Virus

Virus is a short story from The Path to Ascension, first book in the Course Books series. It centers around a planet on which nearly every living thing has been wiped out by a genetically-engineered virus which then infects some of the Saratoga's crew. After some deliberation, and finding a loan survivor to fill them in on the details, the Saratoga crew settles on time travel to solve the problem.

This story is the first incidence of time travel in the series, but not the first chronologically.