For the last 12 years, NASA’s Cassini spacecraft has orbited Saturn, taking some of the most detailed images of the gas giant yet captured. Now, at long last, it’s time for the spacecraft to retire—but not before one last pass up close and personal with the planet’s rings.
Saturn’s rings are its most well-known feature, but there is plenty for astronomers to learn about it. Over the years as telescopes became increasingly powerful, researchers with their eyes to the skies managed to spot all sorts of new details, such as faint, wispy outer rings and tiny little moons spinning around the gas giant, Loren Grush reports for The Verge. As Cassini enters its final orbit, it will be able to snap never-before-seen pictures of these rings and objects.
"We're calling this phase of the mission Cassini's Ring-Grazing Orbits, because we'll be skimming past the outer edge of the rings," Linda Spilker, Cassini project scientist at NASA's Jet Propulsion Laboratory, says in a statement. "In addition, we have two instruments that can sample particles and gases as we cross the ring plane, so in a sense Cassini is also 'grazing' on the rings."
Starting tomorrow, Cassini will swing around Saturn’s moon Titan for one last look before entering its final orbit. The spacecraft’s path will first take it through a faint outer ring before skimming the edge of the F ring—a narrow band of dust and particles that sits on the outskirts of Saturn’s most visible rings, Sarah Lewin writes for Space.com. At just 500 miles wide, it’s one of the thinnest of Saturn’s rings and features constantly shifting filaments and streamers of dust, unlike its larger cohorts.
In addition to studying the makeup of its rings, researchers hope to learn more about the gas giant’s gravitational and magnetic fields. Its path will take it closer to Saturn than any other spacecraft before it—and with Cassini scheduled to take a nosedive into the planet next September, getting as much information out of its instruments as possible is critical, Nicola Davis reports for The Guardian.
“We are going to try and understand what is going on in the interior of Saturn and we are going to try and work out how long a day on Saturn is—it is a bit embarrassing, but we still don’t know,” Michele Doherty, the lead researcher on Cassini’s Magnetometer, tells Davis. “You use the magnetic field, which is what my instrument measures, to almost see inside the planet.”
While it might seem like a shame to send Cassini on a kamikaze mission, its unfortunate end is for in the name of science. The spacecraft is just about out of fuel, and the last thing its handlers want is for the little craft to drift uncontrollably, smashing into one of Saturn’s moons—two of which could harbor the conditions to support life. So before it takes the plunge to Saturn's surface, Cassini provide one last look at the magnificent ringed planet.