Retrograde /
(Book)

Venturing into space and traveling to Mars sounds like an exotic adventure, but the reality of living on a rocky, frozen, lifeless planet is exacting on the Mars Endeavour crew. The only viable option for long-term habitation lies hundreds of feet beneath the surface, in lava caves that shield humans from harsh cosmic radiation. Connor, Harrison, and Liz are senior members of the U.S. module.When war breaks out on Earth and rumors spread to Mars, their core principles are rocked by the devastation and loss of friends and family. Whom can you trust on an international mission when your countries are at war? As colonists from different nations struggle to figure out  what really happened on Earth, grief and anger become pitted against camaraderie and the spirit of exploration.