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On the morning of August 5, at 2:34 AM ET, a discarded SpaceX Falcon 9 upper stage roughly the height of a five-story building will slam into the Moon near Einstein Crater. A coordinated campaign of professional and amateur astronomers spanning three continents is already in place to watch — and a new preprint from 23 researchers argues that the ejecta plume rising above the lunar limb may offer the clearest view anyone has had of a human-made object striking another world in a paper calling on the global astronomy community to observe the event.
Set your alarm. This is the most precisely predicted unplanned lunar impact ever, and a 14-day countdown has begun.
SpaceX Rocket Left Behind After Delivering Two Landers
The upper stage in question — catalogued as 2025-010D — was the workhorse second stage of a Falcon 9 that lifted off from Kennedy Space Center on January 15, 2025, carrying two private lunar landers to trans-lunar trajectories. Its job was to carry two private lunar landers: Firefly Aerospace's Blue Ghost Mission 1 and ispace's Hakuto-R Mission 2. Blue Ghost landed successfully on March 2, 2025, marking the world's first fully successful commercial lunar soft landing. Hakuto-R's attempt ended when contact was lost roughly 90 seconds before touchdown on June 5, 2025, as ispace's technical analysis later confirmed a laser range finder anomaly caused the hard landing.
After separating from both spacecraft, the upper stage was supposed to reenter Earth's atmosphere and burn up — the standard fate for Falcon 9 second stages after low-Earth-orbit missions. Instead, the high-energy "trans-lunar injection" needed to send the landers moonward left 2025-010D in a highly elongated orbit that swings between roughly 220,000 km (137,000 miles) and 510,000 km (317,000 miles) from Earth — in the same gravitational neighborhood as the Moon. Over 18 months, the Moon's gravity slowly reshaped that orbit until an impact became inevitable.
Bill Gray, the independent astronomer who developed the Project Pluto orbital tracking software, flagged the collision in September 2025 after his software analyzed more than 1,000 observations gathered by asteroid surveys and amateur observers at facilities in Mississippi, Utah, Beijing, and England. By February 26, 2026, the observation count reached 1,053 data points. The longer the tracking baseline, the tighter the prediction.
Why Predicting the Exact Spot Is Hard
Gravity alone would make this prediction almost trivially precise — lunar gravity, Earth gravity, and the gravitational pull of the Sun and planets are all known to extraordinary accuracy. But 2025-010D is also pushed by sunlight.
Solar radiation pressure is a real but extraordinarily gentle force: the cumulative push of individual photons on a tumbling, hollow metal cylinder. Over months, it introduces deviation that grows in ways that are only partly predictable. As the rocket stage spins — UK amateur Grant Privett recorded it brightening and fading in a 12-minute observation at the British Astronomical Association — it catches sunlight at varying angles, producing a small but irreducible nudge sideways as well as away from the Sun.
As of Bill Gray's July 17, 2026 update — the most recent as of today — the best predicted impact time is 06:34:32.9 UTC (2:34:32.9 AM ET) on August 5, with coordinates of 19.455° N, 93.594° W, near Einstein Crater on the Moon's western limb. Gray estimates the uncertainty at "a few seconds" in time and "a few kilometers" in position. In the final days before impact, additional tracking will tighten those numbers to tens of meters and a fraction of a second.
What Happens When It Hits
At impact, 2025-010D will be traveling at approximately 2.43 km/s (about 8,700 km/h, or 5,400 mph — roughly seven times the speed of sound in air), per the Fernando et al. paper's impact analysis. The object is about 12 m (40 ft) long and 4 m (13 ft) in diameter, with an estimated mass of approximately 4,000 to 4,900 kg.
Bill Gray calculates the collision will release approximately 14.5 billion joules — the kinetic energy equivalent of roughly three tons of TNT. That is an enormous amount of energy for something moving this slowly by asteroid standards.
Here is the physics problem that makes the flash so uncertain: whether the impact produces a visible flash depends heavily on whether the rocket stage hits loose regolith or harder bedrock. The speed of sound in lunar regolith is only a few hundred meters per second, so 2.43 km/s would exceed it — generating a shockwave and releasing a fraction of the energy as light. But the speed of sound in harder bedrock is 1,000 to 2,000 m/s, meaning 2.43 km/s might be subsonic in those materials, and shockwave-driven light emission would be dramatically suppressed. The research team's models span a range from visual magnitude +3 (potentially visible in a telescope) to fainter than +15 (undetectable) depending on which surface material the stage hits. That uncertainty cannot be resolved in advance.
