13 ms·

Keep in mind that at best it would take maybe 1,000 years with current technology to get there with a probe or human-supporting ship. It would be highly unpopul

by afreak 10y ago

Keep in mind that at best it would take maybe 1,000 years with current technology to get there with a probe or human-supporting ship. It would be highly unpopular however as it involves exploding nuclear bombs behind the craft to get it there that fast--that and it would probably cost trillions to build the thing.

fapjacks 10y ago
<Obligatory flamewar-starting "Em Drive" comment>
DominikR 10y ago
Actually the 1000 year number comes from Project Orion in the 1940ties and 50ties. https://en.wikipedia.org/wiki/Project_Orion_(nuclear_propulsion) https://en.wikipedia.org/wiki/Project_Orion_(nuclear_propuls... An updated design from the 80ties calculated a time of 100 years: https://en.wikipedia.org/wiki/Project_Longshot https://en.wikipedia.org/wiki/Project_Longshot And a nuclear fusion design is calculated to achieve 12% of light speed, thereby reducing time to reach the fourth nearest sun system in 46 years. https://en.wikipedia.org/wiki/Project_Daedalus https://en.wikipedia.org/wiki/Project_Daedalus So there are concepts that could make unmanned interstellar travel possible, even within a humans life span, it's just that it costs so much and the incentive is pretty low compared to the incentive countries had for getting objects into space. (primarily military incentives - get spy satellites and nuclear warheads into space to not fall back behind adversaries) I believe that given a strong enough incentive humans could do it, no matter what current consensus is telling us. Humans set out to work on reaching outer space without even having a design on how this could be achieved and we did it anyway.
- jnicholasp 10y ago
  50ties - Fifty-ties -- Fifties - 50s / 50's
  - DominikR 10y ago
    Thanks, English is not my native language. So what is correct, 50s or 50's?
    - jnicholasp 10y ago
      Yeah, I figured, no worries. Your English is excellent, apart from this little oddity. Either way to put the 's' is fine, really, but I think with the apostrophe (50's) is more common.
      - DominikR 10y ago
        Thanks a lot! Very kind of you.
- Trufa 10y ago
  At current rates, it would be 137 thousand years. http://www.ucolick.org/~mountain/AAA/aaawiki/doku.php?id=how_long_would_it_take_us_to_travel_to_alpha_centauri http://www.ucolick.org/~mountain/AAA/aaawiki/doku.php?id=how...
cheez 10y ago
Can you link to more information?
- boxy310 10y ago
  He's probably thinking of Freeman Dyson's Project Orion: https://en.wikipedia.org/wiki/Project_Orion_(nuclear_propulsion) https://en.wikipedia.org/wiki/Project_Orion_(nuclear_propuls...
- afreak 10y ago
  Not the best link but here's something to chew on: http://www.universetoday.com/15403/how-long-would-it-take-to-travel-to-the-nearest-star/ http://www.universetoday.com/15403/how-long-would-it-take-to... >However, despite these advantages in fuel-efficiency and specific impulse, the most sophisticated NTP concept has a maximum specific impulse of 5000 seconds (50 kN·s/kg). Using nuclear engines driven by fission or fusion, NASA scientists estimate it would could take a spaceship only 90 days to get to Mars when the planet was at “opposition” – i.e. as close as 55,000,000 km from Earth. > But adjusted for a one-way journey to Proxima Centauri, a nuclear rocket would still take centuries to accelerate to the point where it was flying a fraction of the speed of light. It would then require several decades of travel time, followed by many more centuries of deceleration before reaching it destination. All told, were still talking about 1000 years before it reaches its destination. Good for interplanetary missions, not so good for interstellar ones. There's talk of other drive systems being able to pull it off but this is the only one that actually has been tested but never built to scale.
- Cozumel 10y ago
  http://breakthroughinitiatives.org/Initiative/3 http://breakthroughinitiatives.org/Initiative/3 http://www.spaceflightinsider.com/missions/stephen-hawking-russian-billionaire-announce-mission-alpha-centauri/ http://www.spaceflightinsider.com/missions/stephen-hawking-r... It says the probe would be able to get there in about 20 years, travelling at 20% the speed of light, that's around 37,200mps. There's going to be a relativistic effect, I think 20 years from our perspective will be slightly shorter from the probes point of view?
boxy310 10y ago
I'm interested in NASA's work on the Alcubierre drive [1]. Still likely to require much more energy than we'll be able to produce in the near future, but 100 years ago we were just getting a firm handle on the basic mechanics of flight. [1] http://ntrs.nasa.gov/archive/nasa/casi.ntrs.nasa.gov/20110015936.pdf http://ntrs.nasa.gov/archive/nasa/casi.ntrs.nasa.gov/2011001...
- krastanov 10y ago
  The Alcubierre drive is just a solution to the equations of general relativity that most probably can not be achieved in practice. Sure, maybe one day we will have drives like that, but we do not have any idea currently that even remotely resembles a warp drive permitted by the laws of nature.
- openasocket 10y ago
  That would require us to create matter with a negative energy density, which has never been detected and is likely impossible.
- deleted 10y ago
  [deleted]
- gnaritas 10y ago
  Still fiction; it relies on magic, i.e. things not known to actually exist.
  - naasking 10y ago
    Magic operates in ways we don't understand. I think we understand negative energy density, we just don't know if it's possible in reality.
    - gnaritas 10y ago
      > Magic operates in ways we don't understand. Witches would disagree. :) > I think we understand negative energy density, we just don't know if it's possible in reality. Exactly as in magic. When you propose things are possible if only X material with some magical property necessary for thing to work, that's speculative fiction. Especially when those constructs only make sense mathematically. Math isn't physics, but physics is math, there's an important implication there.
brazzledazzle 10y ago
I'm reminded of the books Illium and Olympos by Dan Simmons.
- civilian 10y ago
  I've read them--- how and why are you reminded of them by this story?
  - brazzledazzle 10y ago
    I was referring to the comment I replied to.
sehugg 10y ago
