GRAVITY by Tess Gerritsen

Emma Watson, a brilliant research physician, has been training for the mission of a lifetime: to study living organisms in the microgravity of space.  But the true and lethal nature of this experiment has not been revealed to NASA, and once aboard the space station things begin to go terribly wrong.  A culture of single-celled Archaeons, gathered from the deep sea, begins to rapidly multiply and infect the crew - with agonizing and deadly results.

As her estranged husband and the ground crew at NASA work against the clock to launch a rescue, Emma struggles to contain the lethal microbe.  But with the contagion threatening Earth's population, there are those who would leave the astronauts stranded in orbit, quarantined aboard the station - where they are dying one by one...

Soft cover, fairly good condition.  The spine has a bit of damage.  342 pages.