Posts Tagged ‘water’


Hi, comicbook friends. Any fan of Warren Ellis out there? Me, I like Chris Sprouse as well, so it is only natural I enjoyed Ocean. Set 100 years from now, the story focuses on a UN special weapon inspector sent to Cold Harbor, a UN research station in orbit around Europa. Deep, under the ice surface of that moon, there is an ocean and a set of nonhuman artifacts have been discovered. I’m not going further into the plot, in case anyone wants to read it spoiler-free and also because I don’t need to. It was only natural at the time that Ellis thought of Europa as a background for his plot: the smoothness of the surface has led people to think there might be a water ocean beneath its icy crust, kept liquid by tidal acceleration. Nasa also reported detection of water vapor plumes in 2013.


However, it turns out it’s its bigger sister Ganimede who might be proven to yield an ocean first. NASA’s Hubble Space Telescope has the best evidence yet for an underground saltwater ocean on Ganymede, Jupiter’s largest moon. The subterranean ocean is thought to have more water than all the water on Earth’s surface.


And, because science is cool like that, they figured it out by observing Ganymede’s aurorae borealis. The idea behind this statement is pretty simple. Aurorae appear when plasma from a solar storm reaches Earth. Our electromagnetic field basically works like a shield that deflects particles from the storm.


The shape of the magnetic field lets some particles reach our magnetic poles, both when it moves past us and backwards,sort of like a wave in the sea that hits you when the water retreats. An excellent explanation of the full process can be watched in the following 4 minutes video.

So far, so good, but what does this have to do with Ganymede? Easy. Ganymede is the only moon in our system that has its own magnetic field and, hence, aurorae in regions circling the north and south poles of the moon. However, since it is so close to Jupiter, its own magnetic field interacts with Jupiter’s. As a result, its aurorae “rock” back and forth. The plot below, for example, shows how our geomagnetic field changes depending on Earth orbital motion due to interaction with the interplanetary magnetic field brought to you by courtesy of the solar wind (see full explanation on A Hitchhiker’s Guide to Space and Plasma Physics).


According to calculations, given the proximity of Jupiter and Ganymede, aurorae should rock up to 6 degrees. However, if a saltwater ocean were present, Jupiter’s magnetic field would create a secondary magnetic field in the ocean1 that would counter Jupiter’s field. That second field would actually suppress the rocking of the aurorae. And, ta-daaa, indeed they rock only 2 degrees according to estimations!


Scientists estimate the ocean is 60 miles (100 kilometers) thick — 10 times deeper than Earth’s oceans — and is buried under a 95-mile (150-kilometer) crust of mostly ice.


1. Dissolved salts in seawater conduct electricity, and as ocean currents move within the planet main magnetic field, they generate their own secondary magnetic field (see here).

Have you already planned where to go on holidays this summer? How about Mars? Quaid may drop a hint or two on this destination for you: In fact, people started theorizing quite early about the possibility of Mars being habitable. The first one would be Schiaparelli, at the Milan Observatory (1877), who observed that the whole of the tropical and temperate regions from 60° N. to 60° S. Lat. in Mars were covered with a remarkable network of broader curved and narrower straight lines of a dark color. These formations were called  Canals and, at the time, believed to be artificial.  Furthermore, Mr. W. H. Pickering discovered in 1892 that these canals intersected by means of some circular black spots. By the time, observations of color changes led (optimistic) people to believe that canals were in fact used for irrigation. It wasn’t until 1894 that astronomers started to put in doubt the existence of water in Mars. S730a It was at this point (1911) that Edgar Rice Burroughs wrote his well known John Carter series, where Mars was inhabited by at least three different races of martians, with canals, buildings, palaces and flying machines, too.  And, of course, one could walk the surface without a suit. Gee, gotta love this guy’s books! princessdj Whereas McMillan’s Man’s Place in the Universe (1902) happily claimed that Mars had a weather similar to the south of England, Lowell’s book, Mars and its Canals (1907) made a (detailed) point on how a thinner atmosphere, and the consequent harsh temperatures made it impossible for the Red Planet to support life, putting special emphasis on the lack of water evidence on the surface. Since then, the main issue to support that Mars has never been habitable, as portrayed in Total Recall, has always been the lack of evidence of water on its surface. However, the arrival of rovers to our neighbor planet actually allowed us to go beyond the surface, right? Since its arrival to Mars, the Curiousity rover have been roaming around and drilling here and there to gather rock and ground samples. And  last march, it hit jackpot.


While drilling at Yellowknife Bay, Curiosity found both clays and sulfate minerals, materials that only form in water, and only in water that is low in potentially life-killing acids. Given that Mars was once much wetter and warmer, and that there are minerals that can be formed only in the kind of water that can support life, the probability of organic life there is not a total zero anymore. It is important to hit the brakes, though: although life would have been possible in theory, there are absolutely no signs of past inhabitants in Mars (thus far :D). The next big question here is, obviously, if we could make Mars habitable: terraforming has always been a big part of scifi. Apparently, scientists say yes, but don’t get your hopes too high, you’re not having a holiday in Mars anytime soon. It seems that rovers have found some organics in the planet, most likely unwillingly brought there by the previous robot. However, findings show that it is entirely possible there is microbial life on Mars now.