There's a $100 million effort to develop tiny spacecraft that are accelerated to 10%-20% the speed of light with ground-based lasers: https://en.wikipedia.org/wiki/Breakthrough_Starshot https://en.wikipedia.org/wiki/Breakthrough_Starshot
- mrfusion 10y ago
  This should be the top comment! Not the guy poo pooing on the idea of checking out this planet.
- afreak 10y ago
  (ignore what I said here)
  - zeven7 10y ago
    The laser is only on each device for 10 minutes. And there are 1,000 of them. So the hope is that at laest 1 in 1,000 will make it.
    - dingbat 10y ago
      if even a tiny fraction of those 1000 tiny probes hit that planet at 20% of speed of light, could that pose a problem? it sounds like a shotgun approach, not so figuratively, using pellets loaded with plutonium.
      - jessriedel 10y ago
        The probes would each be only a few grams, so they'd have about 10^13 J of relativistic kinetic energy, or a half kilotons of TNT equivalent. This can be compared with the 15 kilotons for the (small, by modern standard) Little Boy atomic bomb. So it's probably noticeable for any inhabitants in the area, depending on how the energy is dissipated in the atmosphere, but still quite small on the scale of a planet.
        10y ago
the_rosentotter 10y ago
How does it slow down?
- seizethecheese 10y ago
  This comment left me flabbergasted. Great thinking. What about orbiting the planet and using the lasers when the craft is orbiting towards us in blasts to slow it down gradually?
- dogma1138 10y ago
  It doesn't hence its going to be used for flyby missions and not orbit/capture missions. Many missions to the outer planets are flybys since we can't have enough fuel to actually slow down.
  - omginternets 10y ago
    Would it be possible to drop a payload that would enter orbit?
    - baq 10y ago
      slowing down from that kind of velocity is serious business. you're talking about braking from 75000km/s to ~8km/s and not blowing up in a spectacular explosion.
    - outworlder 10y ago
      The payload would need to slow down to be captured by the planet just the same. Normally you could try aerobraking and the like, but we are talking about relativistic speeds here.
      - jcoffland 10y ago
        There may not be any significant atmosphere for aerobraking. This likely would not be known until long after the probe arrived.
      - 10y ago
ourmandave 10y ago
I wonder what it would be like to be the Nth generation of guys-that-left-in-2016 finally arriving and be greeted by the descendants of the FTL guys that arrived 800 years before you.
- zrail 10y ago
  This is the plot of at least one Star Trek: Enterprise episode.
  - Grishnakh 10y ago
    Which one? I Netflix'ed my way through that whole show a couple years ago and didn't see any like that. It does sound a little bit like "Space Seed" from TOS though, except I don't remember that ship having a particular destination. There was another TOS episode where they find a stray asteroid that turns out to actually be a generation ship inside. And there was some TNG episode where they find a ship with some 20th-century Earthers in cryogenic storage because they had just died of medical ailments. But I don't remember any ENT episodes like this, just some talk about "slow" Earth ships traveling at only Warp 1.5 or so, so that people lived their whole lives on them while on long-term trading missions (their helmsman came from one of these ships).
  - blakeyrat 10y ago
    ... are you sure? There's one episode where they visit a colony established decades previous by a warp 1 or warp 2 ship, but they don't beat the colonists to the planet.
  - MeetTheCryo 10y ago
    I'm pretty sure you're wrong and it was an episode of 'The Next Generation, although I've no idea what the title of the episode was... [0] [0] I've watched the episode only once (I'm not a Trekkie :) ), but if I remember correctly a synopsis of the plot was that decades (at least...) ago an automated ship containing Klingons in cryogenic suspension was launched to colonise a distant planet; in the time following the launch of that ship, the Federation reached and colonised that planet using faster ships, unaware that the Klingon ship was on the way... The crew of the Enterprise [D] has to try to figure out how to stop the Klingon ship from introducing the Federation colonists on the planet to the magic of orbital bombardment (a casus belli) without destroying the Klingon ship (a casus belli).
pjmlp 10y ago
Yeah, I smiled when I read "Just over four light-years" as if just around the corner kind of thing. It might be just around the corner in space travel time, but those are quite a few light years still.
- TheLarch 10y ago
  Also no one knows how to shield a spaceship from the interstellar medium https://en.wikipedia.org/wiki/Interstellar_travel#Interstellar_medium https://en.wikipedia.org/wiki/Interstellar_travel#Interstell... over such distance.
defen 10y ago
Imagine the political implications of choosing who will go onto that ship, as well (assuming the intent is to colonize the world and fill it up with humans)
- deleted 10y ago
  [deleted]
- oslavonik 10y ago
  A poet.
  - sandebert 10y ago
    This is a (likely) reference to Contact (1997), with Jodie Foster. Some celestial event. No - no words. No words to describe it. Poetry! They should've sent a poet. So beautiful. So beautiful... I had no idea.
- ianai 10y ago
  Only the richest, elites. I say we ship them immediately! /s Let's get real, they wouldn't go anyway. It's too good for them here where they have people to do things for them.
  - tzs 10y ago
