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I'm pretty certain this is a "no", but I'm a biologist, not a space scientist, and I'm attempting to answer this question over on Biology.SE - basically, if we launched a (very slow) craft/object today towards Alpha Centauri, assuming a 65,000yr travel time, are there any organisms that could survive the trip?

To answer the "how many attempts would it take" part, I'm assuming that there is literally no mechanism that would still retain any power or remain working, and therefore be capable of managing deceleration upon arrival, locating a planet and landing safely - so we'd basically be throwing darts at a very small dartboard very far away. Is this correct?

(I couldn't find any related questions except this one, which was closed without an answer and sounds like was asking about human-crewed ships anyway, and this one, which is much closer but the answers are mostly either about completely passive satellites or not actually answers, but speculation about some of the possible challenges).

I basically want to throw a small rock very slowly at Alpha Centauri, which I assume we have the technology to do even if it takes forever and almost certainly misses.

I'm assuming significant issues would include vacuum welding and micrometeorite bombardment, as well as power sources, demagnetisation, etc.

tardigrade
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    I mean realistically you'd probably have to use self replicating and repairing machines as there's not much else that we currently envision having this type of lifespan. What exactly is your question here? – Dragongeek Feb 27 '18 at 18:36
  • Nothing current would be expected to work for that long. Power is a big problem, radio-thermal-generators are good for decades, but nothing like 65,000 years. That long a cold soak is going to damage the mechanicals. The electronics are going to take a lot of radiation damage. Could we figure out how to do it? Probably if we had to, but it would be difficult and really costly. – zeta-band Feb 27 '18 at 18:52
  • Agreed on the challenges identified in these comments. There's a real need for active control during coast too - it really isn't realistic to consider a purely "ballistic" shot at those ranges - there's too much fuzziness in our n-body calculations, and uncertainty in orbital elements and atmosphere of any potential target - we need to aim at the star in question, and let the probe refine it's targeting as it nears and sensor resolution improves. This really is well outside our current technology. – Saiboogu Feb 27 '18 at 19:25
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    We're not really how to build a clock that can operate for 10,000 years, let alone a spacecraft: http://longnow.org/clock/. – Chris B. Behrens Feb 27 '18 at 22:16
  • I think all of the conceptual answers devolve towards "generation ship". – Chris B. Behrens Feb 27 '18 at 22:17
  • Is your question "Are there any mechanisms that would allow automated landing on a planet after 65,000 years?" or "assuming a 65,000yr travel time, are there any organisms that could survive the trip?" They seem like 2 different questions to me. Unless you mean mechanisms instead of organisms in the 2nd one. – Organic Marble Feb 27 '18 at 22:59
  • @Dragongeek The question's in the title; it's pretty specific. Since we don't have self-replicating machines (well, apart from the ones we deal with over at Biology.SE) it sounds like you're confirming my expectation that the answer is a "no". Feel free to post this as an answer, but it'll need some evidence. – tardigrade Feb 28 '18 at 09:28
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    @OrganicMarble I agree they're two questions; I have answered the organisms one myself at the link (since that was on-topic for Biology.SE). This question is about mechanisms; I am asking it in order to use the answer to improve my own answer about the organisms one. – tardigrade Feb 28 '18 at 09:32
  • @ChrisB.Behrens I've upvoted this since it's the sort of thing I want to see in an answer, but I think this should really be (the start of) an answer, rather than a comment. – tardigrade Feb 28 '18 at 09:33
  • @Saiboogu you don't think if we used a rail gun or something to launch literally billions of very small, inert packages at the target it might work? That's the sort of approach I was thinking of. There's no ethical problem if billions of small bacterial colonies drift in space forever or crash into a star. – tardigrade Feb 28 '18 at 09:35
  • What does automated landing mean? Impact? Slow impact? There are passive methods of slowing down a spacecraft such as solar sails, or, you could just make the spacecraft a massive sphere of ultra light foam, or something which slows itself down when it hits something and has an extremely low density. As for aiming for a planet and hitting it, that would be basically impossible with current technology as we don't even know the exact orbits of planets at Alpha Centauri – Dragongeek Feb 28 '18 at 09:35
  • @zeta-band Sort-of agree, but I was wondering about very, very simple and reliable materials-science "technologies" like bimetallic strips or shape-memory alloys that change configuration when they reach the destination as a response to the heat from the star. I reckon you could probably build something that orients to face an external heat source and then outgasses in a predictable way, for example (although I don't think that would help much, it could allow braking or maybe even increase the chances of insertion into an orbit). – tardigrade Feb 28 '18 at 09:41
  • @Dragongeek Happy with either; an answer addressing slow impact would be preferable to an answer offering high-speed impact, and some idea of the impact speed and likely deceleration and temperature experienced by the payload would be useful. And I'm thinking very much of a shotgun approach - anything that increases the chance of hitting the target would be good, even if it only goes up to 0.01%. – tardigrade Feb 28 '18 at 09:43

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I would say that the answer is "not yet". The field of study in creating these kinds of either hyper-reliable or else self-healing systems is nascent, at best. The only serious project I'm aware of along these lines is the Clock of the Long Now, a clock built inside a mountain and designed to run for 10,000 years.

But even that specification indicates minimal maintenance, which is to say, non-zero. And that implies human intervention, which means it's not entirely automated.

It's worth considering, however, the idea of lithopanspermia - the idea that bacteria may be naturally transferred between planets. What you might do is set up a huge number of small (so you're not nuking the target) asteroids, seed them with bacteria hardy enough to last the trip, and then fire them all in a trajectory that would take them there. Micrometeoroid bombardment, indeed.

Chris B. Behrens
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    Rather than asteroids, what about a large swarm of small darts, each with a cargo of bacterial spores abc each designed to lithobrake and shatter, exposing the spores if it happens to hit a planet. A few billion of them would give you a reasonable chance of hitting a planet if there is one – Steve Linton Feb 28 '18 at 20:18
  • You could encase them in larger lithospheres to protect from radiation that would crumble on atmospheric entry. – Chris B. Behrens Feb 28 '18 at 20:22