The good news, according to the paper's simulation work using the HOSS (Hybrid Optimization Software Suite) multiphysics code developed at Los Alamos National Laboratory, is that the impact will excavate roughly 1.1 million kg of lunar regolith — about 150 to 200 times the rocket stage's own mass. Those billions of particles will be lofted into ballistic trajectories at a range of speeds. The fastest resolved particles in the simulation reach 130 m/s (about 290 mph), but smaller, unresolved fragments will travel much faster. The slowest half of resolved ejecta re-impacts the surface within 5 seconds; roughly 2% remain airborne after 30 seconds.
The most important number for observers: the HOSS model estimates the plume will reach altitudes of at least 1.5 km (0.93 miles) above the surface, and unresolved smaller particles almost certainly reach higher. Because the impact occurs almost exactly on the Moon's visible limb as seen from Earth, that plume could rise above the edge of the lunar disk and become visible against the dark sky beyond it — something no ground observer has ever caught from a human-made lunar impact.
What Scientists Expect to See — and When
William Cooke, program manager of NASA's Meteoroid Environment Office at Marshall Space Flight Center, described his expectations straightforwardly: "I think it's going to be very subtle. I think it's going to be very, very hard to see, if not impossible. But there's always a chance." He added that the limb geometry makes the ejecta plume a more promising target than the flash itself.
The impact flash, if it occurs on the sunlit lunar surface (which it will), has never been detected on the lit hemisphere for any natural or artificial impact. Observers hoping for a flash should use high-cadence video — at least 20 frames per second — as recommended in the Fernando et al. observing strategy, so the sub-second flash isn't missed between frames. Near-infrared J-band imaging can help observers in daylight regions reduce sky background. An unfiltered observation still has value.
Those watching for the ejecta plume — the better scientific bet — should expect it to evolve over minutes, not milliseconds, and should frame a region just beyond the lunar limb rather than on the surface itself.
The crater will not be visible from Earth — current modeling suggests 20 to 30 m across and roughly 5 m (16 ft) deep — but it will be imaged by spacecraft.
Why This Impact Is Different From 2022
The previous comparable event was March 4, 2022, when a spent rocket stage — independently identified as the upper stage from China's Chang'e 5-T1 mission — struck the far side of the Moon near Hertzsprung Crater. NASA's Lunar Reconnaissance Orbiter eventually photographed a double crater roughly 28 to 29 m across in its longest dimension — two craters of nearly equal size side by side.
That double crater surprised researchers. Tanner Campbell, then a doctoral student at the University of Arizona and lead author of a 2023 follow-up study in The Planetary Science Journal, noted that producing two craters of nearly equal size requires "two roughly equal masses that are apart from each other." China National Space Administration denied responsibility for the impactor and has not disclosed what the undisclosed payload may have been.
The August 5 event is fundamentally different in two ways. First, 2025-010D carried no secondary payload; its job was simply to deliver Blue Ghost and Hakuto-R to trans-lunar trajectories, and it did exactly that. Scientists therefore expect a single crater rather than a double one — and they can test that expectation against known physics for the first time, since the object's mass, dimensions, and composition are well-established. Second, the impact will occur on the lunar near side, partially observable from Earth, rather than the far side — opening the possibility of real-time observation for the first time in decades.
A Coordinated, Multi-Instrument Observation Campaign
The new paper (arXiv:2607.14625) published July 16 is the organizing document for the global observation effort. Lead author Benjamin Fernando of Los Alamos National Laboratory and 22 co-authors — drawn from NASA Ames, Michigan State University, the Korea Aerospace Research Institute, Johns Hopkins University Applied Physics Laboratory, the European Southern Observatory, the University of Maryland, Boston University, New Mexico State University, and seven other institutions — outline the scientific rationale and observational strategies.