    > Only the richest, elites. Would they actually want to go? If we are talking about a 1000 year voyage, and not assuming a major breakthrough in cryogenics or longevity, signing up for that trip means you are going to spend the rest of your life on that ship, mostly outside but near our solar system. I don't see that being particularly enticing to rich elites. I don't remember were I read this so cannot properly give credit, but I saw an interesting variation on the generation ship. The conventional approach is to send a large crew, whose job is to operate the ship, reproduce, and raise their kids to take their place, generation after generation until the ship arrives and they become colonists. The variation would be to start with a much smaller crew and large collection of frozen embryos. You make use of the embryos when you arrive to build up the population to full colony size. The advantage of this approach is that since there are fewer people during the trip, you have more capacity for supplies. You can better equip the ship to deal with unforeseen problems. For instance, suppose taking the embryo approach, you can get it down to a crew of 6. You'll have 12 when the crew is overlapping with their kids. Call it 18 if the crew's parents have not yet died when the crew has their kids. Suppose each crew member needs 3000 calories per day. Then on a 1000 year voyage, you need 18 people x 3000 calories/person/day x 365.2422 days/year x 1000 years = 19.7 billion calories. I have a protein bar by my desk at the moment. It is 190 calories, and is about 125 mm x 30m x 20mm = 75000 mm^3. So, 19.7 billion calories x 1 bar/190 calories x 75000 mm^3/bar gives a volume of 7.8 x 10^12 mm^3. Stored in a cubic storage container, this would require a container with an interior length, width, and height of 19.8 m. The "small active crew, everyone else a frozen embryo" generation ship could start out with enough food on board to last the entire voyage, and so would not need to raise food onboard. That alone should greatly simplify things, and greatly improve the chances of making it. Of course they probably would still grow food, but now it would be for added variety and flavor, not a necessity. (I'm not going to do the calculation to see if they could start with enough water for the whole trip. Water is very bulky and we use a lot of it, so my totally uneducated guess is that it would take too much space. However, I believe that efficient water recycling in a closed environment is something we know how to do very well, and so water should not be a problem).
Nadya 10y ago
Proxima Centauri is 4ly away. New Horizons (the Pluto Probe) was travelling at 15.73km/second (just over 34,000/mph) You're looking at closer to 75,000 years - not 1,000 years - to reach Proxima Centauri. E: Did actual maths. Closer to 75,000 not 100,000.
- Retric 10y ago
  New Horizons is a traditional design with chemical propultion. Ion drives should hit ~5.5x that speed fairly easily. (http://www.extremetech.com/extreme/144296-nasas-next-ion-drive-breaks-world-record-will-eventually-power-interplanetary-missions http://www.extremetech.com/extreme/144296-nasas-next-ion-dri...) A larger issue is RTG's are not useful on a very long long timescale. ITER style fusion is likely the best power source for such missions and should hit ~1-10% of light speed fairly easily. But, building something that large is a major issue. On the upside, we have already gone 18.1 light hours, 4.2 light years is not an unreasonable jump.
  - Nadya 10y ago
    ~5.5x that speed is still about 13,636~ years. Much better but still not very realistic.... 18.1 lighthours is 3/4ths of 1 lightday. Which is 1/1533 of 4.2 lightyears or in other words: 0.06% of the way there. Going the remaining 99.94% is a massive jump!
- simplemath 10y ago
  This whole conversation reminds me of Europeans who have never been to the states thinking of flying over for a week, renting a car and visiting the Florida Keys, Times Square, the grand Canyon and Disneyland. At 34k MPH it would take 75 Millenia to reach our literal stellar next door neighbor. Makes the blood boil how vast and empty space really is, when you think about it
  - Nadya 10y ago
    As you mention - comprehending how large/small countries are is tough for some people. Planet-size differences even more so. Many probably don't realize how big the sun is! Then you have to comprehend that on a galactic scale - our sun is really, really tiny [0]. We exist on a tiny spec of dust; inside of a solar system that is no larger than a tiny spec of dust; inside of a galaxy that is no larger than a tiny spec of dust; inside a supercluster that is only a tiny spec of dust. [0] http://i.imgur.com/DUzDo3k.gifv http://i.imgur.com/DUzDo3k.gifv
kilroy123 10y ago
What about a solar sail mixed[1] with, ion engine[2] and nuclear powered[3]? With all those things combined, you would constantly be accelerating for many years. [1] http://www.planetary.org/explore/projects/lightsail-solar-sailing/ http://www.planetary.org/explore/projects/lightsail-solar-sa... [2] http://www.nasa.gov/centers/glenn/about/fs21grc.html http://www.nasa.gov/centers/glenn/about/fs21grc.html [3] https://en.wikipedia.org/wiki/Radioisotope_thermoelectric_generator https://en.wikipedia.org/wiki/Radioisotope_thermoelectric_ge...
gene-h 10y ago
Well using laser propulsion, we might be able to get a very lightweight probe up to 1/4 c using technology that isn't too far off.[0] Coincidentally, the group working on this will be presenting some of their most recent work on this at 2:55 EST today. You can watch that live here[2]. [0] http://www.deepspace.ucsb.edu/projects/directed-energy-interstellar-precursors http://www.deepspace.ucsb.edu/projects/directed-energy-inter... [1]https://www.nasa.gov/sites/default/files/atoms/files/2016_symposium_agenda_0.pdf https://www.nasa.gov/sites/default/files/atoms/files/2016_sy... [2]http://livestream.com/viewnow/NIAC2016 http://livestream.com/viewnow/NIAC2016
- ams6110 10y ago
  Don't forget that halfway there you have to turn it around and start slowing down.
- mikro2nd 10y ago
  The bigger deal is, How do you deal with the ablation problem at those speeds? Given the likely density of H in interstellar space, erosion is your primary problem.
  - nsxwolf 10y ago
    Add the Broussard ramscoop, magnetically deflect the atoms into an accelerator and expel them to add to your propulsion.
ams6110 10y ago
Why would it be unpopular? On the scale of the space involved, any "pollution" would be literally inconsequential. On the cost, I agree and think we have much bigger fish to fry on our own planet than to spend huge sums to discover what is in all likelihood a barren rock.
- mikeash 10y ago
  Frying every piece of electronics on the ground below the ship when you fire it up, and every satellite visible above the horizon, would be bad PR. You could potentially boost it far away from Earth by more conventional means before turning on the nukes, but suddenly it becomes a far larger and more difficult thing.
  - tokai 10y ago
    Just build it in space.
  - Grishnakh 10y ago
    Oh please. Any interstellar ship like this is not going to be built on Earth's surface, it's going to be constructed in space somewhere. Building a craft that large on the surface is far more difficult than just assembling it in zero-g from components, since the stresses of leaving the gravity well through the atmosphere on a large object are huge.
