Astronomers discovered a rocket body heading toward a lunar collision late last year. The impact occurred March 4, with NASA’s Lunar Reconnaissance Orbiter (LRO) later spotting the resulting crater. Surprisingly, the crater is actually two craters, an eastern crater (18 meters in diameter, or about 19.5 yards) superimposed on a western crater (16 meters in diameter, or about 17.5 yards).

The double crater was unexpected and may indicate that the rocket body had large masses at each end. Typically, a spent rocket has mass concentrated at the motor end, and the rest of the rocket stage mainly consists of an empty fuel tank. Since the origin of the rocket body remains uncertain, the double nature of the crater may indicate its identity.

No other rocket body impacts on the Moon have created double craters. The four Apollo S-IVB craters (created by Apollo 13, 14, 15, and 17) were somewhat irregular in outline and were substantially larger (greater than 35 meters, or about 38 yards) than each of the double craters. The maximum width (29 meters, or about 31.7 yards) of the double crater of the mystery rocket body was near that of the S-IVBs.

LRO is managed by NASA’s Goddard Space Flight Center in Greenbelt, Maryland, for the Science Mission Directorate at NASA Headquarters in Washington, DC. Launched on June 18, 2009, LRO has collected a treasure trove of data with its seven powerful instruments, making an invaluable contribution to our knowledge about the Moon. NASA is returning to the Moon with commercial and international partners to expand human presence in space and bring back new knowledge and opportunities.