228 
70° can be mapped on a daily basis using this mode. The operation plan calls 
for the radar beam to be redirected to the south of the ground track twice 
during the mission to enable the first high resolution radar maps of the whole 
of Antarctica to be made, one at the time of maximum ice cover and one at 
the minimum. 
Since the 500 km swath also represents the range of access made possible by 
pointing the radar beam, these maps show the area of opportunity for 
selective imaging using higher resolution beams within one and three days 
respectively. Figure 3 also shows the station masks for the north american 
receiving stations. 
The orbit is sun-synchronous which, besides simplifying the spacecraft design, 
also means that satellite over-passes are always at the same local time. This 
is particularly important for the RADARSAT mission because much use will 
be made of multi-temporal data sets for crop prediction and so the influence 
of effects due to diurnal variations must be minimised. 
Figure 3 
RADARSAT 1 Day Coverage 
90' 
fy-;j SAR Coverage for 
500 km Swath 
RADARSAT 3 Day Coverage 
Cirdes are station masks for 
baseline data reception 
(5‘ Elevation) 
50' 
III;:;;;;] SAR Coverage for 
500 km Swath