Living organisms change after being sent to space. Bacteria is no exception. Astronaut Cheryl Nickerson brought salmonella up into space and kept it for eleven days. Upon its return to Earth, researchers quickly infected mice with the salmonella to see how they would react. Normally, mice infected would die in seven days, but the ones infected with the space salmonella died two days earlier and from lower doses. Similar experiments have been done to other bacteria, but results have been unpredictable and inconclusive; there’s really no telling how these microorganisms will change and what impact that change could have upon returning to Earth.