Summer of 2037 sees America and China vying to land the first humans on Mars. But China intends to be the only human presence on Mars. Midway to Mars, the Chinese ship Ming-Xi fires on America's Aurora. Aurora is damaged, but Rae Anne Chavez, with her two crew-mates and Jason, the ship's computer AI persona, repair it at the cost of the ship's commander's life. Rae Anne convinces the Space Agency to allow her and Rob Harris to continue the Mars-II mission. But Rob dies suddenly when a DVT blood clot hits his heart. The Agency scrubs the mission.
With Jason her only companion, Rae Anne looks into diverting Aurora to Saturn. (Earth, Mars, Jupiter and Saturn in 2037 are in ideal planetary alignment.) She determines she has just enough fuel and provisions for a one-way five-year trip to Saturn. Realizing this may be the only opportunity for human exploration of Saturn's moon, Titan, she decides that this trip is worth the sacrifice of her life.
Meanwhile, the Chinese reach Mars, but their lander explodes, leaving two taikonauts stranded in Mars orbit and abandoned by the Chinese space agency.
Rae Anne launches to Saturn, but the Agency, under military control, cannot condone a hijacking and declares Aurora "lost in space" and ceases all communication with Aurora.
During the next five years, Aurora is engulfed in a coronal mass ejection (CME), breached by a small meteorite, and forced to alter course and extend the mission another three months. Through it all, Rae Anne maintains her astronomy research, sending discoveries back to Earth, hoping someone is listening. She directs her computer skills to reprogramming Jason to create a more human-responsive computer interface.
Meantime, Odysseus, America's Mars-III mission, leaves Earth with Ian Bentley in command. Ian establishes communication with Rae Anne from Odysseus, making her an ex-officio member of his crew. It is Ian's "heads-up" that saves Rae Anne's life during the CME event. Rae Anne's contributions to his Mars mission prove crucial to that mission's success.
One task for Odysseus is to locate the Chinese module still in orbit to find evidence of missile launchers used in the attack on Aurora. They discover and rescue the lone Chinese survivor. Her story of abuse from her male crew mate creates a bond with the Odysseus crew.
When Odysseus returns to Earth, Rae Anne's contact with humans is again cut off until she discovers the long sought "Planet X" beyond the Kuiper Belt. Astronomers who have been following Rae Anne all along broadcast this discovery world-wide, making her an instant celebrity. The Agency is forced to admit their duplicity and reestablish communications with Rae Anne.
When Rae Anne reaches Saturn and takes the lander to Titan's surface, she discovers unique phenomena, such as methane lakes with huge ammonia geysers, grotesque methane-water clathrate formations, and a lake warmed from radioactive minerals that harbors microscopic life. At all three landing sites, the terrifyingly hostile environment nearly kills her. On two of these occasions, Jason exhibits a near-human capacity for abstract reasoning to save her, demonstrating sentience.
On her return to Aurora, Rae Anne packs her samples aboard the lander, refuels it with the remaining fuel on Aurora, and launches it to Earth with a radio beacon, hoping that years hence, someone might intercept it and distribute her samples among interested laboratories on Earth. Rae Anne awaits her impending demise as Aurora's decaying orbit will soon plunge her into Saturn's atmosphere.
(In Saturn Rendezvous, Book Two of The Saturn Accords, an alien battle cruiser patrolling the Kuiper Belt rescues Rae Anne and her story resumes.)
