Interstellar Probes

[KAL 9000]

How could we get data with a probe from, say, Alpha Centauri?

[UmbralRaptor]

Technically I'd expect so, though we'd need a great deal of R&D in propulsion technologies and possibly some in high powered message lasers. (Check out laser-sail/beamed power propulsion as well as projects Daedalus, Longshot, and Icarus)

[KAL 9000]

Maybe we could use a Starwisp-style probe? The main difficulty would be communicating with the probe.

[fairytalefox]

The only more or less plausible way to communicate with the probe I can think of is to manipulate the star's light. A planet-size mirror, or a cloud of vapor, something like that. My point is, we have to either use an existing extremely powerful source of radiation or create our own one.

Yes, it's far beyond our current or near future technologies, just like the probe itself.

Or maybe we can just refuel the probe and return it back home. Somehow. ISRU or whatnot.

[Apexazimuth]

I think the first interstellar probe mission will be through the use of swarm probes; hundreds to thousands of cubesat-or-smaller-sized probes equipped with microthrusters, similar to MIT's microthrusters (http://www.engadget.com/2012/08/18/mit-microthrusters-for-cubesats/).

In order to communicate with earth at that distance, a very, very large area transmitter/receiver would be needed, so instead of using a gigantic, heavy dish, each swarm probe would be equipped with a micro transmitter/receiver and the swarm would operate together to amplify the signal, in the same way that the deep space network uses multiple arrays across the globe.

A swarm of interstellar probes would be resilient to damage and failure through high-redundancy (knock out a few probes and there are still a few hundred left).  And due to their size and networking, there's less of a limit to the total mass of the swarm, since they could be launched in phases.  This would also eliminate the need for in-space assembly.

 

Obviously we don't have the microtechnology to do this yet, but our technology seems to get smaller just as fast or faster than it gets "better".

[SargeRho]

Lasers. It's not very hard to outshine a star in a narrow range of wavelengths using lasers.

[KAL 9000]

The probe would probably be solar-powered. That way, when it reached Alpha Centauri, its light would hit the solar cells and power the probe up. For a solar sail probe, returning would be "easy":

Upon arrival, the probe detaches the outer part of the sail. That way, laser light from Earth would bounce off it and hit the probe, slowing it into orbit. After collecting data, the process would repeat, and the probe would accelerate back to the Solar System. When it gets back, a final pulse of laser light would slow it into Earth orbit, where collecting the Science would be "simple".

[PB666]

How long do solar cells last? Certainly not 40,000 years are even 4000, prolly not even 4 hundred. 

[SomeGuy123]

We ride the probes.

1.  We continue research neuroscience, pouring ultimately trillions of dollars into it, until we have massive machines that occupy entire buildings that can emulate the circuits of an entire human brain.

2.  We build 3d computer chips that can implement the machine that took up a whole building in about a cubic meter or less of space and less than 1000 kilograms.

3.  We take people who are terminally ill or just tired of being mortal.  We preserve their brains using plastic or freezing, then slice them into very fine pieces, and scan them with electron beams.  They get loaded into the chips from #2.  

4.  Among the pool of people we have as digital beings in #3, we select some of them to be astronauts.  We build some kind of starship probe and they ride them.  No return journey is planned - instead of planning to get our starship back, the astronauts send a digital data stream that includes the changes in their own mind as they experience the mission.  Using this digital data stream, you can sync up a local (in Sol) copy of the astronaut's mind  and basically have the astronaut back home.

The advantages of this approach are myriad, but one of the big ones is that these "astronauts", not being limited by human lifespans and capable of thinking faster than living humans, could become experts on every field of science, engineering, and technical ability needed to produce the very starship they are riding.  They would literally be capable of tearing the ship down to the bolts and rebuilding it, and they would have the same knowledge and skills as the people who designed the ship.  This both means that once they arrive at another star, they could mine some asteroids and launch followup missions to other stars, and they could solve any fixable technical problem on the journey.

The ship would have to have equipment on board ultimately capable of recycling back to atoms and then remanufacturing every component on the ship.  Using today's tech, we can barely imagine such equipment, and it would be very large, but nanotechnology could enable you to eventually miniaturize such equipment to maybe the size of a shipping container and 10 metric tons or so.

