A SpaceX rocket's upper stage, which launched lunar landers over a year ago, is on an unintentional collision course with the moon. The impact is expected to occur on Wednesday, creating a crater and releasing a plume of dust and rubble.
Space tracking expert Bill Gray predicts the impact will happen at 5,400mph (8,700km/h) near the Einstein Crater on the moon's sunlit western limb. The collision will pack the equivalent energy of three tons of TNT explosives.
While the impact flash will likely be too dim for Earth-based observation, the ejected material could stretch for several miles and remain visible to telescopes for tens of minutes. Scientists, including Benjamin Fernando from Los Alamos National Laboratory, are encouraging observations to understand the hazard debris impacts pose to future astronauts.
Fernando anticipates the impact will create a crater nearly 90ft across and 16ft deep, which will be too small to see from Earth but visible to spacecraft. Nasa’s Lunar Reconnaissance Orbiter and South Korea’s Danuri lunar orbiter are expected to gather before-and-after images of the crash site.