News | April 11, 2013
Cassini Significant Events 04/03/2013 - 04/09/2013
The Cassini spacecraft is orbiting Saturn with a 9.6-day period in a plane inclined 61.7 degrees from the planet's equatorial plane. The most recent spacecraft tracking and telemetry data were obtained on April 9 by a 34-meter Deep Space Network station at Madrid, Spain. 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 of the Cassini spacecraft may be found on the "Present Position" page at: http://saturn.jpl.nasa.gov/mission/presentposition/.
Flying by Titan this week pushed Cassini's orbit to its highest inclination until 2016; the T-90 encounter raised the spacecraft's orbital plane to 61.7 degrees from Saturn's equatorial plane. From now through March 2015, most Titan flybys will be used to decrease Cassini's inclination until it is again closely aligned with the ring plane after the T-110 Titan encounter.
Wednesday, April 3 (DOY 093)
Cassini passed through periapsis going 39,284 kilometers per hour relative to Saturn, at about 424,000 kilometers above the cloud tops, just beyond the diffuse E ring's outer edge. While close-in to Saturn, the Composite Infrared Spectrometer (CIRS) measured temperatures of ring particles as they passed from within Saturn's shadow into sunlight; this observation to determine the particles' thermal inertia covered from the inner edge of the C ring to the outermost sections of the A ring.
The Ultraviolet Imaging Spectrograph (UVIS) observed an occultation of the star Delta Centauri as it made a full radial cut behind the main ring system due to Cassini's motion in orbit. UVIS stellar occultations are the only observations that have high enough spatial resolution to resolve waves seen in the C ring that are of unknown origin.
Thursday, April 4 (DOY 094)
UVIS observed the sunlit side of the rings while behind the planet's day-night terminator to reduce the amount of Saturn shine and stray light. The observation's phase angles, 30 to 38 degrees, will help characterize the scattering behavior of ring particles and provide information on particle albedo and composition. The Visible and Infrared Mapping Spectrometer (VIMS) watched an occultation as the star R Hydrae as it passed behind the rings. CIRS then took its turn studying the rings.
Friday, April 5 (DOY 095)
Cassini carried out its first Titan (T-90) encounter in 47 days. The 1,400 kilometer altitude flyby concentrating on infrared observations in the low northern latitudes is detailed here:
Saturday, April 6 (DOY 096)
VIMS looked back at Titan for clouds at northern mid-latitudes that were expected to form during northern spring according to global circulation models. CIRS made a detailed sampling of the atmosphere at high southern latitude to monitor Titan's fall season in the south. The Imaging Science Subsystem (ISS) watched a region on Titan where extensive surface changes were observed in late 2010 and an area at mid-southern latitudes on the trailing hemisphere that has only been imaged at lower resolution.
The 70-meter diameter Deep Space Network (DSN) stations in Madrid, Spain and Goldstone, California flawlessly captured every bit of the telemetry data that Cassini played back to Earth, carrying results of all the T-90 science observations.
Sunday, April 7 (DOY 097)
Observations dedicated to Titan composition science kept CIRS, ISS and VIMS busy today, as well as much of Monday and Tuesday. While carrying out tracking operations and capturing telemetry, the 34-meter diameter DSN station in Madrid, Spain participated in an operations readiness test to prepare for a Radio Science Saturn atmosphere occultation experiment coming up on Thursday.
Saturn is featured in today's Astronomy Picture of the Day, this time as seen from Germany just before Earth's Moon passed in front of the ringed planet: http://apod.nasa.gov/apod/ap130407.html
Monday, April 8 (DOY 098)
Orbit Trim Maneuver 347, the post-T-90 trajectory cleanup maneuver, was performed today using the Reaction Control Subsystem thrusters. The 115-second burn provided Cassini a change in velocity, delta-V, of 123 millimeters per second.
The region on Titan known as Senkyo, where there are vast fields of dunes of dark hydrocarbon particles, can be seen in an image featured today: /resources/15770
Tuesday, April 9 (DOY 099)
This week, DSN stations on three continents carried out communications with Cassini on eight occasions. The two-way communications time ranged from 74.1 to 73.8 minutes, since Earth's motion in solar orbit is closing the distance somewhat these days. This also means that Saturn is beginning its prominent yearly display in the night sky, which is an experience not to be missed by anyone who has a small telescope, or a friend or relative with one. For more information on catching the view, see NASA's "What's Up In the Night Sky":