In its final three days of existence, the Cassini space probe is ensuring that NASA is really going to miss it by delivering a series of stunning photographs that required getting closer to Saturn than ever before.
On Monday, the probe flew within 120,000 km of the giant moon Titan (normally it sits at an altitude more like 790,052 miles or 1,000,000 kilometres above), an encounter that bent the craft’s trajectory just enough to start it on the fateful collision course.
Now nothing can stop the death plunge, as Cassini will be melted by Saturn’s atmosphere and disappear forever.
Having been observing Saturn for over thirteen years, on the behalf of the space agency, Cassini has now completed its last full orbit allowing experts to learn more about it than ever before.
The latest RAW images, taken over the weekend and be sent back towards the Earth, show the camera pointing towards Saturn.
According to NASA, the images clearly show the wave structure of Saturn’s rings in B ring, known as the Janus 2:1 spiral density waves.
Resulting from the same process that creates spiral galaxies, spiral density waves are much more tightly wound, with every second wave crest in the image actually being the same spiral arm which has encircled the entire planet multiple times.
The photographs give the illusion that the ring plane is tilted away from the camera toward upper-left, but this is not the case. Because of the mechanics of how this kind of wave propagates, the wavelength decreases with distance from the resonance.
Therefore, the upper-left of the image is just as close to the camera as the lower-right, while the wavelength of the density wave is simply shorter.
Because of the limited space on Cassini’s recorder and the time it takes to transmit that data, cameras on board the spacecraft were built to have the ability to compress the data, that is, to have it take up less space on the recorder.
Not only have these latest flybys allowed the team to take these photographs, but also to send detectors to directly sample the gases found in the planet’s upper atmosphere.
One of the big mysteries the team was hoping to solve is the simple question of just how long a day is on Saturn.
Michele Dougherty, Cassini magnetometer investigation lead at Imperial College, London, said: “We have not been able to resolve the length of day at Saturn so far, but we’re still working on it.”