Holger Kurtz, Custodian of the starship Jolene, became interested in the Battle of Borodino, the name of which he found striking. This led him to Tolstoy's War and Peace, and he decided in due course to learn Russian so he could read it in the original language (or languages, since some of the dialogue in the original was in French, which Kurtz already understood). Having quickly mastered the Cyrillic alphabet, Kurtz was working on vocabulary and grammar when his daily inspection of the Jolene's instruments brought the rock to his attention.
The rock was about the same size and shape as Manhattan, and although its official name (as per established protocols) was Jolene 140622, that's how Kurtz thought of it. Manhattan was no threat to Jolene herself; it was far outside the ship's relativistic frame of reference, and would approach no closer than 6000 astronomical units. It was an unusual object nevertheless. It was a lot bigger than your typical chunk of interstellar debris, and it was traveling at nearly two thirds lightspeed. A data search showed that Manhattan was the largest natural object ever found to be moving at such a speed. There was a distinct possibility that at some point a scientific expedition would be organized to study it, and Kurtz, who took a proprietary pride in Jolene, was pleased that the ship would be immortalized in this way. Kurtz plotted the rock's projected course through space, and that's when the trouble began.
In about four years' objective time, Manhattan would pass through the heart of the Calypso system, and there was a seventeen percent chance that it would impact with Calypso III, last reported human population thirty-three million. Something, Kurtz knew, would have to be done about Manhattan, and Jolene was in the right time and place to do it.
Of course, Kurtz knew with a sinking feeling, it would mean bringing one or more members of Jolene's crew out of Shimizu.