Ionosphere Measurements During Cassini's Earth Fly-by
                        The NASA/ESA Cassini-Huygens spacecraft completed a pass by Earth
                        toward its encounter with Saturn in 2004. The Earth flyby occurred at 3:28 UT
                        on 18 August and gave the space probe a 5.5 km/s boost in speed. The spacecraft
                        will pass by Jupiter on 30 December 2000.

                        During the Earth flyby, nine of the twelve scientific instruments on Cassini were
                        turned on to gather data on the Earth/Moon system. The Huygens Probe and its
                        six scientific instruments remained dormant during the Earth fly-by.

                        In outline, the fly-by timeline was

                        Magnetometer boom deployment:  ~07 UT 16 Aug
                        Inbound bow shock/magnetopause crossing (approx subsolar):  ~02 UT 18 Aug
                        Closest approach:  ~03 UT 18 Aug
                        Outbound magnetopause crossing (at ~75 RE downtail on dawn flank):
                        ~12 UT 18 Aug
                        Outbound shock crossing (between ~175-275 RE downtail on dawn flank):
                        ~2-12 UT 19 Aug
                        Crossing of Earth's distant tail/wake region (~7000 RE): ~9-19 Sept

                        During the Earth flyby, the Sondrestrom incoherent scatter radar measured the
                        high-latitude ionosphere. The radar was operated between 00 UT and 15 UT on
                        18 August to measure F-Region Convection, Hall and Pedersen Conductivity,
                        Electron temperature at different altitudes, Ion temperature at different altitudes,
                        among other fundamental measurements.

                      Composite scans along magnetic meridians parallel to Sondrestrom's were used
                        to measure these parameters over 3 degrees invariant latitude in the E-region and
                        9 degrees in the F-region. Below are clockdial plots of the measurements.
 

NASA Cassini Homepage

ESA Huygens Homepage

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