NASA’s Lunar Orbiter Jiggled By Meteoroid Hit

The first wild back-and-forth line records the moment on October 13, 2014 when the left Narrow Angle Camera’s radiator was struck by a meteoroid. Credit: NASA’s Goddard Space Flight Center/Arizona State University

On Oct.13, 2014 something very strange happened to the camera aboard NASA’s Lunar Reconnaissance Orbiter (LRO). The camera normally does a bang up job producing sharp and beautiful images of the lunar surface, but this one had the jitters. From the sudden and jagged pattern apparent in the image, the orbiter team determined that the camera must have been hit by a tiny meteoroid, a bit of space rock perhaps on its way to the moon’s surface.

Maybe you’ve had a similar experience with your own camera though instead of a meteoroid, it was someone’s elbow. LRO’s camera is really a system of three cameras: two Narrow Angle Cameras (NACs) capture high resolution black and white images. The third Wide Angle Camera captures medium resolution photos using filters to provide information about the properties and color of the lunar surface.

LRO takes amazing photos of the moon’s surface. This one narrows in on a small part of the floor of Lavoisier crater and shows a concentric crater at lower left and fractures riddling the landscape. The width of the photo is about 6 miles (10 km). Credit: NASA/GSFC/Arizona State University

The NAC works by building an image one line at a time. The first line is captured, then the orbit of the spacecraft moves the camera relative to the surface, and then the next line is captured, and so on, as thousands of lines are compiled into a full image.The jittery appearance of this photo is the result of a sudden and extreme movement of the left Narrow Angle Camera. Scientists ruled out a spacecraft event like the movement of a solar panel or antenna because both cameras would have been affected identically, leaving a space rock as the best explanation.

The next question then, especially if you’re of scientific mind, might be to ask how massive the object was that struck the camera. It so happens that during testing, the cameras were attached to a vibration table that simulated the launch to make sure they wouldn’t fail from the severe vibrations during liftoff. Using a computer model of the simulation, the orbiter team tried to reproduce the distortions in the image to determine the size of the meteoroid.

The moon is a regular presence in the night sky this week. This photo, taken last night, shows the moon and Jupiter in conjunction. Credit: Bob King

They estimated the impacting rock would have been about half the size of a pinhead (0.8 millimeter), assuming a velocity of about 4.3 miles (7 km) per second and a density of an ordinary chondrite meteorite. Chondrites are the most common meteorites seen to fall to Earth.

“The meteoroid was traveling much faster than a speeding bullet,” says Mark Robinson, professor and principal investigator of LROC. “In this case, LROC did not dodge a speeding bullet, but rather survived a speeding bullet!”

Fortunately, the craft survived, but the impact reminds us that because of the tremendous speed of objects in space, even sand-sized materials can be hazardous. Take a minute to browse some of LRO’s amazing close-up photos of the lunar surface by visiting the gallery.