Efectos DEl Polvo En El Radar

Lunar and Planetary Science XXXII (2001)

1264.pdf

LABORATORY MEASUREMENTS OF RADAR TRANSMISSION THROUGH DUST WITH
IMPLICATIONS FOR RADAR IMAGING ON MARS. K.K. Williams and R. Greeley,Department of
Geological Sciences, Arizona State University, Tempe, AZ 85287-1404, e-mail: kkw@asu.edu.

Introduction: As NASA's exploration plan for
Mars advances with additional missions, the type andabundance of data increase. High-resolution images
are revealing numerous wind-related features and
suggest widespread distribution of aeolian deposits.
These deposits reflect the current and pastwind
regimes on Mars, but they also obscure some of the
bedrock geology. A complementary experiment to
those already proposed for Mars would be a Synthetic
Aperture Radar (SAR) mission [1].Because such a
mission is constrained by antenna size and power, it is
important to understand radar penetration through
aeolian materials such as sand and dust so that the
most effective radarfrequencies would be used.
Background: There have been many studies of
radar penetration of sand in arid areas such as the
Sahara Desert [2,3] and the U.S. Southwest [4]. The
earliest works showed thatL-band (λ=24 cm) radar
was able to penetrate 1-2 meters of extremely dry sand
[e.g. 3] to return images of the subsurface obscured by
the sand. These radar images of the subsurface
revealed ancientriver channels that existed prior to
the Sahara Desert [2] and have greatly added to the
understanding of the climatic history of that region.
A previous study of the ability of radar to penetratesand involved laboratory measurements of the
attenuation of a radar signal as it passed through
quartz sand [5]. That experiment was conducted over
a frequency range of 0.5-12.6 GHz and formoisture
contents of 0.3-10.7 % [5]. Results showed that the
lowest frequency (longest wavelength) signals
penetrated through dry sand with an attenuation of
less than 5 dB/m. Those frequencies enable...