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Cassini Significant Events 03/31/10 – 04/06/10

The most recent spacecraft telemetry was acquired on April 6 from the Deep Space Network tracking complex at Canberra, Australia. The Cassini spacecraft is in an excellent state of health and all subsystems are operating normally. Information on the present position and speed of the Cassini spacecraft may be found on the "Present Position" page at: http://saturn.jpl.nasa.gov/mission/presentposition/.

Wednesday, March 31 (DOY 090)

This week the Magnetospheric and Plasma Science teams continued the solar wind ­ auroral campaign, began a magnetospheric boundaries campaign, and conducted some dusk magnetosphere observations. Radio Science and the Radio and Plasma Wave Science (RPWS) instruments both performed Periodic Instrument Maintenance. The Ultraviolet Imaging Spectrograph (UVIS) performed mosaic scans of Saturn's magnetosphere, and observed a solar ingress occultation by Saturn with the Visual and Infrared Mapping Spectrometer (VIMS) riding along. Imaging Science (ISS) observed the transit of Epimetheus across Janus for orbit determination purposes, and led an Optical Remote Sensing campaign to monitor the clouds on Titan. VIMS performed an E/G ring phase observation and globally mapped Titan. The Magnetospheric Imaging Instrument (MIMI) continued its campaign to observe the interaction between the magnetospheric hot ion and electron distributions, rings, and icy satellites.

Thursday, April 1 (DOY 091)

The S59 background sequence was uplinked over DSS-45 in Canberra today. Receipt and registration have been verified. The sequence will begin execution on Sunday, Apr. 4.

Friday, April 2 (DOY 092)

Uplink Operations sent commands to the spacecraft today for a Titan 67 Live Inertial Vector Propagator update to execute on Monday, Apr. 5, and an S58 end of sequence real time reaction wheel bias.

Orbit Trim Maneuver (OTM) #241 was performed today. This was the approach maneuver setting up for the Titan T67 and Dione D2 encounters on April 5 and 7. The reaction control subsystem burn began at 7:59 AM PDT. Telemetry immediately after the maneuver showed a burn duration of 26.625 seconds, giving a delta-V of 0.033 m/s. All subsystems reported nominal performance after the maneuver.

In a special double flyby early next week, Cassini will visit Titan and Dione within a period of about a day and a half, with no maneuvers in between. A fortuitous alignment of these moons allows Cassini to do this doubleheader, and the interest in a close Dione encounter influenced the design of the extended mission.

Sunday, April 4 (DOY 094)

The S58 sequence concluded and S59 began execution today at 2010-095T02:49 SCET. The sequence will run for 43 days and conclude on May 17. During that time there will be three targeted encounters, one each of Titan, Dione, and Enceladus, and twelve non-targeted flybys. Six OTMs are scheduled, numbered 242 through 247.

Monday, April 5 (DOY 095)

The second of two important Titan encounters for the Imaging Science Subsystem (ISS) in the extended mission (XM) occurred today as Cassini flew past Titan for the T67 targeted flyby. Closest approach occurred at 10:01 AM Pacific Time, latitude 0 deg, altitude of 7,462 kilometers, and a speed of 5.7 km/sec. High flybys of about 7,000 kilometers (about 4,500 miles) were designed specifically to provide very long, low phase views of Titan's surface.

CIRS observations provided the farthest north vertical profiles of the atmosphere in the Extended Mission. The instrument took data on the composition and temperature profiles at 70 degrees N, and possibly observed the break up of the winter/spring vortex.

During this flyby, VIMS rode along with ISS at closest approach and mosaiced the equatorial terrains from Belet to Senkyo with a resolution from 4 to 20 km/pixel. VIMS also obtained higher resolution images of a circular feature about 500 kilometers in diameter observed during T34.

UVIS obtained an image cube of Titan's atmosphere at extreme and far ultraviolet wavelengths by sweeping its slit across the disk. These cubes provide spectral and spatial information on nitrogen emissions, H emission and absorption, absorption by simple hydrocarbons, and the scattering properties of haze aerosols. This is one of many such cubes gathered over the course of the mission to provide latitudinal and seasonal coverage of Titan's middle atmosphere and stratosphere.

MIMI measured the energetic ion and electron energy input to the atmosphere with excellent opportunities for measurement of energetic neutral atoms.

RPWS measured thermal plasmas in Titan's ionosphere and surrounding environment, searched for lightning in Titan's atmosphere, and investigated the interaction of Titan with Saturn's magnetosphere.

This flyby was higher than usually desired for the Ion and Neutral Mass Spectrometer, but the instrument team elected to ride along anyway, performing observations to expand their dataset.

For more details on this flyby link to here:

A digitally re-mastered image of Prometheus was Astronomy Picture of the Day today. Check it out here:

Tuesday, April 6 (DOY 096)

The command loss timer value was increased to 110 hours today to accommodate larger than usual periods of time between DSN tracks.

The Spacecraft Office Engineering Preview for sequences S64-S73 took place today. This preview/overview covered the Equatorial ­1 part of Extended Extended Mission from October 2010 to April 2012. Several topics including overlapping maneuvers and dust hazards needing main engine cover closure were discussed.

Coming Up:

In the early morning of Wednesday, April 7 in UTC time zones, around 9 p.m. on Tuesday, April 6 in California, Cassini will make its closest approach to the medium-sized icy moon Dione, passing within about 500 kilometers (311 miles) of the surface. The details of this event will be reported in Significant Events next week.