The whole time I was reading PHM I kept staring at the cover wondering which scene it was representing (and fearing that Grace's tether would break), and I think it could represent any of the EVA scenes, but my personal belief is that it's meant to be the climax where Grace launches himself from the Hail Mary towards the Blip-A as a last desperate attempt to reach Rocky and save him.
Which is, in itself, what would be called a "Hail Mary".












