Spock refused to list the captain as a casualty. The furthest he was willing to go in his reports was 'missing in action'.
At first Uhura took hope from the wording, but as days stretched into weeks and weeks became months she had mixed feelings any time she read the phrase. Sometimes it reminded her that Scotty and the engineering team came closer to finding a way to track the mysterious ship every day. Other times she thought it tasted of denial--that Kirk was simply gone and they were never going to find him, but no one, not even Spock, could accept that.
Despair ate at all of them, making the crew quieter and suffusing the mood of the ship with a dull ache. They all had their coping mechanisms (Gaila threw herself into her work so completely it was a wonder she hadn't collapsed yet), and Uhura worried these would become new norms if (when) they admitted he was not coming back. They might never admit that, though, because fighting against despair was the unrealistic conviction that it wasn't supposed to be like this; they weren't supposed to lose their captain only a year out, and he certainly wasn't supposed to just up and vanish.
In her more practical moments, she recognized there was no 'supposed to' on a deep-space exploration mission. They knew so little about the further reaches of the Galaxy that everything was game and anything was possible. Even, it turned out, your captain disappearing after a shuttle accident in an asteroid field.
She rubbed her eyes and adjusted the subspace array again, inputting the new frequencies Sulu and Chekov had helped her work out. While the long range sensors hunted the faint warp signature gleaned from the now-dead shuttle's logs, Uhura sifted through the noise of space, listening for a voice in the wilderness that might bring her one step closer to finding him.