Cassini Significant Events for 09/18/2013 – 09/24/2013
Cassini is orbiting Saturn with a 31.9-day period in a plane inclined 51.9 degrees from the planet’s equatorial plane. The most recent spacecraft tracking and telemetry data were obtained on Sept. 25 using the 70-meter diameter Deep Space Network station at Goldstone, California. Except for some 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 and speed of the Cassini spacecraft may be found on the “Present Position” page at:
http://saturn.jpl.nasa.gov/mission/presentposition/.
The on-board sequence S80 issued commands controlling Cassini this week. Meanwhile, work proceeded at JPL on the ten-week command sequences S81, S82, and S83, and on planning for the 2016 start of the F-ring and Proximal Orbits phase.
Wednesday, Sept. 18 (DOY 261)
The Ultraviolet Imaging Spectrograph (UVIS) completed a 37-hour long mosaic scan of Saturn’s magnetosphere, part of a yearly campaign to image oxygen in the vicinity of the Saturn disk. Similar observations, of roughly similar lengths, were repeated on Thursday going into Friday, and on Saturday into Sunday.
Thursday, Sept. 19 (DOY 262)
The Navigation team used the Imaging Science Subsystem (ISS) to take an image of Saturn’s moon Iapetus for Optical Navigation purposes. Typically, such “opnav” images purposefully overexpose the body so that the background stars can be seen; their relative positions are then measured. Next, ISS performed an observation in the satellite orbit campaign looking at small objects near Saturn, and searching for new ones. Then, prior to UVIS’s next long-duration oxygen search, the Visible and Infrared Mapping Spectrometer (VIMS) made a two-minute Saturn storm watch observation.
Friday, Sept. 20 (DOY 263)
The Radio and Plasma Wave Science subsystem (RPWS) collected data for its survey of emissions in the neighborhood of 80 kilohertz. RPWS actually takes data frequently in the background as the spacecraft moves through various parts of the Saturnian environment, while the other instruments are prime.
Saturday, Sept. 21 (DOY 264)
UVIS began a 31-hour long mosaic scan of Saturn’s magnetosphere, the last of three observations this week as part of a yearly campaign to image oxygen in the vicinity of the Saturn disk.
Our name for this day of the week comes from the Roman god Saturn who was, among many other things, the god of time: literally Saturn’s day.
Sunday, Sept. 22 (DOY 265)
The Realtime Operations team sent part two of the S80 command sequence to the spacecraft today using the 70-meter aperture DSN station at Goldstone, California. After a round-trip light time of two hours fifty-seven minutes, telemetry confirmed that all 4861 individually timed commands had been received intact and stored onboard. They will control the spacecraft’s activities through October 22, when S81 will take over.
Monday, Sept. 23 (DOY 266)
Calibrations are important components of Cassini’s science observations, though they are not frequently mentioned in these reports. Today the Magnetometer (MAG) performed a calibration that involved rotating the spacecraft about its X-axis, pitching the MAG boom “head over heels.” At other times, the spacecraft performs MAG calibrations by rolling about its Z-axis while keeping the high-gain antenna pointing toward Earth for communications. Following the MAG calibration, the Cosmic Dust Analyzer (CDA) began a 29-hour observation of dust that orbits Saturn in the retrograde direction.
Enceladus and its enigmatic constantly erupting jets are seen under unusual lighting conditions in an image featured today:
http://saturn.jpl.nasa.gov/photos/imagedetails/index.cfm?imageId=4890
Tuesday, Sept. 24 (DOY 267)
The Radio Science team conducted a calibration of the Deep Space Network (DSN) Monopulse system using Cassini’s Ka-band (32 GHz) downlink radio signal. Monopulse, when operating, constantly makes fine adjustments in the DSN antenna’s pointing while producing a record of those adjustments. One of the 34-meter diameter DSN stations at Goldstone, California participated in the calibration while conducting two-way digital and radiometric tracking of the spacecraft at the same time; this was one of five DSN-Cassini tracking periods this week.
Visit the JPL Cassini home page for more information about the Cassini Project: http://saturn.jpl.nasa.gov/
