I was very pleased to learn that yet another extrasolar planet has been discovered, this time closer to Earth than ever before. It turns out that Alpha Centauri, our closest neighboring star system, has an Earth-like planet. Yay! However, this sort of news never manages to totally counteract the conflicted feelings I have about our prospects for deep space exploration.

On the one hand, every extra-solar planet we find is another datum for the famous Drake equation (taking a stab at the probability of alien life existing in the universe), and the odds are getting better all the time. Over the last two decades we’ve learned that extra-solar planets of the gas giant variety are pretty common (I fondly remember when the first one was discovered; my parents sent me a special newspaper clipping while I was at Girl Scout camp), and now the astronomical observations are getting precise enough that we’re finding that smaller rocky planets are common as well. Although this most recent find orbits much too close to its star to have anything like our own life (it’s closer to its sun than Mercury is to ours), it’s yet another indication that such planets are plentiful. (And given the imagination of some science fiction authors, totally habitable.) The more plentiful they are, the more likely that some will be in the ‘Goldilocks zone’ where liquid water is possible and life like ours could arise. This also means that the chances that we’ll be able to find a hospitable planet when and if we escape our solar system are getting better by the day.

However, I always get melancholy about these things for two reasons. One goes back to the Drake equation with a dash of the Fermi paradox: if planets like ours are common, how come no one’s dropped by to say hi? How come we haven’t had any (official) alien contact? I fear that travel between even ‘closely spaced’ star systems (and 4.3 lightyears, or 25 trillion miles, is nothing to sneeze at–Mars is at most 249 million miles away*) is so difficult and expensive that the fact no aliens have come here reduces the chances of our ever being able to go there.

On a related note, even traveling around our own solar system is really hard. It’s hard to accelerate things to very high speeds, it’s hard to maintain a closed ecosystem for a long period of time, it’s hard to get down to a planet’s surface and back up. Every time I hear folks talking about generation starships or terraforming a planet, I remember that the Biosphere 2 experiments have not yet proven successful, and those have much more hospitable conditions than any generation starship could dream of. The International Space Station has to be regularly re-supplied with food, air, and water (although the VEGGIE mission recently launched to ISS aboard the SpaceX Dragon capsule might help on the food front).

It’s easy to feel dismal; working on engineering projects as I do, it’s sometimes hard to believe that anything can ever work, especially when you’re sitting in technical committee meetings. Then I remember that it’s possible to do new things and big things. Apollo aside, even just the fact that we have a permanent space station with six people on board is a major step in the right direction. It may not happen as quickly as I want it to, but eventually we’ll accumulate the resources, the technical expertise, and the motivation to get off this chunk of rock. And when we do, knowing that there are Earth sized planets out there, not too far away, means that we’ll likely have someplace to go.

* Jonathan Strahan mentioned a good way of emphasizing the difference in orders of magnitude on the latest Coode St podcast, so let me try it here; Mars is 250 million miles away. If you were to count to 250 million at one number per second, it would take you almost eight years. Alpha Centauri is 25 trillion miles away. If you were to count to 25 trillion at the same rate, it would take you closer to eight hundred thousand (800,000) years. OMGWTFBBQ, you know?

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