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Uploaded:2017-02-17
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NASA has proposed a mission that would land on Europa to search for signs of life & we've learned something sad about one of our neighbors, Proxima b.

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Sources:
http://solarsystem.nasa.gov/docs/Europa_Lander_SDT_Report_2016.pdf
http://www.popsci.com/heres-what-nasas-europa-lander-could-look-like
http://solarsystem.nasa.gov/missions/europaflyby/indepth
http://iopscience.iop.org/article/10.3847/2041-8213/836/1/L3
http://www.space.com/35649-proxima-b-alien-life-superflares.html
https://www.nasa.gov/feature/jpl/eso-discovers-earth-size-planet-in-habitable-zone-of-nearest-star

Images:
https://commons.wikimedia.org/wiki/File:Europa-moon.jpg
https://commons.wikimedia.org/wiki/File:EuropaInterior1.jpg
https://commons.wikimedia.org/wiki/File:Europa_Mission_Spacecraft_-_Artist%27s_Rendering.jpg
https://commons.wikimedia.org/wiki/File:Europa_Clipper_orbit_away_from_Jupiter_radiation.jpg
https://www.nasa.gov/feature/nasa-receives-science-report-on-europa-lander-concept
https://commons.wikimedia.org/wiki/File:Artist%E2%80%99s_impression_of_Proxima_Centauri_b_shown_hypothetically_as_an_arid_rocky_super-earth.jpg
https://commons.wikimedia.org/wiki/File:Artist%27s_impression_of_the_planet_orbiting_Proxima_Centauri.jpg
https://commons.wikimedia.org/wiki/File:New_shot_of_Proxima_Centauri,_our_nearest_neighbour.jpg
https://www.nasa.gov/feature/goddard/2017/nasa-finds-planets-of-red-dwarf-stars-may-face-oxygen-loss-in-habitable-zones
In the last few years, there’s been a lot of talk about a mission to fly by Jupiter’s moon Europa -- and last week, NASA proposed a follow-up mission to land on its surface.

All this talk about Europa has been for good reason. Under its surface is an ocean containing three times as much water as the entire Earth, which makes it a great candidate for finding extraterrestrial life.

But before we land, the Europa Multiple Flyby Mission will check it out first. The probe, which should launch in the early 2020s, will fly by Europa 45 times and collect data on its composition and surface. Then, if this new lander gets approved, it’ll launch in 2024 or 2025.

The lander’s main goal will be to determine if there is or ever was life on Europa, and it’ll do that by digging around 10 centimeters below the surface and take at least five samples. Then, using a microscope on board, the lander will analyze those samples, looking for tiny cells or any sign that life may have once existed on the moon. According to NASA, the lander’s microscope will be so precise that it can identify cells as small as 0.2 microns in diameter — that’s two ten-millionths of a meter!

It’s important to take underground samples because Jupiter gives off a lot of extreme radiation, so life probably wouldn’t have evolved on the surface. We wouldn’t be able to get these samples from just a flyby mission, so landing on Europa is the only way to get the full picture. But even if it doesn’t find signs of life, the lander will also study whether life has the potential to evolve -- in other words, if Europa could be habitable at all, based on factors like the depth of underground water and the chemistry of the samples.

Finally, the lander’s third goal will be to gather information for future exploration and match up data on the ground and data from the flyby mission. And all of this will have to happen in less than three weeks! The scientific instruments onboard the lander will live inside a compartment called a radiation vault, but they’ll still be really sensitive.

And Jupiter’s radiation is so strong that the instruments will only be able to last about twenty days on the surface before they break down. There’s still a lot of work to be done on this mission before it’s approved for development, but if that happens, you can look forward to three intense weeks of science around 2030! And speaking of life elsewhere in the universe, you might have heard last year about a rocky, Earth-sized planet called Proxima b.

Proxima b, which orbits our closest neighboring star, Proxima Centauri, is only four light years away, and astronomers think it’s located in the star’s habitable zone. In other words, Proxima b is just the right distance from its star to have liquid water and relatively mild temperatures. When the discovery was announced, it make a lot of people -- including us here at SciShow -- really excited, because it was the first time we’d found a planet so close to Earth so that could potentially be habitable. ...but all good things must come to an end.

It turns out that Proxima b isn’t habitable after all, according to a study published in The Astrophysical Journal Letters last week. The problems have to do with its star, Proxima Centauri, which is a red dwarf. Proxima b’s orbit is really close to the star -- about 10 to 20 times closer than we are to the sun.

Red dwarfs are smaller and colder than our sun, so the planet’s close orbit puts it right in the sweet spot where liquid water — and therefore life — could potentially exist. Unfortunately, though, red dwarfs are also really active, and they can shoot out deadly superflares of X-ray and ultraviolet radiation -- right into the habitable zone. Now, with a strong atmosphere and magnetic field, it’s possible the radiation wouldn’t be too much of an issue.

But when the researchers modeled planets around red dwarfs, taking the stars’ radiation into account, they found that the superflares can actually strip the electrons off of molecules in a planet’s atmosphere. Then, those molecules -- which can include oxygen, hydrogen, and nitrogen -- easily get dragged out into space, which is bad news if life is trying to evolve. Not only are these elements the building blocks of life as we know it, but hydrogen and oxygen also make up water.

So if there’s no water in the atmosphere, there probably isn’t any on the surface, either. The researchers found that a young red dwarf star could make its planets uninhabitable within less than a hundred million years, which is much less time than it would take for life to develop. So, it looks like we won’t be visiting our neighbors on Proxima b any time soon.

But even though it crushed our hopes and dreams, this research is also helping astronomers redefine the definition of a habitable zone around a red dwarf. They used to only include factors like temperature, but now they can start including radiation, too. And even if there’s no hope for life on Proxima b, maybe in a decade or two we’ll find something a little closer to home if the Europa lander works out.

We’ll just have to wait and see! Thanks for watching this episode of SciShow Space News, and especially to our patrons on Patreon. If you’d like to help us bring you space news every week, go to patreon.com/scishow.

And don’t forget to go to youtube.com/scishowspace and subscribe.