(A/N: Just a brief scene I'd have liked to see amongst the goodbyes in End of Time. Hey, if Joan got one...)
The visit only occurs to him midflight, and he doesn't have time to consider it once it's in his head. More than ever time is slipping as sand between his fingers, and he simply acts, mentally apologising to the TARDIS as she protests at the sharp alterations he makes to her path through the vortex.
The launch of Earth's first lightspeed ship is a triumphant one, full of the best kind of pomp and circumstance.
Susie Brooke, he can see from afar in the corner that all parties reserve for someone collecting their courage for whatever reason, is the centre of this. She bears it with all the grace that could be asked for and more, and he supposes it's only his own knowledge of the history of today that alters his own view of how she seems... melancholy. He brushes a twinge off as radiation.
When the Doctor finally gathers himself and goes to shake her hand, for once in his life, he doesn't allow himself the indulgence of an apology. Nor does he allow himself to look away from the consequences he can see in her eyes, still slightly reflecting of the sadness in time's ripples even now.