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Cassini Significant Events 03/21/2012 – 03/27/2012

The most recent spacecraft tracking and telemetry data were collected on March 28 using the Deep Space Network's 70 meter Station 43 at Canberra, Australia; data from the Enceladus E-17 encounter were captured successfully. Aside from the issue in work with the Ultrastable Oscillator (see the Jan. 5, 2012 Significant Events), the Cassini spacecraft is in an excellent state of health and all subsystems are 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 Enceladus encounter E-17 occurred Tuesday, and by the end of the day, all the encounter observations resided as telemetry on Cassini's Solid-State Recorder. The playback to Earth didn't begin until Wednesday; it will be listed among next week's significant events. The E-17 webpage will include the data as they become available: http://saturn.jpl.nasa.gov/mission/flybys/enceladus20120306/

Wednesday, March 21 (DOY 081)

The Imaging Science Subsystem (ISS) spent 12 hours searching for possible satellites near the zone of stability 60 degrees ahead of Titan in its orbit about Saturn, known as the L4 Lagrange point.

Thursday, March 22 (DOY 082)

The Cosmic Dust Analyzer (CDA) spent 13.5 hours collecting data on interstellar dust.

An image was posted today showing the Cassini Program Manager accepting the 2012 Smithsonian National Air and Space Museum's Trophy for Current Achievement for the Cassini Team on Wednesday, with the 1903 Wright Flyer in the background: http://saturn.jpl.nasa.gov/news/newsreleases/newsrelease20120322/

Negotiations for Deep Space Network antenna allocations to support the S73 sequence continue to run quite late. This will require either commanding spacecraft telemetry modes in real time to compensate for allocation changes after the sequence has been uplinked to the spacecraft, or losing the data for lack of a DSN station during the downlink.

Friday, March 23 (DOY 083)

ISS conducted another observation in the Satellite Orbit Campaign, looking near Saturn where small satellites ("rocks") may be found, hoping to improve knowledge of their orbits or make new discoveries. More accurate orbit determinations lead to better predictions of the satellites' future positions for observation planning and potentially even spacecraft safety purposes.

The Navigation Team acquired five images for Optical Navigation purposes, and the Ultraviolet Imaging Spectrograph (UVIS) made scans of Saturn's magnetosphere for 16 hours in order to image hydrogen and oxygen, while VIMS and ISS performed a Saturn Storm Watch observation.

Saturday, March 24 (DOY 084)

Orbit Trim Maneuver (OTM)-313, the E-17 approach maneuver, was executed by turning the spacecraft and firing the Reaction Control Subsystem thrusters for 10 seconds, providing a delta-V of approximately 16.3 mm/s.

After the OTM, the Attitude and Articulation Control Subsystem executed a Reaction Wheel Assembly (RWA) bias maneuver to adjust wheel speeds. When this was completed, ISS did another Satellite Orbit Campaign observation while VIMS did more storm watch observations. UVIS and VIMS then started an 11 hour watch of Saturn's aurorae.

Sunday, March 25 (DOY 085)

ISS began a 13 hour observation of the edge of Saturn's shadow on the Phoebe ring, which is likely composed of particles ejected during micrometeoroid impacts on the small moon. Orbiting Saturn nearly 13 million kilometers out, Phoebe and its ring particles go around the planet in a retrograde direction.

The main engine cover was deployed to its closed position.

Monday, March 26 (DOY 086)

ISS, CIRS, and VIMS made Titan Monitoring Campaign observations that showed cloud features and how they change over time across the Senkyo dune field from a distance of 1.44 million kilometers. ISS and VIMS then searched the L5 Lagrange point 60 degrees behind Titan, again looking for any new satellites.

A feature on the upcoming Enceladus E-17 encounter was published:

An image dubbed "Quieted Storm" was highlighted today:
Tiny Enceladus, visible as a small dot in this image, perhaps illustrates the challenge of conducting a low-altitude flyby, although the Cassini flight team accomplishes such technical feats routinely.

Tuesday, March 27 (DOY 087)

Cassini flew by Enceladus at an altitude of 74 kilometers, with the Optical Remote Sensing instruments as well as the direct sensing instruments in play. ISS imaged the icy satellite's south polar plume while Enceladus was just a thin crescent. Next, the Composite Infrared Spectrometer (CIRS) acquired a series of mid-infrared scans across the night side as well as a pair of scans across the south polar terrain, which is home to numerous thermal hotspots, and then did a far-infrared raster scan. For the two hours surrounding closest approach, the Ion and Neutral Mass Spectrometer (INMS) was prime, while CDA and CAPS contributed to measuring the plume's composition as the spacecraft flew through it along the length of Baghdad Sulcus. These instruments were poised to resolve individual jets from this "tiger stripe" fracture. Finally, ISS acquired nine frames forming a mosaic of Enceladus's leading hemisphere as the spacecraft receded.

ISS then acquired a series of 29 images of one of Saturn's smaller satellites, Janus, with Saturn as a backdrop, at a closest approach distance of 43,850 kilometers.

Leaving Enceladus behind, Cassini passed through periapsis going 68,120 kph, and slightly closer to Saturn than Mimas's orbit.