NASA's Cassini spacecraft is less than two months away from ending its twenty year long mission to unravel the mysteries of Saturn. Even towards the end of its mission, Cassini continues to perform excellently, advancing scientific knowledge, gathering new data, and capturing breathtaking images of the gas giant. While Cassini has definitely advanced scientific understanding over the course of its mission, some of its findings have stumped scientists.
One of these is the observation that the magnetic field on Saturn is surprisingly well aligned with the rotation of axis of the planet. This just does not fit into the current scientific understanding of how planetary magnetic fields should behave. Without a tilt, the currents flowing through the liquid metallic hydrogen deep within the surface of the planet cannot be sustained, and the magnetic field would disappear. The finding indicates that there is an unknown factor in the internal structure of Saturn, which can be discovered in future missions.
Cassini has also captured the first particles from the gas giant for direct analysis. The ion and neutral mass spectrometer (INMS) sampled particles from the outermost layers of the Saturnian atmosphere, while the cosmic dust analyzer (CDA) instrument collected small particles from the rings of Saturn. During the dives, Cassini uses its antenna to shield its sensitive instruments from large particles, but the CDA was allowed to extend from behind the antenna to collect the samples.
The imaging sensors on Cassini also captured bright bands in the ring system, known as plateaus. These areas differ significantly in texture from nearby bands. The adjacent regions have a clumpy structure, or no clear structure at all. Cassini is currently in the sixteenth grand finale dive, and there are six more orbits to go before the spacecraft ends its mission by falling into the atmosphere of Saturn. During the final dive, Cassini will continue to beam back observations till the very last moment. The INMS sensor on board is expected to beam back critical data on the composition of Saturn's atmosphere during its final, science rich plunge.