Despite the climate we see on Mars today, scientists now agree it was warmer and wetter 3.5 to 4.1 billion years ago, during the Noachian and Hesperian eras. Evidence of this first emerged with the first robotic probes to explore Mars, but became undeniable with the arrival of landers and surface rovers, i.e., Viking 1 and 2 , Curiosity , and Perseverance . This has raised the question of whether Mars could have hosted life during this period, most likely in the form of microbial organisms.

Hoping to shed light on this, a research team led by scientists from the Institute of Science Tokyo created a global map showing where ancient rains may have delivered an important prebiotic molecule, formaldehyde (H₂CO), across the planet billions of years ago. This map could help guide future astrobiology efforts on Mars by directing robotic and crewed missions to sites where evidence of past life could still be preserved.

The research was led by Dr.…