This is how you deal with the immense length of the journey (centuries, maybe over 1000 years).  You continually replace worn and damaged components.  The minds of the crew are modular and you can replace individual compute/memory modules without losing any data.

Frankly, I don't think interstellar travel is possible with anything less.  I think you have to have sentient crew, you are years from radio messages getting back and forth, and the ship is encountering a constant damaging stream of high energy particles.  You have to be able to restore components as they get damaged.  Once you arrive at the destination, being years from any commands, you need human level judgement to decide what to do next.  And since bringing actual humans on a centuries long journey is even harder, this is probably what will ultimately be the solution, if we ever have interstellar journeys.

Edited December 1, 2015 by SomeGuy123

[PB666]

Humans are not  computers are neuromuscular system is integral with the CNS. NOt a simple as you think, unused human systems have to be fiktered out and new observational systems would have to be integrated in.  Anyway it doesnt matter having a cyborg at alpha centuari is of no more use than having a simple computer, it doesn't solve the call back home and inform mission. 

[SomeGuy123]

2 hours ago, PB666 said:

Humans are not  computers are neuromuscular system is integral with the CNS. NOt a simple as you think, unused human systems have to be fiktered out and new observational systems would have to be integrated in.  Anyway it doesnt matter having a cyborg at alpha centuari is of no more use than having a simple computer, it doesn't solve the call back home and inform mission. 

It doesn't? You don't see the possibilities here?

Look, first of all, your "humans are not computers are neuromuscular systems" is correct but you're strawmanning.  Obviously, any civilization capable of emulating the core of a brain can emulate a virtual body that is adequate to act like an I/O interface.  Or just build a real body.  The fact that quadriplegics are still sentient beings pretty much disproves your point entirely.  (not saying the crew of a starship would have poor I/O as if they were a quadriplegic, just it shows you do not need a data connection to a human body at all to be sentient and capable of making decisions) 

Second, once you can convert a human being to a few petabytes of data, you can travel to the stars quite easily.  Once the destination star has a receiver (probably high frequency laser light would be used) you just encode the visitors as a bitstream.

Concerned with having your body destroyed and not having a backup?  Not to worry.  Prime you never leaves, you send a copy to go exploring, and then the copy returns a decade or so later with the memories of a few years at the other star.

Look, this is the only feasible way.  Instead of trying to send a colony ship big enough for primates (and with adequate radiation shielding), you send something just barely large enough to make it, with enough smarts and manufacturing capability at arrival to build a receiver.  You never send another ship to that star again, just data.

Edited December 2, 2015 by SomeGuy123

[KerbMav]

SomeGuy123, I think you unintentionally touch deep philosophical and ethical topics.

The movie "The 6th day" touches a similar topic: The antagonist - when mortally injured or maimed or just severly damaged but still alive - loads up his mind into a clone of himself and then disposes of the damaged body. As the clone only receives a copy of his mind, the old body is still him, still a sentient being, still an individual, still very much alive. How mentally deranged must someone be to copy his mind to a healthy body and instantly forget or willingly ignore he has been this person in the injured body - and still is? The mind has not undergone a spritual soultransfer leaving the old body behind, it is just a copy - a copy that than chooses to kill its other (not former!) self to remain unique.

The movie "The Island" deals with clones serving as organ banks for their "originals"/the customers. These customers agree to have a real human being grown from their DNA and to kill this new human being should they ever need spare parts.

Back to your suggestion: A copy of the downloaded mind is sent on a century long voyage, the mastercopy (Prime you, as you call it) remaining on earth, maybe even consenting (are they being asked or treated as property of the ministry of science?) that its copy has to endure the hardships of the voyage (does the copy get to decide for itself too?) - the question remains, would it be the right thing to do?

[SomeGuy123]

1 hour ago, KerbMav said:

SomeGuy123, I think you unintentionally touch deep philosophical and ethical topics.

century long voyage, the mastercopy (Prime you, as you call it) remaining on earth, maybe even consenting (are they being asked or treated as property of the ministry of science?) that its copy has to endure the hardships of the voyage (does the copy get to decide for itself too?) - the question remains, would it be the right thing to do?