    - mikeash 10y ago
      The point is, not only does it need to be built in space, but it needs to be built (or moved) pretty far away from Earth before you light it up. You can't just build it in Earth orbit. And even that would be well beyond modern capabilities. A ground-launched Orion could be built now, but constructing an interstellar ship in solar orbit will require a lot more work on space access.
      - Grishnakh 10y ago
        A ground-launched Orion could be built now, but it'd make a mess when it launches, and it'd probably be much too small for a useful interstellar mission anyway, because of that scaling problem I mentioned. The stresses are just too high, and it's pointless because you don't need a ship that rugged in space, only for transiting planetary atmospheres. I don't think we have the capability now to build a sufficiently large ship on the ground anyway, even if we decided to say "screw it, we don't care if it's wasteful to massively overbuild this thing"; our materials science probably isn't up to the task. So we need to learn to build things in space anyway. No, we don't really have this capability right now. But we need to assume we'll have it when we need it, and we need to work towards it, and not try any kind of missions requiring it until we do. Thinking about interstellar missions right now is really putting the cart before the horse; we haven't even gotten manned missions beyond the Moon, and even those were pretty simple (walk around, hit some golf balls, drive a rover around), not anything involving real work such as building a habitat or serious excavation or mining. This is why I think all this talk about going to Mars is silly too; we need to be concentrating on closer things, like near-Earth asteroid retrieval and prospecting, and building a Moon base, and figuring out how to mine materials and build larger ships offworld. We need a bigger ship to go to Mars, not some little tin can that you can stick on top of a rocket; something the size of the ISS would be good, because the crew will have to be trapped in it for months, and they need stuff for landing on the surface and doing real work there. You can't do all that with something the size of the lunar modules we launched on the Saturn V.
dTal 10y ago
It's not quite that bad. Have you heard of fission-fragment rockets? Highly feasible, and travel times to Alpha Centauri on the order of decades, not millennia. Baffles me that no one talks about them. https://en.wikipedia.org/wiki/Fission-fragment_rocket https://en.wikipedia.org/wiki/Fission-fragment_rocket
- greglindahl 10y ago
  Someone mentioned them in this discussion ~30 minutes before you posted.
  - dTal 10y ago
    Where? I'm ctrl-f-ing here and seeing nothing older than my comment.
    - greglindahl 10y ago
      OK, the previous ref was for nuclear pulse propulsion, which I'm sure you consider completely different.
      - dTal 10y ago
        They are extremely different. One is a highly impractical idea from the 1940s, and the other is a relatively recent and promising design that continues to be refined.
        m_mueller 10y ago
        What's exactly impractical about a nuclear pulse drive - conventionally launched and activated outside the atmosphere? We know how to build that stuff safely to account for launch failures, it has been done with RTGs many times already.
beefman 10y ago
Fission fragment rockets are well within current technology and can achieve delta-vs of 0.1c at reasonable payload fractions, getting us there in ~ 40yr. Edit: Nuclear pulse propulsion is good for about half that (80yr, not 1000).
Merad 10y ago
Didn't Project Orion determine that it's theoretically feasible to accelerate to not-insignificant fractions of c using NPP? If your journey could average even 0.05c, you can potentially make it within a human lifespan.
- pc86 10y ago
  I thought the issues were: - navigation at any non-trivial fraction of *c* (not running into something that would obliterate the vessel) - slowing down and actually arriving where you wanted to and not overshooting it or stopping .5 LY away
  - marcosdumay 10y ago
    About slowing down, it's pretty predictable. The idea is even to run the ship in constant acceleration. I don't think you'll want to actually navigate that ship. It's a point and go task. But if needed, you rotate the ship and keep accelerating. But I have no idea on how much you'd be able to fix your route after you discovered it is wrong. I think the main issues are how do we make a ship where people can live for decades? And how do we launch it from the ground?
- dghughes 10y ago
  I think speed is only one part of it you'd be dead from radiation over such a long period of time unless you were surrounded by lead.
Trufa 10y ago
At current rates, it would be 137 thousand years. http://www.ucolick.org/~mountain/AAA/aaawiki/doku.php?id=how_long_would_it_take_us_to_travel_to_alpha_centauri http://www.ucolick.org/~mountain/AAA/aaawiki/doku.php?id=how...
m_mueller 10y ago
I think you're conflating a few things here: 1.) A probe and a human spaceship are vastly different problems. Since all a probe really needs is electricity to sustain itself, you could get away with a tiny payload and some long lasting radioactive energy source, light sails or even sending the energy from earth's orbit. Such a thing would be either slow and cheap or fast (a few percent of light speed) and expensive, but not both at the same time and I doubt it would be in the trillion dollar range whatever you do. 2.) I completely agree that sending humans would currently not be feasible within a single nation's budget and the technology for that is still at the very least decades out (cryogenics, EM shielding, better propulsion systems, using mass from cheaper solar system bodies than earth etc.). 3.) 1000 years is what we'd need with conventional current technology. The theoretical limit for a nuclear impulse propulsion drive is 20% of light speed if you want to break or 40% for a fly-by.
c3534l 10y ago
According to Niel DeGrasse Tyson, you could send a tiny, pocket-sized payload and get it there in only a few decades. So if we just want a couple snapshots and not the sort of thing we typically send to orbit planets, it could be done in a reasonable amount of time.

