it might be prudent to first consult with the legal experts and diplomats of the Galactic Council, to clear this type of activity with them first, minimize interpretation of this probing as a hostile interstellar act.
Clearing it with the Galactic Council definitely sounds like a good idea. Do you have their phone number handy? I seem to have deleted their contact info by accident.
It made me realize that the civil defense films we watched in the '50s weren't so misguided after all:
https://www.google.com/#q=when+you+see+the+white+flash+duck+...
An intelligent civilization with a 1000 year head start whose presence was just proven by device that arrived at 10% the speed of light would pretty much scare any government on earth.
I would assume it would scare the aliens there too.
Or if we sent them in single file several seconds apart they could each relay what they see to the ones behind them and then back to us. Effective oh giving us a long exposure.
http://www.centauri-dreams.org/?p=31913
Nothing that could be implemented in any foreseeable future though.
Simply: we slam the probe into the planet, a few milliseconds after it transmits the final images. One gram going at 20% of the speed of light has kinetic energy that bears comparison to the Hiroshima bomb.
At a steep angle of entry, the huge entry glow will give a reading of the atmospheric molecular makeup. And if we can ionize some of the crust, massive space telescopes can get a spectroscopic measurement of the composition, four light years away.
You can watch it live here: http://livestream.com/viewnow/NIAC2016
A single probe in orbit could obviously do this but with this idea there's no way to slow down.
http://www.lunarsail.com/LightSail/rit-1.pdf
>The lightsail is built in two sections, an outer doughtnut- shaped ring, and an inner circular section 30 km in diameter. This 30 km payload section of the sail has a mass of 71 metric tons, including a science payload of 26 metric tons. The remaining, ring-shaped "decel" stage has the mass of 714 metric tons, or ten times the smaller payload "stage". The central payload section of the sail is detached from the larger stage and turned around so that its reflecting surface faces the reflecting surface of the ring-shaped portion (see Fig. 4). At a time 4.3 years earlier, the laser power from the solar system was upgraded to 26 TW (there are 37 years to get ready for this increase in power). The stronger laser beam travels across the space to the larger ring sail. The increased power raises the acceleration of the ring sail to 0.2 m/s2 , and it continues to gain speed. The light reflected from the ring sail is focused onto the smaller sail, now some distance behind. The light rebounds from the 30-km sail, giving it a momentum push opposite to its velocity, and slowing it down. Since the smaller sail is 1/10 the mass of the larger one, its deceleration rate is 2.0 m/s2 , or 0.2 g. The light flux on the smaller sail has increased considerably, but it is only two-thirds of the maximum light flux that the sail can handle.
That faster ship just won't appear out of the blue.
You need to launch slower ones to get to the faster ones.
Its like the original inventor of the car opting not to build it because someday there would be a Ferrari.
Sounds like the interstellar version of Zeno's paradox.
Yet another comment plugging a story involving some novel interplanetary travel (this one involving a species from a red dwarf): https://en.wikipedia.org/wiki/The_Mote_in_God%27s_Eye
0.20 c
The press release was made in July 2015, and there has been no communication about it since then. I'm not sure how seriously to take this group.
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).
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.
[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).
The resulting practical problem is that the energy requirements necessary for the solution are far greater than what we can feasibly achieve now or in the future (exotic matter's existence notwithstanding).
But the fact that a physicist was able to derive this metric (energy requirements aside) is significant. Given the history of science, I would not discount the possibility that someone else will come along in the future with another solution which lowers the energy requirements to something feasible. But we can't predict this.
But isn't it amazing that the math checks out at all? I find it inspiring...
https://en.wikipedia.org/wiki/Alcubierre_drive#Experiments
> In 2012, a NASA laboratory announced that they had constructed an interferometer that they claim will detect the spatial distortions produced by the expanding and contracting spacetime of the Alcubierre metric. The work has been described in Warp Field Mechanics 101, a NASA paper by Harold Sonny White.[5][6] Alcubierre has expressed skepticism about the experiment, saying "from my understanding there is no way it can be done, probably not for centuries if at all".
> In 2013, the Jet Propulsion Laboratory published results of a 19.6-second warp field from early Alcubierre-drive tests under vacuum conditions.[33] Results have been reported as "inconclusive".[34]
> Although the metric proposed by Alcubierre is mathematically valid (in that the proposal is consistent with the Einstein field equations), it may not be physically meaningful, in which case a drive will not be possible.
That drive is nothing more than speculative science fiction.
Also, the energies involved are absurd.
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
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
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.
http://www.ucolick.org/~mountain/AAA/aaawiki/doku.php?id=how...
It might be just around the corner in space travel time, but those are quite a few light years still.
Edit: Nuclear pulse propulsion is good for about half that (80yr, not 1000).
