It is purely accidental, but there will be some consequences. NASA has chosen SpaceX, founded by Elon Musk, to provide a spacecraft for astronauts to return to the moon. Although this mission is still years away, a 4-ton upper stage of a SpaceX rocket launched seven years ago is expected to collide with the moon on March 4. This prediction is based on recent observations and calculations by amateur astronomers. The impact is anticipated to occur at 7:25 am Eastern time, with some uncertainty regarding the exact time and location. Bill Gray, creator of Project Pluto, a set of astronomical software for calculating orbits, stated that the rocket fragment will not miss the moon. Gray stated that it is highly likely that the object will impact as predicted, likely within a few minutes and a few kilometers of the estimated time and location. Throughout the Space Age, various man-made objects have ventured into the solar system, with some not expected to return. An example of this is Musk's Tesla Roadster, launched into orbit around Mars during SpaceX's Falcon Heavy rocket launch in 2018. However, occasionally these objects do return, as seen in 2020 when a mysterious object was discovered to be part of a rocket launched in 1966 during NASA's Surveyor missions to the moon. Gray has been monitoring a specific piece of SpaceX debris for years, which played a role in launching the Deep Space Climate Observatory on February 11, 2015. The observatory, also known as DSCOVR, was originally intended for Earth observation under the name Triana, supported by Al Gore. However, it was repurposed to provide early warning of solar storms. Today, it regularly takes images of Earth from space, including events like lunar eclipses. Typically, the upper stage of a Falcon 9 rocket is intentionally pushed back into Earth's atmosphere after delivering its payload to avoid space debris. However, the upper stage of the rocket used up all its fuel to propel DSCOVR to its destination, leaving it in a high, elongated orbit around Earth that crosses the moon's orbit. This raised concerns about a potential collision in the future. The motion of the Falcon 9 stage, now inactive and uncontrollable, is influenced by the gravitational forces of Earth, the moon, and the sun, as well as pressure from sunlight. While debris in lower Earth orbit is closely monitored for satellite and International Space Station safety, objects like the DSCOVR rocket in more distant orbits are often overlooked. Gray stated that he is the only person tracking these objects. While many spacecraft have crashed on the moon, this seems to be the first instance of something from Earth unintentionally reaching the moon. On January 5, a rocket stage came within 6,000 miles of the moon, being pulled by the moon's gravity on a trajectory that could potentially lead to a collision. Amateur astronomer Peter Birtwhistle, who lives near London, was one of those who responded to a call from Gray to observe the object as it passed by Earth in January. The large 16-inch telescope in his garden, known as the Great Shefford Observatory, was aimed at the section of the sky where the rocket stage swiftly passed by. Birtwhistle noted the speed at which it was moving. The observations were precise enough to forecast a possible impact. Astronomers will have an opportunity to observe it once more before it travels beyond the moon for the final time. Subsequently, it is expected to collide with the far side of the moon, beyond the view of Earth. NASA's Lunar Reconnaissance Orbiter will not be able to witness the impact as it happens, but it will fly over the expected impact location later to capture images of the newly formed crater. Mark Robinson, a professor at Arizona State University who leads the Lunar Reconnaissance Orbiter's camera team, estimates that 4 tons of metal traveling at a speed of 5,700 mph will create a crater 10 to 20 meters wide. This impact will allow scientists to study the lunar surface below the crater. Unlike meteor strikes, the exact size and time of this impact will be known. India's Chandrayaan-2 spacecraft, also in lunar orbit, may also be able to photograph the impact site. Other spacecraft aiming for the moon in the coming year may have the opportunity to observe the impact location, unless they too accidentally create craters. ©2022 The New York Times Company.