Apollo 9

Following the collossal gamble and achievement that was Apollo 8, NASA went back to checking the boxes: "The primary objective of Apollo 9 was an Earth-orbital engineering test of the first crewed lunar module, or LM. Other prime objectives included an overall checkout of launch vehicle and spacecraft systems, the crew, and procedures." — NASA.gov Starting on March 3rd, 1969, everything went more-or-less to plan. And that's part of why you don't remember much about it. Jim McDivitt (Gemini 4 veteran — yes, he commanded the mission with Ed White's first-American-spacewalk), Dave Scott (Gemini 8 veteran — yes, the one where he and Neil Armstrong spun out while attached to the Agena and nearly died — Scott would go on to command Apollo 15), and Rusty Schweickart (rookie, this was his only spaceflight) flew "as successful a flight as any of us could ever wish for, as well as being as successful as any of us have ever seen." — George Mueller, associate NASA administrator.

Jayne and I came in August of 2023 to the San Diego Air & Space Museum to see Apollo 9's "Gumdrop" command module. It was only the second crewed mission to use the Saturn V launch vehicle, but also "only" went to low/medium Earth orbit. The third-stage S-IV-b rocket was used to propel itself into heliocentric (solar) orbit where it remains to this day, but the LM-CSM spacecraft stayed closer to Earth. I assume its lower speed in LEO and at re-entry explains why so much of the silver Kapton foil seems to have survived compared to the moon-bound capsules I've seen.

Anyway, she's a beautiful ship in an accessible display surrounded by a first-class museum. Go check Gumdrop out when you can.