The Inner Ring (gxg)

The year is 2050, and humanity is moving beyond earth. While the Mars colony is all the rage, having been founded almost ten years ago, things are going to change rapidly when unassuming photo analyst Pepper Simmons makes a startling discovery while reviewing photos sent back from a probe orbiting Uranus. A hasty mission is planned to capitalize on the discovery before anyone else, but can the crew survive together for a 10 year mission? Love, anger, jealousy, anything is possible in deep space.

If you're looking for more gxg books, there are several here on this profile, so by all means go check out:
A Rock and a Heart Place (Mature)
Full Circle (Not Mature)
To Those Who Wait (Mature)
Dead Men's Bells (Mature)