Question: What was the point of temporarily shutting down every electrical system in the command module?
Question: Why couldn't the crew put on their spacesuits, then go out and assess the damage?
Answer: That would involve depressurizing the command module and LEM. Given that a substantial percentage of their on-board O2 supply just got vented into space, wasting more at that point to only confirm what they already knew wasn't worth the trouble.
Answer: Even if they could go out and assess the damage, they didn't have the tools, materials, or knowledge to actually be able to fix it.
Question: Since it was so cold on the return journey to Earth, why didn't the astronauts wear their full space suits they wore on lift-off to keep warm? The just seem to be wearing their lightweight flight overalls.
Answer: Because they need to be able to move quickly through the confined space of the module, and the full suits would be far too bulky in an emergency.
The older Apollo missions all splashed down with full suits and helmet on. Just the launch suits, not the much bulkier EVA (moon walk) suits.
Answer: According to Jim Lovell in a later interview about the mission, the crew considered putting on their space suits but in addition to them being too bulky, there was concern the suits would make them perspire too much, thus making them wet and even colder. It wasn't quite as cold as depicted in the movie, it was always above freezing, and there were no icy windows or frozen hot dogs.
According to Lovell in his book, there actually were frozen hot dogs.
Answer: In addition, since they have to leave the ship after landing, the suit filling with water would be very dangerous.
The launch abort mode was for an ocean landing, so they would have been just as vulnerable at the start of the mission. I get your line of thinking though.
Answer: Don't remember the source (the actual movie or one of many books) but I do remember there were only two moon suits on board (the CMP, Swigert, doesn't land on the moon). I believe they decided to suffer together. I misread the question, but the option for wearing the Lunar EVA suits was considered. IIRC, they did actually wear the boots at one point.
Question: What did Houston mean by they need Omni bravo?
Answer: The Apollo spacecraft had 4 omni-directional control antennas, designated A, B, C, and D. "Omni Bravo" was the B antenna. When Mission Control in Houston said they needed Omni Bravo, it meant they wanted Apollo 13 to try to activate the B antenna.
What were Omni-directional control antennas?
Omni Directional Control Antennas were capable of sending and receiving signals from any direction. The Apollo 13 spacecraft had 4 redundant antennas of this type, which allowed Mission Control in Houston to remotely control certain systems when necessary.
Answer: Omni directional antennas can broadcast in any direction at once, as opposed to one that can only broadcast to a particular spot.
Answer: To save the re-entry batteries.
David George