Tomorrow, at precisely one minute before midnight, Eastern Daylight Time, three crew members will be back on Earth from the International Space Station. Their Soyuz capsule will plop down in Kazakhstan, where it will be mid-morning. NASA's Kate Rubins, Anatoly Ivanishin of the Russian space agency Roscosmos, and Takuya Onishi of the Japan Aerospace Exploration Agency will take their first breath of fresh air in 115 days.

Back in August, Rubins, who is formally Dr. Rubins, the holder of a Ph.D. in cancer biology from Stanford University, became the first person ever to sequence DNA in space. She has been an astronaut since 2009, but didn't necessarily set out with that job in mind—instead, she has simply followed her scientific interests, building an impressive resume along the way.

"I have not particularly tried to go in any direction in my career," she said from orbit recently, speaking with Francis Collins, the director of the National Institutes of Health. "I actually applied to become an astronaut while procrastinating a little bit on writing an R01 grant application."

Given her background in molecular biology, NASA tasked Rubins with handling the DNA sequencing experiment. The agency believes the technology has a variety of applications, but the first step was just seeing if it would be possible at all.

"We did not know if it was going to work," Rubins said. "Like every lab experiment, you put your pipettor down, and give it a try."