Voyager is about to break out of our solar system any time now.
I think Voyager 1 illustrates very well the enormity of the task facing anyone who has ambitions of going to the stars. The basic facts are these: it is the fastest ever man-made object, clocking in at about 38,000 miles per hour, and it was launched nearly 35 years ago. It has been traveling so fast for so long, and only now is it getting anywhere close to the interstellar medium. It may still be decades before it gets there because we don't know exactly how far away it is.
And that's just for leaving
our solar system, never mind entering another. If it were heading towards our nearest neighbor, Proxima Centauri, it would take about 74,000 years to get there. 4.3 light years; a tiny hop as far as astronomical distances are concerned. We may have to go hundreds or thousands of light years to find a planet suitable for colonization.
And Voyager is just a probe. It has no need to carry propellant, no need to carry air, food, water, plumbing, sanitation, radiation shielding, or entertainment for a human crew. The fastest a
human has ever traveled was 25,000 miles per hour on board Apollo 10 during re-entry. On a small craft capable of supporting three men for just 8 days.
But what we do have going for us is time. Assuming we manage to avoid nuking ourselves into oblivion, we may have millions of years before an extinction-level event comes along, and we may only really need a few hundred or a few thousand years to do it. The most feasible design for an interstellar spacecraft using current technology was Project Orion; a massive and heavy craft propelled by a series of nuclear explosions. The largest feasible designs would be capable of reaching about 10% of the speed of light. It would still take longer than an average human lifespan to get to Proxima and back. More fancifully, we may be able to construct craft that propel themselves via the annihilation of matter and antimatter. Or we could create and harness a micro-black hole which would convert any matter you place into it into huge amounts of Hawking Radiation (essentially being a perfect matter-to-energy conversion engine), which you could direct out of the back of the ship. These designs would have the potential of reaching much more respectable fractions of light-speed.
Or we could forget about speed and construct immense city-ships in space, which take generations to reach their destinations. Less ambitiously, we could avoid a lot of the technical difficulty by sending embryos in small probes, to be artificially grown and raised by robots upon arrival.
And in the meantime, there's plenty of cool stuff in our own solar system. Mars is practically habitable already; it has the CHON elements necessary to sustain life, we just need to construct the machines to process them. Saturn's moon Titan also appears to be rich in the organic chemistry required to sustain a colony, and it is suspected that Jupiter's moon Ganymede may do as well. I suspect that traveling to the stars will seem a lot easier when we have the resources of the entire solar system at our disposal.
