A spent SpaceX Falcon 9 upper stage is on a collision course with the Moon, scheduled to slam into the lunar surface at about 5,400 mph on August 5, 2026. The high-speed impact near Einstein Crater offers scientists a rare controlled test to study crater formation and ejecta dynamics.
SpaceX is about to leave another unintended mark on the lunar landscape. A discarded Falcon 9 upper stage is hurtling toward a direct collision with the Moon, with impact predicted for 06:35 UTC on August 5, 2026. The errant piece of hardware was left over from a January 2025 launch that successfully hoisted Firefly’s Blue Ghost-1 lander and the ispace Hakuto-R Resilience lander toward the lunar surface.
While those robotic missions achieved their own mixed outcomes—with Blue Ghost-1 nailing its landing and contact subsequently lost with the Resilience lander—the mission’s upper stage met a very different fate. With its work done, the rocket lacked the fuel to return to Earth or move into deep space,
explained Gregory Radisic, Fellow at the Centre for Space, Cyberspace and Data Law at Bond University, in a piece for The Conversation as noted in published accounts. The spent metal cylinder remained trapped in an unstable, moon-crossing high-Earth orbit until celestial mechanics finally set it on a collision course.
The Physics of a Hollow Metal Impact on Lunar Regolith
Measuring roughly 12 meters long and 4 meters wide with an estimated mass of 4,000 kilograms, the discarded stage presents a starkly different profile than a dense natural asteroid. Researchers used the Hybrid Optimization Software Suite, or HOSS, to simulate the oncoming collision as a vertical, end-on strike into lunar regolith. The simulations reveal that the collision will crush the hollow metal structure while excavating massive quantities of underlying soil and rock.
Mathematical modeling points to a fresh crater measuring roughly 20 to 30 meters wide and approximately 5 meters deep. Analysts note that a double crater remains entirely possible, echoing the precedent set when China’s Chang’e 5 upper stage produced a twin indentation after striking the Moon’s far side in 2022, likely because the cylindrical body broke apart during the terminal plunge.
When the rocket strikes near Einstein Crater on the Moon’s western edge, it will hit with a kinetic energy of 11.8 gigajoules and a momentum of 9.7 meganewtons according to a new scientific paper. That energetic punch equals roughly 2.8 metric tons of TNT, driving the metal body into the surface at 2.43 kilometers per second—translating to roughly 8,750 kilometers per hour at an angle of 34 degrees from vertical.
Tracking the Dust Plume and Evaluating Flash Visibility
The impact is expected to excavate about 1.12 million to 1.2 million kilograms of lunar material, hurling debris high above the grey plains. Simulations show that the vast majority of these particles will fall right back down within seconds, with about half returning to the surface in under five seconds and potentially forming secondary craters along the surrounding landscape. Only a tiny fraction—about 2 percent—will remain airborne after 30 seconds.
However, the smallest, finest fragments will travel significantly faster and stay aloft much longer. The highest resolved particles in computer models reached an altitude of 1.5 kilometers, while finer dust could climb several kilometers and linger for roughly 10 minutes. Sunlight scattered off this towering dust plume may make it detectable near the lunar limb, even though the Moon will be about 56 percent illuminated during the last quarter phase.
While the physical ejecta blanket offers a clear target for spaceborne cameras, the impact flash itself remains a major wildcard. Researchers caution that flash brightness decreases nonlinearly with impact velocity, making slow-moving space debris disproportionately dim compared to natural meteoroids that hit at supersonic speeds. Observers might see a flash reaching visual magnitude +3 under favorable conditions, or it could prove entirely invisible if it dips below magnitude +15.
What Orbiters and Earth-Bound Observers Hope to Learn
Amateur astronomers positioned in South America and low-middle North America will enjoy the best visibility during the darkness of the 06:35 UTC impact window. Because ground telescopes cannot directly resolve a crater only 30 meters across, professional teams are turning to dedicated assets in orbit. NASA’s Lunar Reconnaissance Orbiter and Korea’s Pathfinder Lunar Orbiter are scheduled to gather detailed before-and-after imagery, with the Korean spacecraft expected to streak past within a few kilometers of the rocket stage just two minutes before impact.
By treating this accidental strike as a controlled experiment, scientists expect to refine impact models that inform future moonquake experiments and debris tracking between Earth and the lunar environment. Furthermore, modeling indicates that the maximum ballistic range of resolved particles will reach slightly under 1,000 kilometers—a distance significant enough to factor into safety hazards for future human infrastructure and lunar astronauts.
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