Astronauts face many challenges to their health, due to the exceptional conditions of spaceflight. Among these are a variety of infectious microbes that can attack their suppressed immune systems.

Now, in the first study of its kind, Cheryl Nickerson, lead author Jennifer Barrila and their colleagues describe the infection of human cells by the intestinal pathogen Salmonella Typhimurium during spaceflight. They show how the microgravity environment of spaceflight changes the molecular profile of human intestinal cells and how these expression patterns are further changed in response to infection. In another first, the researchers were also able to detect molecular changes in the bacterial pathogen while inside the infected host cells.

mprovising new stuff from the stuff you have is part of an astronaut's job description—think Apollo 13's crew refitting CO₂ filters to save their own lives, or stranded Mark Watney in The Martian, feeding himself on the Red Planet. Now plans are underway to manufacture items in orbit, and ESA astronaut Alexander Gerst argues this could make a big difference to living and working in space.

Alexander—who has spent just under a year in orbit, becoming the second European to command the International Space Station (ISS) – spoke at ESA's Workshop on Advanced Manufacturing, which included a special session on out-of-Earth manufacturing.

While plastic-producing 3D printers have already reached space, the virtual event heard how ESA will fly the first metal 3D printer in 2022, and researchers are also planning large-scale manufacturing such as spacecraft printing their own antennas or solar arrays after launch.

A new study that characterizes the climate of Mars over the planet's lifetime reveals that in its earliest history it was periodically warmed due to the input of greenhouse gases derived from volcanism and meteorites, yet remained relatively cold in the intervening periods, thus providing opportunities and challenges for any microbial life form that may have been emerging on the Red Planet. The study involved a national team of scientists that included Joel Hurowitz, Ph.D., of Stony Brook University. The findings are detailed in a paper published in Nature Geoscience.