Perseverance’s Mission: A Search for Ancient life

Since landing in the Jezero Crater four years ago, Perseverance has been diligently exploring this region of Mars as part of the Mars 2020 mission. The primary objective: to seek out traces of possible past life. The rover has already covered 35 kilometers, meticulously analyzing the geological diversity of the area in preparation for a future return of Martian rock samples to Earth.

Crucial to the mission is SuperCam, a state-of-the-art laser camera mounted on Perseverance’s mast. This instrument, partially designed and still remotely controlled from Toulouse, France, has fired its laser over half a million times at Martian rocks, providing invaluable data about their composition.One of these laser shots led to the groundbreaking discovery of quartz.

SuperCam: A Versatile Tool for Martian Exploration

SuperCam’s capabilities extend far beyond a simple camera. As Agnès Cousin, a leading co-researcher for SuperCam, noted, Supercam is a super Swiss knife, it brings together five different measures to analyze the rocks at a distance. It is indeed the combination of its three spectral techniques which made it possible to conclude that we were in the presence of quartz.

This suite of instruments allows scientists to remotely analyze the chemical composition and mineral structure of martian rocks with unprecedented precision. For the quartz discovery, supercam utilized three key spectral techniques:

• Laser-Induced Breakdown spectroscopy (LIBS): This technique vaporizes a tiny portion of the rock with a laser, allowing scientists to determine its chemical composition. In this case, LIBS revealed that the rock was composed of approximately 70% silica.
• Infrared Spectroscopy: By analyzing the infrared light reflected from the rock, scientists can identify the presence of specific minerals and assess their degree of crystallization. the infrared signal indicated notable crystallization, ruling out amorphous forms of silica like opal.
• Raman Spectroscopy: Considered the “top of the top” for determining crystalline structure, Raman spectroscopy uses a laser to probe the vibrational modes of molecules within the rock. This technique confirmed the presence of crystalline quartz. Though, the Raman laser is used sparingly, requiring precise targeting of the same spot multiple times.

The Significance of Quartz: Evidence of Past Water Activity

The discovery of quartz reinforces the hypothesis that water once circulated in the Jezero Crater, which scientists believe was formed by a meteorite impact approximately 3.8 billion years ago. On Earth, quartz can form in several ways, including:

1. Magmatic Rocks: Quartz can crystallize directly from molten rock (magma).
2. Alteration by Water: Water can dissolve other elements from rocks,leaving behind concentrated silica that then forms quartz.
3. Hydrothermal Processes: Changes in the environment can cause silica to precipitate out of solution, forming quartz.

Researchers believe the third scenario, a hydrothermal process, is the most likely explanation for the Martian quartz. As Agnès Cousin concludes, On earth, quartz can form in three ways: in magmatic rocks, after an alteration by water which has won all the elements except silica or by haste silica due to a change in the environment. It is indeed this third hypothesis that we favor for this Martian rock, very homogeneous. It could be born from a hydrothermal process, outcome of heat and circulation of fluids in rocks fractured by the impact.

This process would have involved heat and the circulation of fluids through rocks fractured by the impact event. This theory aligns with previous findings indicating the presence of a past lake in the Jezero Crater.

Implications for Exobiology and Future Research

Beyond quartz, the Perseverance rover has also identified other forms of silica, including opal and chalcedony. These minerals are of particular interest to exobiologists because of their potential to trap and preserve signatures of past life. Imagine finding fossils trapped within a geode, but on Mars!

The discovery of these silica-rich minerals strengthens the case for Jezero Crater as a prime location to search for evidence of ancient Martian life. The Perseverance rover is currently collecting samples of these rocks, which are intended to be returned to Earth for further analysis in the future. These samples could provide invaluable insights into the history of Mars and the potential for life beyond Earth.

This discovery highlights the importance of continued exploration of Mars. Future missions could focus on further investigating hydrothermal systems and searching for more concentrated deposits of biosignatures. The data collected by Perseverance and future rovers could eventually answer the fundamental question: Was there ever life on mars?