Cassini is orbiting Saturn with a twelve-day period in a plane inclined 57 degrees from the planet's equatorial plane. The most recent spacecraft tracking and telemetry data were collected on March 26 by the 70-meter Deep Space Network station at Goldstone, California. Except for some science instrument issues described in previous reports, the spacecraft continues to be in an excellent state of health with all of its subsystems 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/ .
Cassini's Sequence Implementation Process (SIP) teams continued working on the ten-week command sequences S79 and S80, which will go active on the flight system in June and August respectively, and planning continued for the 2016 start of Cassini's F-ring and Proximal Orbits phase. Meanwhile, commands from the on-board S77 sequence finished controlling the spacecraft's activities in flight and commands from S78 started taking effect on Tuesday as planned.
Wednesday, March 20 (DOY 079)
Cassini flew across Saturn's night-side southern auroral oval, carrying out observations for nine hours coordinated among the telescopic optical remote sensing (ORS) instruments and the magnetospheric and plasma science (in-situ) instruments. The latter measured field-aligned currents, auroral plasma populations, and plasma waves across different latitudes, to help scientists understand the energy balance of Saturn's upper atmosphere.
Thursday, March 21 (DOY 080)
The Cosmic Dust Analyzer (CDA) took measurements of the dust impacting the instrument during ring plane crossing. CDA can discern the mass, quantity, impact speed and direction, chemical composition, and electrical charge of grains the size of smoke particles.
Friday, March 22 (DOY 081)
Cassini passed through periapsis going 39,250 kilometers per hour relative to Saturn, at about 425,000 kilometers above the cloud tops.
The Magnetometer executed a calibration while rotating the spacecraft about its X axis for sensor offset determination. The Ultraviolet Imaging Spectrograph (UVIS), in collaboration with the Composite Infrared Spectrometer (CIRS) and the Visible and Infrared Mapping Spectrometer (VIMS) riding along, observed the north pole for 11.5 hours to study auroral morphology at high spatial resolution from low altitude and high inclination.
Saturday, March 23 (DOY 082)
UVIS, with CIRS and VIMS, which were also taking data (riding along), observed the giant gas planet's dayside aurora at low phase angles for 13.5 hours, covering more than one planetary rotation. The objective is to identify rotating features and signatures of solar wind interaction under varying conditions, such as spots related to Kelvin-Helmholtz viscous interaction
(see http://saturn.jpl.nasa.gov/photos/imagedetails/index.cfm?imageId=582 for an image)
dor arcs produced by magnetopause reconnection. Spectral analysis of any features, such as differences in atomic hydrogen (H) versus molecular hydrogen (H2) or trihydrogen (H3+) emissions, reveals precipitating electron energy from coupling of the solar wind, the magnetosphere, and the ionosphere.
Sunday, March 24 (DOY 083)
The Realtime Operations team uplinked the first part of the S78 command sequence using the 70 meter Deep Space Network station at Goldstone, California. The team confirmed that all 9000 individual commands were received and properly stored on the spacecraft after a round-trip light time of 2 hours 30 minutes. The team will uplink the second part in mid-May when enough on-board memory will be available.
Monday, March 25 (DOY 084)
An image featured today illustrates the violent history recorded on the surface of Saturn's second largest moon Rhea:
Tuesday, March 26 (DOY 085)
The final S77 commands executed today and the S78 sequence began controlling the spacecraft. Back on Earth, the S78 SIP team assumed responsibility and authority for operations.
The Imaging Science Subsystem (ISS) and UVIS made a 4.5-hour observation of the 8-kilometer irregular moon Hyrrokkin in its retrograde orbit about Saturn. They then began a 19-hour observation of the irregular retrograde moon Narvi, which is about six kilometers in diameter. These tiny objects orbit Saturn more than eighteen million kilometers away with periods on the order of a thousand days.