Cassini Update - December 28, 2004

http://saturn.jpl.nasa.gov/news/sig-...cfm?newsID=523

Cassini Significant Events 12/21/04 - 12/27/04
December 28, 2004
(Source: Jet Propulsion Laboratory)

The most recent spacecraft telemetry was acquired from the Goldstone
tracking station on Monday, December 27. The Cassini spacecraft is in
an
excellent state of health and is operating normally.

Diary of a Probe Release:

It's Tuesday, December 21.

Only 4 more shopping days till Christmas.

Yesterday the loading of the Probe Relay default pointing vectors to
the
spacecraft took longer than anticipated. The flight team was not able
to
complete this activity before the Probe Mission Timing Unit (MTU)
loading window opened. It was decided to postpone the final two uplinks
until today.

Huygens personnel reported that the MTU loading went well. They saw the
timer counting down. As battery power on board the probe is limited,
the
timer is responsible for activating the Probe suite of instruments
about
four hours prior to entering the atmosphere of Titan.

Just found out that the Probe is carrying rock-n-roll on board! Lalala,
Bald James Dean, Hot Time and No Love are all heading for Titan. The
European Space Agency (ESA) wanted to have music on board to arouse the
interest of the world's public, particularly the young, and to leave a
trace of humanity in the unknown. The music will be available on the
Music2Titan website starting today, 21 December. For more information
link to http://www.esa.int/SPECIALS/Cassini-...EAXJD1E_0.html
and http://www.music2titan.com/.

Wednesday, December 22.

The minor delays reported yesterday were just that - minor. We are back
on schedule. All subsystems are normal.

There were three spacecraft activities today. The S07 online background
sequence was re-activated, and we performed Inertial Reference Unit
(IRU) Calibration #6 - the last calibration prior to Probe Release. The
third activity was Orbital Trim Maneuver (OTM) #9, the Probe Targeting
Clean-up maneuver. This maneuver is based on the long-planned Probe
Release attitude with no update required, since the trajectory control
has been right on target up to this point. That means there will be no
changes to the current Probe Release sequence. The Integrated Test
Laboratory is currently testing the Iapetus mini-sequence. They can now
let it continue to clock out.

We have heard back from the maneuver team. OTM #9 was successfully
completed on the spacecraft. This maneuver refines Cassini's trajectory
in preparation for the Huygens probe mission.

The reaction control system (RCS) burn began at 6 p.m. Pacific Time.
The
"quick look" immediately after the maneuver showed the burn duration
was
18.8 sec, giving a delta-V of approximately 20 mm/s. This was the
shortest duration RCS maneuver performed to date.

Off-Earth engineering data from SSR partition B-6 was successfully
played back once the spacecraft was back on Earth point. This contained
high-rate propulsion data. ACS, Propulsion, and Thermal teams all
reported nominal states.

Tomorrow will be a quiet day for the spacecraft.

Thursday December 23:

We received a Go at the Probe Release Approval Meeting for uplink of
the
Probe Release sequence. We will be uplinking the Release sequence and
the two supporting files tonight.

ACS has analyzed the data from yesterday's IRU calibration #6. IRU A is
nominal.

Mission support area staffing for probe release begins at 3 PM
tomorrow.

Tomorrow evening is Probe Release!

Friday, December 24. Christmas Eve.

Made sure to get all my shopping done. Have plans for the 24th.
Supporting Probe release!

Everything looks good and nominal.

JPL provided dinner for those of us who had to work. Slight congestion
at the dessert table, but everything else nominal.

Navigation reported that their orbit solutions from yesterday have not
changed.

All Orbiter instruments reported in. Everyone is in the correct
configuration and is ready for release.

Set up a conference line so that Cassini flight team members that are
not working the event but who came in anyway to show their support can
listen in on events as they unfold.

The Huygens Probe was successfully deployed from the Cassini Orbiter!
Navigation and Spacecraft Operations Office teams confirmed the nominal
separation of the Probe at 7:24 Pacific time. The Probe is now in free
flight at a spin rate of 7.5 rpm as detected by the Magnetometer
Subsystem. All systems performed as expected, there were no problems
reported with the Cassini spacecraft, no red alarms, no fault
protection
responses. Congratulations everyone!

The Head of Science Programmes for the European Space Agency expressed
his thanks to the team for a wonderful adventure in the exploration of
Saturn. Huygens personnel are now awaiting with great expectation the
Probe descent on January 14, 2005.

After release, the Uplink Operations (ULO) sequence lead called for the
start of planned Probe optical navigation imaging. This is a 4.5 hour
process. Currently we are on schedule.

The orbiter instrument restoration mini-sequence was uplinked around 10
pm local time.

Saturday, December 25. Christmas Day:

All quiet in the trenches.

Uplinked the first Probe Imaging Sequence. The first Optical Navigation
Images (OPNAV) of the Probe are in. We nailed it! With the wide-angle
camera image, we were able to see the Probe about 3 pixels wide.
Confirmed that the Probe is well within the entry corridor with an
entry
flight path angle estimate of -65.1 degrees (target was -65.0!).

ACS has released a preliminary analysis. ACS will not need to send up
an
ACC Parameter patch tomorrow morning.

ULO will be sending up the Probe Support Avionics (PSA) checkout
sequence today. This sequence will verify that the avionics are still
functioning correctly.

This afternoon, we will also be uplinking the second Probe imaging
sequence. This sequence uses the narrow angle camera (NAC). The Probe
should be about 10 pixels across in this image.

PSA checkout executes on the spacecraft after the probe imaging
sequence.

Telemetry has been received for the instrument restoration sequence.
The
Orbiter instruments are nominal.

Sunday, December 26:

The spacecraft is nominal.

Navigation stopped by and gave a status on Probe image #2. They got a
good picture of the Probe with the NAC. The Probe is about 10 pixels
across, round, and one can see what looks like sun glint off the
backside of the Probe.

Probe personnel reported on the PSA checkout. ESA reviewed the dump
packets. They look good. ESA is ready to go.

Tonight we will uplink the sequence for the third and last Probe
imaging
OPNAV. Generating the OPNAV sequence took a really long time last
night.
Those involved expect the process to go faster tonight.

Monday, December 27:

The third Probe OPNAV image is available. They got a nice 6-pixel image
of the Probe. Two of the Probe OPNAV images are posted on the Cassini
web site at http://saturn.jpl.nasa.gov

ACS will execute their 7th IRU calibration during the last Probe
imaging
OPNAV.

Orbital trim maneuver #10 (OTM-10) was successfully completed on the
spacecraft today. This maneuver, also called the Orbit Deflection
Maneuver (ODM), takes Cassini off of a Titan-impacting trajectory and
on
to a flyby trajectory with the required altitude to receive data from
the Huygens probe as plunges into Titan. The main engine (ME) burn
began
at 5:44 p.m. Pacific time. The "quick look" immediately after the
maneuver showed the burn duration was 153.4 sec long, giving a delta-V
of 23.7 m/s.

ACS reported the burn termination was a "nominal complete" with an
accelerometer cutoff. Propulsion and thermal teams also reported
nominal
conditions. There was no unexpected CDS or Fault Protection activity.

Tomorrow's schedule shows another quiet day for the spacecraft.

As of today (December 28), the Program is 17 days from Probe relay.

Image advisories, press releases and the latest Cassini information can
be found at http://saturn.jpl.nasa.gov.