NASA Curiosity Finds Organic Carbon on Mars That May Be From Ancient Life

The authors emphasise that they have been unable to identify the source of the organic carbon, but they cannot completely rule out a biological origin.

Studies investigating the history of life on other planets have long focused on Mars. 

. It is a frigid, empty globe without much atmosphere now, but billions of years ago it was considerably warmer

had an atmosphere that was thicker and more like Earth's

rippling with rivers and ponds that would have provided a habitat for microbial life.

Cosmic winds are assumed to have degraded Mars

atmosphere and water about 3.7 billion years ago since the planet lacks a strong magnetic field.