Apollo 11 astronauts left an array of "corner mirrors" on the Moon, each one consisting of three mirrors arranged at mutual right angles like the corner of a box. A corner mirror has the property that light shined on it from any angle is reflected back exactly in the direction from which it came. Scientists subsequently directed a brief pulse of light from a powerful laser at the mirror assembly on the Moon, and measured the time required for it to travel to the array and return back to Earth: 2.56 s. How far away was the array of mirrors at that time?