A world-first study has revealed how space travel can cause lower red blood cell counts, known as space anemia. Analysis of 14 astronauts showed their bodies destroyed 54 percent more red blood cells in space than they normally would on Earth, according to a study published in Nature Medicine.

"Space anemia has consistently been reported when astronauts returned to Earth since the first space missions, but we didn't know why," said lead author Dr. Guy Trudel, a rehabilitation physician and researcher at The Ottawa Hospital and professor at the University of Ottawa. "Our study shows that upon arriving in space, more red blood cells are destroyed, and this continues for the entire duration of the astronaut's mission."

Before this study, space anemia was thought to be a quick adaptation to fluids shifting into the astronaut's upper body when they first arrived in space.

NASA's Curiosity rover landed on Mars in August 2012, and its investigations revealed that Mars was once a potentially habitable planet. One of Curiosity's most exciting observations has been periodic, unusually high abundances of methane in Mars's atmosphere. Over the past seven years, Curiosity has established a background signal of methane of about 0.41 part per billion by volume (ppbv), and these periodic spikes can increase atmospheric methane to as much as 21 ppbv.

Luo et al. note that these methane spikes could "have profound implications for geology and astrobiology." On Earth, almost all methane emissions have biological origins, from cow flatulence to the decay of plant material.