This envelope was on board the International Space Station.
The cover was marked with the “ISS” octagonal board seal, the “Russian Post. ISS. Russian Segment” round board post mark and the “Russian Segment of International Space Station” board souvenir seal both dated 19 April 2019, the day when the US “Cygnus NG-11”, previously known as “Cygnus CRS OA-11”, unmanned supply spacecraft docked to the ISS. The cover was autographed by all 6 cosmonauts/astronauts who were aboard the station on 19 April 2019: Russian cosmonauts Aleksey Ovchinin and Oleg Kononenko; Canadian astronaut David Saint-Jacques; American astronauts Tyler «Nick» Hague, Christina Koch and Anne McClain. It is necessary to remark that the cover was not carried by the "Cygnus" spacecraft. The cover was delivered to the ISS and then back to Earth by a Russian cosmonaut aboard a Soyuz MS spacecraft.