by afreak 10y ago

fapjacks 10y ago

DominikR 10y ago

Actually the 1000 year number comes from Project Orion in the 1940ties and 50ties. https://en.wikipedia.org/wiki/Project_Orion_(nuclear_propulsion) https://en.wikipedia.org/wiki/Project_Orion_(nuclear_propuls... An updated design from the 80ties calculated a time of 100 years: https://en.wikipedia.org/wiki/Project_Longshot https://en.wikipedia.org/wiki/Project_Longshot And a nuclear fusion design is calculated to achieve 12% of light speed, thereby reducing time to reach the fourth nearest sun system in 46 years. https://en.wikipedia.org/wiki/Project_Daedalus https://en.wikipedia.org/wiki/Project_Daedalus So there are concepts that could make unmanned interstellar travel possible, even within a humans life span, it's just that it costs so much and the incentive is pretty low compared to the incentive countries had for getting objects into space. (primarily military incentives - get spy satellites and nuclear warheads into space to not fall back behind adversaries) I believe that given a strong enough incentive humans could do it, no matter what current consensus is telling us. Humans set out to work on reaching outer space without even having a design on how this could be achieved and we did it anyway.

jnicholasp 10y ago
50ties - Fifty-ties -- Fifties - 50s / 50's
- DominikR 10y ago
  Thanks, English is not my native language. So what is correct, 50s or 50's?
  - jnicholasp 10y ago
    Yeah, I figured, no worries. Your English is excellent, apart from this little oddity. Either way to put the 's' is fine, really, but I think with the apostrophe (50's) is more common.
    - DominikR 10y ago
      Thanks a lot! Very kind of you.
Trufa 10y ago
At current rates, it would be 137 thousand years. http://www.ucolick.org/~mountain/AAA/aaawiki/doku.php?id=how_long_would_it_take_us_to_travel_to_alpha_centauri http://www.ucolick.org/~mountain/AAA/aaawiki/doku.php?id=how...

cheez 10y ago

Can you link to more information?

boxy310 10y ago
He's probably thinking of Freeman Dyson's Project Orion: https://en.wikipedia.org/wiki/Project_Orion_(nuclear_propulsion) https://en.wikipedia.org/wiki/Project_Orion_(nuclear_propuls...
afreak 10y ago
Not the best link but here's something to chew on: http://www.universetoday.com/15403/how-long-would-it-take-to-travel-to-the-nearest-star/ http://www.universetoday.com/15403/how-long-would-it-take-to... >However, despite these advantages in fuel-efficiency and specific impulse, the most sophisticated NTP concept has a maximum specific impulse of 5000 seconds (50 kN·s/kg). Using nuclear engines driven by fission or fusion, NASA scientists estimate it would could take a spaceship only 90 days to get to Mars when the planet was at “opposition” – i.e. as close as 55,000,000 km from Earth. > But adjusted for a one-way journey to Proxima Centauri, a nuclear rocket would still take centuries to accelerate to the point where it was flying a fraction of the speed of light. It would then require several decades of travel time, followed by many more centuries of deceleration before reaching it destination. All told, were still talking about 1000 years before it reaches its destination. Good for interplanetary missions, not so good for interstellar ones. There's talk of other drive systems being able to pull it off but this is the only one that actually has been tested but never built to scale.
Cozumel 10y ago
http://breakthroughinitiatives.org/Initiative/3 http://breakthroughinitiatives.org/Initiative/3 http://www.spaceflightinsider.com/missions/stephen-hawking-russian-billionaire-announce-mission-alpha-centauri/ http://www.spaceflightinsider.com/missions/stephen-hawking-r... It says the probe would be able to get there in about 20 years, travelling at 20% the speed of light, that's around 37,200mps. There's going to be a relativistic effect, I think 20 years from our perspective will be slightly shorter from the probes point of view?

boxy310 10y ago

I'm interested in NASA's work on the Alcubierre drive [1]. Still likely to require much more energy than we'll be able to produce in the near future, but 100 years ago we were just getting a firm handle on the basic mechanics of flight. [1] http://ntrs.nasa.gov/archive/nasa/casi.ntrs.nasa.gov/20110015936.pdf http://ntrs.nasa.gov/archive/nasa/casi.ntrs.nasa.gov/2011001...

krastanov 10y ago
The Alcubierre drive is just a solution to the equations of general relativity that most probably can not be achieved in practice. Sure, maybe one day we will have drives like that, but we do not have any idea currently that even remotely resembles a warp drive permitted by the laws of nature.
openasocket 10y ago
That would require us to create matter with a negative energy density, which has never been detected and is likely impossible.
deleted 10y ago
[deleted]
gnaritas 10y ago
Still fiction; it relies on magic, i.e. things not known to actually exist.
- naasking 10y ago
  Magic operates in ways we don't understand. I think we understand negative energy density, we just don't know if it's possible in reality.
  - gnaritas 10y ago
    > Magic operates in ways we don't understand. Witches would disagree. :) > I think we understand negative energy density, we just don't know if it's possible in reality. Exactly as in magic. When you propose things are possible if only X material with some magical property necessary for thing to work, that's speculative fiction. Especially when those constructs only make sense mathematically. Math isn't physics, but physics is math, there's an important implication there.

brazzledazzle 10y ago

I'm reminded of the books Illium and Olympos by Dan Simmons.

civilian 10y ago
I've read them--- how and why are you reminded of them by this story?
- brazzledazzle 10y ago
  I was referring to the comment I replied to.

