NASA’s LRO Snaps a Picture of NASA’s LADEE Spacecraft

With precise timing, the camera aboard NASA’s Lunar Reconnaissance Orbiter (LRO) was able to take a picture of NASA’s Lunar Atmosphere and Dust Environment Explorer (LADEE) spacecraft as it orbited our nearest celestial neighbor. The Lunar Reconnaissance Orbiter Camera (LROC) operations team worked with its LADEE and LRO operations counterparts to make the imaging possible.

LRO imaged LADEE, about 5.6 miles beneath it, at 8:11 p.m. EST on Jan. 14, 2014. (LROC NAC image M1144387511LR. Image width is 821 meters, or about 898 yards.) Image Credit:  NASA/Goddard/Arizona State University

LRO imaged LADEE, about 5.6 miles beneath it, at 8:11 p.m. EST on Jan. 14, 2014. (LROC NAC image M1144387511LR. Image width is 821 meters, or about 898 yards.). Image Credit: NASA/Goddard/Arizona State University.

This subsection of the LRO image, expanded four times, shows the smeared view of LADEE. Image Credit: NASA/Goddard/Arizona State University

This subsection of the LRO image, expanded four times, shows the smeared view of LADEE. Image Credit: NASA/Goddard/Arizona State University

LADEE is in an equatorial orbit (east-­to-­west) while LRO is in a polar orbit (south-­to-­north). The two spacecraft are occasionally very close and on Jan. 15, 2014, the two came within 5.6 miles (9 km) of each other. As LROC is a push-broom imager, it builds up an image one line at a time, so catching a target as small and fast as LADEE is tricky. Both spacecraft are orbiting the moon with velocities near 3,600 mph (1,600 meters per second), so timing and pointing of LRO must be nearly perfect to capture LADEE in an LROC image.

LADEE passed directly beneath the LRO orbit plane a few seconds before LRO crossed the LADEE orbit plane, meaning a straight down LROC image would have just missed LADEE. The LADEE and LRO teams worked out the solution: simply have LRO roll 34 degrees to the west so the LROC detector (one line) would be in the right place as LADEE passed beneath. As planned at 8:11 p.m. EST on Jan. 14, 2014, LADEE entered LRO’s Narrow Angle Camera (NAC) field of view for 1.35 milliseconds and a smeared image of LADEE was snapped. LADEE appears in four lines of the LROC image, and is distorted right ­to­ left.

This animation compares the LRO image (geometrically corrected) with a computer-generated image of LADEE. Image Credit: NASA/Goddard/Arizona State University.

This animation compares the LRO image (geometrically corrected) with a computer-generated image of LADEE. Image Credit: NASA/Goddard/Arizona State University.

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