Shine a laser beam on your target planet and drop nanobots into the beam. Photons strike the nanobots and imbue them with momentum, eventually accelerating our little "nano-nauts" to some useful fraction of c.
A second, annular laser beam of higher energy surrounds the first beam to keep the little nano-nauts on course. The second beam actively contains the bots (some science types down under figured this out already).
The beams are controlled to track the target planet, again with the second beam keeping the nano-nauts contained in the accelerating central beam.
Turn the central beam off when it's time to decelerate the nano-nauts. If we play nice, the target planet's sun will slow things down with its solar wind.
With a bit of luck, some of our little friends will arrive at the target planet intact. Hopefully we pre-programmed them with instructions, otherwise we can send them orders via laser pulses.
Harvesting raw materials at their destination, the nano-nauts build power stations, farms, habitats, and cloning vats. We then use the laser beam to transmit encoded brain scans of each of us, which are implanted into the colonizer clones as memories.-- the porpoise, Apr 11 2014 Hey this could happen! http://www.reuters....ilner-idUSKCN0X91YE [the porpoise, Apr 12 2016] Yup. Another Halfbakery idea adopted? http://www.nytimes....n-hawking.html?_r=0 [doctorremulac3, Apr 13 2016] //Turn the central beam off when it's time to decelerate the nano-nauts. With a bit of luck, some of our little friends will arrive at the target planet intact.//
Sp.: "Turn the central beam off when it's time to stop accelerating the nano-nauts. With a bit of luck, some of our little friends will impact the target planet at an appreciable fraction of c."-- MaxwellBuchanan, Apr 11 2014 Indeed, Max, decelerating would be a concern. I thought I could hand-wave through that bit. I will suggest that, if we ask nicely, the target planet's sun might project enough solar wind to slow things down to a reasonable approach speed. Solar wind would increase as we approach, so it might work out nicely. A solar parachute, if you will. Idea updated.-- the porpoise, Apr 11 2014 Laser propulsion of solar sails as a form of interstellar propulsion is a pretty well-discussed idea already, and has been for a few decades. And so has interstellar colonization via replicating nanomachines, although mostly among the more out-there singularity types.
The only difference in this concept, as far as I can tell, is the novel concept of a beam aiming system so precise as to track a planet over interstellar distances, and the idea that one should eschew the traditional solar sail and instead use a beam orders of magnitude more intense, so that the requisite photon pressure can be applied to the much smaller area of the payload itself, rather than spread out over a sail.-- Hive_Mind, Apr 11 2014 //Solar wind would increase as we approach, so it might work out nicely// Well, if you rely on solar flux to decelerate, then the maths will probably come out that you gain no advantage by using a laser to accelerate in the first place.
What I mean is that acceleration and deceleration have to match, so you may as well use the sun to accelerate, and the distant star to decelerate.
I could be wrong. But it smells of symmetry.-- MaxwellBuchanan, Apr 11 2014 [Max], I suppose it depends on the superposition of the photon density curves of the laser and the distant star, or something. Acceleration at this end may be very small and gradual. At the distant star it might be more sudden.
[Hive] that is an apt summary. I would also add that the payload survival rate need not be 100% or even 1%, so I see that as a bit of a difference too.-- the porpoise, Apr 11 2014 Sounds a bit like "Router" by Strossy....-- not_morrison_rm, Apr 11 2014 What is that, [nm]?-- the porpoise, Apr 14 2014 //Acceleration at this end may be very small and gradual. At the distant star it might be more sudden.//
I'm not convinced. The acceleration will be some sort of U-shaped curve - highest (acceleration) near to earth/sun, and highest (deceleration) near the distant star.
If you rely solely on the light from each star (sun and distant star), the curve will be a symmetric U. If you try to speed things up by using a laser at this end, then the deceleration at the other end will not be enough to stop the nanonaut.
You can think of it like a ballbearing in U-shaped track. If the U is symmetric, a ball released at the top of the left arm will come to rest at the top of the right arm. If you raise the height of the left arm (equivalent to using a laser to add acceleration), the ball will just fly off the end of the right arm.
In other words, I suspect that you cannot gain an advantage by using a laser to boost the acceleration as the thing leaves earth, unless you can arrange for a laser at the other end to increase the deceleration.-- MaxwellBuchanan, Apr 14 2014 How about this: The first batches splat on the planet until they build up a molten metal crater.
