The 18th and 19th Space Defense Squadrons (SDS) at Vandenberg Space Force Base, Calif., have issued recommendations for future satellite operators on how to lessen the chances of collision in low Earth orbit (LEO)–impacts that may spur the so-called Kessler effect, named after a paper in 1978 by NASA scientist Donald Kessler, in which the generation of debris leads to an increase in the probability of more LEO collisions.

In a paper for the Small Sat conference in Logan, Utah, Cynthia Wilson and Corey Best, identified at the beginning of the paper as members of the 18th SDS, wrote that the Department of the Air Force created a Space Situational Awareness Program after the collision of the Russian Kosmos 2251 and Iridium 33 satellites in 2009–the first crash divulged between two satellites.

“This incident generated thousands of pieces of debris that would continue to pose a threat to spaceflight safety for years to come, so the decision was made to provide data and thus awareness to all satellite owners and operators,” Wilson and Best wrote. “While the primary focus of 18 SDS and 19 SDS is providing comprehensive space domain awareness to enable space defense, we realize that spaceflight safety and promoting responsible behavior in space is paramount to continuing assured access to space for our partners and allies as well as for all space operators around the world.”

The 18th and 19th SDS have catalogued 44,800 space objects, including 8,600 satellites, at

The 18th SDS “collects hundreds of thousands of metric observations daily from the U.S. Space Surveillance Network [SSN] and calculates current and predicted orbits for all artificial objects in Earth
orbit,” the paper said. “We monitor all activity to, in, and from space, and maintain custody of all resident space objects.”

SSN includes four Northrop Grumman [NOC] Geosynchronous Space Situational Awareness Program (GSSAP) satellites, launched between 2014 and 2016, and two GSSAP birds launched on Jan. 21 last year. The U.S. Space Force/National Reconnaissance Office SILENTBARKER satellites–the first of which may launch this year–are planned to be a significant improvement to GSSAP (Defense Daily, June 26).

In their paper for the Small Sat conference, Wilson and Best advise satellite providers to ensure that their LEO birds are at least 1U–10 cm by 10 cm by 10 cm–to ensure that 18th SDS can track them easily. The authors also advise satellite providers to register their missions on, to contact 18th SDS early on future planned missions, and to use a unique satellite name for each mission.

“As space congestion and competition increase, it is crucial for space actors to collaborate, share operational data, and exchange best practices to ensure safe, secure, and sustainable space operations,” Wilson and Best wrote. “While there is no legal obligation for satellite owners to collaborate with 18 SDS and 19 SDS, early communication and coordination with these organizations enhance mission success through accurate tracking, early identification, and collision warnings.”

Last month, Anduril Industries received an $8.1 million contract as part of Space Systems Command’s mesh networking effort for Space Domain Awareness Space Surveillance Network Sensors (Defense Daily, July 13).