sehugg 10y ago

There's a $100 million effort to develop tiny spacecraft that are accelerated to 10%-20% the speed of light with ground-based lasers: https://en.wikipedia.org/wiki/Breakthrough_Starshot https://en.wikipedia.org/wiki/Breakthrough_Starshot

mrfusion 10y ago
This should be the top comment! Not the guy poo pooing on the idea of checking out this planet.
afreak 10y ago
(ignore what I said here)
- zeven7 10y ago
  The laser is only on each device for 10 minutes. And there are 1,000 of them. So the hope is that at laest 1 in 1,000 will make it.
  - dingbat 10y ago
    if even a tiny fraction of those 1000 tiny probes hit that planet at 20% of speed of light, could that pose a problem? it sounds like a shotgun approach, not so figuratively, using pellets loaded with plutonium.
    - jessriedel 10y ago
      The probes would each be only a few grams, so they'd have about 10^13 J of relativistic kinetic energy, or a half kilotons of TNT equivalent. This can be compared with the 15 kilotons for the (small, by modern standard) Little Boy atomic bomb. So it's probably noticeable for any inhabitants in the area, depending on how the energy is dissipated in the atmosphere, but still quite small on the scale of a planet.
      - 10y ago

the_rosentotter 10y ago

How does it slow down?

seizethecheese 10y ago
This comment left me flabbergasted. Great thinking. What about orbiting the planet and using the lasers when the craft is orbiting towards us in blasts to slow it down gradually?
dogma1138 10y ago
It doesn't hence its going to be used for flyby missions and not orbit/capture missions. Many missions to the outer planets are flybys since we can't have enough fuel to actually slow down.
- omginternets 10y ago
  Would it be possible to drop a payload that would enter orbit?
  - baq 10y ago
    slowing down from that kind of velocity is serious business. you're talking about braking from 75000km/s to ~8km/s and not blowing up in a spectacular explosion.
  - outworlder 10y ago
    The payload would need to slow down to be captured by the planet just the same. Normally you could try aerobraking and the like, but we are talking about relativistic speeds here.
    - jcoffland 10y ago
      There may not be any significant atmosphere for aerobraking. This likely would not be known until long after the probe arrived.
    - 10y ago

ourmandave 10y ago

I wonder what it would be like to be the Nth generation of guys-that-left-in-2016 finally arriving and be greeted by the descendants of the FTL guys that arrived 800 years before you.

zrail 10y ago
This is the plot of at least one Star Trek: Enterprise episode.
- Grishnakh 10y ago
  Which one? I Netflix'ed my way through that whole show a couple years ago and didn't see any like that. It does sound a little bit like "Space Seed" from TOS though, except I don't remember that ship having a particular destination. There was another TOS episode where they find a stray asteroid that turns out to actually be a generation ship inside. And there was some TNG episode where they find a ship with some 20th-century Earthers in cryogenic storage because they had just died of medical ailments. But I don't remember any ENT episodes like this, just some talk about "slow" Earth ships traveling at only Warp 1.5 or so, so that people lived their whole lives on them while on long-term trading missions (their helmsman came from one of these ships).
- blakeyrat 10y ago
  ... are you sure? There's one episode where they visit a colony established decades previous by a warp 1 or warp 2 ship, but they don't beat the colonists to the planet.
- MeetTheCryo 10y ago
  I'm pretty sure you're wrong and it was an episode of 'The Next Generation, although I've no idea what the title of the episode was... [0] [0] I've watched the episode only once (I'm not a Trekkie :) ), but if I remember correctly a synopsis of the plot was that decades (at least...) ago an automated ship containing Klingons in cryogenic suspension was launched to colonise a distant planet; in the time following the launch of that ship, the Federation reached and colonised that planet using faster ships, unaware that the Klingon ship was on the way... The crew of the Enterprise [D] has to try to figure out how to stop the Klingon ship from introducing the Federation colonists on the planet to the magic of orbital bombardment (a casus belli) without destroying the Klingon ship (a casus belli).

pjmlp 10y ago

Yeah, I smiled when I read "Just over four light-years" as if just around the corner kind of thing. It might be just around the corner in space travel time, but those are quite a few light years still.

TheLarch 10y ago
Also no one knows how to shield a spaceship from the interstellar medium https://en.wikipedia.org/wiki/Interstellar_travel#Interstellar_medium https://en.wikipedia.org/wiki/Interstellar_travel#Interstell... over such distance.

defen 10y ago

Imagine the political implications of choosing who will go onto that ship, as well (assuming the intent is to colonize the world and fill it up with humans)

