Space Master

‘Space Master’ covers were made by Robert Rank. I’d be interested to know if there are more designs than those shown below. ‘Space Master’ covers seem to have been a short-lived series issued between 1976-1978. They are typically hand-cancelled rather than machine-cancelled. All have ‘Certified Mail’ stickers, and most are numbered on the back (see scans below). I’m guessing these were more expensive to buy than regular ‘Space Voyage’ covers at the time. Can anyone share some information about these ?

Space Master A – Palapa 1 – 8th Jul 1976:


Space Master # 1 – Viking 1 Lands – 20th Jul 1976:


Space Master # 2 – Viking 2 Landing – 3rd Sep 1976 (i’m missing this cover, but an example is shown below):


Space Master # 3 – OV101 Shuttle Rollout – 17th Sep 1976:


Space Master # 4 – Shuttle Training Aircraft – 27th Oct 1976:


Space Master # 5 – First Captive Inert Unmanned Flight of Shuttle Enterprise – 18th Feb 1977:


Space Master # 6 – First Manned 747 / Captive Shuttle Flight – 18th Jun 1977:


Space Master # 7 – First Shuttle Free Flight and Landing – 12th Aug 1977:


Space Master # 8 – Voyager 2 Launch – 20th Aug 1977:


Space Master # 9 – Voyager 1 Launch – 5th Sep 1977:


Space Master # 10 – Pioneer Venus 1 Orbiter – 20th May 1978:


Space Master # 11 – Pioneer Venus 2 Multiprobe Spacecraft – 8th Aug 1978: