Life in an Alien Ocean

Jupiter's-Moons-May-17-BlogThe US space agency, NASA, is currently planning a mission to one of Jupiter’s moons, Europa. This is an icy, frozen world five times further from the Sun than we are. So why does NASA want to visit? To find life.

Europa has a diameter of 3,100km, which is quite big for a moon and actually larger than Pluto. And, as far as conditions for life are concerned, Europa is more like Earth than any other planet or moon in our solar system. The reason – liquid water.

You may be wondering why anyone expects to find liquid water on Europa. After all, it is immensely cold. Temperatures can drop as low as -220° Celsius. As you’d expect, the moon’s surface is frozen solid. However, the ice has some cracks in it and, from time to time, these emit jets of water vapour.

This makes scientists think that there must be liquid water beneath the ice. But how can water be a liquid under such cold conditions? There are two possible explanations. Firstly, Europa orbits the largest planet in the Solar System, Jupiter. Now, we know that the Moon’s gravity pulls on Earth’s oceans creating tides. Just imagine what effect Jupiter’s gravity (15 times stronger than that of the Moon) has on Europa!

Icy-Geyser-May-17The second explanation for liquid water on Europa is heat coming from the moon itself. We think it has an iron core surrounded by a rocky mantle similar to Earth’s. On our home world the oceans are heated by deep sea volcanic vents which provide the energy necessary for life. Whole ecosystems have evolved to exploit these. Might the same also have happened on Europa?

As well as liquid water, Europa has something else which certain forms of life require – an abundance of oxygen. These two conditions together make Europa the most life-friendly place we know of, after Earth itself.

To find out whether or not there is any life in Europa’s oceans, NASA intend to send a probe there sometime during the next 10 years. It won’t be easy. After landing on the icy world the probe will have to drill through the ice, which may be several kilometres thick. After that it will be able to venture into the waters beneath in search of alien life.

What will the probe find in the dark depths? Microbes, multicellular organisms, primitive animals, advanced life? I can’t say – but I can’t wait to find out!

What do you think we’ll find on Europa? Let Education Quizzes know by filling in the comments box below – and let your imagination run riot!

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