The upper stage of a SpaceX Falcon 9 rocket has collided with the Moon, leaving a newly formed crater near the prominent Einstein crater. The impact occurred on Wednesday at approximately 5,400 mph (8,700 km/h).
While the brief flash of the collision would have been difficult for amateur astronomers to observe, major observatories in the Americas are now analyzing the data. Scientists anticipate it may take days or weeks to fully understand the event and its implications. For planetary geologists, this unintended lunar impact represents a valuable research opportunity.
The Falcon 9 rocket, a reusable model used in various missions, has sections that are shed into space after launch. This particular spent stage, measuring roughly the size of a five-story building and weighing at least 4,000 kilograms (8,800 pounds), was ejected after its January launch last year. Its mission was to propel two lunar landers out of Earth's orbit and onto a trajectory toward the Moon.
Over an 18-month period, the upper stage followed a long, looping orbit that brought it back towards the Moon. A combination of the gravitational pull from the Earth, Moon, and Sun, along with subtle pressure from sunlight, gradually altered its path. Astronomers monitoring the rocket's trajectory determined that these small forces had set it on a collision course with the Moon, with its speed increasing daily.
The accidental nature of the collision makes it a unique scientific gift. The data gathered from the impact site could prove crucial for future lunar missions. Planetary geologists are particularly interested in the composition of the ejected lunar soil and the characteristics of the new crater formed by the impact. This event offers a rare chance to study the lunar surface in a way that planned missions might not afford.