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Emily Lakdawalla is the senior editor and planetary evangelist for the Planetary Society. She's also one of the most knowledgeable people I know about everything that's going on in the Solar System. From Curiosity's exploration of Mars to the search for life in the icy outer reaches of the Solar System, Emily can give you the inside scoop.

In this short interview, Emily describes where she thinks we should be looking for life in the Solar System.

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http://www.planetary.org/blogs/emily-...

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TRANSCRIPT

My name is Emily Lakdawalla, and I'm senior editor and planetary evangelist for the Planetary Society.

There's a lot of different places to search for life in the solar system. If you use liquid water as your proxy for places we should search for life, there's actually liquid water all over the place, because most icy moons of outer planets probably have liquid ocean layers inside them. There might even be some Kuiper belt objects that have liquid oceans - Pluto could have liquid ocean.

However, liquid ocean isn't quite enough, because you also need active chemistry, and for that you really need for the ocean to be in contact with rock or some material that is not just more ice, because that is where you can get all kinds of chemical elements to build interesting molecules out of.

And so there are a couple of places where we know that's happening. Europa being the big one, where its a large moon that has a thin ocean that's likely in direct contact with a warm rocky core, and it's a world that we know is geologically active, so we know that there's a source of energy coming up from below. And geologic activity brings up all kinds of chemistry - you might have black smoking vents on the ocean floor of Europa, and we know what kinds of cool stuff we find in those environments on Earth, so it would be really awesome to explore Europa and find the same kind of black smoking vents, and who knows - maybe little microbes swimming around.

Europa's one of the likeliest places to search for life outside of the Earth. A problem, though, is that it's ice shell is very thick, so if you want a place where it's ocean is likely in contact with rock on a geologically active world that is much easier to get to, it's hard to do much better than Enceladus, which a very small moon of Saturn which has these active geysers spewing from it's south pole.

Those geysers are salty - it's a salt water ocean, so we basically have a world that is conveniently venting it's ocean out into space. You don't even have to land - you can just fly right through that plume and check to see what kinds of cool chemistry is happening there. So yeah, I think Enceladus would be a really cool place to explore for life.

After years of searching, Clyde Tombaugh discovered tiny Pluto on February 18th, 1930, Little did he realize this was just one icy object in a vast belt of material known as the Kuiper Belt.

Mike Brown explains, "The Kuiper Belt is a collection of bodies outside the orbit of Neptune that, if nothing else had happened, if Neptune hadn't formed or if things had gone a little bit better, maybe they could have gotten together themselves and formed the next planet out beyond Neptune. But instead, in the history of the solar system, when Neptune formed it led to these objects not being able to get together, so it's just this belt of material out beyond Neptune."

After Tombaugh's discovery, other astronomers guessed that Pluto wasn't alone and there would be more planets to discover in the outer Solar System. But nothing turned up for decades.

Back in 1951, the Dutch astronomer Gerard Kuiper proposed that out beyond Neptune, material was spaced too far apart to form into a single large planet. Instead, he predicted that there would only be a small collection of icy objects. Occasionally one of these objects would wander into the inner Solar System and become a comet.

The idea of this "Kuiper Belt" made sense to astronomers, and it helped explain why there were no large planets further out in the Solar System.

It also conveniently wrapped up another mystery of the Solar System: where do comets come from? Astronomers assumed these objects were out there, but they had no evidence of anything other than Pluto. A few icy objects were found between the orbits of Saturn and Uranus, but nothing out past Neptune.

After searching the region for five years, and using the latest in telescope technology, astronomers David Jewitt and Jane Luu finally confirmed the existence of the Kuiper Belt in 1992.

They found a tiny object, a fraction of the size of Pluto, and the techniques they used unlocked an icy land rush. Six months later, the next object was found. And many more came after that.

Fortunately for us, Kuiper was wrong, and the belt hadn't been cleared out billions of years ago.

It's still a busy place. There have been more than a thousand objects discovered, and it's theorized that there are as many as 100,000 objects larger than 100 km in diameter.

One part Kuiper was definitely right about is that these objects won't last forever.

Mike Brown continues, "We call it a belt, but it's a very wide belt. It's something like 45 degrees in extent across the sky - this big swath of material that's just been churned and churned by Neptune. And these days, instead of making a bigger and bigger body, they're just colliding and slowly grinding down into dust. If we come back in another hundred million years, there'll be no Kuiper Belt left."

Keeping Pluto company out in the Kuiper belt, are many other objects worthy of mention: Quaoar, Makemake, Haumea, Orcus and Eris are all large icy bodies in the Belt. Several of them even have moons of their own. These are all tremendously far away, and yet, very much within reach.

NASA's New Horizons spacecraft will reach this region in 2015, and capture the first ever close up pictures of a Kuiper Belt object, images of the surface of Pluto.

Even more exciting for ancient ice-rock enthusiasts, it looks like our Solar System isn't unique. There have been icy debris belts - other Kuiper Belts - discovered around nine other star systems. There are narrow ones, like our own Solar System, and then wider belts extending much further out. Infrared surveys suggest that at many as 20% of star systems have one of their own.

Vast and unexplored, the Kuiper belt is the source of many comets, and contains ancient ice that was formed at the beginning of the Solar System. Let's hope New Horizons is just the beginning of future decades of research into this mysterious region.