Close encounters of the classified kind

The first days of June 2017 were a busy period at the International Space Station (ISS). The SpaceX Dragon CRS-11 cargo ship arrived and berthed, and the Orbital ATK Cygnus OA-7 “S.S. John Glenn” cargo ship unberthed and departed. There was also another spacecraft sneaking up for a close approach, one that was classified and not supposed to be noticed. On June 3, the US military satellite USA 276 approached the ISS to a nominal distance of 6.4 kilometers and effectively circled the ISS in both the cross-track and along-track directions. More

(Source: The Space Review - Jul 4)