I’ve heard that before a launch American astronauts had one last chance to see their family by waving across a ditch (which apparently wasn’t really a ditch?). I’m curious, where and exactly when (day before, day of launch) did this take place?
For the Space Shuttle, it took place at the launchpad, one day before the launch.
Mark Kelly described it in his book about his wife:
When Dan was finished, buses were waiting to take our family members several miles away to the launchpad, where my crew and | would show up to meet them. It’s another NASA tradition—the extended family farewell.
Everyone stood behind a rope line, facing the launchpad. On my earlier flights, we stood with a ditch separating the crew from the guests, so the ritual came to be called “the wave across the ditch.” This time, the six of us drove up in our convertibles, got out, and stood together on the other side of the rope. Because we were still in quarantine, we couldn’t get too close to anyone. I always feel like a circus animal as everyone takes photos at the wave across the ditch.
Because the crew's wives had been given physicals and deemed healthy, they were allowed to join us for photos. Gabby had been in these photos during my past missions, but since she was still not up to being seen publicly, she wasn’t there for this one. So it was just me, my five crew members, and their five wives. We were all lined up and everyone was clicking away.I| smiled through it, but I was thinking of how the sixth wife belonged in those photos.
Twice in the history of the shuttle program—the final launches of Challenger and Columbia—the wave across the ditch was the last time astronauts’ loved ones saw them alive. Everyone on both sides of the rope—astronauts, wives, siblings, cousins, parents—was aware of that.
(a page or so earlier, he states it's the day before the launch)