Key assets in place:
NASA's Lunar Reconnaissance Orbiter (LRO) will acquire baseline imagery of the expected impact site before August 5 and return to photograph the fresh crater afterward, repeating the role it played after the 2022 Chang'e impact. On the ground, three professional observatories have allocated observation time: high-cadence imaging at the Astrophysical Research Consortium 3.5-meter telescope at Apache Point Observatory in New Mexico; spectroscopic observations targeting sodium emissions at the 4.3-meter Lowell Discovery Telescope in Arizona; and sodium, OH, and potassium spectroscopy from the UVES instrument on the 8.2-meter Very Large Telescope Unit 2 in Chile.
Korea's Pathfinder Lunar Orbiter — known as Danuri — will pass within a few kilometers of 2025-010D approximately two minutes before the stage's impact, a close conjunction that baseline imaging has already been acquired for.
Amateur observers are actively encouraged to participate. The NASA-affiliated "Impact Flash!" citizen science project (science.nasa.gov/citizen-science/impact-flash) and the Lunar Impact Flash Network (lif.mi.imati.cnr.it) both accept submitted data. The British Astronomical Association has published how-to guides for observers without prior lunar impact experience. Anyone with a telescope and a video camera is a potential contributor.
Who Can Watch and When to Look
For ground-based observers in the Americas, the geometry is favorable. The Moon will be above the horizon at 2:34 AM ET on August 5 for anyone in the eastern half of the United States, Canada, and much of South America. The Moon will be past last quarter — roughly 56% illuminated — with the impact site near the sunlit western limb.
For maximum flash detection probability, find dark skies and point a video-capable telescope at Einstein Crater, on the Moon's far-left edge as seen from the northern hemisphere. High-cadence imaging, 20 or more frames per second, is optimal for flash detection. For the ejecta plume, start recording at least a minute before impact and continue for at least 10 minutes afterward; frame the region just outside the visible limb.
The paper recommends a practice run on the night of August 4 (UTC) — one night before impact — to test camera settings and confirm pointing under similar illumination conditions.
Observers west of the Mississippi River will see the Moon lower in the sky, which reduces observing quality but does not eliminate the opportunity. Hawaii and Alaska are excluded: the Moon will be below the horizon at impact time. Observers in Europe and Africa will be in daytime, which does not entirely rule out flash detection (J-band infrared imaging of daytime flashes has been demonstrated in recent literature) but greatly reduces sensitivity.
What the Science Will Deliver
This is only the second time a spent rocket stage has been tracked, predicted, and deliberately studied as it strikes the Moon — and it arrives in a far more instrumented era than 2022. The science goals are specific and practical.
First, the observation campaign will test a pipeline for localizing impacts on the lunar surface using flash timing combined with orbital mechanics — a capability with direct relevance to the seismometer networks planned for NASA's Artemis program. Future lunar infrastructure will need to detect, locate, and characterize meteoroid impacts in real time; the August 5 event, with its precisely known time window and trajectory, provides the ideal calibration dataset.
Second, spectroscopic observations of the ejecta plume will reveal the composition of regolith in the Einstein Crater region — a part of the Moon that has received comparatively little close study. The LCROSS mission in 2009 used a similar deliberate impact at the lunar south pole to confirm the presence of water ice there; this impact, while unplanned, offers a comparable window into a different, unexplored region's subsurface chemistry.
Third, the event refines orbital decay models for debris in cislunar space — the volume between geostationary orbit and the Moon. That information will matter more and more as commercial and government missions multiply. The HOSS simulation data from this event will join a thin but growing library of observations that constrain how uncontrolled artificial objects behave when they hit the lunar surface.
Space Debris Governance Has Not Caught Up
The 2025-010D story does not end on August 5. It is a data point in a larger, unresolved problem: the commercial lunar economy is expanding into regulatory territory where almost no binding rules exist.
The Inter-Agency Space Debris Coordination Committee — the international body that maintains debris mitigation guidelines for low Earth orbit — has no equivalent framework for cislunar space. The Outer Space Treaty of 1967 covers space junk in principle but provides no enforcement mechanism and predates the commercial sector entirely. The FCC's 5-year deorbit mandate applies only to LEO satellites. There is no international law that required anyone to put 2025-010D on a disposal trajectory — and there still isn't, even as dozens of additional commercial lunar missions are in planning or development.