Many missions to the outer planets are flybys since we can't have enough fuel to actually slow down.
Although I'm not sure these probes are at all steerable, either autonomously or remotely.
Even if your probe had the computing power to run orbital mechanics calculations, there's no guarantee that it'd be in a position to actually make it work when it got there. Of course, that's ignoring the mass constraints involved.
But that doesn't discount the value of even 'just' flyby missions. The scientific benefit would be, literally, incalculable. And the data could help with followup missions, assuming we develop a drive system that could get there and slow down.
Many galaxies we see are moving at very high speeds due to the expansion of the universe hence the doppler shift and we can take both optical and radio images of them.
I'm not an RF/Optical engineer but I would think that it would be possible to capture and send some data back to earth even its minimal it's still might be better than nothing / what we can get from earth/our solar system, at the end we only might have to account for the doppler shift.
IIRC there have been also other tricks like deploying very large sails and using them as drag chutes or using some mechanical trickery and deploying a very small probe by literally like having it on some pendulum and some other weird stuff so you would transfer most of the momentum it has to the probe and you'll release it with considerably less momentum than the rest of the spacecraft.
I suppose it's possible that the laser could produce a much more stable and precise trajectory, while a magsail would just slow it's descent towards or accelerate it away from the sun. But I think it's more likely to be a case of the materials science and energy density being in favor of the laser method over sails.
What if we used lasers to send a fleet of laser ships with powerful one-time-use chemical lasers, then the front set of laser ships fired the same kind of beam back at the rearmost ship to to slow it down?
If you launch a strong magnet in interstellar space, it will slow down relatively to plasma by deflecting charged particles.
In order to speed up, you need to spend energy.
The symmetry is broken between accelerating and slowing down relatively to interstellar plasma (Edit: or solar wind).
I assumed the magsail operated in a similar fashion to a solar sail, depending on the solar wind. If the destination's solar wind was sufficient to slow us down, I expected that the Sun's solar wind would be sufficient to speed us up.
Thanks for the explanation!
What about orbiting the planet and using the lasers when the craft is orbiting towards us in blasts to slow it down gradually?
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.
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.
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).
tbh I think storing enough food for the journey is going to be the least of all problems
Or maybe an all female crew that does crew replacement either using frozen sperm or frozen embryos, and selects for female replacements.
When the ship arrives and it is time to start the colony, I don't think you'd try to grow to thousands of people quickly. I think you'd want to go slow early to make sure you understand your new environment. Maybe 12 years out, the crew switches from 1:1 replacement to 3:1. Sticking with 6 as the main crew, plus possibly up to 6 of the crew's parents still alive, plus 18 kids. I think you'd want to spend a few years based on the ship studying the planet and conducting research expeditions to figure out if the planet really is suitable for colonization and figure out dangers that unmanned probes and study from Earth may have missed. When that is done, the kids should be 18 or so, and you can start the colony with them and with their grandparents, with the main crew staying with the ship to provide support. That would give 18-24 people on planet attempting to live there, but not needing to be self-supporting yet because of the ship.
In a few years, the colony population should start naturally growing. If the babies do OK, people can be encouraged to have bigger families, with one or two per family being from the frozen embryos and the rest produced the old fashioned way.
> tbh I think storing enough food for the journey is going to be the least of all problems
Yeah, there will be a lot of problems.
Many of the hard ones will not even be technical. For instance, you'd want to have some way to stop from happening something that happened to a colony in Larry Niven's "Known Space" universe. When the colony ship arrived the crew decided to set up the colony so that the crew was the ruling class and the colonists essentially serfs.
The ship in that Niven story wasn't a generation ship. Crew and colonists were cryogenically suspended for the trip, with the crew being automatically revived when the ship arrived. I supposed one advantage of the traditional generation ship is that it has some protection against that scenario because during the trip everyone is crew.
I would suspect you would want to have at least 10-20 people in each 5 year age bracket. Then people will have a fighting chance at developing their own social lives and maybe even their own culture.
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.
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-inter... [1]https://www.nasa.gov/sites/default/files/atoms/files/2016_sy... [2]http://livestream.com/viewnow/NIAC2016
[1] http://www.planetary.org/explore/projects/lightsail-solar-sa... [2] http://www.nasa.gov/centers/glenn/about/fs21grc.html [3] https://en.wikipedia.org/wiki/Radioisotope_thermoelectric_ge...
[1] http://ntrs.nasa.gov/archive/nasa/casi.ntrs.nasa.gov/2011001...
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.
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.
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.
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.
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.
- 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 awayI 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?
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.
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.
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!
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
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.
https://upload.wikimedia.org/wikipedia/commons/d/d0/Comparis...
This is a bloody big country.
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.
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?