Yeah, but...
The anniversary year does not end in a 5 or 0, so it doesn't count for this year. :^)
Cause if we did do every space anniversary, then I could mention Gus Grissom's
Mercury-Redstone 4 (Liberty Bell 7) suborbital flight on July 21, 1961.
Or the fact that Zond 3 flew by the Moon on July 20, 1965 and took the first images
of the lunar farside since Luna 3 in October of 1959 (now there's an upcoming anniversary that meets the criteria).
Or that Mariner 4 already flew by Mars on July 14, 1965 and disappointed a lot of
people about what they thought the Red Planet was like.