52 years ago today was Gus Grissom's flight in Liberty Bell 7 for the Mercury-Redstone 4 mission.

It was the second US manned suborbital flight. It was also the first with a large view window for the pilot (a specific request of the Mercury astronauts) and an explosive hatch release that would cause controversy after Grissom's splashdown.

I believe this weekend marks some other space achievement as well but I can't think of what it might be ;)