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Figure 2 illustrates in cartoon form their geometrical relationships of these 
different modes. The experimental modes will be available for operational 
use and, indeed, are expected to be of great value for tracking icebergs and 
supporting a variety of offshore activities where enhanced contrast with the 
sea surface is important. They are called experimental because the SAR 
performance is optimised for the standard modes. 
Figure 2 
The orbit 
The orbit chosen for RADARS AT has also been selected to optimise the 
application benefits. It has an exact repeat period of 24 days but, although 
it circles the earth approximately 14 1/3 times a day, it does not have a true 
three day subcycle. A true three day sub-cycle has a time interval between 
the closest satellite ground tracks of three days; for RADARSAT this time 
interval is seven days. There is a three day near sub-cycle but the ground 
track spacing is three times the minimum spacing. 
At equatorial latitudes, this orbit permits complete coverage with a choice of 
incidence angle every 24 days using the 100 km swath. For latitudes greater 
than 45°, it also provides half swath overlap every seven days using the 150 
km wide swath beam; this is important for monitoring crop condition. 
By way of illustration Figure 3 shows the one and three day coverage maps 
for latitudes 30° to 90° for the 500 km wide scansar mode. Because the SAR 
beam points to the north of the ground track, all of the Arctic north of about