An abandoned 5-ton SpaceX rocket stage is on a collision course with the Moon, marking an uncontrolled event that could provide valuable scientific data. The spent Falcon 9 upper stage, which previously launched two lunar landers, is expected to impact the lunar surface early next month.
Bill Gray, head of the "Pluto Project" which tracks celestial objects, developed the software used to calculate the debris' trajectory. According to his projections, the discarded Falcon 9 upper stage will strike near the Einstein crater on the Moon's western edge at approximately 2:34 AM Eastern Time on August 5, traveling at 5,400 miles per hour. Gray was the first to identify that this object would hit the Moon and has been tracking its orbit ever since. He has also co-authored a research paper on the impact with an international team of scientists, which was recently published on the open-access preprint platform arXiv and has not yet undergone peer review.
Benjamin Fernando, a postdoctoral researcher at the Los Alamos National Laboratory in New Mexico and the paper's lead author, stated in an interview: "We expect the rocket booster to completely vaporize upon impact, producing a flash and likely ejecting a plume of material, including lunar dust, soil, and other mixed substances. It will definitely carve out a new impact crater on the lunar surface."
Fernando explained that this human-made rocket collision offers a unique study sample for the scientific community. While meteoroid impacts on the Moon are frequently observed, scientists often cannot precisely determine the mass and velocity of these incoming objects. In this case, the research team has exact data on both critical parameters for the rocket stage. This allows them to treat the event as a calibration reference, which can be used to validate all analytical techniques typically employed to study natural celestial impacts—events that are unpredictable—while this debris impact is entirely known and controllable.
Researchers will also use this event to further analyze the Moon's material composition. The ejecta plume kicked up by the rocket's collision is a key focus for scientists. "If we can detect the composition of the plume, we can work backward to infer the geological makeup of the lunar surface in that region," Fernando explained.
The National Aeronautics and Space Administration (NASA) plans to return astronauts to the Moon as early as 2028 and eventually build a permanent lunar base. Fernando noted that this impact also provides a research opportunity to assess lunar collision risks and ensure the safety of personnel and equipment. "Events where space objects hit the Moon will become more frequent. In the future, with more astronauts stationed on the lunar surface and infrastructure like habitats being built, we must understand the actual threat level posed by such impacts."
He added, "This is an excellent research chance to assess both direct risks—being hit by debris or blinded by the impact flash—and indirect risks, such as the ejecta cloud potentially striking orbiting spacecraft, disrupting or even destroying their operations."
On January 15, 2025, SpaceX launched a Falcon 9 rocket carrying two lunar landers: Firefly Aerospace's "Blue Ghost 1" and the Japanese company ispace's "Resilience" lander. The "Blue Ghost 1" successfully soft-landed on the Moon on March 2, 2025, while the "Resilience" lost contact 90 seconds before landing and ultimately crashed onto the lunar surface.
According to researchers, after the mission was completed, the Falcon 9 upper stage was left abandoned in a high-Earth orbit that would eventually intersect with the Moon's path, and it has now finally settled on a collision trajectory. Fernando stated, "We cannot determine how much SpaceX knew about this impending impact. What is certain is that because this upper stage carried lunar payloads, it was placed into an orbit that inherently had a possibility of hitting the Moon. Whether the company foresaw the risk and chose not to disclose it, or simply did not perform the orbital calculations, we have no way of knowing."
The flash from the impact will be extremely faint and completely invisible to the naked eye. It will require a telescope to observe, and even then, the success rate for detection is low. No impact flash has ever been recorded on the sunlit portion of the Moon, and this event will occur on the illuminated side. Nevertheless, Fernando encourages astronomy enthusiasts to try observing with small amateur telescopes. The research team also appeals to willing observers, whether night owls or early risers, to record and report their findings. "Observers might see the flash, or they could capture the debris plume. Without a doubt, the larger the telescope aperture and the better the observing conditions, the higher the chance of capturing a useful image."
He added, "This type of impact event is very rare. We cannot predict the actual observation outcome, and that is precisely the core reason we are calling on the public to participate."
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