PARIS — Mobile satellite services operator Iridium Communications on Dec. 5 reaffirmed that its Iridium 91 satellite was fully operational in orbit and had experienced no breakup or other anomalies despite a U.S. Air Force assessment to the contrary.
Via the Space Track orbit-determination service, the U.S. Joint Space Operations Center (JSpOC) at Vandenberg Air Force Base, California, on Dec. 4 identified several new pieces of debris as coming from Iridium 91, one of the satellites in McLean, Virginia-based Iridium’s low-orbiting fleet.
The JSpOC conclusion followed several days of speculation about an event occurring around Iridium 91 on or about Nov. 30.
Iridium spokeswoman Diane Hockenberry, in response to SpaceNews inquiries Dec. 4 and 5, said the company had no reason to believe Iridium 91 was struck by a piece of debris insofar as the satellite was working fine.
T.S. Kelso, a senior research astrodynamicist for Analytical Graphics’ Center for Space Standards and Innovation in Colorado Springs, Colorado, said JSpOC cannot track objects below around 10 centimeters in diameter. To have registered four objects as Iridium debris, the objects would need to be fairly large.
“Obviously something happened to generate four pieces of debris large enough for the SSN [Space Surveillance Network of ground and orbital sensors] to track them,” Kelso said.
Kelso said it would be unusual if Iridium had not had any indication via telemetry from the satellite of an impact that generated debris of this size.
Kelso said he did agree with Iridium that it would not have received a JSpOC warning about a debris threat in the days before Nov. 30.
“My analysis does not show any cataloged objects anywhere near Iridium 91 at the time of the event,” Kelso said. “And the four pieces come together very nicely with Iridium 91 — both in-track and cross-track, at 16:15 UTC [Nov. 30], so that had to be the time of the event.”
“All we can say is that Iridium 91 is working fine, and we’ve had no debris avoidance information from JSpOC regarding 91 recently,” Hockenberry said. “We are seeing no issues with any other satellites.”
