Being 516 kilometers, or 321 miles from a moon being a spacecraft flying all alone in the dark, empty space must be like finding a friend and get a hug. This is the experience awaiting the NASA spacecraft Cassini as it makes its fourth flyby so far of one of the least studied moons of Saturn, Dione. The closest one was done at a distance of only 100 kilometers (60 miles), and it was in December 2011.
With the flyby, scientists hope to find more data about the mysterious white streaks found on the surface of Dione by Voyager – over 35 years ago. They were first thought to be extruded to the moon surface by ice volcanoes, but later on images from Cassini rather enabled the scientists to determine that they were an intricate network of braided canyons, lined with bright walls, called linea.
Another job for Cassini this time around is to investigate the potential presence of any fine particles that could have been emitted from Dione. Finding them could indicate geologic activity at a low level. Cassini is well equipped for advanced jobs like these; the team made sure to attach stuff like a Cosmic Dust Analyzer, a Magnetometer as well as an Ion and Neutral Mass Spectrometer to the tool belt before take-off.
Even though the spacecraft will be at the closest point to Dione this time on June 16th, scientists still need to wait a few days for the images to reach Earth. To pull off this project, called the Cassini-Huygens mission, NASA, ESA and the Italian Space Agency have put their resources into a cooperative effort.
Later on in 2015, Cassini leaves the equatorial plane of Saturn to start preparing for the final year of the mission. After finishing that setup, Cassini will dive through the space between Saturn and its rings. Best to make the most use possible of expensive, time-consuming space missions, right?