Cassini Radio Detection and Ranging (RADAR): Earth and Venus observations

Abstract

Abstract. The Cassini Radio Detection and Ranging (RADAR) was operated in scatterometric and radiometric modes during the Venus ! 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.

Cassini RADAR Sequence Planning and Instrument Performance

“…During the Earth flyby in August 1999, some scatterometry data over the Pacific Ocean and South America were obtained. However, comparing Cassini results with other Earth-orbiting sensors required model-based extrapolation to line up the position, incidence angle, and frequency of the results [18]. The results were good for validation and relative observation, but not for precision absolute calibration.…”

Liquid‐filled canyons on Titan

“…Furthermore, the exceptionally strong reflection from altimetry returns with subradar point that falls onto these radar-dark patches requires exceptional flatness of < 2.7 mm (= λ/8, according to the Rayleigh Criterion) root-mean-square (RMS) height and is a strong indication of the liquid nature of these features. It is also interesting to note that Cassini has observed liquidfilled channels previously-strong near-nadir radar echoes observed during Cassini's flyby of Earth were determined [Lorenz et al, 2001] to be due to the dammed Paranaiba River in Brazil. In these cases, the backscattered signal, composed by both coherent and incoherent power, is mainly dominated by the coherent component and the resulting fraction of total incident power specularly reflected is equal to e À2 2πσ h =λ ð Þ 2 [Skolnik, 2008].…”

“…In these cases, the backscattered signal, composed by both coherent and incoherent power, is mainly dominated by the coherent component and the resulting fraction of total incident power specularly reflected is equal to e À2 2πσ h =λ ð Þ 2 [Skolnik, 2008]. It is also interesting to note that Cassini has observed liquidfilled channels previously-strong near-nadir radar echoes observed during Cassini's flyby of Earth were determined [Lorenz et al, 2001] to be due to the dammed Paranaiba River in Brazil. At the end of its mission (15 September 2017) the Cassini RADAR in its imaging mode (SAR+ HiSAR) will have covered a total area of 67% of the surface of Titan [Hayes, 2016].…”

High-Overtone Bulk Acoustic Resonator (HBAR) as Passive Sensor: Towards Microwave Wireless Interrogation

“…Although a wide range of RADARs operate in the HF and VHF bands -especially when long range is needed -multiple configurations operate in the microwave range as well [5], [6]. In [7], the requirement of the lack of local energy source on the target sensor (in their case a passive microwave reflector trihedrons (so called "passive markers") and all weather operation emphasizes the advantages of the use of a microwave RADAR (18-26 GHz frequency-stepped RADAR operating over a 8 GHz bandwidth) associated with cooperative targets for monitoring with sub-mm resolution landslide environments.…”