The second stage of a SpaceX Falcon 9 rocket is expected to hit the moon. According to experts, in March, after an odyssey of seven years around the earth and the moon, the four-tonne part will hit the earth’s satellite at a speed of around 2.6 km/s.
It would be the first time a rocket part had accidentally hit the moon. The first stage of a Falcon 9 will be returned to Earth in a controlled manner and reused. SpaceX originally planned to reuse the second stage as well, but hasn’t found a viable solution for this. Therefore, the stage is usually arranged to return to Earth and burn up upon entering Earth’s atmosphere. In this case, however, there was not enough fuel left.
Earlier this month, astronomer Bill Gray called on colleagues and amateurs to make their own observations. Based on the data they submitted, he expects the rocket stage to hit the moon on March 4th. He also published the expected coordinates on his weblogthat are close to the lunar equator.
Accurate prediction could allow lunar satellites like NASA’s Lunar Reconnaissance Orbiter and India’s Chandrayaan-2 to pay attention to the impact and collect data. NASA had planned such a thing in 2009 when they hit a rocket part with a mass of 2.4 tons in a crater area near the South Pole on the moon’s surface and caused a cloud of material to whirl up. A short time later, the “Mission Lunar CRater Observation and Sensing Satellite” (LCROSS), which was supposed to analyze the nature of the cloud, flew through this cloud. Astronomer Jonathan McDowell confirms March 4th date on Twitter. The event was “interesting, but not a big deal”.
The second stage was part of a Falcon 9 that launched NOAA’s Deep Space Climate Observatory (DSCOVR) satellite in February 2015. Gray writes that he has a fairly complete mathematical model of how the gravity of the earth, moon, sun, and planets will affect them. He also has a rough idea of how sunlight moves the rocket part, but this is made more difficult by the fact that it tumbles.