PASADENA, Calif. — A pair of NASA spacecraft tumbled out of orbit around the moon and crashed back-to-back into the surface on Monday, ending a mission that peered into the lunar interior.
Engineers commanded the twin spacecraft, Ebb and Flow, to fire their engines and burn their remaining fuel. Ebb plunged first, slamming into a mountain near the moon’s north pole. Its twin, Flow, followed about a half minute later and aimed for the same target.
By design, the final resting place was far away from the Apollo landing sites and other historical spots on the moon.
Since the crash site was in darkness, the final act was not visible from earth. The Lunar Reconnaissance Orbiter circling the moon will pass over the mountain and attempt to photograph the skid marks left by the washing machine-sized spacecraft as they hit the surface at 3,800 miles per hour.
After rocketing off the launch pad in September 2011, Ebb and Flow took a roundabout journey to the moon, arriving over the New Year’s holiday on a gravity-mapping mission.
Ebb and Flow focused exclusively on measuring the moon’s lumpy gravity field in a bid to learn more about its interior and early history. The mission was led by scientists from the Massachusetts Institute of Technology. After flying in formation for months, the spacecraft produced the most detailed gravity maps of any body in the solar system.
Secrets long held by the moon are spilling out. Ebb and Flow discovered that the lunar crust is much thinner than scientists had imagined. And it was severely battered by asteroids and comets in the early years of the solar system — more than previously realized.
Data so far also appeared to quash the theory that the earth once had two moons that collided and melded into the one we see today.
Scientists expect to sift through data from the $487 million mission for years.