Friday, August 26, 2016

Do Aliens Live Here?

The short answer is that we have no idea. But the more intriguing answer is that they could - and we might even be able get there with the right kind of spacecraft. Astronomers have recently announced the discovery of a rocky planet in orbit around Proxima Centauri, the closest star to our solar system. What's more, this planet lies in the star's habitable zone, with expected surface temperatures that would allow liquid water to be present.

So if aliens have visited Earth, is this their home world? Statistically it's a good guess, since unlike in science fiction television and movies, interstellar travel is incredibly difficult and consumes vast amounts of energy. From a purely statistical standpoint, we can assume that it's far more likely for visiting aliens to come from another system close by. Of course, whether or not they've visited at all is still debated.

Researchers have long looked to Alpha Centauri for study. Now, they want us to go there.

Programs like Mission Centaur intend to design and build a space mission with a small telescope to point at the star system. It would look for exoplanets by imaging or other techniques that could find more of them around these three stars.

Given how long it took us to confirm Proxima b and the fact that the researchers encountered a puzzling extra signal in some of their data and models, it's entirely possible that there are more planets to be found.

It is also the target of the Starshot project, which aims to create and send ultra-fast light-driven nanocraft that would reach the system 20 years after launch and beam home images. This is on the list of Breakthrough initiatives, an effort whose board includes Stephen Hawking and Mark Zuckerberg.

If Starshot's probes can really reach 20% of the speed of light and cover the distance in twenty years, it would be about twenty-four years before we received any telemetry back. But in interstellar terms, that's not much time at all. It would be fascinating to live long enough to see it, though that depends on how quickly they can design, build, and launch the probes.

Proxima b is similar to Earth in terms of size and surface temperature, but that's where the similarities end. Proxima Centauri is a red dwarf, so the planet's orbit is much closer to its star. This is one of the reasons it was hard to detect, despite how close it is. This poses some problems for the development of life, but they are not necessarily insurmountable.

Orbiting so close, the planet may be tidally locked, meaning that one side always faces the star so there is no cycle of day and night. The planet is also exposed to higher levels of radiation for the same reason. It seems that it would be difficult for an advanced civilization to evolve on such a world, but if they were very different from us, who knows?

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