NASA is seriously looking at hibernation ships.
Activity here reminded me that this image is mega-cool.

Very high-res photo in the direction of the galactic center. Phil Plait discusses why this is impressive.
This is pretty much the coolest:
This is quite an old topic, I hope noone has anything against reviving it though.

elfprince13 wrote:
This is pretty much the coolest:
I can imagine how those poor (or should I say lucky?) guys had to hunt the whole ISS for drops of water floating around!

My contribution to this topic:
Breakthrough initiatives plan a probe to Alpha Centauri since the summer 2016: StarChip!
Official website, with quite interesting technical details and the possibility to contribute with your own ideas!

A quick mission summary:
A fleet of about a thousand, gram scale spacecraft is expected to travel at 0.15 - 0.2c (!!!), this equals roughly 45 000 - 60 000 km/s.
Since the Theory of Relativity states that the mass of an object grows with its speed, going toward infinity at speed of light, the actual energy is FAR more than just this relativistic speed itself - which would've been insane anyway. (For curious ones: This statement also means faster-than-light travel is impossible. However, the Alcubierre Drive might be a possible backdoor...)

So, back to our nanocrafts: How would one accelerate a ship with such an energy? Light sails! Solar sails were already proven to work. The weird particles of light, the photons, excert a tiny amount of pressure, when they bounce off of a reflective surface. On a large scale this can be exploited to drive a craft with huge light sails.
For such immense speeds, an array of surface based super-lasers is planned. With a total power of about 100GW (For comparison: No human powerplant is yet able to produce more than 30-35GW) they will accelerate the craft, with its 4m² light sail, over a span of ten minutes.

This poses serious challenges for our crafts:
1) During earth departure: The ground station, aswell as the craft will have to be accurately engineered. Due to atmoshperic turbulences, it is hard to focus the lasers on a 4m² square >100km away. The light sail must be EXTREMELY reflective. Would it absorb any non negligible portion of the energy, it would simply evaporate. The electronics have to withstand immense accelerations of thousands of G's - hard to accomplish given the few gram limit.
2) During cruise: The craft needs to be powered. Solar panels are only useful, if there is a star nearby - for example, Juno at Jupiter is the farthest manmade object from the sun able to use solar panels - they are roughly 24m² big, had to be extremely specialized and still generate only a few Watts of power. We are talking big. We are talking interstellar! So, solar power is not an option. Luckily, there is another source of power, used by probes like Voyager 1 & 2 or New Horizons: Radioisotope Thermoelectric Generators (RTGs)! Those exploit the radioactive decay of some elements and generate electricity from the heat energy. But there is more still: Space is not complete vacuum. There still is some matter. At such speeds, violent collisions are inevitable - and a particle of 1 micron of diameter is estimated to penetrate the probe by ca. 0.5mm! Also, tiny particles will generate heat due to friction. So we need strong shielding - a possible solution would be aiming the craft sideways, so only a small surface is exposed. Also, all the equipment needs to be operable for at least 20 years - that's how long the 4 light-year journey to our nearest-neighbour star will take. Not an easy task given the harsh environment.
3) During arrival: An RTG will only yield tiny amounts of power - and the probe will pass by the system in one to two days. So the scientific operations need to be performed lightning-fast! The speed can be compared to travelling to the moon in 6 seconds. If we estimate a minimum radius for observations equal to the orbital height of our moon, we would have maximally 12 seconds for any science while flying past a planet. With electricity barely sufficient for a power-saving mode.
4) At communications: The main idea of the communications is to recycle the photon thruster and the light sail both for making a dish and communicating with light. This sort of communication is already used on earth for very fast signal transmissions. Due to the 4 light years between Alpha Centauri and us, any data and images will take at least four years to reach us.

Most of these problems are yet to be solved - Breakthrough initiatives plans 20 years for development of the probe. And ANYONE can contribute!

A craft will be equipped with a Light sail, ~150mg RTG, Photon Thrusters, tiny cameras, tiny processors and shielding. No matter how good they are - huge losses due to malfunctions are expected. That's why not one or two probes are launched, but one thousand.

So, with 20 years of develpment + 20 years of flight + 4 years of time for the data transmission back, it will not be before 2060 that we will see the first snapshots of the Alpha Centauri system. But who knows? Many of us probably have the chance of winessing this event, which will surely make it into every history book in the distant future, marking the point, at which humanity extends its sphere of influence to truly other worlds.
So, what if you took the Earth away and substituted it with blueberries? Turns out, Randall (the guy behind xkcd) is not the only one answering what-if questions, as this paper on arXiv someone linked me recently shows, also proving that scientists have a better sense of humor than many seem to give them credit for. But honestly, this was just a really nice and fun read, and I felt like sharing it here. Smile
Yeah he's done a lot of interesting short papers on what-if questions Smile I absolutely love them.
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