By Dean Murray
Astronauts are to search for life in space - clinging to the International Space Station.
NASA crew will swab the exterior of the orbital outpost next week to collect microbiological samples surviving in the vacuum of space.
The External Microorganisms experiment could help researchers understand how so-called extremophiles - organisms able to live in extreme environments - may affect human life on Mars and the Moon.
Station Commander Suni Williams and Flight Engineer Butch Wilmore are scheduled to spacewalk on 30 January.
Their investigation will focus on sampling at sites near life support system vents to examine whether the spacecraft releases microorganisms, how many, and how far they may travel.
NASA says spacecraft and spacesuits are thoroughly sterilized before missions, however, humans carry their own microbiomes and continuously regenerate microbial communities.
The space agency said: "It's important to understand and address how well current designs and processes prevent or limit the spread of human contamination.
"The data could help determine whether changes are needed to crewed spacecraft, including spacesuits, that are used to explore destinations where life may exist now or in the past."
NASA added that the study of extremophiles is also of interest to industries on Earth such as pharmaceuticals and agriculture.