According to scientists, part of a rocket will hit the moon. It wasn’t planned, but it offers research opportunities. What kind of rocket it is, however, the assessments differ.
Earlier this year, Bill Gray received an error message from his program. The scientist programmed the software himself and has been using it to track space – asteroids, space debris and other objects close to Earth – from the US state of Maine for a long time. However, the software simply did not want to give him a long-term route for a missile. “Then I realized my software was complaining because it couldn’t project this object’s flight path past March 4,” Gray told the Washington Post. “And she couldn’t because the rocket then hit the moon.”
A part of the rocket will hit the moon on Friday (March 4), wrote Jonathan McDowell, astronomy professor at the US elite university Harvard, on Twitter in January. “Interesting, but not a big deal either.” Countless scientists and aerospace fans around the world now see things differently, after all it would be the first known unplanned impact of a rocket part on the moon. “This unique occurrence represents an exciting research opportunity,” said the US space agency Nasa.
However, one central question has not yet been clarified: What exactly is supposed to hit the moon? Researcher Gray and NASA originally spoke of part of a SpaceX rocket. This is a “Falcon 9” rocket stage, which was launched in 2015 from the Cape Canaveral spaceport and brought the “Deep Space Climate Observatory”, an earth observation satellite, into space. After that, however, the rocket stage didn’t have enough fuel to get back to Earth, which is why it has been in space ever since.
A short time later, however, Gray and NASA corrected their statements after evaluating further data: It was not a SpaceX rocket after all, but part of an old Chinese rocket, probably the carrier rocket of the “Chang’e 5-T1” – Mission launched from Earth into space in 2014. This was concluded from analyzes of the object’s orbits in 2016 and 2017.
However, China denied these reports. “China has taken note of expert analysis and media reports,” said Wang Wenbin, a spokesman for the Beijing Foreign Ministry. According to their own findings, however, the rocket in question was burned.
In any case, it will not be possible to observe or measure the impact on the far side of the moon. There is currently no seismometer on the moon that could measure the impact. There are also no telescopes or probes that could directly track the crash. In hindsight, however, an Indian orbiter and one from NASA could be on the lookout for the fresh crater. According to NASA, this can take weeks or even months.
It would be the first known unplanned collision of a rocket part with the moon – but not the first collision at all. “On the contrary,” says Ulrich Köhler from the German Aerospace Center (DLR). “Some of that was deliberately aimed at doing science.” In the “Apollo” era of NASA, this was even part of the mission concept.
“Lunar modules were uncoupled at the time and placed on a collision course,” says Köhler. “The shaking of the lunar soil was then measured by the seismometers left on the moon. Sort of like a small moonquake.” From this – together with the many moonquakes and natural impacts – conclusions can be drawn about the properties of the moon’s crust, says the planetary geologist at the DLR Institute for Planetary Research in Berlin-Adlershof.
Later moon missions were also brought to impact in the end. “The goal was to geochemically record the resulting ejecta cloud – for example, to be able to detect ice molecules in isolated craters.” The impending crash could also be useful, says Köhler. “The lunar soil has matured over millions of years from solar wind, cosmic rays and impacted micrometeorites. The impact is now exposing virtually pristine material – and on the understudied far side of the Moon at that.”
For scientist Gray, who was one of the first to predict the impending impact, the unplanned crash is also a sign that the trajectories of space debris would have to be monitored much better and more systematically in order to avoid such a “mess” and also possible dangerous situations in the space to avoid future. He is annoyed that he first misidentified the object as a SpaceX rocket stage. “It annoys me that I didn’t get it right, but I’m still very interested to see what comes out of it.”