TL;DR
After being jettisoned, the Service Module remained dangerously close to the Command Module during re-entry, so there was a risk that the two could have collided
After being jettisoned, the Service Module remained dangerously close to the Command Module during re-entry, so there was a risk that the two could have collided
I’m not sure that the whole command/service module separation issue was actually classified, or if it is just a less commonly known part of the story.
Conclusion
Tip-off moments applied to the service module at jettison cause the spin vector to be misaligned with the service module X-axis. The rigid body spin motion of the service module excites longitudinal slosh of the propellants in tanks. The sloshing then becomes the dominant force and causes the spin vector to approach a position normal to the service module X-axis. The sloshing can orient the service module spin axis such that the net -X thrusting over a period of 300 seconds can not only reduce the separation velocity of the service module but also reverse its direction. This condition introduces a remote possibility of recontact between the service modules and command module. An optimum separation velocity can be obtained for a range of propellant loads by restricting the spin thrusting to 2 seconds and the X-axis thrusting to 25 seconds of firing time.
It doesn't reveal how they kept the astronauts' comments looking out the window secret. Weren't they broadcast live?
It seems like the fact of the SM and its fragments not falling behind must mean something important about hypersonic flight.
The plasma buildup around the vehicle interferes with radio communication -- though I'm not sure in exactly which phases of the reentry.
Or maybe the window orientation made that hard to see?
Nope. Communications were split into multiple channels, all of which were monitored at the PAO, or Public Affairs Office console in mission control by a NASA official. It was deliberately designed so that the public only heard what NASA wanted them to hear.