Titan 125 Flyby isn’t Cassini’s last close flyby of Saturn’s largest moon Titan, but it marks a critical time for NASA’s Saturn mission. During the flyby yesterday, Cassini changed its orbit to begin what NASA describes as “perhaps the boldest and most thrilling segment of Cassini’s nearly 20-year mission.” Cassini is entering the last phases of its mission at Saturn.
Using Titan’s gravity, the spacecraft tweaked its orbit to begin a set of ring-grazing elliptical orbits. Cassini will swing far away from Saturn before diving to within just 6,800 miles of Saturn’s F ring. The first ring graze is set for December 4th. And Cassini will repeat the maneuver 20 times (about once a week) between then and April.
The science from Cassini’s first ring-grazing orbit
During its closest approach, Cassini’s Radio Science instrument will fire a signal to Earth through Saturn’s rings in a “uniquely long sweep” according to NASA. The spacecraft’s main engine will fire briefly to keep the spacecraft on track for subsequent ring-grazing orbits.
Cassini’s Visual and Infrared Mapping Spectrometer will also observe Saturn’s north pole and create a nine-hour video of it. We’ve seen the gas giant’s “hexagon” in motion before.
Did You Know: A massive hurricane tightly spins at Saturn’s north pole. Its eye is nearly 50 times larger than the average hurricane we see back on Earth. The clouds at its center spin almost twice as fast as the planet itself. Winds are estimated to hit speeds of around 340 miles per hour according to NASA. And a sister hurricane sits at Saturn’s south pole.
Scientists back on Earth will soon have another good look at it.
Several other instruments will conduct crucial measurements of the boundaries of Saturn’s upper atmosphere. These measurements will be vital for tweaking Cassini’s last set of orbits that take it between Saturn’s rings and its upper atmosphere. During the spacecraft’s final orbits, instruments will measure the gas giant directly in the atmosphere.
The Grand Finale
Today marks the start of this phase, but Cassini’s Grand Finale won’t truly begin until April. Then, the spacecraft will make a series of dives taking it between the inner edge Saturn’s rings and the planet’s atmosphere. At its closest approach, Cassini will be just 2,000 kilometers above Saturn’s cloud tops.
Besides images that will make all of our jaws drop, the science gathered here could be some of the most important. Here are just some of the incredible science Cassini is expected to gather:
Detailed maps of Saturn’s gravity and magnetic fields. These maps can tell us how Saturn is made up on the inside. They could also help scientists get a better handle on just how fast the interior is rotating.
How much material sits in Saturn’s rings. The more we know about the makeup of Saturn’s rings, the closer we are to understanding their exact origins. Cassini’s particle detectors will sample some of the icy ring particles falling in Saturn’s atmosphere due to its magnetic field.
Jaw-dropping images. Cassini will blow us away again with close-up images of Saturn’s rings and its cloud tops.
The final months of Cassini’s mission will increase our understanding of how gas giants form and evolve over time. On September 2017, Cassini will take its final look at Saturn before slamming into the gas giant’s atmosphere and coming to a fiery end.