Tracking the Lunar Reconnaissance Orbiter with a laser

Cool, especially the photo. [Link]

On certain nights, an arresting green line pierces the sky above NASA’s Goddard Space Flight Center in Greenbelt, Md. It’s a laser directed at the moon, visible when the air is humid. No, we’re not repelling an invasion. Instead, we’re tracking our own spacecraft.
28 times per second, engineers at NASA Goddard fire a laser that travels about 250,000 miles to hit the minivan-sized Lunar Reconnaissance Orbiter (LRO) spacecraft moving at nearly 3,600 miles per hour as it orbits the moon.
The first laser ranging effort to track a spacecraft beyond low-Earth orbit on a daily basis produces distance measurements accurate to about four inches (10 centimeters). For comparison, the microwave stations tracking LRO measure its range to a precision of about 65 feet (20 meters).