Virginia-based DARPA is trying to develop a technological toolkit by genetically engineering a wide range of organisms. This toolkit will have abilities to transform hostile places like Mars by recreating conditions needed for life to thrive. The goal would be to thicken the Martian atmosphere by designing organisms that would pull some specific gases out of the Mars atmosphere and release some other gases, for instance taking in carbon dioxide and releasing oxygen and nitrogen. 

Using this technological toolkit, DARPA wants to grow bacteria, photosynthesizing plants, and algae on Martian surface. 

"For the first time, we have the technological toolkit to transform not just hostile places here on Earth, but to go into space not just to visit, but to stay." Alicia Jackson, the deputy director of Darpa's Biological Technologies Office in Virginia was quoted as saying by Motherboard.