And now for a bit of positive news. In this video from Seeker, the host discusses NASA’s announcement four days ago on 14th April 2017 that the Cassini probe had discovered traces of hydrogen above Saturn’s moon, Enceladus. Saturn’s moon is believed to have an ocean beneath its icy surface. The hydrogen is believed to have been produced by hydrothermal vents, like those at the bottom of Earth’s oceans, and have escaped through the ‘tiger stripes’, or cracks in the moon’s ice sheet. This could indicate that life is also present on Enceladus’ ocean floor, as the hydrothermal vents or ‘black smokers’ in Earth’s oceans are also the haven for life. The ecosystems that have developed there are based on methanogenesis, in which hydrogen is combined with carbon dioxide to produce energy. The process is believed to have been at the basis of the evolutionary tree of terrestrial life, and may even have been the origin of life on Earth. The presenter states that the probe has not discovered the other two chemicals necessary for the presence of life, sulphur and phosphorus, but these are believed to be present as well.
It is, however, possible that Enceladus is too young for life to have evolved there yet. If life does exist on the moon, Cassini won’t be looking for it either. The probe was not designed to land on Saturn’s moons. Instead, it is scheduled to end its nearly 20 year mission by crashing into Saturn’s atmosphere, where it will be crushed by the immense pressures of the gas giant. This was to prevent it contaminating Enceladus or Saturn’s other moons by crashing on them. NASA is planning to send another probe to Saturn in the 2020s. This probe will also investigate Europa, which may be a better candidate for the presence of life. It not only also has an ocean, but is also older, at 4 billion years old, and so may have been around for enough time for life to evolve.