A paper authored by the Russian team is circulating in satellite-watcher circles. That paper contains a revealing look at one of their observational targets: the U.S. spysat Lacrosse 5.

The U.S. military's 20-year-old Lacrosse 2 spy satellite appears to be missing in orbit. Amateur satellite trackers suspect the Lacrosse 2 spy satellite has re-entered Earth's atmosphere.

Technicians work on a radar-imaging Lacrosse satellite, a component of the U.S. network that can work at night and penetrate clouds.

A Lacrosse satellite is 12m long, 4.4m in diameter, weighs 14,515kg (6,590lbs) and features a synthetic aperture radar system having a phased array antenna a deployed diameter of about 20m.