Space Cover 878: Astronaut Richard H. Truly: A TributeNASA astronaut Richard H. Truly began his distinguished career as a Naval aviator. He later became an instructor at Edwards Air Force Base and in 1965 was selected as one of the 17 pilots in the Manned Orbiting Laboratory program (MOL). After its cancelation, in 1969 he was selected as one of the seven NASA Group 7 astronauts from the canceled MOL program.
Above is a cover for a MOL-related test flight, with the cover below signed by Truly and the six other NASA Astronauts of Group 7 who were selected from the 17-pilot MOL program.

Truly was one of the four astronaut pilots in the Shuttle Approach and Landing Test program at Edwards. He and Joe Engle piloted Enterprise on two Active Captive flights and two free flights, then later he and Engle flew together on STS-2.

Truly served as the PLT on STS-2, the second Space Shuttle mission, and was the CDR of STS-8, the first Shuttle night launch. Both of these covers were signed by Truly in person in 1985 at Robbins AFB, on the occasion of his induction into the Georgia Aviation Hall of Fame.
Truly retired from the US Navy as a Vice Admiral and at the apex of his career, became the 8th NASA Administrator. He passed away in 2024 at the age of 86.

This STS-8 flown cover is missing something that only ten of the 260,000 other STS-8 flown covers do have:
And that's Dr. William Thornton's autograph.
Dr. Thornton was generally good about autographing and autographed other non-flown STS-8 covers, but it's established that he added his autograph to only ten flown covers. These 10 were officially done with one given to each STS-8 crew member and one each to five dignitaries, including the NASA Administrator and US President Ronald Reagan.
This flown cover was signed by the other four members of STS-8. There's no estimate on how many of the flown covers have autographs of 4 of the 5 crew members, but they may be considered scarce - and frustratingly incomplete to Space Shuttle crew signed cover collectors.
The STS-8 flown cover saga has been covered well here, including SCOTW #423 of June 25, 2017.
Of significance, RR Auction has the "William E. Thornton's Space Collection" now active, with his STS-8 flown cover offered in lot 6430 with the bid on October 18 at $5,395 and closing on Oct. 22.