A Tardigrade.

We believe that water is an essential ingredient for life; all living things we know of need water to some extent; we are somewhere between 50% and 65% water (depending on age and fitness) whilst the Tardigrade (or Water Bear) the most resilient creature known can survive with only 3% of its body mass as water. (The Tardigrade is an amazing almost unbelievable creature; it is 0.5mm long and can withstand temperature ranges from −272 °C (which is almost absolute zero, the coldest temperature possible) to 150 °C and pressures about six times greater than those found in the deepest parts of the ocean trenches. It can also survive doses of radiation that would quickly kill a human as well as the vacuum of outer space.)

So discovering water is believed to be a key to finding life; the recent announcement by NASA that the Hubble Space Telescope has seen water jets on Jupiter’s moon Europa is exciting.

Europa has been considered a potential candidate for life with its great subsurface ocean. Therein lies the problem. To get to the ocean would require drilling through a layer of extremely cold and hard ice of unknown thickness. Whilst we are used to drilling through the Earth getting the necessary machinery, making sure it is totally germ and microbe free and then operating it on a hostile world would be incredibly challenging.

The plumes provide a tantalizing opportunity to gather samples originating from under the surface without having to land or drill through the ice.


Hubble Image of plumes with a photo of Europa superimposed.

Amazingly this was not what the scientists were looking for! They wanted to find out if Europa had an atmosphere. It seems strange to think that they would try to find an atmosphere on such a small object (it is 3,100 km or 1,900 miles in diameter) so far away (some 628.3 million kilometres away) with a telescope.

There is a technique used for finding planets around distant stars which looks for an object passing in front (transiting) a star. As an object transits a star it blocks a fraction of the light from the star making it fade slightly which can be measured. If this happens more than once then there is a chance that it is a planet. Astronomers can then observe the light from the star (using an instrument known as a Spectrograph) to see it’s chemical make-up and then look again at the star as the object passes in front. Any difference in the reading of the star’s chemical make up allows astronomers to work out what makes up the atmosphere of the planet. The first technique was the one used was on Europa.


The astronomers spent 15 months observing ten transits by Europa and saw these plumes three times. Another team had detected something similar in 2012 using the same piece of equipment on Hubble (the Imaging Spectrograph.) however neither team has been able to observe the same event at the same time. That is the next challenge, once that has been done then there will be a very strong case for the plumes existence.

The findings of the two teams are very similar though; suggesting that the water vapour is erupting from the frozen southern polar region of Europa and reaching more than 100 miles (160 kilometers) into space. Maybe as much as a few million tonnes of water are expelled this way. It is believed there is more water under Europa’s surface than on the Earth!! Observations thus far have suggested the plumes could be highly variable, meaning that they may sporadically erupt for some time and then die down. This makes them very difficult to be seen by more than one group of astronomers at a time.

If confirmed, Europa would be the second moon in the solar system known to have water vapor plumes. In 2005, NASA’s Cassini orbiter detected jets of water vapour and dust coming from the surface of Saturn’s moon Enceladus.


NASA hope to launch a mission to Europa called, for now, the Europa Multiple flyby Mission. It is in the planning stages now and one of the ideas is to send a lander to the moon to sample the surface if not try to drill into it.

Here is a NASA clip about the mission:

Exciting times ahead!

Published in: on September 27, 2016 at 16:30  Leave a Comment  
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