[music] 90 meters. The
distance between each laser pair. In order to measure the slope
across the laser's path in a single pass of the satellite, ATLAS
uses three pairs of beams spaced 90 meters apart with a
reference track between the beams. Then on following
passes, even if the two beams are slightly upslope or downslope from
where they were on the first pass, scientists can still calculate the elevation
change of that key track. [music]