Light and Dark Moons |Cassini's

Move Over Caravaggio: Cassini's Light and Dark Moons:

NASA's Cassini spacecraft has returned Saturnian moon images from its flyby late last week, revealing light and dark contrasts worthy of chiaroscuro painters like Caravaggio. The flyby on August 13 targeted the geyser moon Enceladus, but also brought Cassini close to two other moons--Tethys and Dione.

Enceladus 'E9' Flyby |Cassini

Enceladus 'E9' Flyby: Plume-crossing, Gravity-measuring Encounter:

On this flyby, the Cassini Radio Science Subsystem (RSS) tracks Enceladus through a close pass to determine the nature of the interior beneath the south polar hot spot. quelle: nasa |jpl

Rhea and Edge-On Rings

quelle: NASA Rhea and Edge-On Rings:

From just below the plane of Saturn's rings, the Cassini spacecraft looks at the rings edge-on and sees the planet's second largest moon beyond. Although Rhea may appear to be in the foreground of this image, it is not. The rings are closer to Cassini. The small moon Prometheus, orbiting between the A ring and the thin F ring, is also visible here near the upper middle of the image.

Complex Orbital Planning Will Keep Cassini Flying Seven Extra Years on Tiny Remaining Fuel Supply

Complex Orbital Planning Will Keep Cassini Flying Seven Extra Years on
Tiny Remaining Fuel Supply:

Cassini arrived in Saturn's neighborhood in 2004 for a four-year mission, but it
performed so well and remained in such good shape, its mission was extended
for two more years. In that time it's made countless discoveries, generated a
wealth of scientific data and spawned well over 1,000 academic papers. It's also
burned three quarters of its fuel.
For the NASA Jet Propulsion Lab mission designers tasked with extending Cassini's
mission for an extra seven years, the project became a convoluted whirl of math and
politics. Here, The New York Times explains the orbital mechanics of the new Cassini
mission, which has to more than double the length of the mission using just a quarter
of the craft's original propellant, all while appeasing opposing scientific interests.
It makes for a complicated equation, to say the very least.
But during the last six years, mission planners had so much practice mapping out
Cassini's trajectory in the most efficient ways possible that they think they can
extend the mission another seven years even though only 22 percent of the original
propellant is left in Cassini's tanks.
In what the Times calls 'an astonishingly complex exercise in Keplerian physics and

geometry,' mission designers balanced the push and pull of various research interests,
Cassini's capabilities and laws of physics to map out seven years worth of loops around
Saturn and its moons, pulling gravity assist maneuvers around the ringed planet and
its largest moon Titan to extend the mission.
After the new mission gets underway in September of this year, Cassini will make
12 passes at Enceladus, 5 at other large moons, 56 flybys of Titan and 155 orbits of Saturn
at various angles before crashing spectacularly into the planet in 2017. But a lot has to
happen between now and then; check out the Times piece for the whole story.
quelle: [New York Times]