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Cassini Significant Events 05/21/2014 - 05/28/2014 Cassini is orbiting Saturn with a 31.9-day period in a plane inclined 44.3 degrees from the planet's equatorial plane. The most recent spacecraft tracking and telemetry data were obtained on May 28 using the 70-meter diameter Deep Space
Network (DSN) station at Goldstone, California. Except for the 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 "Eyes on the Solar System."
With the ten-week command sequence known as S84 stored safely on board the spacecraft, Cassini's Sequence Implementation Process teams worked on S85 and S86, and tasks for the implementation work on S87 have been scheduled. The Navigation
team continued to estimate Cassini's orbital path and work on upcoming opportunities for Orbit Trim Maneuvers. Also, the science and engineering team continue to plan for the 2016 start of the F-ring and Proximal Orbits mission phase. One current activity
is a proximal orbit planning exercise designed to test the science and engineering activity integration processes during this very busy period. Wednesday, May 21 (DOY 141) Since Cassini flew past Titan last Saturday, the Cassini Navigation team has obtained three days of precision tracking data from the DSN: Doppler shift (velocity) and ranging (distance) information. After processing these data to provide
an updated trajectory, the flight team prepared and uplinked commands to perform Orbit Trim Maneuver (OTM) 380. These commands turned the spacecraft and fired its small rocket thrusters for 13 seconds, producing the desired change in velocity of 20 millimeters
per second to remove the small trajectory error that the T-101 flyby introduced. Following the OTM, the Ultraviolet Imaging Spectrograph (UVIS) observed Saturn’s northern aurora for five and one-half hours, while the Composite Infrared Spectrometer (CIRS) and the Visible and Infrared Mapping Spectrometer (VIMS) also
took data in "ride-along" mode. Spacecraft pointing control was then given to the Navigation team to begin taking images of Saturn's small satellite Mimas against the background of stars for optical navigation purposes. Thursday, May 22 (DOY 142) As the optical navigation image-taking finished about one and one-quarter hours into the day, UVIS turned back to observe Saturn’s aurora again. This time the observation was to last just over a day and a half. CIRS and VIMS again participated. Friday, May 23 (DOY 143) The Spring 2014 Cassini Scientist for a Day contest challenged students to select from three targets, Saturn’s north pole, Saturn's F ring, or Titan, and to write an essay supporting their selection. The winning essays were posted online
today: Saturday, May 24 (DOY 144) The 10-week-long S84 sequence began to take control of the spacecraft today as soon as S83 completed its execution. Among its first activities was to continue pointing UVIS's telescope towards Saturn's northern auroral oval to make observations
with CIRS, VIMS, and the Magnetospheric Imaging Instrument (MIMI) also participating. This observation also lasted about a day and a half. Yet another such observation was started on Monday. Sunday, May 25 (DOY 145) The DSN carried out communications sessions with Cassini on four nights this week, using the 70-meter station and the 34-meter stations at Goldstone, California. Each lasted nine hours. The round-trip light time was just over 2 hours 28
minutes today, and it is increasing slowly, by roughly two seconds each day, while Earth and Saturn linger on the same side of the Sun. Monday, May 26 (DOY 146) A small image of a large icy moon was featured today. The day-night terminator is seen cutting across a crater on the 1,123-kilometer diameter moon Dione: Tuesday, May 27 (DOY 147) Sunsets are typically reddish on Earth, bluish on Mars. A news feature released today discusses the spectral signature as sunlight filters through Titan's atmosphere, and how it might relate to studying the spectral signatures of exoplanets
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