NASA Cassini Significant Events for 07/28/05 – 08/03/05

The most recent spacecraft telemetry was acquired Wednesday, August 3, from the Madrid tracking stations. The Cassini spacecraft is in an excellent state of health and is operating normally. Information on the present position and speed of the Cassini spacecraft may be found on the “Present Position” web page located at

http://saturn.jpl.nasa.gov/operations/present-position.cfm .

Activities this week:

Thursday, July 28 (DOY 209):

The Composite Infrared Spectrometer instrument team delivered version 4.0 of their flight software to the Program Software Library. A Software Review/Certification Requirements meeting will be scheduled sometime in August and the software will be uplinked and an on-board checkout performed in mid October.

The IGAP/ Kinematic Prediction Tool (KPT) Working Group kicked off today. This group is comprised of representatives from the Mission Sequence Subsystem team, Science Planning, SCO, and the Imaging Science Subsystem. The goal is to devise a way to identify workable solutions that facilitate the search for moons in Saturn’s ring gaps. One way to achieve this is to complete mosaics of Saturn’s rings by targeting a point as it moves upstream, producing concatenated overlapping footprints, while compensating for the motion of the spacecraft.

Uplink Operations (ULO) sent the S13 live Inertial Vector Propagator update, background sequence, and Instrument Expanded Block (IEB) files to the spacecraft. All files necessary to support S13 are now on board the spacecraft. In addition, commands were sent to power cycle the Magnetometer Subsystem on Friday, and perform a memory readout for the Ion and Neutral Mass Spectrometer on Saturday.

Cassini’s top ten science highlights for the first year in Saturn orbit are featured on the Cassini website. Check it out at:

http://saturn.jpl.nasa.gov/news/features/feature20050715.cfm

Friday, July 29 (DOY 210):

A Delivery Coordination Meeting was held for the Remote Terminal Interface Unit (RTIU) V3.3, and the electronic Command Request Form (eCRF) version 1.4.4 The update to RTIU fixes several minor bugs to software that provides Instrument Teams a CDS/Bus simulator interface to their engineering model test beds. The eCRF delivery responds to an approved engineering change request and fixes three minor bugs.

A news release has been issued on the evidence for active ice volcanism recently observed on Enceladus. The Cassini spacecraft has found a huge cloud of water vapor over the moon’s south pole, and warm fractures where evaporating ice probably supplies the vapor cloud. Cassini has also confirmed Enceladus is the major source of Saturn’s largest ring, the E-ring. For more details from this release go to the news and media section at: http://saturn.jpl.nasa.gov

Uplink Operations sent commands to the spacecraft for the S13 Live Movable Block (LMB) files, additional Visual and Infrared Mapping Spectrometer (VIMS) IEB load and triggers, and the S12 end-of-sequence reaction wheel assembly (RWA) bias commands. ULO confirmed that the S13 DOY 214 LMB, VIMS Triggers, and AACS RWA Bias registered nominally on-board the spacecraft, and VIMS team members confirmed successful execution of their IEB Load.

Sunday, July 31 (DOY 212):

The keys to the spacecraft were officially handed over to the S13 leads today. S13 runs for 31 days beginning on July 31, and ending on August 30. During the sequence there will be one targeted encounter of Titan (T6), and six non-targeted encounters – one each of Mimas, Prometheus, Calypso, Titan, Tethys, and Telesto. Orbit Trim Maneuvers (OTM) #26, 27, 28, 29, and 30 will execute, along with one live moveable block, two ground movable blocks, and two live IVP updates.

Monday, August 1 (DOY 213):

The S16 Science Operations Plan Update process kicked off today.

Waiver and Sequence Change Request disposition meetings were held for both S14 and S15.

Tuesday, August 2 (DOY 214):

The Rev 12 Radio Science Subsystem (RSS) Saturn/Rings Ingress and Egress occultation completed successfully today. This occultation is the sixth out of eight highly optimized diametric occultations taking place this summer during Revs 7-14, between May and September, and is the last occultation in the Cassini Tour that includes both ingress and egress occultations of the rings and atmosphere.

The occultation was covered by Madrid’s DSS-63 for S- and X-band, dual polarizations, and DSS-55 for X- and Ka-band. A Goldstone DSS-14 pass that overlapped with Madrid and started just before the beginning of egress also captured the egress part of the occultation. Open loop S- and X-band dual polarizations data were acquired at DSS-14 as well. As with the previous occultation, the S-band data were noisy due to solar conjunction. It is at this time that this signal with the longest wavelength is the most sensitive. The Sun-Earth-Probe separation angle today is about 7.5 degrees.

Non-targeted flybys occurred today of Mimas, Prometheus, Calypso, and Titan.

The main engine cover was opened today in preparation for OTM-26. It will be closed again on August 19 after OTM-28, right before the Titan-6 flyby on August 22.

It’s been a while since I reported it so here is a day in the life of the flight team as they get ready to support an OTM. This flow happens for every OTM. Only the days and times vary. The driver is the actual burn time for the OTM. Everything counts back from then.

Tuesday, 8/2/05:

2 pm NAV delivers the final maneuver solution to the Spacecraft Operations Office (SCO)

2-3 pm Systems does a final Maneuver Automation Software (MAS) run and publishes the maneuver to the program file repository (DOM)

3 pm Attitude control (ACS) begins Flight Software Development System testing

3-4 pm The sequence leads merge the maneuver file with the background sequence, then publish the merged products to DOM

4 pm The Subsystem leads start checklists on the merged {OTM + background sequence} files

6 pm NAV & ACS maneuver approval slides are due to the OTM lead

7 pm Subsystem checklists are due to OTM lead

8 pm Maneuver Approval Meeting and Command Approval Meetings are held

Wednesday, 8/3/05:

Midnight on-stations time

0:11 am Beginning of Track

6:14 am burn ERT

Wednesday, August 3 (DOY 215):

Orbit trim maneuver #26 (OTM-26), the Enceladus 2 cleanup maneuver, was completed today. The main engine burn began at 6:14 am PDT (Earth receive time). A “quick look” immediately after the maneuver showed the burn duration was 16.7 sec long, giving a delta-V of 2.6 m/s. All subsystems reported nominal performance after execution.

The Magnetospheric Imaging Instrument team gave a Cassini internal Tour Science Talk today. The presentation was entitled: “Energetic neutral atom imaging of Saturn’s magnetosphere: Remote sensing isn’t just optical”.

The S18 Aftermarket assessment meeting was held today.

A delivery coordination meeting was held for the Navigation Ancillary Information Facility (NAIF) Toolkit N0058. At this meeting Instrument Operations delivered the latest toolkit and associated core software. New capabilities include support for satellite IDs in the Range 10000-99999, which allows for more than 99 bodies to be identified in the Saturn System.

Wrap up:

Check out the Cassini web site at http://saturn.jpl.nasa.gov for the latest press releases and images.

The Cassini-Huygens mission is a cooperative project of NASA, the European Space Agency and the Italian Space Agency. The Jet Propulsion Laboratory, a division of the California Institute of Technology in Pasadena, manages the Cassini-Huygens mission for NASA’s Science Mission Directorate, Washington, D.C. JPL designed, developed and assembled the Cassini orbiter.