NASA has had a pretty incredible run lately, culminating with the truly stupefying discoveries of the New Horizons space probe out at Pluto. Today, they announced that the Kepler space telescope — which is itself an awe-inspiring feat of engineering — has discovered a planet that is pretty close in size to earth, orbiting a star pretty close in our own, at a distance that makes it strongly likely that it will have liquid water.
So: that is amazing news! For one, it is confirmation of a long-held assumption that in the nearly uncountably large number of planets in the universe, surely some have to exist in conditions similar enough to ours that we could imagine ourselves living there. For another, it is the culmination of the $600 million Kepler telescope project, which had produced incredible science since 2009 — a literal explosion of exoplanet discovery. Many people feared it would be permanently ruined when two of its four gyroscopes stopped working in 2013, since that meant it could no longer stabilize itself in three dimensions to keep hunting planets. But the ninja-engineers at NASA recently figured out that they could stabilize it in its third axis by balancing the spacecraft against the pressure of photons emitted by the sun. They literally are balancing it on sunlight to look for planets.
Sorry, that leaves me a bit breathless.
But anyway, this new planet, Kepler 452b, has a lot going for it: the right size, the right star, the right temperature zone, the right length of year, and so on. It is about as close to a “twin” to our own planet that you can think of. But one thing it does not have going for it is how far away it is.
See, Kepler 452b is 1,400 light years away. And that’s a real problem because space is big. Really big. So big I don’t think we’ll ever be able to visit any of it in person.
Think of it this way: The fastest space probe we’ve built is probably Voyager 1 — as it is currently cruising into the interstellar medium it is going around 38,000 miles per hour (faster than New Horizons by a bit, and a little more than twice as fast as a Soyuz capsule). And it has taken Voyager 1 over thirty five years to reach a region of space we can reasonably say is outside the solar system.
Voyager 1 is going too slowly to ever reach a planet like Kepler 452b. If we stay within the realm of the physically conceivable, considering what we know of the physical world, we might be able, some day, to accelerate a spaceship to 0.1C, or 1/10th of the speed of light. It seems slow, but that is actually unbelievably fast, around 67,061,663 miles per hour. To put it in terms of Voyager 1, it is 1,765 times faster. We would need to go several orders of magnitude faster than the fastest things we’ve ever built to even dream of reaching another star system.
But Kepler 452b isn’t just a nearby star system, it is 1,400 light years away: 350 times further away than the closest stars. Traveling at 1/10th the speed of light, 0.1C, would mean traveling to Kepler 452b would take well over 14,000 years (I have no idea how long it would take to accelerate to that speed, but it would take at least ten times as long to get there as that distance traveling at the speed of light). The first written language (ish, I know) is Cuneiform, which emerged around 5,000 years ago. It would take three times longer to reach Kepler 452b than we have had the capacity to write in a coherent language.
Unfortunately, this planet is, as far anyone can conceive of using known physics, impossible for us to reach. We just do not know how to do it. Even if we could, in theory, accelerate something to the tiny speed of 0.1C, we do not have the means the safeguard the spacecraft against routine hazards — even a grain of dust impacting the front of the spacecraft at that speed would go off like a ton of dynamite and destroy everything. We could not keep any of its electronics powered: solar radiation is too weak to use photovoltaic panels, and a theoretically efficient breeder fission reactor would only last a few hundred years. We could not sustain any biological system for that long, since we have no idea how to make a complex ecology function. We have no idea how to repair broken stuff on a spaceship when there are no new supplies. Our machines cannot be programmed to be smart enough to adapt without human input.
And so on. It’s kind of sad to think about: science is amazing, and I am humbled and left in awe by this sort of discovery. But I also left saddened, chagrined even, at how impossible it will be to ever see a place like this in person. I suppose our imaginations will have to do for now.