A ring of shiny metal crashed into Earth. No one knows where it comes from

It’s been more than a week since reports first emerged about a “shiny metal ring” falling from the sky and crashing near a remote village in Kenya.

According to the Kenya Space Agency, the object weighed 1,100 pounds and had a diameter of more than 8 meters when measured after landing on December 30. A couple of days later, the space agency was confident that the object was a piece of space debris. , saying it was a ring separating from a gun. “Such objects are usually designed to burn up when re-entering the Earth’s atmosphere or to fall on unoccupied areas, such as oceans,” the space agency. he told the New York Times.

Since those initial reports were published in the Western media, a small band of dedicated space trackers have been using open source data to try to identify precisely which space object fell in Kenya. So far, they have not been able to identify the rocket launch to which the large ring can be attributed.

Now, some space trackers believe that the object did not come from space at all.

Did it really come from space?

Space is increasingly crowded, but large pieces of metal from rockets usually do not fly into Earth’s orbit undetected and without a trace.

“It has been suggested that the ring is space debris, but the evidence is marginal,” he wrote Jonathan McDowell, an astrophysicist who works at the Harvard-Smithsonian Center for Astrophysics. McDowell is highly regarded for his analysis of space objects. “The most likely possibility of space is the reentry of the SYLDA adapter from Ariane flight V184, object 33155. However, I am not completely convinced that the ring is space debris,” he wrote.

Another prominent space tracker, Marco Langbroek, believes that it is plausible that the ring came from space, so he investigated further into the objects that could have been returned around the time of the discovery of the object in Kenya. In a blog post written on Wednesday noted that in addition to the metal ring, other fragments that appeared to be consistent with space debris – including material resembling a carbon film and an insulating sheet – were found several kilometers away from the ring

Like McDowell, Langbroek concluded that the most likely source for the object was an Ariane V launch which happened in July 2008, in which the European rocket brought two satellites into geosynchronous transfer orbit.

The Ariane V rocket was a rather unique craft in that it was designed with the ability to launch two medium satellites into geostationary transfer orbit, a much more popular destination in the late 1990s and early 1990s. 2000 than today. To accommodate the two satellites, a SYstème de Lancement Double Ariane (SYLDA) was placed on the lower satellite to support the mounting of a second satellite above. During the launch in 2008, this SYLDA shell was ejected into a geosynchronous transfer orbit inclined by 1.6 degrees, Langbroek said.

Could it have come from a European missile?

Over the years, this object has been tracked by the US military, which maintains a database of space objects so that active spacecraft can avoid collisions. Due to the lack of tracking stations near the equator, this object is observed only periodically. According to Langbroek, its last observation occurred on December 23, when it was in a highly elliptical orbit, reaching a perigee of only 90 miles (146 km) from Earth. It was a week before an object crashed in Kenya.

Based on his model of the possible re-entry of the SYLDA shell, Langbroek believes it is possible that the European object could have landed in Kenya at the time its entry was observed.

However, an anonymous X account using the DutchSpace handle, which despite being anonymous has provided reliable information about Ariane launch vehicles in the past, posted a thread indicating that this ring could not be part of the SYLDA shell. With the images and documentation, it seems clear that neither the diameter nor the mass of the SYLDA component matches the ring found in Kenya.

In addition, Arianespace officials he told the newspaper Le Parisien on Thursday that they do not believe that the space debris was associated with the rocket Ariane V. Essentially, if the ring does not fit, you must pay.

So what was it?

This story originally appeared Ars Technica.