Radar Exploration of Mars: Recent Results and Progresses - Planetary Exploration and Science: Recent Results and Advances - page 78

Fig. 5.2 Characteristics of a radar waveform

5.3.1 The Radar Equation

In the radar systems analysis, it is fundamental to know the maximum distance at
which it is possible to detect a target once the power of the transmitted signal is
fixed. This information, which is the basis of radar performance, is expressed in the
radar range equation:

P p G 2 2

P r D (5.1)

.4/ 3 R 4 L

where P r is the power of the signal sensed by the receiver in W; P p is the peak
transmitted power in W; G is the radar antenna gain, which is the ratio of focused
signal over isotropic radiation; is the wavelength of the transmitted signal in m;
is the target radar cross section in m 2 ; R is the radar to object range in m; and L is a
loss factor due mainly to imperfect dielectric medium (Skolnik 1980 ).

5.4 Two Radars on Mars Exploration: MARSIS

and SHARAD

Radar capabilities to penetrate a planet surface, tested on Earth to map the crust
composition, suggested to study the feasibility to use specialized radar devices
on Mars exploration. Two instruments were developed for this purpose by the
University of Rome “La Sapienza,” Italy, in partnership with NASA's Jet Propulsion
Laboratory (JPL) in Pasadena, California, USA: MARSIS and SHARAD.