COLONEL KAROL J. BOBKO - FIRST DAY COVER SIGNED CO-SIGNED BY: ANTHONY ENGLAND, JOHN "ANTHONY" LLEWELLYN, F. CURTIS MICHEL, WILLIAM E. THORNTON - HFSID 54257

KAROL J. BOBKO CO-SIGNED BY JOHN "ANTHONY" LLEWELLYN, WILLIAM THORNTON, TONY ENGLAND, AND F. CURTIS MICHEL
A group of astronauts signed this first day of issue envelope commemorating the Mariner 10launch
First Day Cover Signed: "Karol J. Bobko/NASA Astronaut", "Anthony Llewellyn", "W. Thornton", "Tony England",  and "F. Curtis Michel", 6½x3½. First Day Cover bearing 10-cent stamp honoring the Mariner 10 spacecraft launched to explore the atmospheres of Venus and Mercury, postmarked "Pasadena, CA/Apr/4/1975". Colonel Karol J. Bobko (1937-2023) became a NASA astronaut in 1969 and participated in the Skylab Medical Experiment Altitude Test (SMEAT) just three years later. The ground simulation was essential to future Skylab missions. He later flew on the Challenger STS-6 (1983), Discovery STS-51-D (1985) and Atlantis STS-51J (1985). Bobko became the first astronaut to fly on three different space shuttles. Anthony Llewellyn (1933-2013) was a chemist and NASA astronaut, first selected to join the NASA astronaut program as a space candidate in 1967. As a member of Astronaut Group 6, he participated in flight training but ultimately quit the program in 1968 when he couldn't pass the rigorous flight training requirements, particularly the "flying blind" test. Instead, he began teaching at the University of South Florida, where he conducted groundbreaking research in bioelectrochemistry, designing monitoring instruments for living human tissue. William Thornton (1929-2021) flew on Challenger STS-8 (1983) and Challenger STS-51B/Spacelab (1985). Selected by NASA in 1967, he stayed with the government agency working on improving mechanical hardware for missions until he retired in 1994. As part of this research, he holds over 35 patents concerning medical, military, and aeronautical technology applications. Tony England (b. 1942) was selected as a NASA astronaut in 1967, serving as a backup for the Apollo and Skylab programs. He flew on Challenger STS-51F/Spacelab 2 (1985) and racked up 188 hours in space. He currently serves as the Dean for the University of Michigan, Dearborn campus, College of Engineering and Computer Science. F. Curtis Michel (1934-2015) was selected by NASA as a candidate in 1965 for the Apollo missions into space. He resigned from NASA in 1969 to return to teaching at Rice University once he discovered he would not be assigned to a mission. His time at NASA was sandwiched between years spent teaching at Rice University, where he retired in 2000 after 37 cumulative years. Residue of a removed label at lower right over which they signed. Fine condition.