The Cassini Radio Detection and Ranging (RADAR) was operated in scatterometric and radiometric modes during the Venus 1 and Earth swingbys to verify its functionality. At Venus, only the thermal emission from the thick absorbing atmosphere was detected. At Earth both the radar echo and the microwave emission from the surface were detected and reveal ocean surface disturbances, the rough, high, and cold Andes mountains, and surface features including a small reservoir in Brazil. Instrument performance appears to be excellent.
Lorenz, R. D., Elachi, C., West, R. D., Johnson, W. T. K., Janssen, M. A., Moghaddam, M., ... Posa, F. (2001). Cassini Radio Detection and Ranging (RADAR): Earth and Venus observations. Journal of geophysical research : Space physics, 106(A12), 30271-30279. https://doi.org/10.1029/2001JA900035