This is a beautiful sheet of 6, issued in 2010, displaying space probes and astronomers. Featured on the sheet are the joint NASA/ESA/ASI robotic spacecraft CassiniÂ?Huygens, the US orbiter spacecraft Mars Global Surveyor, the unmanned interplanetary space probe Voyager 2, Italian physicist & mathematician Galileo Galilei, British astronomer & composer William Herschel, and French astronomer Nicolas Louis de Lacaille. The sheet is fresh, mint never hinged, and F/VF.