In their analysis of imagery and data collected by the Perseverance rover on Mars, researchers have discovered traces of organic molecules in the Jezero Crater. This finding has significant implications as it suggests that Mars may have had the necessary conditions to support life and its carbon cycles in the past.
It’s important to note that this discovery does not confirm the existence of past life on Mars, but rather indicates that the planet once had the suitable environment for life as we understand it. Perseverance’s primary objective is to investigate whether Mars could have hosted life in its ancient history, and this discovery contributes to that investigation.
The researchers used the SHERLOC instrument (Scanning Habitable Environments with Raman and Luminescence for Organics and Chemicals) to examine ten specific targets in the Jezero Crater. They found signals of organic molecules in all of the targets studied. The team’s recent research on the organic-mineral associations in the Jezero Crater has been published in the journal Nature.
Since landing on Mars in February 2021, Perseverance has been exploring the western end of the Jezero Crater and collecting rock samples. The plan is to eventually bring these samples back to Earth in the early 2030s, provided everything goes as expected.
Perseverance’s mission goes beyond collecting rocks. Scientists are using the rover’s cameras to study the Martian terrain and gather valuable information. The sweeping views captured by the rover offer evidence of past turbulent rivers on the now dry planet. Additionally, close-up images taken by Perseverance’s SHERLOC camera provide new insights into the chemistry of Martian rocks.
Joseph Razzell Hollis, an astrobiologist at NASA’s Jet Propulsion Laboratory and the Natural History Museum in London, explained that the findings support previous observations by robotic missions, indicating that Mars was once rich in organic material. These organic compounds primarily consist of carbon and hydrogen, and their detection even after billions of years provides incremental knowledge about Mars’ history and its potential for supporting life in the past.
Apart from capturing images, Perseverance’s SHERLOC instrument utilizes Raman and fluorescence spectroscopy to analyze the molecular composition of Martian rocks and understand how molecules and minerals are distributed across their surfaces. Importantly, these analyses do not damage the rocks, which is crucial for a rover aiming to send samples back to Earth.
If life did exist in the Jezero Crater, scientists believe it likely thrived in a river delta located on the crater’s western rim. This hypothesis is supported by the presence of 3.5-billion-year-old fossilized microbial mats called stromatolites in similar shallow environments on Earth. With water flowing into Jezero for a prolonged period and the existence of organic molecules on the crater’s subaquatic floor, it suggests a potentially habitable environment for life as we know it.
The recent targets examined by SHERLOC were Máaz and SéÃtah, two formations on the Jezero Crater’s floor. While the exact dating of the discovered molecules was not possible, Hollis explained that some of the signatures they detected were associated with minerals altered by water 3-4 billion years ago. This finding suggests a more complex geochemical process may have occurred on Mars than previously thought and that the necessary building blocks for life were present.
Although we are still far from finding the conclusive evidence Bowie once pondered about, it is unlikely that we will ever have a smoking gun. As Abigail Allwood, the principal investigator of Perseverance’s PIXL instrument, previously emphasized, understanding the potential existence of past life requires multiple scales of observation that together form a complex tapestry.
Therefore, while the confirmation of organic molecules in the Jezero Crater adds further evidence to the possibility of past life on Mars, it does not provide definitive proof. It is considered a stepping stone toward a better understanding of the planet’s history. To conclusively confirm the presence, type, and mineral associations of organic molecules and evaluate them as specific evidence of past life, the samples collected by Perseverance will need to be brought back to Earth.
Thus, the Mars Sample Return (MSR) mission, which involves bringing the collected samples back to Earth, will be crucial in providing more definitive insights into whether life existed in the Jezero Crater. Although it may take time for the mission to be executed successfully, there is hope for unlocking further knowledge about Mars and its potential as a habitat for life.
Reference:
Sharma, S., Roppel, R.D., Murphy, A.E. et al. Diverse organic-mineral associations in Jezero crater, Mars. Nature (2023). DOI: 10.1038/s41586-023-06143-z
