Jupiter's moon Europa is considered one of the best places in the Solar System for discovering life outside of our own planet Earth. But could life have already presented itself to us right under our noses?
How Could Europa Harbour Life?
The moon is thought to have a warm salty ocean that could be many kilometres deep below the icy crust. Ideal conditions for the development of life. The heat to warm the ocean comes from the friction effects of being repeatedly squashed by Jupiter's immense gravity. Much in the same way that a squash ball can be warmed by continually squashing it under your foot. So even though Europa has a thick icy crust and is an incredible distance from the Sun, this effect allows for the ocean to warm.
Does Europa Have any Signs of Life?
Here is where things get interesting. Many of the pictures of Europa show red coloured lines running across the surface. The lines are thought to have been made by cracks in the icy crust as the ocean moves beneath. The cracks rapidly fill with the ocean water and freeze. Planetary Biologists back in 2002 at the NASA Ames Research Center compared the infrared signature of the red lines on Europa with the infrared signature of polyextremophile bacteria (see image) and found that they formed a very close match. Could the red lines be evidence of bacteria on Europa? Well certain salts can also produce a similar infrared signature and would help to confirm the presence of a salty ocean, but no single salt has been found to match the infrared signature on Europa yet.
It's not definitive proof of life on another world but it certainly makes the argument for studying Europa much stronger and adds a frustratingly tantalising twist in the search for extraterrestrial life. Let's plan a trip now.
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Top image: NASA
bottom image: DOE