. Although, I suppose even in space they have to withstand similar loads. But the point is that if you start in space you have many more options.

    And I think it's high time we restarted research into nuclear propulsion.

  • There goes next years vacation plans.
  • When I first read this, and someone saying it would take 180,000 years to travel there, I thought, "Maybe we can bring that planet to us!"

    But then the various issues with this, not least of which that location matters when discussing habitability, struck me and I thought, "Okay, that wouldn't work."

    Even if you made a spaceship sized tunnel between here and there, essentially pulling some section of their solar system across the light years to meet with a section of ours...a wormhole if you will...

  • Just had to mention Heim Theory here: []

    Extended Heim theory (EHT) is being researched as a possible way to utilize non-propellant methods of interstellar travel, specifically in overcoming the massive distances involved in any space journey. [39]

  • Current space-travel technology, even accounting for an Orion ship powered by every nuke on Earth, would take so long to get there as to receive a warm welcome by the travelers' own great^N-grandchildren, whose ancestors stayed behind long enough to develop Dilithium Crystals, Warp Drives, and/or whatever technology will whisk travelers there on the order of a few hours.

  • by BJ_Covert_Action ( 1499847 ) on Tuesday October 05, 2010 @02:55PM (#33797830) Homepage Journal
    Sure, chucking a probe 20 lightyears away would be awesome, and if we could scrape together the international will and resources necessary to do that I would be all for such an effort. But what about exploring some of the more exciting areas in our own celestial backyard, if you will?

    To date we have only had landers on a few of our planets. We only have functioning rovers on one. We had an impact probe on only one of the moons circling the gas giants. We have rendezvoused with one asteroid, and we have gotten two probes into the Kuiper belt. So, before we go dumping trillions of dollars (and it will cost at least that much) into a tiny (and it will be tiny) scientific payload to another solar system, can we start funding some serious exploration here first?

    I want to see landers, rovers, and submersibles on Europa, Enceladus, Titan, Ganymede, Io, and Callisto. I want to see regular sample return missions to near Earth asteroids. I want to start a ferry program between LEO and the Earth's surface for more than a handful of elite astronauts. I want to see experimental habitats on the moon, rovers on Venus, probes on Mercury, orbiters around Jupiter, Saturn, Neptune, Uranus, and even Pluto, and I want to have at least ten more robots actively exploring Mars. Don't get me wrong, Gliese 158g is one hell of an interesting planet and we should study it as best as we can with out long range sensors and, as one 'dotter even suggested, perhaps we should try communicating with it. I see no reason to evens start thinking about sending a matter-based payload to that planet, however, until we really take some time and effort to start exploring our own solar system. For as much as we have done here, we still really don't know all that much about our home system. I, for one, am not convinced that there are not colonies of methane-based life on Titan and a whole city of icy fish people swimming under the crust of Europa. Let's not even start talking about the possible cloud people of Venus or the cave-dwellers of Mars...
    • Re: (Score:3, Interesting)

      I'm with you on most of that, but unfortunately with limited budget we need some priority. Colonizing our Solar System, to me, should be our top priority, so we should focus on the places where we stand the best chance of building permanent habitats in a relatively short time. The moon, obviously, plus Mars, asteroids including especially Ceres and Vesta, Jupiter's Galilean moons (though probably not Io), and Titan for its nitrogen-rich atmosphere. It will be very interesting when our Dawn spacecraft rea

  • by MichaelCrawford ( 610140 ) on Tuesday October 05, 2010 @03:32PM (#33798394) Homepage Journal
    It would be easier to build a telescope that could resolve the surface of the planet, than it would be to travel there.

Nondeterminism means never having to say you are wrong.