3-5/8x6.5" First Day Cover (FDC) envelope for "Man-In-Space - Mission Of Project Mercury" bears July 21, 1961 Patrick Air Force Base, FL. postmark and has been signed in black felt tip pen by Wernher Von Braun, a German rocket engineer and space architect who first developed rockets for the Nazis during World War II before he and select members of his rocket team were brought to the US as part of the then-secret Operation Paperclip. Von Braun worked on the US Army Intermediate Range Ballistic Missile (IRBM) program before his group was assimilated by NASA. Under NASA, he served as director of the newly formed Marshall Space Flight Center and as the chief architect of the Saturn V launch vehicle, the superbooster that propelled the Apollo spacecraft to the Moon. He is credited as being the "Father of Rocket Science." Envelope has some trace corner tip wear but is o/w Exc. Comes with Hake's COA and JSA LOA.