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NASA moon mission captures fleeting view of sister craft

Posted: January 29, 2014

Coupling a fortuitous orbital alignment with meticulous planning, a camera aboard NASA's Lunar Reconnaissance Orbiter caught a smeared glimpse of another moon probe in an image released Wednesday.

NASA's LADEE spacecraft is seen in this geometrically corrected image from the Lunar Reconnaissance Orbiter taken on Jan. 14, U.S. time. Photo credit: NASA/GSFC/Arizona State University
LRO and the Lunar Atmosphere and Dust Environment Explorer, or LADEE, mission are NASA's two probes currently flying around the moon. The two satellites fly in different orbits and only occasionally pass near each other.

But scientists in charge of the Lunar Reconnaissance Orbiter Camera calculated how to record a view of LADEE on Jan. 14 as the two probes traveled at near-perpendicular angles more than 20 miles over the moon's tortured surface.

"Since LROC is a pushbroom imager, it builds up an image one line at a time, thus catching a target as small and fast as LADEE is tricky! Both spacecraft are orbiting the moon with velocities near 1600 meters per second (3600 mph), so timing and pointing of LRO needs to be nearly perfect to capture LADEE in an LROC image," wrote Mark Robinson, LROC's principal investigator at Arizona State University in Tempe.

During the Jan. 14 encounter, controllers commanded LRO to roll 34 degrees to the west to line up the spacecraft's narrow-angle camera with LADEE's expected position on its flight path. LRO's imager was designed to snap sharp pictures of the moon, not fast-moving nearby spacecraft, so the initial result showed LADEE as a smeared streak backdropped by a clear landscape of lunar craters.

A comparison of LADEE's image from the LRO camera with an artist's concept. The labels on the artist's concept are matched to the resolution of LRO's narrow-angle camera. See a larger version. Photo credit: NASA/GSFC/Ames/Arizona State University
Scientists used a technique known as geometric correction to sharpen the view of LADEE, but the spacecraft is still blurry. The corrected image also had the result of smearing the lunar landscape in the background.

"Despite the blur it is possible to find details of the spacecraft, which is about 1 meter wide and 2 meters long. You can see the engine nozzle, bright solar panel, and perhaps a star tracker camera (especially if you have a correctly oriented schematic diagram of LADEE for comparison)," Robinson wrote.

LRO launched in June 2009 to map the lunar surface and complete a geological survey of the moon, revealing new insights into how the moon formed and evolved, creating a global lunar atlas, and helping scientists find deposits of watery compounds.

Since arriving in lunar orbit in October, LADEE achieved the first high-speed laser communications link-up between the moon and Earth and is now collecting data on the moon's tenuous atmosphere.

LRO and LADEE were joined at the moon in December by China's Chang'e 3 lander, which deployed a small mobile rover. LRO's camera has already imaged the Chinese probe on the lunar surface.

Follow Stephen Clark on Twitter: @StephenClark1.