deleted 10y ago
[deleted]
oslavonik 10y ago
A poet.
- sandebert 10y ago
  This is a (likely) reference to Contact (1997), with Jodie Foster. Some celestial event. No - no words. No words to describe it. Poetry! They should've sent a poet. So beautiful. So beautiful... I had no idea.
ianai 10y ago
Only the richest, elites. I say we ship them immediately! /s Let's get real, they wouldn't go anyway. It's too good for them here where they have people to do things for them.
- tzs 10y ago
  > Only the richest, elites. Would they actually want to go? If we are talking about a 1000 year voyage, and not assuming a major breakthrough in cryogenics or longevity, signing up for that trip means you are going to spend the rest of your life on that ship, mostly outside but near our solar system. I don't see that being particularly enticing to rich elites. I don't remember were I read this so cannot properly give credit, but I saw an interesting variation on the generation ship. The conventional approach is to send a large crew, whose job is to operate the ship, reproduce, and raise their kids to take their place, generation after generation until the ship arrives and they become colonists. The variation would be to start with a much smaller crew and large collection of frozen embryos. You make use of the embryos when you arrive to build up the population to full colony size. The advantage of this approach is that since there are fewer people during the trip, you have more capacity for supplies. You can better equip the ship to deal with unforeseen problems. For instance, suppose taking the embryo approach, you can get it down to a crew of 6. You'll have 12 when the crew is overlapping with their kids. Call it 18 if the crew's parents have not yet died when the crew has their kids. Suppose each crew member needs 3000 calories per day. Then on a 1000 year voyage, you need 18 people x 3000 calories/person/day x 365.2422 days/year x 1000 years = 19.7 billion calories. I have a protein bar by my desk at the moment. It is 190 calories, and is about 125 mm x 30m x 20mm = 75000 mm^3. So, 19.7 billion calories x 1 bar/190 calories x 75000 mm^3/bar gives a volume of 7.8 x 10^12 mm^3. Stored in a cubic storage container, this would require a container with an interior length, width, and height of 19.8 m. The "small active crew, everyone else a frozen embryo" generation ship could start out with enough food on board to last the entire voyage, and so would not need to raise food onboard. That alone should greatly simplify things, and greatly improve the chances of making it. Of course they probably would still grow food, but now it would be for added variety and flavor, not a necessity. (I'm not going to do the calculation to see if they could start with enough water for the whole trip. Water is very bulky and we use a lot of it, so my totally uneducated guess is that it would take too much space. However, I believe that efficient water recycling in a closed environment is something we know how to do very well, and so water should not be a problem).

Nadya 10y ago

Proxima Centauri is 4ly away. New Horizons (the Pluto Probe) was travelling at 15.73km/second (just over 34,000/mph) You're looking at closer to 75,000 years - not 1,000 years - to reach Proxima Centauri. E: Did actual maths. Closer to 75,000 not 100,000.

Retric 10y ago
New Horizons is a traditional design with chemical propultion. Ion drives should hit ~5.5x that speed fairly easily. (http://www.extremetech.com/extreme/144296-nasas-next-ion-drive-breaks-world-record-will-eventually-power-interplanetary-missions http://www.extremetech.com/extreme/144296-nasas-next-ion-dri...) A larger issue is RTG's are not useful on a very long long timescale. ITER style fusion is likely the best power source for such missions and should hit ~1-10% of light speed fairly easily. But, building something that large is a major issue. On the upside, we have already gone 18.1 light hours, 4.2 light years is not an unreasonable jump.
- Nadya 10y ago
  ~5.5x that speed is still about 13,636~ years. Much better but still not very realistic.... 18.1 lighthours is 3/4ths of 1 lightday. Which is 1/1533 of 4.2 lightyears or in other words: 0.06% of the way there. Going the remaining 99.94% is a massive jump!
simplemath 10y ago
This whole conversation reminds me of Europeans who have never been to the states thinking of flying over for a week, renting a car and visiting the Florida Keys, Times Square, the grand Canyon and Disneyland. At 34k MPH it would take 75 Millenia to reach our literal stellar next door neighbor. Makes the blood boil how vast and empty space really is, when you think about it
- Nadya 10y ago
  As you mention - comprehending how large/small countries are is tough for some people. Planet-size differences even more so. Many probably don't realize how big the sun is! Then you have to comprehend that on a galactic scale - our sun is really, really tiny [0]. We exist on a tiny spec of dust; inside of a solar system that is no larger than a tiny spec of dust; inside of a galaxy that is no larger than a tiny spec of dust; inside a supercluster that is only a tiny spec of dust. [0] http://i.imgur.com/DUzDo3k.gifv http://i.imgur.com/DUzDo3k.gifv

kilroy123 10y ago

What about a solar sail mixed[1] with, ion engine[2] and nuclear powered[3]? With all those things combined, you would constantly be accelerating for many years. [1] http://www.planetary.org/explore/projects/lightsail-solar-sailing/ http://www.planetary.org/explore/projects/lightsail-solar-sa... [2] http://www.nasa.gov/centers/glenn/about/fs21grc.html http://www.nasa.gov/centers/glenn/about/fs21grc.html [3] https://en.wikipedia.org/wiki/Radioisotope_thermoelectric_generator https://en.wikipedia.org/wiki/Radioisotope_thermoelectric_ge...

gene-h 10y ago

Well using laser propulsion, we might be able to get a very lightweight probe up to 1/4 c using technology that isn't too far off.[0] Coincidentally, the group working on this will be presenting some of their most recent work on this at 2:55 EST today. You can watch that live here[2]. [0] http://www.deepspace.ucsb.edu/projects/directed-energy-interstellar-precursors http://www.deepspace.ucsb.edu/projects/directed-energy-inter... [1]https://www.nasa.gov/sites/default/files/atoms/files/2016_symposium_agenda_0.pdf https://www.nasa.gov/sites/default/files/atoms/files/2016_sy... [2]http://livestream.com/viewnow/NIAC2016 http://livestream.com/viewnow/NIAC2016

ams6110 10y ago
Don't forget that halfway there you have to turn it around and start slowing down.
mikro2nd 10y ago
The bigger deal is, How do you deal with the ablation problem at those speeds? Given the likely density of H in interstellar space, erosion is your primary problem.
- nsxwolf 10y ago
  Add the Broussard ramscoop, magnetically deflect the atoms into an accelerator and expel them to add to your propulsion.

ams6110 10y ago

Why would it be unpopular? On the scale of the space involved, any "pollution" would be literally inconsequential. On the cost, I agree and think we have much bigger fish to fry on our own planet than to spend huge sums to discover what is in all likelihood a barren rock.

