Signs of life on Earth can show us what to look for on Mars and other planets, and we have covered topics along these lines. Researchers at the University of Kansas note that their recent learnings about rocks in Colorado, Utah and Wyoming can serve as guides for questions we should ask in our research for life in space. The team recently published a paper in the journal Astrobiology about their study.

The study took place in the Green River Formation, a system of lakes located in the three western states. There, the researchers found rocks that indicate the presence of life-- and they think that Mars probes should look for similar indicators on the red planet, and later conduct chemical analysis on the specimens, according to a release.

"Once something is launched into space, it becomes much harder to do tweaks - not impossible, but much, much harder," Alison Olcott-Marshall at the University of Kansas said in the release. "Scientists are still debating the results of some of the life-detection experiments that flew to Mars on the Viking Missions in the late '70s, in a large part because of how the experiments were designed. Looking at Earth-based analogs lets us get some of these bumps smoothed out here on Earth, when we can revise, replicate and re-run experiments easily."

In the western study, the team looked at cored rock samples from 50 million years ago, including "microbial mats." These are layers of microbes, each with a different form of metabolism, noted Olcott-Marshall in the release. "Generally, the photosynthetic microbes are at the top, and then every successive layer makes use of the waste products of the level above. Thus, not only does a microbial mat contain a great deal of biology, but a great number of chemicals, pigments and metabolic products are made, which means lots of potential biosignatures."

The Green River Formation has many preserved bits of microbial mats, and such structures are one way to detect life on Mars, noted Olcott-Marshall in the release.