A significant part of the Perseverance rover's mission is to search for signs of ancient life on Mars. Since February 2021, the rover has been exploring the remnants of an ancient river delta inside the Jezero Crater. And recently, NASA announced the rover had discovered diverse organic matter on Mars.

The Perseverance rover is an unmanned vehicle whose mission is to survey the red planet, characterize the planet's geology and past climate, pave the way for human exploration and be the first to collect and cache Martian rock and regolith (broken rock and dust). A key objective for Perseverance's mission on Mars is astrobiology, including the search for signs of ancient microbial life.

The mission scientists chose the Jezero Crater because it is the site of an ancient lake basin that they suspected had a high potential for past habitability. They also knew that the crater floor possessed clays and other minerals that can preserve organic materials.

Organic Matter on Mars

According to Space.com, organic compounds are molecules composed of carbon and often include other elements, such as hydrogen, oxygen, nitrogen, phosphorus and sulfur. These organic carbon-based molecules are considered to be the building blocks of life.

Scientists had previously detected several types of organic molecules of Martian origin that were blasted off Mars thousands or even millions of years ago and then made their way to the surface of Earth as meteorites. But the Perseverance rover has been looking for this type of organic material on Mars itself. Since early July 2022, the Perseverance rover has been collecting rock samples from the ancient river delta formation. Each of the samples was drilled out of rocks that show this part of Mars likely could have supported Earth-like organisms in the ancient past and might still preserve signs of such microbial life.

Scientists examined the rock samples using one of the Perseverance rover's instruments called the Scanning Habitable Environments with Raman and Luminescence for Organics and Chemicals (SHERLOC). SHERLOC utilizes a technique that looks at the chemical makeup of rocks by analyzing how they scatter light. The instrument directs an ultraviolet laser at its target, which then allows scientists to classify organics and minerals present in a rock based on the distinctive spectral "fingerprint" of different molecules. Salty water, for example, can result in the formation of different minerals than fresh water.

The Building Blocks of Life on the Martian Surface

Out of 10 sites within the crater that the rover explored, all 10 came back with signs of organic molecules. These organic compounds mostly appeared connected to minerals linked to water. This type of organic matter on Mars points to the possibility that the building blocks of life could have been present on the surface of the red planet for a long time.

Additionally, researchers discovered evidence of many different classes of organic molecules. This suggests that the organic molecules might have originated from several minerals and mechanisms of formation.

Organic matter can be produced by geological processes as well as biological ones, so scientists have posited a few explanations for the existence of organic matter on Mars. One possibility is that the materials could have formed when water and dust interacted or were dropped onto the planet by dust or meteors. But the study's authors wouldn't rule out the possibility that the organic matter on Mars may be biotic, which means it came about due to the existence of life on the surface of Mars.

Even if the materials are not biological in origin, though, research into them could be crucial in the search for alien life. The organic matter on Mars can tell us more about the existence of carbon sources, and this could change our understanding of the red planet and the search for life in the universe.

This part of the Perseverance rover's mission represents the first step of the Mars Sample Return campaign, a joint effort by NASA and the European Space Agency that seeks to bring scientifically selected samples back from Mars to be studied on Earth to confirm the presence of organics. Subsequent missions would send spacecraft to Mars to collect these sealed samples from the surface and return them to Earth for in-depth analysis with lab equipment far more complex than could be sent to the red planet.