Why Is This Russian Satellite Stalking a U.S. Spy Satellite in Orbit?

Kosmos 2542, a Russian inspector satellite, synchronized its orbit with a U.S. National Reconnaissance Office (NRO) satellite called USA 245, and is now trailing the classified satellite from a distance of about 186 miles, MIT Technology Review reports.

Michael Thompson, a graduate student in astrophysics at Purdue University, first raised the alarm about the set of maneuvers on Twitter. Experts believe the Russian satellite may be collecting intel about the U.S. spy satellite.

Prior to the repositioning, the two satellites were in the same plane, but had different orbital periods, meaning they orbited the Earth at the same altitude (in low Earth orbit, between 171 and 630 miles above Earth’s surface), but they only passed each other periodically, maybe every 11 to 12 days, according to Thompson.

Then, on January 20, the Russian satellite used its onboard thrusters to perform the first of four maneuvers the rest occurred over the next three days to position itself closer to USA 245. Raising even more suspicion, the two satellites are farthest away from each other in Earth’s shadow and at their closest when in the sunlight prime conditions for surveillance.

"Things do move around in low Earth orbit, but to expend your valuable propellant in this way to perfectly position yourself to view another satellite like this to me is just beyond the pale,". Thomas Roberts, who was an aerospace security fellow at the Center for Strategic and International Studies, told MIT Technology Review. "It’s not a coincidence."

Kosmos 2542 launched from Russia’s Plesetsk Cosmodrome in November 2019, while USA 245 has been in orbit since the NRO launched it in August 2013. Russia maintained at the time of Kosmos 2542’s launch that it would only monitor its own satellites, as part of a satellite inspection program.

https://www.popularmechanics.com/space/satellites/a30767105/russian-satellite-stalking-us-spy-satellite/