News | June 15, 2016
Cassini Significant Events 06/08/16 - 06/14/16
Cassini is orbiting Saturn with a period of 23.9 days in a plane inclined 43 degrees from the planet's equatorial plane. The most recent spacecraft tracking and telemetry data were obtained on June 14, using the 70-meter diameter Deep Space Network station in Australia. The spacecraft continues to be in an excellent state of health with all of its subsystems operating normally except for the instrument issues described at http://saturn.jpl.nasa.gov/anomalies .
Cassini spent the week coasting outbound from Saturn, slowing towards a June 17 apoapsis. The new, increased inclination of Cassini's orbit, 43 degrees above the ring plane, makes for spectacular Saturn-viewing geometry. The spacecraft can look down onto the rings and the planet's day-night terminator (never possible from Earth), and the northern hexagon is clearly visible in the sunlight. Earth (not visible in this graphic) is in inferior conjunction with Saturn, far away in the direction opposite the planet's shadow. The illustration may be seen here.
Wednesday, June 8 (DOY 160)
Cassini spent 6.5 hours in one-way and then two-way radio communication with Earth today, the day after closely encountering Titan for the T-120 flyby. Radiometric data were acquired for the Navigation team, and digital telemetry data went to the science teams and spacecraft engineers. As commonly expected, this activity spanning 1,400 million kilometers executed flawlessly. Thanks to forward-error-correction coding among many other factors, results of Cassini's observations were received across the distance with bit-for-bit accuracy.
Following today's session with the Deep Space Network (DSN), Cassini's Imaging Science Subsystem (ISS) spent about six hours controlling spacecraft pointing to monitor Titan, tracking hydrocarbon clouds in its late-springtime, dense, nitrogen atmosphere. The Visible and Infrared Mapping Spectrometer (VIMS) and the Composite Infrared Spectrometer (CIRS) participated. This observation was repeated on Friday. Cassini's Titan-viewing angle is of course similar to the view toward Saturn linked above.
Thursday, June 9 (DOY 161)
ISS made a 60-minute observation in the satellite orbit campaign, looking near Saturn for small objects; CIRS and VIMS rode along. Next, CIRS and VIMS observed Saturn’s atmosphere at far-infrared wavelengths for 12 hours in an effort to determine upper troposphere and tropopause temperatures.
Friday, June 10 (DOY 162)
After today's Titan monitoring, ISS took two minutes for a storm-watch observation on Saturn. Next, ISS watched Saturn's narrow F ring for 15 hours with CIRS and VIMS riding along. This was enough time for a particle in the F ring to go completely around the planet, in its orbital racetrack of about 880,000 km circumference. The observation's results will be combined into a low-resolution movie of the constantly-changing ring.
A unique view of the F ring, with an unusual "jet" feature, was this week's featured image: /resources/17379 .
Saturday, June 11 (DOY 163)
After making another 2-minute Saturn storm-watch observation, ISS held the reins for 4 hours 20 minutes to create a high-resolution color scan of Saturn's main rings. CIRS, VIMS, and the Ultraviolet Imaging Spectrograph (UVIS) rode along.When this was done, Cassini turned to face its high-gain antenna toward Earth again. About halfway through the DSN period, the spacecraft turned and fired its main rocket engine for 1.4 seconds in response to timed commands uplinked the day before. The resulting Orbit Trim Maneuver (OTM)-452 produced the desired change in velocity of 249 millimeters per second for the spacecraft, to clean up its flight path following T-120, adjusting it back towards the planned reference trajectory.
After the OTM and DSN session today, ISS took control again to begin 89.5 hours of observing Saturn's irregular moon Tarqeq; an observation that would occupy the spacecraft through Tuesday, interrupted only by DSN sessions and engineering tasks. The object is about 6 kilometers in diameter and occupies an inclined orbit that reaches as far as 20.9 million kilometers from Saturn; it is named after the Inuit "Moon god."
Monday, June 13 (DOY 165)
Thermal control is an engineering challenge for any spacecraft in the solar system, where a spacecraft such as Cassini has to confront enormous temperature variations. A feature story this week shows how blankets of multi-layer insulation are made and fitted to address the problem. In addition to helping manage temperatures, they also offer some protection from micro-meteoroid impacts. The first image in the article also shows some of Cassini's rectangular arrays of silver-colored thermal-control louvers, which open and close on their own in response to internal temperatures. The feature is available here: https://saturn.jpl.nasa.gov/thermal-blankets .
Tuesday, June 14 (DOY 166)
The Deep Space Network communicated with and tracked Cassini on six days this week, using stations in California and Australia. A total of 4,766 individual commands were uplinked, and about 1,348 megabytes of telemetry data were downlinked and captured at rates as high as 142,201 bits per second.