Low-Gain Antennas

Cassini has two low-gain antennas (LGA). The LGAs are capable of wide angle 2-way X-band (8 Gigahertz) radio communications at low data rates. They served primarily during Cassini's early cruise in the inner solar system while the High-Gain Antenna (HGA) was used as a sunshade to keep the rest of the spacecraft safe from overeating. For this purpose, the spacecraft had to maintain an attitude keeping the HGA pointed toward the Sun, rather than toward the Earth for communications.

Together, the two LGAs offer the capability to communicate in just about any direction when the HGA is not pointing toward Earth. Now that the spacecraft is in the outer solar system, the HGA is used for all routine communications, and LGA #1 remains available for contingencies in case the HGA does not point to Earth as expected.

LGA #1 is mounted atop the HGA. LGA #2 is mounted below the Huygens Probe, and can be seen in this photo, just above the railing toward the right.

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