The problem is these "deep topics", as handled by authors of the past, are handled in asinine, childishly stupid ways.  Philosophers aren't engineers or programmers, and lack the ability to answer  anything, just raise questions.   Virtually all of the objections come from the fact that previous versions of this basic story lack the capability of a "memory merge".  Memory merges would be a technically very difficult thing to accomplish - if you thought merging binary trees was bad, merging 2 massive neural network trees, where at identical places in the network you have conflicting node values, is even worse.

But it's probably possible.  Certainly a much easier problem to solve than the task of actually getting to the point of having the problem in the first place.  Early merge techniques might be pretty lossy but there probably is a near-lossless way to merge 2 forked personalities back into a single personality again.  (by "probably", I actually mean a brief analysis of the problem shows at least for short splits it's easy to do.  In your own mind, you have mornings where you ate eggs and mornings where you ate cereal, right?  So if clone 1 ate eggs and clone 2 ate cereal, then after you go to sleep, upon awakening you remember both mornings.)

Merging answers virtually all of the objections because it stops these identity issues cold.  Identity issues are just a temporary thing.  You'd be constantly merging in the streaming experiences of your "clone" being sent to the other star, and they'd be constantly merging with you, so in reality you would remain the same person.  Any hardships you "subject" your clone to you would be subjecting yourself to, as you would remember them...

Edited December 2, 2015 by SomeGuy123

[Scotius]

As human beings are not machines or computers, philosophy very much applies to us. And asking questions is very important - even if sometimes there is no clean-cut answer. "Should we really do this?", "Is this the right thing to do?", "Is it worth it?", "Do i have the right to demand such sacrifice from my fellow man?"

[SomeGuy123]

6 minutes ago, Scotius said:

As human beings are not machines or computers, philosophy very much applies to us. And asking questions is very important - even if sometimes there is no clean-cut answer. "Should we really do this?", "Is this the right thing to do?", "Is it worth it?", "Do i have the right to demand such sacrifice from my fellow man?"

I'm saying it's dumb to get stuck on questions because you aren't creative enough to see the answer and can't be bothered to research it further.   There are many questions in life that we don't have answers to, but "what would you do if you were a digital being and you had copies of yourself" is not one of them.  Digital systems can be edited, merged, backed up, data corrected, accelerated, and have a dozen other positive properties about them that would make us vastly harder to kill or corrupt if we could migrate our minds to them.

[Scotius]

Asking questions came first "What is that thing?", "Why does it work?", "How does it work?", "Can i build it?", "What will happen if i do this?". Every advance in science or engineering starts with a question. Questions about our world got us from caves to the Moon so far. When we'll stop asking them...well. We won't be Homo sapiens anymore. Your "digital being" might be a fine example - will it still be "human", or just a program set to work like a human being would?

Edited December 2, 2015 by Scotius

[KerbMav]

For me one of the basic principles in a society should be the freedom of choice, refined by setting the bounderies for ones freedom where the freedom of another begins. Therefore I do not think it is dumb to raise these questions - without saying from the start "we must never do this".

If you have the technology and find someone who is ready to hand over his brain to have its contents be digitized and the resulting data be edited as you need it you two can have all the fun in the world for all that I care. But maybe you are not creative enough to see the possibilities to abuse this technology or the person subjected to the process. It is never dumb to ask questions.

 

Interposed question: Have you read The Queendom of Sol science fiction book series by Wil McCarthy?

Just asking because mankind there had the technology to deconstruct a body into its molecules and reconstruct it again, younger, healthy, renewed, with blue skin, two ... organs, etc. - and also to duplicate themselves and merge both versions afterwards including memories. They had some trouble with people copying themselves to make slaves, abuse the copy in some way or another and even kill "themselves".

[RainDreamer]

Sooo, maybe we should get back to the probes rather than the logistics of sending human minds on them. By the point we can do that, we probably have much, much more advanced technology than we could even begin to comprehend now. 

I was thinking sending swarm probes too, but in waves, so the waves of probes sent will form a line between our destination and us, creating a sort of connection. Still, maybe when we are seriously thinking about exploring other stars systems, we would already have the kind of technology to colonize planets and create our own environments, so we can launch generation ships or something similar as relays.

[SomeGuy123]

If you didn't care about decelerating, couldn't you mine out Luna and build gigantic space gun that can fire a small probe, maybe soda can sized, at 0.1 C or so?  It would use some kind of nuclear battery and after launch it might unfurl some antenna and sensors.  You'd have a big honking array at the gravitational lensing point to pick up the very weak radio signals from this probe.

