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Towards the North Pole
On July 4th the LROC Narrow Angle Camera scanned its way towards the north pole at an altitude of 187 km, brushing past the crater Rozhdestvenskiy W.
The LROC Narrow Angle Camera (NAC) scans one line at a time so it builds up a complete picture through the motion of the spacecraft. LRO is traveling about ~1600 meters a second (faster than a speeding bullet), so the NAC must read out its array in less than a millisecond for a full resolution image at its nominal 50-km orbit. Currently LRO is in the elliptical commissioning (30x199 km) orbit. When this 2x-summed image was taken on July 4th, 2009 the spacecraft was at an altitude of 187 km, resulting in an exposure time of 2.5 milliseconds. Scrolling through the lines as a movie gives a feel for the spacecraft’s motion in orbit, albeit at a 30% slower rate.
NASA/GSFC/Arizona State University