As Gray has noted on his Project Pluto tracking page, the rocket stage ended up on its collision course partly because there was no fuel remaining after the mission and no plan in place for responsible disposal. More recently, he notes that the Falcon 9 upper stage that launched the EscaPADE spacecraft in November 2025 was placed on a solar orbit trajectory by SpaceX, suggesting the company is moving toward better cislunar disposal practices. But that development was a commercial choice, not a regulatory requirement.
The Aerospace Corporation has assessed that a single debris-generating collision event in cislunar space could produce a hazard field that persists for thousands of years — far longer than the decades-long debris clouds in low Earth orbit, where atmospheric drag eventually pulls fragments down. With NASA's Moon Base program targeting a first crewed landing in the 2028 timeframe and human missions to the South Pole planned through the 2030s, the window for establishing cislunar debris governance before it becomes an operational safety issue is narrowing.
Frequently Asked Questions
Can I see the Falcon 9 hit the Moon from Earth?
Possibly, but the flash is the harder target and the plume is the better one. The impact flash occurs on the sunlit part of the Moon, where no human-made or natural impact flash has ever been detected. Scientists calculate that the probability depends entirely on what material the rocket stage hits — loose regolith amplifies the light output; harder bedrock may suppress it to undetectable levels. The ejecta plume is a more promising target: HOSS simulations show material being lofted to at least 1.5 km (0.93 miles) in altitude, and the near-limb geometry means some of that plume may appear above the Moon's edge against the dark sky. Observers in eastern North America and South America should have the Moon above the horizon at 2:34 AM ET on August 5. A telescope and a video camera are required; neither binoculars nor naked-eye observation alone is likely to succeed.
What makes this lunar impact scientifically different from the 2022 Chang'e crash?
The August 5 event is a far cleaner experiment. Scientists know the mass (approximately 4,000–4,900 kg), dimensions (roughly 12 m/40 ft long, 4 m/13 ft in diameter), and composition of 2025-010D because it is a documented Falcon 9 upper stage. The 2022 Chang'e 5-T1 event produced a double crater whose explanation — two roughly equal masses at opposite ends of the booster — rested on inference rather than known facts. A single crater is expected on August 5 because 2025-010D carried no undisclosed secondary payload. The resulting crater, once imaged by LRO and Korea's Pathfinder Lunar Orbiter, will allow scientists to compare actual crater morphology with model predictions to a degree that was impossible in 2022. The observation campaign is also larger: three professional ground-based telescopes, two orbiting spacecraft, citizen science networks, and a validated physics simulation were all prepared before this impact — a level of preparation that has no precedent for an unplanned lunar collision.
What does this unplanned crash mean for the future of lunar missions?
There is currently no binding international law requiring commercial rocket operators to plan for end-of-life disposal of upper stages deployed on cislunar trajectories. The 2025-010D event exists because no such requirement applied to the January 2025 mission, and because the remaining propellant after the trans-lunar injection was insufficient to execute any disposal maneuver. SpaceX appears to be moving toward better practices — the EscaPADE upper stage from November 2025 was placed into a long-term solar orbit — but that was a commercial decision, not a regulatory one. As commercial lunar traffic increases toward planned Moon Base operations in the late 2020s and 2030s, unmanaged cislunar debris represents a growing hazard to orbiting spacecraft and eventually to human crews on the lunar surface. The lack of an international cislunar debris governance framework — an equivalent of the Inter-Agency Space Debris Coordination Committee's low-Earth-orbit guidelines — is the governance gap that this impact makes visible.
How precisely do scientists know where the impact will happen?
As of July 17, 2026, Bill Gray's best estimate places the impact at coordinates 19.455° N, 93.594° W — near Einstein Crater on the Moon's western limb — with an uncertainty of "a few seconds" in time and "a few kilometers" in position. The main source of imprecision is solar radiation pressure, the cumulative push of sunlight on the tumbling rocket stage, which introduces small but incompletely predictable deviations over many months. That uncertainty will shrink substantially in the final days before August 5 as additional astrometric observations further constrain the trajectory. LRO and Danuri mission planners will use the refined position to target their cameras; the final predicted crater location will be accurate to within tens of meters.
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