This week marks another important milestone in the Cassini mission at Saturn – as of today, the spacecraft is conducting the last Ring-Grazing Orbit of its mission as it prepares for the Grand Finale, which will culminate in the death of the probe on Sept. 15. On April 21, Cassini will do its very last close flyby of Saturn’s largest moon Titan. Speaking of Titan, Cassini has also apparently solved a perplexing mystery; the unusual “magic island” formations seen in one of the moon’s methane/ethane seas are now thought to be caused by nitrogen bubbles fizzing periodically on the sea’s surface.
For those who are hoping to find evidence of life somewhere else in the Solar System, there was some exciting news this week. Two moons, Europa and Enceladus, were already thought to be among the best places to search, since both have liquid water oceans beneath their outer icy shells. And now, new data from the Cassini spacecraft and the Hubble Space Telescope has increased the potential for some form of living organisms to be found.
Some great new views from the Cassini spacecraft of Saturn’s tiny moon Atlas were released today. Atlas is similar to another Saturnian “ravioli” or “flying saucer” moon, Pan – a central roughly spherical or oblate body with an unusual broad equatorial ridge. Like Pan, the ridge is thought to have formed from material coming from Saturn’s rings, and also like Pan, the ridge on Atlas appears very smooth, but is significantly larger. Atlas orbits just outside the outer edge of Saturn’s A ring and is very small, only about 15 kilometres (9.4 miles) across, but still larger than Pan.
NASA’s Cassini mission to Saturn has been one of the most successful and awe-inspiring ever, studying the giant ringed planet and its many moons since 2004. But now, scientists are preparing for what everyone knew would come eventually – the end of Cassini’s excursions throughout the Saturn system. Yesterday, NASA held a news conference to celebrate what Cassini has accomplished and outline what will happen during the next few months, culminating with the end of the mission in September.
Saturn’s moon Titan is the only other body in the Solar System besides Earth known to have liquids on its surface. In Titan’s case, they are rivers, lakes and seas of liquid hydrocarbons (methane/ethane) instead of water. There is even methane/ethane rain, which further mimics Earth’s hydrological cycle. For the most part, the lakes and seas are fairly smooth, with only small amounts of wave activity. But now, new research suggests that those lakes and seas might be quite fizzy at times – with periodic bursts of nitrogen bubbles.
When it comes to places in the Solar System to search for possible alien life, Saturn’s moon Enceladus is now right near the top of the list. Like Jupiter’s moon Europa, it has a subsurface ocean of water, and even plumes/geysers of water vapour which erupt from fissures in the icy surface near the south pole. Those plumes contain organics as discovered by the Cassini probe and there is evidence for hydrothermal activity on the ocean floor, just like on Earth. The fissures are warmed by heat from below, and now there is evidence that some of them are even warmer than expected, meaning that water could be closer to the surface than previously thought.
NASA’s Cassini mission may be entering its last several months now, but that doesn’t mean there aren’t any more cool science discoveries to be made. Some amazing new images were just posted of one of Saturn’s tiniest moons, Pan. This small asteroid-like object orbits Saturn within a gap in the rings and so is known as a ring moon. Scientists had a basic idea of what it looked like before, kind of like a walnut in earlier Cassini images, but the new images show it in much more detail and reveal how odd-looking it really is – more like a giant ravioli or dumpling. There have also been some incredible new close-up images of Saturn’s rings, as Cassini continues the Ring-Grazing Orbits phase of its mission. The images reveal intricate details never seen before in the structure of the rings.