NASA Cassini Significant Events 02/03/10 - 02/09/10

Status Report From: Jet Propulsion Laboratory
Posted: Monday, February 15, 2010

image The most recent spacecraft telemetry was acquired on Feb. 9 from the Deep Space Network tracking complex at Madrid, Spain. The Cassini spacecraft is in an excellent state of health and all subsystems are operating normally. Information on the present position and speed of the Cassini spacecraft may be found on the "Present Position" page at:

Wednesday, Feb. 3 (DOY 034)

In a news release entitled, "NASA Extends Cassini's Tour of Saturn, Continuing International Cooperation for World Class Science," NASA announced that the Cassini-Huygens mission has been extended through 2017.

The project was originally scheduled to end in 2008, but the mission received a 27-month extension through Sept. 2010 to follow seasonal changes of an outer planet system from near its northern winter solstice through its equinox. This second extension, called the Cassini Solstice Mission, will enable scientists to study seasonal and other long-term weather changes on the planet and its moons to its northern hemisphere summer solstice. Cassini arrived just after Saturn's northern winter solstice, and this extension continues until shortly past northern summer solstice in May 2017. For the full release link to:

Port 1 products were due today as part of the S61 Science Operations Plan (SOP) process. The products will be merged and sent out to the flight team for review.

There have been no changes to the Preliminary Sequence Integration and Validation part 2 merge 2, "g" version of S58, currently going through the final sequence development process. As a result, the sequence leads were able cancel the final phase of the process. The final approval meeting is scheduled for Feb. 24 with sequence execution beginning on Mar. 1.

Thursday, Feb. 4 (DOY 035)

Spacecraft Operations performed a Stellar Reference Unit calibration on Feb. 4. In addition, the main engine cover was closed as a precautionary measure for protection against dust hazards on Feb. 13. The cover will be reopened on Feb. 15.

Each year Cassini scientists pick what they consider to be the top ten highlights of the year. From the view of the rings at equinox to the first visible-light images of the northern polar hexagon in almost thirty years, the scientific bounty continues to grow. For the full descriptions and images for 2009, link to:

Friday, Feb. 5 (DOY 036)

Working with the Deep Space Network, Cassini executed a Radio Frequency Subsystem (RFS) Static Phase Error (SPE) test over DSS-55. The purpose was to characterize tracking loop performance by stretching Static Phase Error. During this test the receiver was locked up and the uplink frequency was changed by +/- 150 kHz to verify that the tracking loop is performing nominally.

On DOY 036 a Solid State Power Switch (SSPS) trip occurred, the 29th such trip since launch. The switch involved controls the Cosmic Dust Analyzer (CDA) replacement heater. SSPS Fault Protection reset the replacement heater switch, and then commanded the CDA instrument off, its proper response. As there was no health and safety concern and critical mission science was not at risk, plans have been put in place to turn CDA back on and reset the SSPS trip counter next Tuesday.

Sunday, Feb. 7 (DOY 038)

Along with Composite Infrared Spectrometer (CIRS) and Visual and Infrared Mapping Spectrometer (VIMS) science observations, the Spacecraft Operations Office performed a reaction wheel bias, the Magnetometer performed a downlink roll calibration, and the flight team had an opportunity for what is called a "Kodak Moment." A Kodak Moment as the name implies is an opportunity for an aesthetically pleasing image to be taken. Mission Planning identifies many such opportunities but only about one per sequence may be implemented, and only if the Navigation team is able to release an Optical Navigation image placeholder, and only if margins and workforce allow. For S57 the team was able to obtain a nice image of Titan, Rhea, the rings, and Saturn to add to the album.

Monday, Feb. 8 (DOY 039):

An SOP kickoff meeting was held today for S62. The process will run for approximately 12 weeks and conclude on May 14. The final sequence development process will begin the following week with execution of S62 beginning on Jul. 30.

This week Imaging Science (ISS), CIRS and the Ultraviolet Imaging Spectrograph (UVIS) performed observations as part of the Titan monitoring campaign. UVIS performed mosaic scans of Saturn's magnetosphere and performed a calibration activity at apoapse to determine the absolute sensitivity of the extreme and far ultraviolet by targeting the star Spica. CIRS performed a spectroscopic observation of an infrared star, measured oxygen compounds in Saturn's stratosphere, and performed a stray light calibration. Sunlight falling on the CIRS telescope can be scattered into the instrument by mirror imperfections. To quantify the effects of ring particle impacts on the mirror performance, CIRS monitored the scattered IR solar radiation as a function of the offset angle from the sun.

This month the Cassini Science league brings information on: Negative Ions, a Positive Sign for Liquid Water in Enceladus. The Cassini plasma spectrometer, originally designed to take data in Saturn's magnetic environment, measures the density, flow velocity and temperature of ions and electrons that enter the instrument. But since the discovery of Enceladus' water ice plume, the instrument has also successfully captured and analyzed samples of material in the jets. Now, Cassini scientists report they have found negatively charged ions in the plume, many of which are water, but also including other hydrocarbon species. Their findings, based on analysis from data taken in plume fly-throughs in 2008, are reported in the journal Icarus. Enceladus thus joins Earth, Titan and comets where negatively charged ions are known to exist in the solar system. At Earth's surface, negative water ions are present where liquid water is in motion, such as waterfalls or crashing ocean waves. For the full text, link to:

The Cassini Science League endeavors to share more of the large and diverse volume of science generated by the scientists on the Cassini mission. Each Science League entry highlights a science paper or set of interrelated papers - and provides information on the publication in which the paper appears. For previous entries link to:

Tuesday, Feb. 9 (DOY 040)

Uplink Operations sent commands to the spacecraft to power on CDA, return the instrument to normal operations, and to reset the SSPS trip response counter.

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