Pause & let cool. Hope the crater is close enough to parabolic & reflective (with the metal from the nanobots).
Now, you have a mirror on the planet, which could reflect your laser back to slow down your approach for the subsequent batches.-- sophocles, Apr 14 2014 [Max], you might be right. I don't know, though.
Think of the laser as a long weak spring and the distant star as a short strong spring. The long spring launches a marble across the floor. The long spring stops expanding and the marble keeps rolling. Eventually the marble hits the short spring, which slows it down with greater force over a shorter distance.
The analogy may not be appropriate, which is where the concept might fall down. I don't know. I find light unintuitive.-- the porpoise, Apr 14 2014 \\Think of the laser as a long weak spring and the distant star as a short strong spring.\\
Ah - I thought the point of the laser was to drive the things faster than by solar radiation alone?
In any case, your laser's thrust will be _added_ to that from the sun, so you'll still have a problem even if the laser is weak.-- MaxwellBuchanan, Apr 14 2014 //Sounds a bit like "Router" by Strossy...
Apologies for obscurity...it's part of the book Accelerando, written by Charles Stross. Some people decide to go interstellar traveling, they copy their minds into a coke-can sized substrate, and (this bit from memory) plan to build bodies at the other end by using nanoware.-- not_morrison_rm, Apr 14 2014 Maybe neutrinos are exactly this idea, on a large scale, but coming from a distant civ?
I mean, our current tech leads us to believe we know how small things are, but each decade, we seem to discover even smaller things.-- sophocles, Apr 14 2014 Well, if the destination star is brighter, we'd need the laser to balance the "U".
Of course all this sounds like people are assuming that the acceleration from the solar sail is larger than the acceleration of gravity for the star you are approaching (and the sun). That may be true for a very large yet light object, but maybe less likely for a nanonaut. I suspect that you'll need to approach the star indirectly to enter a highly elliptical orbit. Hopefully you can get just enough impulse from your solar sail to drop below escape velocity during the first appraoch. Over many orbits with the sail exposed for half the orbit, you can bleed off some energy.-- scad mientist, Apr 14 2014 How does that laser cooling work? Maybe those flavor lasers will slow a thing down.-- bungston, Apr 14 2014 //but each decade, we seem to discover even smaller things.
my bank balance?
//Mint lasers can only add the coloured stripes,
Send the dna of mint in the same laser beam that writes the stripe.-- not_morrison_rm, Apr 14 2014 I read a little about laser cooling. 1. Laser photon thing, gets it excited. 2. In its excitement it emits a photon of higher energy than the one that hit it. 3. Coolth ensues.
If that photon were emitted from a random direction as regards the thing, this should slow it. Emitted back towards original laser will not slow. Lateral emission will move laterally which will be corrected by annular laser. Emission from front of thing will cause it to slow.-- bungston, Apr 15 2014 Looks like something similar is afoot [link]!-- the porpoise, Apr 12 2016 How did I miss this 2 years ago? It's pretty much exactly what Hawking and Milner propose (apart from the building stuff at the destination). I've long suspected that Hawking would be the kind of guy that would stalk the Halfbakery...-- neutrinos_shadow, Apr 12 2016 The Starshot plan is ambitious. From the ArsTechnica article about it, it has this detail:
"The small spacecraft will be equipped with a light sail, and a phased array of lasers in the 100GW range will provide the sail with enough push to get the craft moving at roughly 20 percent the speed of light in just a matter of minutes."
The most powerful (readily available) continuously operating lasers are Industrial cutting lasers which work at up to 5kW. Focusing 20,000 of these lasers at something a few metres in diameter at the distance of the moon (and beyond) is pretty amazing.
Laser light diverges, so to increase range you can fire a laser through telescope. The Hubble telescope can (theoretically) resolve feature on the moon of 200 metres. A telescope would need a diameter of 100 meters to resolve a feature 10 metres in size on the moon (and thus you need that size telescope to fire lasers at a 10 meter solar sail).-- xaviergisz, Apr 12 2016 If Hawking launches a line of traditional flenting products we'll have him bang to rights. Although I suspect only the genuine article is good enough for that speech box thing. I can detect the timbre of a Rentisham's potted capacitor a mile away.-- bs0u0155, Apr 13 2016 random, halfbakery