International Space Station

This is the actual NASA graphic illustrating the "Space Poop Challenge." NASA hide caption

NASA astronaut Shane Kimbrough shows a pouch of turkey he will be preparing for his crew in celebration of the Thanksgiving holiday, aboard the International Space Station. AP hide caption

U.S. astronaut Peggy Whitson gestures before the launch of the Soyuz MS-03 spaceship to the International Space Station on Thursday. Dmitri Lovetsky/AP hide caption

The Soyuz MS-01 spacecraft as it lands with NASA astronaut Kate Rubins, Russian cosmonaut Anatoly Ivanishin and astronaut Takuya Onishi of the Japan Aerospace Exploration Agency on Sunday. Bill Ingalls/NASA hide caption

The Cygnus resupply craft slowly approaches the International Space Station — and its waiting robotic arm, the Canadarm2 — Sunday morning. NASA TV hide caption

Astronaut Kate Rubins and Expedition 48 Cmdr. Jeff Williams speak during an interview aboard the International Space Station last month. NASA via AP hide caption

The SpaceX Falcon 9 and Dragon spacecraft lift off on the CRS-9 mission to bring a new docking adapter and other cargo to the International Space Station. Frank Michaux/NASA hide caption

An artist's concept shows the Bigelow Expandable Activity Module, or BEAM, as it would look when fully installed and inflated on the International Space Station. Bigelow Aerospace/NASA hide caption

Runners make their way across Tower Bridge during the Virgin Money London Marathon on Saturday in London. Ben Hoskins/Getty Images hide caption

The SpaceX Falcon 9 rocket lifts off from launch complex 40 at the Kennedy Space Center in Cape Canaveral, Fla., on Friday. John Raoux/AP hide caption