Astronomers discovered a rocket body heading for a lunar collision late last year. The impact occurred on March 4, with NASA’s Lunar Reconnaissance Orbiter later spotting the resulting crater. Surprisingly, the crater is actually made up of two craters, an eastern crater (18 meters in diameter, approximately 19.5 meters) superimposed on a western crater (16 meters in diameter, approximately 17.5 meters).
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 engine end; the rest of the rocket stage consists mostly of an empty fuel tank. The origin of the rocket body remaining uncertain, the dual nature of the crater may indicate its identity.
No other rocket body impact on the Moon has created double craters. The four Apollo SIV-B craters had a somewhat irregular outline (Apollos 13, 14, 15, 17) and were significantly larger (over 35 meters, about 38 yards) than each of the twin craters. The maximum width (29 meters, about 31.7 yards) of the double crater of the mystery rocket body was close to that of 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. 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 of the Moon. NASA returns to the Moon with commercial and international partners to expand the human presence in space and bring back new knowledge and opportunities.
By Marc Robinson
Arizona State University, Tucson