Radar Mapping of Spherical Targets

The echo waveform from a single conjugate point will experience slightly different delays in reaching the two 

FIGURE 9 Topographic contours for the southern flank (large rectangle) of the Martian shield volcano Arsia Mons, obtained from radar aitimetry. [From Roth, L., Downs, G. S., Saunders. R. S.. and Schubert, G. (1980). Icarus A2, 

The total number of fringes, or cycles of phase shift, spanned by the disk of a planet with diameter D and a distance R from the radar is approximately ( )// )( projA), where proj is the projection of the interferometer baseline normal to the mean line of sight. For example, Arecibo interferometry linked the main antenna to a 30.5-m antenna about 11 km farther north. It placed about seven fringes on Venus, quite adequate for separation of the north-south ambiguity. The Goldstone main antenna (see Fig. 3) has 

Delay-Doppler interferometry is not currently feasible for targets like the Galilean satellites and the largest asteroids, which are low-SNR and overspread (see Sec- 

FIGURE 11 Mars 13-cm radar echo spectra for subradar points along 22° north latitude at the indicated west longitudes obtained in the OC (upper curves) and SC (lower curves) polarizations. In each box, spectra are normalized to the peak OC cross section. The echo bandwidth is 7.1 kHz. Very rough regions on the planet are revealed as bumps in the SC spectra, which move from positive to negative Doppler frequencies as Mars rotates. [From Harmon, J. K., Campbell, D. B., and Ostro, S. J. (1982). Icarus52, 171-187.] 

---