Crucial evidence about life on Mars is stuck ... on Mars

The recent announcement that scientists have spotted what they believe to be evidence suggesting ancient life on Mars seemed like the latest in an endless cycle of tantalising hints followed by pleas for more funding. What will it take for them to declare something definitive? This time, the SUV-sized Perseverance Rover detected minerals called vivianite and greigite, which typically form in marshes, lake bottoms, or hydrothermal sediments — environments where microbes thrive.

- F.D. Flam, Tribune News Service

Here on Earth, microbes play a role in their formation by altering the chemical forms of iron and sulfur. A NASA team concluded that life is the most likely explanation for these minerals’ presence on Mars.

Scientists already have several lines of evidence suggesting life may have arisen on Mars. Raising the probability is intriguing but won't fundamentally alter our understanding of the universe. What would? Actually finding remnants of alien life and using them to understand how it functioned. Martian life might consist of different building blocks and use something other than DNA or RNA to store and copy information.

Because all earthly life shares a common origin, finding a second tree of life would forever change humanity's understanding of ourselves. It would help guide our search for life elsewhere in the solar system and on the many seemingly habitable planets astronomers have discovered orbiting other stars across the galaxy.