mikeash 10y ago
Frying every piece of electronics on the ground below the ship when you fire it up, and every satellite visible above the horizon, would be bad PR. You could potentially boost it far away from Earth by more conventional means before turning on the nukes, but suddenly it becomes a far larger and more difficult thing.
- tokai 10y ago
  Just build it in space.
- Grishnakh 10y ago
  Oh please. Any interstellar ship like this is not going to be built on Earth's surface, it's going to be constructed in space somewhere. Building a craft that large on the surface is far more difficult than just assembling it in zero-g from components, since the stresses of leaving the gravity well through the atmosphere on a large object are huge.
  - mikeash 10y ago
    The point is, not only does it need to be built in space, but it needs to be built (or moved) pretty far away from Earth before you light it up. You can't just build it in Earth orbit. And even that would be well beyond modern capabilities. A ground-launched Orion could be built now, but constructing an interstellar ship in solar orbit will require a lot more work on space access.
    - Grishnakh 10y ago
      A ground-launched Orion could be built now, but it'd make a mess when it launches, and it'd probably be much too small for a useful interstellar mission anyway, because of that scaling problem I mentioned. The stresses are just too high, and it's pointless because you don't need a ship that rugged in space, only for transiting planetary atmospheres. I don't think we have the capability now to build a sufficiently large ship on the ground anyway, even if we decided to say "screw it, we don't care if it's wasteful to massively overbuild this thing"; our materials science probably isn't up to the task. So we need to learn to build things in space anyway. No, we don't really have this capability right now. But we need to assume we'll have it when we need it, and we need to work towards it, and not try any kind of missions requiring it until we do. Thinking about interstellar missions right now is really putting the cart before the horse; we haven't even gotten manned missions beyond the Moon, and even those were pretty simple (walk around, hit some golf balls, drive a rover around), not anything involving real work such as building a habitat or serious excavation or mining. This is why I think all this talk about going to Mars is silly too; we need to be concentrating on closer things, like near-Earth asteroid retrieval and prospecting, and building a Moon base, and figuring out how to mine materials and build larger ships offworld. We need a bigger ship to go to Mars, not some little tin can that you can stick on top of a rocket; something the size of the ISS would be good, because the crew will have to be trapped in it for months, and they need stuff for landing on the surface and doing real work there. You can't do all that with something the size of the lunar modules we launched on the Saturn V.

dTal 10y ago

It's not quite that bad. Have you heard of fission-fragment rockets? Highly feasible, and travel times to Alpha Centauri on the order of decades, not millennia. Baffles me that no one talks about them. https://en.wikipedia.org/wiki/Fission-fragment_rocket https://en.wikipedia.org/wiki/Fission-fragment_rocket

greglindahl 10y ago
Someone mentioned them in this discussion ~30 minutes before you posted.
- dTal 10y ago
  Where? I'm ctrl-f-ing here and seeing nothing older than my comment.
  - greglindahl 10y ago
    OK, the previous ref was for nuclear pulse propulsion, which I'm sure you consider completely different.
    - dTal 10y ago
      They are extremely different. One is a highly impractical idea from the 1940s, and the other is a relatively recent and promising design that continues to be refined.
      - m_mueller 10y ago
        What's exactly impractical about a nuclear pulse drive - conventionally launched and activated outside the atmosphere? We know how to build that stuff safely to account for launch failures, it has been done with RTGs many times already.

beefman 10y ago

Fission fragment rockets are well within current technology and can achieve delta-vs of 0.1c at reasonable payload fractions, getting us there in ~ 40yr. Edit: Nuclear pulse propulsion is good for about half that (80yr, not 1000).

Merad 10y ago

Didn't Project Orion determine that it's theoretically feasible to accelerate to not-insignificant fractions of c using NPP? If your journey could average even 0.05c, you can potentially make it within a human lifespan.

pc86 10y ago
I thought the issues were: - navigation at any non-trivial fraction of *c* (not running into something that would obliterate the vessel) - slowing down and actually arriving where you wanted to and not overshooting it or stopping .5 LY away
- marcosdumay 10y ago
  About slowing down, it's pretty predictable. The idea is even to run the ship in constant acceleration. I don't think you'll want to actually navigate that ship. It's a point and go task. But if needed, you rotate the ship and keep accelerating. But I have no idea on how much you'd be able to fix your route after you discovered it is wrong. I think the main issues are how do we make a ship where people can live for decades? And how do we launch it from the ground?
dghughes 10y ago
I think speed is only one part of it you'd be dead from radiation over such a long period of time unless you were surrounded by lead.

Trufa 10y ago

At current rates, it would be 137 thousand years. http://www.ucolick.org/~mountain/AAA/aaawiki/doku.php?id=how_long_would_it_take_us_to_travel_to_alpha_centauri http://www.ucolick.org/~mountain/AAA/aaawiki/doku.php?id=how...

m_mueller 10y ago

I think you're conflating a few things here: 1.) A probe and a human spaceship are vastly different problems. Since all a probe really needs is electricity to sustain itself, you could get away with a tiny payload and some long lasting radioactive energy source, light sails or even sending the energy from earth's orbit. Such a thing would be either slow and cheap or fast (a few percent of light speed) and expensive, but not both at the same time and I doubt it would be in the trillion dollar range whatever you do. 2.) I completely agree that sending humans would currently not be feasible within a single nation's budget and the technology for that is still at the very least decades out (cryogenics, EM shielding, better propulsion systems, using mass from cheaper solar system bodies than earth etc.). 3.) 1000 years is what we'd need with conventional current technology. The theoretical limit for a nuclear impulse propulsion drive is 20% of light speed if you want to break or 40% for a fly-by.

c3534l 10y ago

According to Niel DeGrasse Tyson, you could send a tiny, pocket-sized payload and get it there in only a few decades. So if we just want a couple snapshots and not the sort of thing we typically send to orbit planets, it could be done in a reasonable amount of time.