NASA Cassini Significant Events for 06/25/2014 – 07/01/2014
Cassini is orbiting Saturn with a 31.9-day period in a plane inclined 46.5 degrees from the planet’s equatorial plane. The most recent spacecraft tracking and telemetry data were obtained on July 2 using one of the 34-meter diameter Deep Space Network stations 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”:
Cassini spent this week coasting “up” from Saturn and slowing towards the high point in its orbit, while the on-board S84 command sequence controlled all its activities. Ongoing radiometric (line-of-sight Doppler-shift and range) tracking by the ultra-sensitive Deep Space Network let the Cassini Navigation team determine that the vehicle was within five kilometers of the planned path. Consequently the opportunity to execute a propulsive maneuver leveraged by being near apoapsis was not needed, and an Orbit Trim Maneuver planned during the Fourth-of-July weekend was cancelled.
Direct-sensing Magnetospheric and Plasma Science instruments collected data most of the time, while optical remote-sensing instruments had the spacecraft rotate about its three axes to point their telescopes at selected targets on Saturn and its satellites. Meanwhile on the ground, Cassini’s Sequence Implementation Process teams worked on the 10-week sequences S85, S86, and S87, and planning continued for the 2016 start of the F-ring and Proximal Orbits mission phase.
Wednesday, June 25 (DOY 176)
The Composite Infrared Spectrometer (CIRS) began a 24-hour observation of Saturn that will create a temperature map of its north polar region in an effort to study the atmospheric vortex there.
Thursday, June 26 (DOY 177)
The Imaging Science Subsystem (ISS) performed a one-hour observation in the satellite orbit campaign, looking at small objects near Saturn while the Visible and Infrared Mapping Spectrometer (VIMS), which enjoys common pointing, was allocated storage space for its data so it “rode along.” The observation was repeated on Monday. When each satellite observation was done, ISS and VIMS took advantage of the near-Saturn pointing and made a two-minute a storm-watch observation.
The week’s Project Science Group meeting #63, at the European Space Research and Technology Center, wrapped up today.
Friday, June 27 (DOY 178)
The Deep Space Network tracked Cassini on five occasions this week, using the 70 meter and 34 meter diameter stations at Goldstone, California. The round-trip light time for two-way communications with the distant robot was 153 minutes as of today, and is increasing by about 12 seconds a day.
Saturday, June 28 (DOY 179)
Saturn is well placed in the sky these evenings for viewing with basically any kind of optical aid. It is high in the east shortly after dark, and bright enough to be seen even from a lighted city environment.
Sunday, June 29 (DOY 180)
CIRS began a 23-hour observation of Saturn’s atmosphere in an effort to determine upper troposphere and tropopause temperatures. ISS and VIMS rode along, and then ISS took two minutes for a storm-watch image when CIRS was done.
Monday, June 30 (DOY 181)
ISS, CIRS and VIMS made a 1.5-hour observation in the Titan monitoring campaign from a distance of 3.8 million kilometers. On the home planet, the Cassini Navigation team determined that the required change in velocity for the Orbit Trim Maneuver (OTM) planned for July 4 would have been too small for the Spacecraft Operations Office engineers to actually achieve, even using Cassini’s small thrusters. Hence all further work to implement OTM-384 was cancelled today.
Results from the public contest to name Cassini’s terminal mission phase were published today. That mission phase will be known as the “Cassini Grand Finale”:
http://saturn.jpl.nasa.gov/news/cassinifeatures/feature20140630
Variations in surface brightness on Saturn’s large moon Dione are evident in an image featured today showing it in its “full-moon” phase of illumination:
http://saturn.jpl.nasa.gov/photos/imagedetails/index.cfm?imageId=5053
Late in the day local time exactly a decade ago, Cassini successfully executed a maneuver that had taken years of meticulous planning, coding, testing, and exercising to prepare. All went perfectly well while the main engine fired for 96 minutes, and none of the spacecraft’s on-board fault-protection safeguards had to snap into action. When the maneuver ended, Cassini had become the most distant spacecraft ever to orbit another planet. This page tells more of the story:
http://saturn.jpl.nasa.gov/news/cassinifeatures/feature20140625
Tuesday, July 1 (DOY 182)
While Cassini was within a day before passing apoapsis nearly three million kilometers from Saturn, the Cosmic Dust Analyzer (CDA) spent 13.5 hours measuring dust that orbits Saturn in a retrograde direction.
Visit the JPL Cassini home page for more information about the Cassini Project: http://saturn.jpl.nasa.gov/
