Status Report

Cassini Weekly Significant Events for 05/04/00 – 05/10/00

By SpaceRef Editor
May 13, 2000
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The most recent spacecraft telemetry data was acquired from the Canberra tracking station on Wednesday, 5/10. The Cassini spacecraft is in an excellent state of health and is operating normally.  The C19 background sequence completed on schedule and C20 started execution on 05/05/00. The speed of the spacecraft can be viewed on the "Where is Cassini Now?" web page ( "" )
An update of the Attitude and Articulation Control Subsystem (AACS) Constraint Monitor was performed and the Ka-Band transmitter onboard the spacecraft was turned on.  Communications received from both Spacecraft and Radio Science Subsystem teams indicated both activities executed properly.
Early on May 9 both the RPWS and MAG instruments detected an interplanetary shock.  This is a boundary in the solar wind where a faster-moving cloud of plasma overtakes one moving more slowly.  Such shocks are common features of the solar wind.  During the peak of solar activity known as solar maximum, the shocks are most commonly driven by coronal mass ejections originating at the Sun and can propagate long distances through the solar system. Cassini observations of such events can be compared to observations by other spacecraft situated in various locations throughout the heliosphere to understand the propagation characteristics of the shock. The Cassini observations also provide information on solar wind conditions which will eventually interact with the Jovian magnetosphere and can be important in understanding that magnetosphere’s interaction with the interplanetary medium.
The Cassini spacecraft has entered a period of superior conjunction where the angle between the sun and the spacecraft as seen from Earth gets very small.  This is important because the near-sun environment influences the signal sent to and from the spacecraft and defines a period where communication with the spacecraft is very difficult.  This week Cassini personnel scheduled and performed the first of ten planned uplink characterization tests.  The purpose of these tests is to characterize the conjunction effects on command radiation at both 250 bits per second (bps) and 500 bps to the spacecraft during superior conjunction.
  –  Passed below a Sun – Earth – Probe (SEP) angle of 4.0 degrees on 5/7/00   –  Passed below a SEP angle of 3.0 degrees on 5/8/00
  –  Passed below a SEP angle of 2.0 degrees on 5/10/00
  –  The minimum angle to be experienced during this sequence will be 0.56 degrees which will occur on 5/12/00
Sequence development continues for C21.  The final SCR approval meeting was held on 5/09. Approved sequence change requests and comments will be incorporated and updated sequence products will be distributed next week.
A Satellite Orbiter Science Team (SOST) meeting was held to continue work on the instrument team allocation of time and resources for the icy satellite flybys. The group also developed recommendations for the Enceladus trajectory tweaks.
All Cassini Teams supported the NASA Quarterly Review (aka GPMC) held this week.
Cassini Outreach
Cassini Mission to Saturn and Titan
Jet Propulsion Laboratory
California Institute of Technology
National Aeronautics and Space Administration

SpaceRef staff editor.