Based on an examination by one business, it appears that a Russian satellite experienced a “low-intensity explosion” that resulted in hundreds of debris pieces in low Earth orbit.

U.S. Space Command and commercial space situational awareness companies have reported that on June 26, there was a breakup event involving the Russian remote sensing satellite Resurs P1. More than 100 bits of debris were produced by that incident, and sensors positioned on the ground could follow them.

The reason for the fragmentation is still unknown, but according to LeoLabs—the first organization to make the incident public—the debris was produced by a “low-intensity explosion” that may have occurred during a collision or inside the spacecraft. At least 250 debris bits from that explosion have been found up to 500 kilometers in the air.

This result was reached after the business analyzed the debris cloud using its own instruments to examine the distribution of debris pieces and gain a better understanding of what caused it.

“While much of the debris cloud has yet to be analyzed fully, our preliminary assessment concludes that the most likely cause of the event is a low intensity explosion,” LeoLabs concluded in a July 3 statement posted on LinkedIn. “This explosion could’ve been triggered by external stimuli such as an impact by a small fragment (not currently cataloged) or an internal structural failure leading to a propulsion system failure.”

This research eliminates the possibility that the satellite, like Cosmos 1408 in November 2021, was the target of an anti-satellite weapons test. Other signs that such a test was organized or conducted had not been present, such as announcements from the US or Russian forces or limits on airspace.

The satellite itself does not seem to have entirely disintegrated as a result of the explosion. Sybilla Technologies, a Polish space situational awareness company, has observed Resurs P optically and found that the main satellite is still present, rotating every two to three seconds.

The Australian company HEO, which employs commercial satellites to examine other space objects, took images prior to the breakup that demonstrate the failure of the solar panels on Resurs P1 and two follow-on spacecraft, P2 and P3, to properly deploy. It’s unclear how the breakup is connected to this deployment issue.

Even though it doesn’t seem to be the worst-case situation, additional satellites in low Earth orbit are still at risk from the fragmentation event. LeoLabs observed that some of the debris is so high that it passes over orbits that are occupied by numerous other satellites in operation, the International Space Station, and China’s Tiangong space station. It is likely that the particles will stay in orbit for “weeks to months” before decaying due to atmospheric drag.

The corporation said, “This event demonstrates the ongoing risk of defunct spacecraft in orbit.” Decommissioned in 2021, Resurs P1 is scheduled to reenter later this year as its orbit, which is currently approximately 355 kilometers, decays.

Not by yourself, LeoLabs said. More than 2,500 long-lived, intact derelict hardware items, including as defunct rocket bodies and non-operational payloads, could eventually meet a similar end as Resurs P1.