In September 2006, the European Space Agency's first lunar mission, SMART-1, came to an end when the probe was deliberately crashed into the surface of the Moon. The exact location of the craft's final resting place wasn't known, but now images from NASA's Lunar Reconnaissance Orbiter (LRO) have found the telltale scars of the crash site.
SMART-1 was essentially a test bed for technologies that would be used in later ESA missions. After about two years in orbit around the Moon, its trajectory was altered to send it plummeting to the lunar surface in one final experiment, simulating a meteorite impact and seeing what materials might be kicked up from underground. A flash of light was detected by Earth-based telescopes at the time, but the exact site had remained unseen.
"SMART-1 had a hard, grazing and bouncing landing at 2 km (1.2 mi) per second on the surface of the Moon," says Bernard Foing, a project scientist on SMART-1. "There were no other spacecraft in orbit at the time to give a close-up view of the impact, and finding the precise location became a 'cold case' for more than 10 years. For this 'Crash Scene Investigation', we used all possible Earth witnesses, observational facts and computer models to identify the exact site and have finally found the scars. The next steps will be to send a robotic investigator to examine the remains of the SMART-1 spacecraft body and 'wings' of the solar arrays."
The researchers located the scene of the crash using high-resolution images gathered by the LRO. It lies 34.262° south and 46.193° west, which lines up with the ESA's initial estimates. There, the orbiter spotted a scar along the surface, 4 m (13 ft) wide and 20 m (65.6 ft) long with a visible spray of dirt kicked up in a fan around the end.
"The high resolution LRO images show white ejecta, about 7 m (23 ft) across, from the first contact," says Foing. "A north-south channel has then been carved out by the SMART-1 spacecraft body, before its bouncing ricochet. We can make out three faint but distinct ejecta streams from the impact, about 40 m (131 ft) long and separated by 20-degree angles."
The results of the observation were presented last week at the European Planetary Science Congress in Riga, Latvia.