Co-Investigator, SETI Institute
For over a decade, planetary geologist Nathalie Cabrol and her husband, Edmond Grin, made the case to land one of NASA’s Exploration Rovers near Gusev crater. Eventually, they convinced their colleagues to choose this site over 184 other candidate landing sites. For years Cabrol and Grin had to study Gusev crater from afar, using information gleaned from earlier missions to Mars. But in January 2004, their dream came true as the Spirit rover safely landed within the crater, providing an on-the-ground proxy they could guide from mission control on Earth. In the following weeks, the rover team announced evidence that water had flowed freely on ancient Mars, confirming the earlier hopes of Cabrol and Grin.
Now that it looks even more likely that Mars was a good habitat for life, they are leading the field work on Earth that will help future missions to Mars with their search for life. “As a geologist and a hydrologist, I have spent many, many years exploring our own planet,” explains Grin. “Today I am applying my experience about terrestrial hydrology to the study of the surface of Mars, where past water activity has left so many messages in the landscapes for the planetary geologists to decipher.”
By studying the images taken with the panoramic cameras onboard the rovers, Cabrol and Grin also get a snapshot of what Earth may have looked like in its infancy. Unlike Mars, the surface of the Earth is constantly transforming, obliterating records of our home world’s earliest geology. Consequently, we have no record of organisms that may have lived prior to Earth’s oldest existing rocks, 3.9 billion years ago.
In contrast to the ever-changing Earth, Mars is a relatively stable planet, with little or no tectonic activity to shuffle its geological layers. As a result, the surface of Mars presents a geologist’s dream, with very old rocks ready to be examined close up, their chemical composition scrutinized by the rovers’ scientific instruments. As Cabrol and Grin learn more about the surface of Mars today, they also hope to gain insights into the structure of primordial Earth.
- SETI Institute Explorer, Special Edition 2005