Cassini Significant Events 06/30/10 - 07/06/10
The most recent spacecraft telemetry was acquired on July 6 from the
Deep Space Network tracking complex at Canberra, Australia. 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:
http://saturn.jpl.nasa.gov/mission/presentposition/.
Wednesday, June 30 (DOY 181)
An encounter strategy meeting was held today to cover the period
between July 7 and Aug. 13, covering Titan flyby T71, Enceladus flyby
E11, and maneuvers 257-259.
Based on the latest Navigation orbit determination solution, Science
Planning is recommending a NO-GO on the DOY 186 Live Inertial Vector
Propagator update. None of the targets called out during the update
period from 2010-186T04:20:00 - 2010-186T08:15:00 SCET has pointing
differences above the required threshold. The Sequence leads have
cancelled the update after reviewing the input from Science
Planning.
Orbit Trim Maneuver (OTM) #255 was performed today. This was the apoapsis
maneuver setting up for the Titan 71 encounter on July 7. The main engine
burn began at 2:00 AM PDT. Telemetry immediately after the maneuver
showed a burn duration of 36.208 seconds, giving a delta-V of 6.251 m/s.
All subsystems reported nominal performance after the maneuver.
Thursday, July 1 (DOY 182)
July 1 represents a number of significant milestones for Cassini.
This year is the second anniversary of the end of Prime Mission and the
start of the Equinox Mission. It is also the 6th anniversary of Saturn
Orbit Insertion in 2004.
A feature story called "Saturn System moves Oxygen from Enceladus to
Titan" is available on the Cassini web site. It describes a
comprehensive model based on research by scientists using the Cassini
plasma spectrometer that could explain how oxygen may end up on the
surface of Titan. The presence of these oxygen atoms could potentially
provide the basis for pre-biological chemistry. For more information link
to:
http://saturn.jpl.nasa.gov/news/cassinifeatures/feature20100701/
Friday, July 2 (DOY 183)
This week science observations were very much about the rings.
Imaging Science (ISS) took data for a spoke movie and searched for
propellers in the A-Ring. The Composite Infrared Spectrometer (CIRS) took
data for a temperature map of the rings. The Visual and Infrared Mapping
Spectrometer (VIMS) performed a high-resolution observation of the rings'
lit face at low phase. The Ultraviolet Imaging Spectrograph (UVIS)
observed a ring and atmospheric ingress occultation of the star ALP VIR
at low incidence angle, and performed spectral mapping of the rings. ISS,
CIRS, and VIMS jointly observed the D-ring.
Additional science activities included CIRS, ISS, UVIS and VIMS scanning
the southern hemisphere of Enceladus to monitor thermal output. UVIS and
the Magnetometer searched for Enceladus's auroral footprint by repeatedly
slewing across Saturn's auroral zone. VIMS and ISS observed Daphnis
during a relatively close fly-by at ~77,300 kilometers. The Radio and
Plasma Wave Science (RPWS) instrument began a three-day campaign to
explore Titan's ionosphere and its interaction with the Saturnian
magnetosphere. RPWS also searched for lightning in the atmosphere of
Titan.
Saturday, July 3 (DOY 184)
Orbit Trim Maneuver (OTM) #256 was performed today. This was the
approach maneuver setting up for the Titan 71 encounter on July 7. The
reaction control subsystem burn began at 7:29 PM PDT. Telemetry
immediately after the maneuver showed a burn duration of 14.625 seconds,
giving a delta-V of 0.022 m/s. All subsystems reported nominal
performance after the maneuver.
Monday, July 5 (DOY 186)
Non-targeted flybys of Calypso, Enceladus, and Daphnis occurred
today.
Tuesday, July 6 (DOY 187)
Cassini flew by Titan at an altitude of 1005 kilometers and a speed
of 5.9 km/sec. Closest approach occurred at 12:22AM SCET on the 7th - or
5:22PM PDT on the 6th - at a latitude of 56.1° S.
ISS rode along with VIMS outbound from closest-approach to observe
Titan's anti-Saturn hemisphere and track any clouds that might be
present. ISS also rode along with CIRS on the day following closest
approach to continue to monitor clouds and their evolution.
The day after closest approach was a caboose period with the Cassini
Plasma Spectrometer as the prime instrument during a Magnetospheric and
Plasma Science campaign.
CIRS obtained a vertical profile for trace species in the stratosphere of
Titan via mid-IR limb sounding, and continued a long-term campaign of
global mapping in the far-IR
UVIS obtained an image cube of Titan's atmosphere at extreme ultraviolet
and far ultraviolet wavelengths by sweeping its slit across the disk.
These cubes provide spectral and spatial information on nitrogen
emissions, H emission and absorption, absorption by simple hydrocarbons,
and the scattering properties of haze aerosols. This is one of many such
cubes gathered over the course of the mission to provide latitude and
seasonal coverage of Titan's middle atmosphere and stratosphere.
RWPS measured thermal plasmas in Titan's ionosphere and surrounding
environment, searched for lightning in Titan's atmosphere, and
investigated the interaction of Titan with Saturn's
magnetosphere.
At the Mission Planning Forum this week, a presentation was given on high
level strategic planning for the 22 proximal orbits planned for the end
of the Solstice Mission. It was decided to initiate this planning effort
while the project is still fully funded, and retains the maximum of
mission expertise. The proximal orbits span the period from April 23,
2017 to September 15, 2017, and are numbered 271-293. They will occur
during the execution of sequences S99-S101. Some topics of discussion
included science activities, possible dust hazards, atmospheric drag,
hydrazine use, performance of engineering activities such as analysis of
active hardware, and possible pyro firing and ejection of the main engine
cover to demonstrate performance after 20 years in flight. The flight
team has a lot to talk about before 2017.
A release titled "A Closer Look at Daphnis" highlighted raw
images obtained by Cassini on July 5. The images are the closest images
of Saturn's moon Daphnis to date. For the full release link to:
http://saturn.jpl.nasa.gov/news/cassinifeatures/feature20100706b/
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