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Cassini Significant Events 08/28/2013 – 09/03/2013

Cassini is orbiting Saturn with a 23.9-day period in a plane inclined 53.4 degrees from the planet's equatorial plane. The most recent spacecraft tracking and telemetry data were obtained on Sept. 4 using one of the 34-meter diameter Deep Space Network station at Madrid, Spain. Except for some science instrument issues described in previous reports (for more information search the Cassini website for CAPS and USO), the spacecraft continues to be in an excellent state of health with all of its subsystems operating normally. Information on the present position of the Cassini spacecraft may be found on the "Present Position" page at: http://saturn.jpl.nasa.gov/mission/presentposition/.

The on-board sequence S80 issued commands controlling Cassini this week. Meanwhile, work proceeded at JPL on the ten-week command sequences S81, S82, and S83, and on planning for the 2016 start of the F-ring and Proximal Orbits phase.

Wednesday, Aug. 28 (DOY 240)

The Imaging Science Subsystem (ISS) created a 14.5-hour low-resolution movie of the F ring, which is the bright, narrow, twisted belt just outside the main A ring. The other optical instruments "rode along," taking data while the prime instrument controlled spacecraft pointing, as was typical for most observations again this week.

Topographic highs on a rigid-surfaced Titan, Saturn's largest, atmosphere-enshrouded, moon might have buoyant roots extending into the subsurface ocean, like icebergs do on Earth, as described in a news feature published today describing results from Cassini's measurements of Titan's gravity field: http://saturn.jpl.nasa.gov/news/cassinifeatures/feature20130828/

Thursday, Aug. 29 (DOY 241)

The Visible and Infrared Mapping Spectrometer (VIMS) observed the red star Beta Andromedae as it was occulted by the rings due to Cassini's motion in orbit. The Ultraviolet Imaging Spectrograph (UVIS) then imaged Saturn’s thermosphere, a very high-altitude region where heating takes place.

Cassini coasted through apoapsis just over two million kilometers from Saturn, having slowed to 12,807 kilometers per hour relative to the planet. This marked the beginning of Cassini's orbit #197.

Friday, Aug. 30 (DOY 242)

ISS imaged Saturn's two-tone moon Iapetus, which orbits 3.5 million kilometers from Saturn, for 90 minutes and then began a 21.75-hour observation of the irregular moon Kiviuq. The latter is a small dark "rock" in an inclined orbit three times the distance of Iapetus from the planet.

The flight team uplinked a late-movable block of sixteen commands to Cassini today. These will cause the spacecraft to point the high-gain antenna along Saturn's limb from behind the planet, maintaining the radio link with Earth during Sunday's Radio Science atmosphere and ring occultation experiment.

Saturday, Aug. 31 (DOY 243)

Two Deep Space Network (DSN) stations in California, a 70-meter aperture and a 34-meter one, participated with the Radio Science team in an operations readiness test to prepare for Sunday's experiment.

Sunday, Sept. 1 (DOY 244)

Cassini passed behind Saturn at a distance of nearly two million kilometers today, while receiving a frequency-reference signal from Earth and transmitting phase-coherent radio tones at S-band (2 GHz), X-band (8 GHz), and Ka-band (32 GHz). Telemetry was turned off to prevent its phase-symbols from altering the pure X-band sine wave. The signals probed Saturn's ionosphere and atmosphere at a high southern latitude on ingress, then on egress passed through the outer part of the ring system. All three 70 meter DSN stations across three continents, plus three 34 meter stations, participated in capturing the incoming signals while the Radio Science team made high-resolution recordings of them for future analysis. The geometry of this occultation experiment was unique, but not completely unlike the one illustrated here: /resources/15816

Monday, Sept. 2 (DOY 245)

The Cosmic Dust Analyzer began a 37-hour observation of dust that orbits Saturn in the retrograde direction.

A view of Saturn's 1,120 kilometer diameter moon Dione was featured today: /resources/15882

Tuesday Sept. 3 (DOY 246)

Water and ammonia, dredged up from lower levels in Saturn's atmosphere, have been identified in the huge convective storm that began in 2010. A news feature published today summarizes the recent paper in the journal Icarus on the findings: http://saturn.jpl.nasa.gov/news/cassinifeatures/feature20130903