1950s-70s USA and Russia philatelic covers that are related to the early satellites development, manned and unmanned spaceflights to the moon.
1969-01-26 USA Apollo 11 Experimental Deployment
Ten days experimental deployment of the Apollo 11 Mobile Quarantine Facility aboard the USS Myles C. Fox on sea trials from Norfolk, Virginia. The Mobile Quarantine Facility is a converted Airstream trailer used by NASA to quarantine astronauts returning from Apollo lunar missions for a duration of 21 days. Its purpose was to prevent the spread of any contagions from the moon, though the existence of such contagions was considered unlikely.
(Note the cover printed "Apollo 10", which should be "Apollo 11").