Remote sensing data at scales of kilometers and an Earth analog were used t
o accurately predict the characteristics of the Mars Pathfinder landing sit
e at a scale of meters. The surface surrounding the Mars Pathfinder lander
in Ares Vallis appears consistent with orbital interpretations, namely, tha
t it would be a rocky plain composed of materials deposited by catastrophic
floods. The surface and observed maximum clast size appears similar to pre
dictions based on an analogous surface of the Ephrata Fan in the Channeled
Scabland of Washington state. The elevation of the site measured by relativ
ely small footprint delay-Doppler radar is within 100 m of that determined
by two-way ranging and Doppler tracking of the spacecraft. The nearly equal
elevations of the Mars Pathfinder and Viking Lander 1 sites allowed a pred
iction of the atmospheric conditions with altitude (pressure, temperature,
and winds) that were well within the entry, descent; and landing design mar
gins. High-resolution (similar to 38 m/pixel) Viking Orbiter 1 images showe
d a sparsely cratered surface with small knobs with relatively low slopes,
consistent with observations of these features from the lander. Measured ro
ck abundance is within 10% of that expected from Viking orbiter thermal obs
ervations and models. The fractional area covered by large, potentially haz
ardous rocks observed is similar to that estimated from model rock distribu
tions based on data from the Viking landing sites, Earth analog sites, and
total rock abundance. The bulk and fine-component thermal inertias measured
from orbit are similar to those calculated from the observed rock size-fre
quency distribution. A simple radar echo model based on the reflectivity of
the soil (estimated from its bulk density), and the measured fraction of a
rea covered by rocks was used to approximate the quasi-specular and diffuse
components of the Earth-based radar echos. Color and albedo orbiter data w
ere used to predict the relatively dust free or unweathered surface around
the Pathfinder lander compared to the Viking landing sites. Comparisons wit
h the experiences of selecting the Viking landing sites demonstrate the eno
rmous benefit the Viking data and its analyses and models had on the succes
sful predictions of the Pathfinder site. The Pathfinder experience demonstr
ates that, in certain locations, geologic processes observed in orbiter dat
a can he used to infer surface characteristics where those processes domina
te over other processes affecting the Martian surface layer.