New look for Titan
A new algorithm was developed to reduce electronic interference in the photos taken by the Synthetic Aperture Radar. The technique is called despeckling and comes 10 years after the arrival of the Cassini spacecraft on Saturn’s orbit. Finally, the images will be sharper and useful.
When a probe is launched into orbit there are many unknowns: it will ever get to your destination? And if it comes to the lens, will it be able to stay in orbit long enough to capture and analyze data? How come these data on Earth is another unknown, because they are often unusable or sometimes do not arrive at all? Then there are missions that last longer than expected or that can obtain images and analyze data that initially seemed impossible. This is because very often the missions are conceived, designed and made in the course of ten or twenty years.
As is the case with the Cassini spacecraft, which is orbiting Saturn for 10 years, after the mission has been extended twice (in 2008 and 2010) and it is thought to take it forward at least until 2017. So Cassini has already begun to speak in 1982, although the actual design started only in the 90s. In 10 years of discoveries the probe, born from the joint work of NASA / ESA / ASI, observed and scrutinized every detail even the most famous one of the moons of the sixth planet of the solar system, Titan. In all these years, though, the ways we look at Titan have changed, or at least have changed the techniques to analyze the data and images that in turn have been sent to Earth. The Italian Synthetic Aperture Radar (SAR) mounted on board Cassini has mapped over time the surface of the largest natural satellite system moons Saturn, tracked and revealed vast stretches of sand dunes and “dipped” in the seas hydrocarbons. But sometimes the pictures that we received were not very sharp, despite their beauty.
Thanks to a technique recently developed for the management of the background noise and electronic interference in radar images of Cassini, Titan has hired a brand new look. The technique, which its developers call “despeckling” (i.e. spotting) produces images of Titan’s surface that are much clearer, sharper and easier to watch than what in recent years, scientists and the public watched. Certainly 10 or 20 years ago, researchers would never have imagined that one day the images of Titan would never have been so sharp.
Usually, the Cassini radar images have a grainy texture (not to mention annoying), which creates what in the jargon is called “noise” interference which makes it difficult to interpret the characteristics smaller or identification details changes in photos taken over time. The new technique developed by Antoine Lucas (who works at the Astrophysics Division of the High Commissioner for Atomic Energy in France) is essentially based on an algorithm to modify this noise and make images accessible. In practice, a mathematical model of “de-noising” or noise suppression.
“Cleaning up” Cassini images radar has a variety of scientific benefits, because it will produce maps 3D digital elevation models (DEM) of Titan’s surface with a noticeable improvement in quality. With a clearer view of river channels, lakes and coastal dunes, researchers will be able to perform more precise analysis of the processes that shape the moon of Saturn. Not to mention the fact that the same noise, the same interference, when analyzed separately, may contain information on the properties of the surface and subsurface.