From Newsgroup: sci.space.news


Cassini Significant Events
for 02/03/16 - 02/09/16

Cassini is currently orbiting Saturn with a period of 16 days in a plane inclined 17.5 degrees from the planet's equatorial plane. The most recent spacecraft tracking and telemetry data were obtained on Feb. 10 using
one of the 34-meter diameter Deep Space Network stations in Australia.
The spacecraft continues to be in an excellent state of health with all
of its subsystems operating normally except for the instrument issues

described at http://saturn.jpl.nasa.gov/news/significantevents/anomalies

Cassini spent this week moving relatively slowly in the outer part of
its 16-day orbit of Saturn, coasting through the space between the orbits
of Saturn's moons Hyperion and Iapetus. Back on Earth, Cassini scientists
met for a weeklong Project Science Group meeting #68 at JPL. Meanwhile, Sequence Implementation Process teams continued working on the 10-week
command sequences S94, which will begin executing on April 18, and S95,
which starts on June 26. Six sequences remain to be worked after that.

Wednesday, Feb. 3 (DOY 034)

While the spacecraft's momentum carried it "upward" in orbit away from
the planet, the Composite Infrared Spectrometer (CIRS) and the Visible
and Infrared Mapping Spectrometer (VIMS) stared back at the sunlit face
of Saturn's rings to study its particles' composition for 15 hours. Even though the main rings span a diameter of hundreds of millions of meters,
they might be only a few tens of meters thick at any given point. Cassini's remarkable viewing geometry of the crescent ringed Saturn illustrated
here:

http://go.nasa.gov/1O3li5a

Next, the on-board S92 command sequence had the spacecraft turn its high-gain antenna toward Earth. Cassini's continuous radio signal propagated for
87 minutes at the speed of light, then a Deep Space Network (DSN) station
in Australia locked onto it began extracting the ones and zeroes of telemetry. After conversion of the binary data to engineering values, Cassini's flight team engineers made a thorough check of the spacecraft's health, and then uplinked 142 freshly prepared commands to carry out an Orbit Trim Maneuver (OTM). The spacecraft turned to the commanded attitude and fired its liquid-bipropellent-fed main rocket engine for 3.3 seconds. This OTM-440 provided the 0.58 meter per second change in velocity required to clean up
the error in Cassini's trajectory introduced during the Feb. 1 Titan encounter.

Such trajectory errors are always expected, but can only be quantified after the
encounter takes place.

Thursday, Feb. 4 (DOY 035)

Today marks 300 days until Cassini begins its F-ring orbits, in which periapses will come close to that narrow and ever-changing strand.

The Imaging Science Subsystem (ISS) controlled spacecraft pointing for
15 hours today to carry out an observation of Saturn's irregular moon Albiorix. Named for the king of the world in Gallic mythology, this moon
has a diameter of about 26 kilometers and moves as far as 23.8 million
km away from the planet, along an inclined, highly elliptical orbit.

Friday, Feb. 5 (DOY 036)

Today, the Cosmic Dust Analyzer (CDA) spent 13.5 hours searching for dust
that might be orbiting Saturn in the retrograde direction.

Saturday, Feb. 6 (DOY 037)

ISS, CIRS and VIMS performed a 14.75-hour observation of the Encke gap
in the outer part of Saturn's A ring. Particles within this 325-km wide
gap take about 14 hours to complete a revolution about Saturn. This was
the final science observation commanded by the S92 sequence.

Sunday, Feb. 7 (DOY 038)

The S93 command sequence, whose 11,911 individual commands were uplinked
on Thursday, began its 72 days of orchestrating Cassini's activities today. Its first science observation was another CDA retrograde dust observation; this one lasted 11.5 hours.

During the CDA observation, Cassini coasted through apoapsis, marking
the start of its Saturn orbit #232. Reaching an altitude of 2.2 million
km from the ringed planet, the spacecraft had slowed to 6,456 km per hour relative to Saturn.

Monday, Feb. 8 (DOY 039)

About 190 scientists who are associated with Cassini, plus many of the engineers on the flight team, convened at JPL today to begin the weeklong Project Science Group meeting #68.

Meanwhile 1,556 million km away from here, CIRS and VIMS observed Saturn's atmosphere for 15 hours, measuring temperatures in the upper troposphere
and the tropopause. Finally, realtime commands arrived and executed OTM-441, turning the spacecraft and firing the main engine for 4.2 seconds. This
OTM provided a change in velocity of 0.75 meters per second, taking advantage of the orbital-mechanics "leverage" near apoapsis to set up for the Feb.
16 Titan flyby dubbed T-117.

At just over a million meters in diameter, Saturn's icy moon Tethys is
massive enough to be very nearly spherical. It is the subject of an image featured today, with Saturn in the background:

http://saturn.jpl.nasa.gov/photos/imagedetails/index.cfm?imageId=5302

Tuesday, Feb. 9 (DOY 040)

Still taking scientific advantage of the environment out near apoapsis,
this week's last science activity was a 14.75-hour CDA interstellar dust observation.

During the past week, the Deep Space Network communicated with and tracked Cassini on 10 occasions, using the 70-meter and the 34-meter DSN stations
in Australia. A total of 12,212 individual commands were uplinked, and
about 1,328 megabytes of telemetry data were downlinked and captured at
rates as high as 124,426 bits per second.

For a glossary of technical terms relating to Cassini's events, click

the "full story" link on this page: http://saturn.jpl.nasa.gov/news/significantevents

This illustration shows Cassini's position on Feb. 9: http://go.nasa.gov/1OdNDqz
. The format shows Cassini's path over most of its current orbit up to
today; looking down from the north, all depicted objects (except the background

stars of course) revolve counter-clockwise, including Saturn along its orange-colored orbit of the Sun.

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Milestones spanning the whole orbital tour are listed here: http://saturn.jpl.nasa.gov/mission/saturntourdates .
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For a glossary of technical terms relating to these events, click the
"full story" link on this page: http://saturn.jpl.nasa.gov/news/significantevents/ .
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Information on the present position and speed of the Cassini spacecraft
may be found on the "Present Position" page at: http://saturn.jpl.nasa.gov/mission/presentposition/ .
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Visit the JPL Cassini home page for more information about the Cassini Project: http://saturn.jpl.nasa.gov/
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