It was not planned, but SpaceX will finally land on the Moon this year. Abandoned in space since its launch seven years ago, the second stage of a Falcon 9 rocket will crash into the lunar surface in March, astronomers announced on Wednesday (January 26th).
The rocket was used in 2015 to orbit a climate observation satellite on Earth, the Deep Space Climate Observatory (DSCOVR). Since that date, the second stage of the spacecraft has been floating in space in an orbit called “chaotic” by mathematicians, because it is difficult to predict, explained astronomer Bill Gray on Wednesday, the first to have noticed the new trajectory.
First known unintended collision
The object passed quite close to the Moon in early January, which changed its orbit, detailed the creator of Project Pluto, software for calculating the trajectories of asteroids and other objects, used by programs observation sites funded by NASA. A week later, the expert was able to observe the piece of rocket again, and realized that it should crash into the far side of the Moon on March 4.
After appealing to amateur astronomers to make additional observations, the data was confirmed. The craft will strike the lunar surface at more than 9,000 kilometers per hour. The precise time and place could still change by a few minutes and kilometers, due to the hardly predictable effect on this hollow cylinder of the light of the Sun, which pushes it in a noticeable way.
The stage of the rocket can again be observed at the beginning of February, and the estimate refined. But the collision is, whatever happens, certain. “I’ve been tracking space junk like this for about fifteen years, and this is the first unintended lunar impact.” detected, pointed out Bill Gray.
Regulate space waste
According to astronomer Jonathan McDowell, it is possible that similar impacts have occurred in the past, without our knowing it. “There are at least 50 objects left in deep space in the 1960s, 1970s and 1980s, just left there, untracked”, he explained. Today’s sightings haven’t found them all. “It is likely that some have hit the Moon accidentally”, he judged.
In March, the explosion of this approximately four-ton object will not be visible from Earth when it occurs. But it should cause a crater which could be observed by scientists later, in particular by NASA’s LRO (Lunar Reconnaissance Orbiter) probe or the Indian one, called Chandrayaan-2, and thus make it possible to learn more about the lunar geology.
Ships have been intentionally launched on the Moon for scientific purposes in the past, such as during the Apollo missions to test seismometers. In 2009, NASA sent the second stage of a rocket to crash in an area near the lunar south pole to study the presence of water.
Few of SpaceX’s rockets travel so far from Earth, usually allowing their respective second stages to return to the atmosphere, where they fall apart. The first floor is recovered and reused.
But these unplanned lunar impacts could multiply in the future, according to Bill Gray, in particular because of the objects that the American or Chinese space programs will leave behind. The United States wants to build a station in orbit around the Moon.
These events “will start to be problematic when there is more traffic”, remarked Jonathan McDowell. « [Aujourd’hui,] it’s nobody’s job to follow the trajectory of the trash we leave in deep space, recalled the expert. It’s time to start regulating [le trafic]. »
Contacted, SpaceX did not respond to Agence France-Presse. Elon Musk’s company is currently developing the lander that should allow NASA to return Americans to the Moon no earlier than 2025.