What remains of a SpaceX Falcon 9 rocket, launched in 2015 under the Dscovr mission, is out of control and could crash into the Moon on March 4th, according to Project Pluto Bill Gray, creator of the Guide astrometry software, used by professional and amateur astronomers around the world to track near-Earth objects, asteroids, minor planets, and comets.
The empty propeller of the Falcon 9, which today orbits chaotically around our satellite and has all the numbers to crash into the dark face of the Moon, has been traveling to the tune since 2015. It was sent to launch the Deep Space Climate Observatory, or Dscovr, into orbit to monitor the solar wind and gain accuracy and timing of alerts and forecasts from the US Oceanic and Atmospheric Administration.
The rocket was able to drop the observatory into place, Lagrange point 1, where Dscovr could orbit the Sun-Earth-Moon system without much effort. It was expected that the rocket’s cap would also remain in that zone of gravitational equilibrium, but it could not be placed in the zone and was abandoned to its fate.
What remains of the Falcon 9 is a cylindrical shell 3.66 meters in diameter, 16 meters long and about 4.5 metric tons. It is piece of space junk similar to the cargo of a tanker truck, which is expected to collide at 2.58 kilometers per second (about 9,288 kilometers per hour) when it crashes.
“Unlike Earth, the Moon has no atmosphere, so the rocket will burn before impact”, reads the channel that is waiting for the collision to occur and follows the movement of the rocket’s cap through a simulation.
According to data from Gray and collaborators around the world, “a certain impact will occur at 12:25:39 UT on March 4th, 2022, latitude +4.93, longitude 233.20 east, on the side of the Mare Orientale”. It will be practically impossible to see it from Earth, although it can be seen before crashing between February 5th and 7th.
Gray has a mathematical model of what the Earth, Moon, Sun, and planets do and how their gravity affects this object. “I have a rough idea of how much sunlight is pushing it out, gently pulling it away from the sun. This usually allows me to make predictions fairly confidently. However, the actual effects of that sunlight are difficult to predict perfectly. Not only does it push out, but some of it ‘bounces back sideways’”, says the scientist.
Space debris is annoying and astronomers looking for asteroids and other stars are warned not to consider it in their observations or not to confuse them. “We are supposed to be looking for a piece of rock, not scrap metal”, Gray clarifies.
In fact, the scientist explains to his followers that he is in favor of thinking about where the rocket propellants will be when missions are launched, and if possible, leaving them in orbits close to the Moon so that they end up crashing and allow selenology to be studied, or lunar geology, after the impact. This, according to Gray, would allow adding knowledge, and would also end up with the garbage, “but I think it is not on the radar of NASA or the CNSA to foresee what they do with the scrap remains of their missions”.
Gray and his professional and amateur peers will be watching the trajectory closely. “We would like to determine the location of the impact as precisely as possible, so that the Lunar Reconnaissance Orbiter (LRO) and Chandrayaan-2 people can find the crater and, if we are lucky, maybe take images of the impact”, says Gray.
