This item is an Space Shuttle STS-4 postal cover featuring the signatures of the two crew on the flight - Ken Mattingly and Henry Hartsfield. This was the last of the four Space Shuttle test flights.
Mattingly (1936–2023) flew around the Moon as Command Module Pilot on Apollo16, having been bumped from the Apollo 13 mission as he was exposed to German measles shortly before the flight. He later commanded the STS-51-C Space Shuttle mission in 1985.
Hartsfield (1933-2014) later commanded the STS-41-D and STS-61-A Space Shuttle missions in 1984 and 1985 respectively.
All of the space covers I am selling were sold to me as signed in person by the astronauts - they are not printed autographs or autopens.
Please see my other signed space and military covers for sale. Note that postage costs are set by eBay.