Cassini Significant Events 03/26/08 - 04/01/08

April 3, 2008

(Source: Cassini Project)

The most recent spacecraft telemetry was acquired on Monday, March 31, from the Madrid, Spain tracking complex. 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, March 26 (DOY 086):

The Spring 2008 edition of the Cassini Scientist for a Day essay contest will be based on three new imaging targets. The essay contest has a deadline of May 8, and the images will be taken on June 10. This contest is open to US students in grades 5-12, with three age categories: Grades 5-6, Grades 7-8, and Grades 9-12. The updated web site can be found at:

Cassini scientists participated in a news briefing at NASA headquarters in Washington, D.C. today where they presented results from the recent close flyby on the composition of the plumes jetting from Saturn's moon Enceladus. The briefing was broadcast to news media on NASA TV and is available for viewing at:

A Perspective on Life on Enceladus: A World of Possibilities - Could microbial life exist inside Enceladus, where no sunlight reaches, photosynthesis is impossible and no oxygen is available? To answer that question, we need look no farther than our own planet to find examples of the types of exotic ecosystems that could make life possible on Saturn's geyser moon. The answer appears to be, yes, it could be possible. It is this tantalizing potential that brings us back to Enceladus for further study. For the details in this feature link to:

New heat maps of the surface of Enceladus show higher temperatures than previously known in the south polar region, with hot tracks running the length of giant fissures. Additionally, scientists say the organics "taste and smell" like some of those found in comets. The jets themselves harmlessly peppered Cassini as the spacecraft flew though the plume, exerting measurable torque, and providing an indirect measure of the plume density. For the full details in this news release, link to:

Thursday, March 27 (DOY 087):

Port 1 of the Science Operations Plan process for S43 occurred today. The files were merged and reports were sent out to the teams for review and resolution. Port #2 is scheduled for April 15.

The Solid State Power Switch (SSPS) for the Cassini Plasma Spectrometer (CAPS) replacement heater tripped about 14 hours before the start of the overnight DSN pass on Mar. 27, almost a week after the last such trip, TWTA-B line A on Mar. 20. The response to any instrument replacement heater trip is to clear the trip by turning the heater OFF, then turning it ON. The response then turns OFF the instrument. The response table has no knowledge about whether the switch had been set to ON or OFF, and so has to assume that the heater could have been either ON or OFF. The CAPS instrument was turned back ON, and the replacement heater turned OFF, via real-time commands on Mar. 29.

Prior to apoapsis, which occurs late this evening, the Composite Infrared Spectrometer (CIRS) will be leading a joint Optical Remote Sensing (ORS) campaign to observe Titan, with CIRS looking to obtain measurements of nitriles, hydrocarbons, an oxygen compound, and CO2 as a function of latitude and emission angle at the equator. Meanwhile, the Magnetospheric and Plasma Science (MAPS) teams will be conducting their ongoing campaign to image the dynamics of Saturn's inner magnetosphere.

Friday, March 28 (DOY 088):

In the months ahead, Saturn's rings will appear thinner and thinner until, on Sept. 4, 2009, they vanish as seen from Earth. As Saturn goes around the sun, it periodically turns its rings edge-on to Earth - once every 14-to-15 years. Because the rings are so thin, they can actually disappear when viewed through a small telescope. When this happened to Galileo in 1612, he briefly abandoned his study of the planet. Ring plane crossings are actually good times to discover new Saturnian moons and faint outer rings. For the full story go to the following NASA Science News report:

Imaging Science (ISS) and the Visual and Infrared Mapping Spectrometer (VIMS) kick off a science collection activity today with observations of Titan. ISS will also be collecting images of the smaller rocks. CAPS will have a period of rare pointing control to survey the Saturn system before the Ultraviolet Imaging Spectrograph (UVIS) points the spacecraft at Enceladus to map volatiles in the immediate neighborhood and test the connection of changes in volatiles to plume eruptions. CIRS will wrap up the major events of the day with a look at the rings.

Monday, March 31 (DOY 091):

The DOY 92 live update was originally planned to cover approximately two weeks until DOY 105, and involved four different vectors, those for Saturn, Mimas, Rhea, and Pan. After getting together Thursday and Friday of last week, the science teams involved agreed that only the Mimas vector needed to be updated, reducing the update to impact only DOY 102. In order to allow plenty of time for production and review of the relevant files, it has been decided to put work on this activity on hold for now and resume about Apr. 7.

An amazing close-up image of Enceladus' tiger stripes is Astronomy Picture of the Day today. Check it out at:

Tuesday, April 1 (DOY 092):

Non-targeted flybys of Titan, Pallene, and Janus occurred today.

Cassini's passage through periapsis today saw a flurry of rings-oriented observations. Both UVIS and VIMS observed bright star occultations, while ISS and VIMS scanned the rings at high resolution. The Ion and Neutral Mass Spectrometer (INMS) took prime pointing responsibilities to study the composition of Saturn's inner magnetosphere. Later in the day, Radio Science monitored a ring occultation as Cassini slipped behind Saturn's rings as viewed from Earth. Following a scan of the rings with ISS, CIRS ended the day with a 7-hour observation of the lit side of the rings. The MAPS instruments continued to monitor the Saturnian magnetosphere.