I still think we would need a form of human immortality - the digitizing method I mentioned above is the most technically plausible method I know of - to embark on a project like this.

That is because even if we have self-replicating robots, a project like this might take 20 years to build the space gun and launch the first of the probes.  So, it would be about 70 years before you first got an up close glimpse - at an ultra high speed flyby pass - of alpha centauri.  Long after the billionaires or politicians who funded the project are gone.

Edited December 3, 2015 by SomeGuy123

[AngelLestat]

Solar sails probes with the science instrument imprinted in the same sail, using graphene or CNT with quarter wave holes in the sail, you can make a surface reflecting with almost no mass.

The same sail works also as parabolic to help in the laser communications, in a close diving by the sun, you can reach 7% the speed of light and you can brake using the same method when you reach the star destination.

The sail would be cheap to make so you would not waste a lot of money until you get it.  Once you get it you can sent more than one and at many stars. Even higher speeds can be achieve it if you reduce your diving distance in the apogee. Superconductor "weights" can move over magnetic veins on the sail to equal loads and shape.

Edited December 3, 2015 by AngelLestat

[SomeGuy123]

Got a source for 7% of the speed of light?  Photon sail acceleration is abysmal - I know this because a solar sail is equivalent to a photon drive powered by a perfectly efficient solar panel, which requires 300 megawatts/newton.

And if you fly close to the sun, yes your acceleration is higher, but if your acceleration is higher, you hurtle away from the sun faster, reducing the acceleration.

I'd have to check the math on it but even the roughest of wild ass estimates seems to say you wouldn't have enough thrust to hit even a tiny fraction of the speed of light before you were too far from the sun.

Yes, a solar sail probe would be really nice.  If you have really really compact nanotechnology you could use it to fly interstellar missions with ease, and actually set up industry on the other end, so you'd only ever have to do this once.

 

[AngelLestat]

I show the links and I provide more math here:

The thing is that like radiation follows the inverse square rule, each time you get close to the sun, the power by m2 increase a lot, so with that power over a very light sail, the acceleration you get is close to 4000g. That is why you need to imprint the instruments in the sail itself, bidimensional bodies does not get affected by huge accelerations (in case you can kept that constant in the whole area).

Of course accomplish that is super difficult, but the development to that point is very cheap. We would be able to make the first graphene quarter wave sails (or something similar) in 10 years, from that point you can launch some and start practicing to see how much close you can get, starting from 0.3au periapsis to 0.007au which is your goal.  This might take 30 or 40 years more from that point.

But the good news is that these sails would be very cheap, you dont even need higher area sails to test this, the power-mass ratio is the same.

If you try to make a conventional interstellar probe using fusion or other technology, its mass will be huge, thousands of tons, and we know almost nothing from the interstellar medium, what if we lose it?

With the sails you can sent a lot. Other methods like a huge particle accelerator or something similar had their issues too, first you need higher accelerations if you dont want to increase to the infinite the cost of your accelerator. You can not brake on destination. A solar sail if accomplish to brake in destination, it can explore the whole star system with all its planets.

[KAL 9000]

What about a nuclear pulse drive (miniaturized with nanotechnology)?

[SomeGuy123]

3 hours ago, KAL 9000 said:

What about a nuclear pulse drive (miniaturized with nanotechnology)?

Nuclear fission requires a critical mass.  There has to be a minimum quantity of fissionable material present (a few kilograms) or you don't get a chain reaction.  Fusion also has critical mass requirements, albeit for a different reason (only a tiny puff of fusion fuel is needed to get a reaction.  It is the apparatus in the fusion reactor - lasers or magnets or electric fields, etc - that forces the fuel to fuse.  However, scaling laws mean you actually want a very large fusion reaction going because you only have to pay to press on the fuel at the surface of the plasma sphere, so bigger fusion reactors give dramatically more power output per unit of equipment mass)

[Spaceception]

A 2 stage probe slightly shorter and several times wider than a Falcon 9 driven by 2 Mini-Mag Orion pulse drives, with laser communication and a small space-capable 30MW nuclear reactor with enough fuel to last 120 years. (It would be built in space)

Edited December 3, 2015 by Spaceception