High-Gain Antenna

Cassini's High-Gain Antenna (HGA) is used for routine radio communications at X-band frequencies (~8 Gigahertz) including telemetry containing science data and spacecraft health data, navigation via Doppler shift and ranging tones, and command reception. The HGA will receive the signals from the Huygens Probe during the Probe's mission descending through Titan's atmosphere, and then will relay them back to Earth. The HGA is rigidly attached to the spacecraft, so the entire spacecraft rotates in order to point the HGA.

The HGA also serves for Radio Science experiments using X-band, S-band (5 Gigahertz), and Ka-band (32 GHz).

Cassini's RADAR science instrument uses this antenna for synthetic aperture imaging, radiometry, scatterometry, and altimetry measurements. In the photo of Cassini's HGA above, the multiple-feed assembly used by Radar can be seen at the center of the dish.

The HGA also served as a sun shade during Cassini's inner-solar system cruise, and will serve as a micrometeoroid shield during some crossings of the ring plane while in Saturn orbit.

Cassini's HGA was supplied by Italian Space Agency.

Back to Cassini in the Basics of Space Flight

High-Gain Antennas and Low-Gain Antennas in Basics of Space Flight