(covers information from several alternate timelines)
In an alternate timeline, Chakotay discovered on Annorax's Krenim weapon ship in 2374 that eight months earlier, component 37329 caused Voyager to set a course so the ship would avoid it completely, which led to them entering Krenim space. Chakotay suggested that Annorax remove the comet from the timeline, so Voyager would not encounter the Krenim Imperium and be severely damaged by their ships.
This was because four billion years earlier, fragments of the comet impacted a planet, and Hydrocarbons from those fragments gave rise to several species of plant life, which in turn sustained more complex organisms, and eventually several space-faring civilizations which colonized the entire sector. (VOY: "Year of Hell, Part II")