Cassini Significant Events
for 8/6/08 - 8/12/08
The most recent spacecraft telemetry was acquired on Aug. 12 from the
Deep Space Network tracking complex at Goldstone, Calif. 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/operations/present-position.cfm.
Wednesday, Aug. 6 (DOY 219):
The S43 background sequence was radiated to the spacecraft today.
Execution will begin on Aug. 10.
Friday, Aug. 8 (DOY 221):
Orbit Trim Maneuver (OTM) #163, scheduled for today was cancelled.
Uplink Operations sent commands to the spacecraft today for a Cosmic
Dust Analyzer (CDA) Enceladus 4 Flyby real-time activity that will
begin execution on Aug. 11 at 17:59 Spacecraft Event Time (SCET)
Sunday, Aug. 10 (DOY 223):
The main engine cover was closed Aug. 10 for a potential dust hazard
at Enceladus on Aug. 11 and Aug. 19, and will be reopened on Aug. 19.
The S42 sequence concluded and S43 began execution at 20:00 on Aug.
11 spacecraft time. The sequence will run for 35 days and conclude on
Sep. 13, 2008. During that time there will be targeted encounter of
Enceladus and seven non-targeted flybys – one each of Pallene and
Pan, Atlas, Titan, Janus, Methone and Epimetheus. Only one orbit
trim maneuver (OTM-164) is scheduled. During this sequence, solar
conjunction will occur Sept.1-7.
Monday, Aug. 11 (DOY 224):
Non-targeted flybys of Methone, Mimas and Daphnis occurred today.
Cassini flew past Enceladus today 50 kilometers from the surface, and
at a speed of 17.7 kilometers per second. Closest approach occurred
at 21:06 spacecraft time at 28 degrees S latitude, 98 degrees W
longitude. The main goal was to obtain detailed images and remote
sensing data of the geologically active features on Enceladus. From
this data, scientists may learn more about how eruptions, tectonics
and seismic activity alter the moon’s surface. Instruments on board
Cassini will map the Enceladus’ surface in visible, infrared and
ultraviolet light. Measurements will help determine the size of the
ice grains and distinguish other elements mixed in with the ice, such
as oxygen, hydrogen, or organics.
Science highlights:
The Imaging Science Subsystem executed a “skeet shoot” series of
images to carefully balance light and smear during the closest
approach of this fast flyby. The result will be the highest-ever
resolution images of the tiger stripes, and clues to what drives the
jets that feed the plume.
The Composite Infrared Spectrometer observed south polar temperatures
during solar eclipse to determine the heat capacity and textural
properties of the regolith; maps from these data will complement data
obtained in the previous flyby.
The Visual and Infrared Mapping Spectrometer performed compositional
mapping to determine the identity of volatiles, organics and minerals
and place them within a geologic context.
The Ultraviolet Imaging Spectrograph obtained spectral images of
Enceladus in the extreme-ultraviolet and far-ultraviolet to map
surface composition, including water ice abundances and grain sizes,
and searched for volatiles off the limb.
Magnetospheric and Plasma Science instruments examined the particle
environment at 54 kilometers from the surface. The fields and
particles instruments will eventually determine the nature of the
material coming from the surface and its relationship to the
E-ring. In addition, they will distinguish between two potential
populations of particles: particles from the plume and particles
sputtered from elsewhere on the surface. The magnetometer team
hopes to determine whether Enceladus generates an induced magnetic
field from a subsurface ocean and to determine the composition of
plume material by studying ion cyclotron waves in the magnetic field
measurements.
For images, videos and a mission blog on the flyby, visit:
http://saturn.jpl.nasa.gov/news/press-release-details.cfm?newsID=863
http://saturn.jpl.nasa.gov/news/events/enceladus20080811/index.cfm
http://blogs.nasa.gov/cm/blog/cassini-aug08
Tuesday, Aug. 12 (DOY 225):
A kick-off meeting will be held today for the first of two possible
live updates during the execution of S43. The first update is for
Saturn vectors on DOY 232 with the Visual and Infrared Mapping
Spectrometer as the driving instrument. A Go/No Go decision will be
made no later than Aug. 13.
Visit the JPL Cassini home page for more information about the
Cassini Project: http://saturn.jpl.nasa.gov/