Reading the Rocks: The Importance of the Margin Carbonate Unit on Mars

Perseverance’s Location: This is an orbital view showing the approximate location of the Perseverance rover and the Ingenuity helicopter. The fractured, light-toned material on the left-side of the panel, ~400 m ahead of the rover, corresponds to the Margin Carbonate Unit. Credits: NASA/JPL-Caltech.  View Interactive Map

After more than two and a half years of driving and exploring, Perseverance is closing in on an eagerly anticipated destination: the margin carbonate unit.

The Mars 2020 scientists have been buzzing with excitement this past week as Perseverance makes its final approach towards a special rock unit that played a pivotal role in selecting Jezero as the landing site for exploration. Located in a narrow band along the inner edge of Jezero’s western crater rim, this layer showcases pronounced signatures of a mineral known as carbonate. On Earth, carbonates typically form in the shallow shoals of freshwater or alkaline lakes. It's hypothesized that this might be the case for the margin carbonate unit on Mars too—over 3 billion years ago, the waters of a lake in Jezero crater might have lapped against its shores, depositing this carbonate layer. An alternative hypothesis is that the carbonates formed through mineral carbonation, where silicate minerals (like olivine) react with CO₂ and are converted to carbonates.

Carbonates are intriguing for several reasons. Firstly, carbonates can offer insights into Mars' bygone atmosphere. These minerals form through a series of chemical reactions that begin when carbon dioxide (CO₂) from the atmosphere reacts with liquid water. Thus, by studying the presence, abundance, and isotopic composition of these carbonates, our team may be able to infer Mars’ past atmospheric CO₂ levels and glean insights into its climatic history.

Second, carbonate minerals are an excellent medium for preserving traces of ancient life if it existed. When carbonates precipitate early in the rock-forming process, they can capture a snapshot of the environment in which they formed, including any signs of microbial life. On Earth, carbonate minerals have been observed to form directly around microbial cells, encapsulating them and rapidly turning them to fossils. This is particularly valuable because once an organism is encased in carbonate it can be preserved for a very long time. Another example of carbonate fossilization on Earth is stromatolites—layered structures created by microbial colonies growing in mineral-saturated waters. Stromatolites represent some of the earliest records of life on Earth. 

Although we don’t yet know exactly how the margin rocks, or the carbonate within them formed, the team is eager to drill into these rocks and unlock their secrets. 

About This Blog

These blog updates are provided by self-selected Mars 2020 mission team members who love to share what Perseverance is doing with the public.

Dates of planned rover activities described in these blogs are subject to change due to a variety of factors related to the Martian environment, communication relays and rover status.

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  • Mariah Baker
    Planetary Scientist, Smithsonian National Air & Space Museum
    Washington, DC
  • Matthew Brand
    SuperCam/ChemCam Engineer, Los Alamos National LaboratoryLos Alamos National Laboratory
  • Sawyer Brooks
    Docking Systems Engineer, NASA/JPL
    Pasadena, CA
  • Adrian Brown
    Deputy Program Scientist, NASA HQ
    Washington, DC
  • Denise Buckner
    Student Collaborator, University of Florida
    Gainesville, FL
  • Fred Calef III
    Mapping Specialist, NASA/JPL
    Pasadena, CA
  • Stephanie Connell
    SuperCam, PhD Student, Purdue University
    West Lafayette, IN
  • Alyssa Deardorff
    Systems Engineer, NASA/JPL
    Pasadena, CA
  • Kenneth Farley
    Project Scientist, Caltech
    Pasadena, CA
  • Phylindia Gant
    Mars 2020 Student Collaborator, University of Florida
    Gainesville, FL
  • Brad Garczynski
    Student Collaborator, Purdue University
    West Lafayette, IN
  • Erin Gibbons
    Student Collaborator, McGill University
    Montreal, Canada
  • Michael Hecht
    Mars Oxygen In-Situ Resource Utilization Experiment (MOXIE) Principal Investigator, Massachusetts Institute of Technology
    Westford, MA
  • Louise Jandura
    Chief Engineer for Sampling & Caching, NASA/JPL
    Pasadena, CA
  • Elisha Jhoti
    Ph.D. Student, University of California, Los Angeles
    Los Angeles, CA
  • Bavani Kathir
    Student Collaborator on Mastcam-Z, Western Washington University
  • Lydia Kivrak
    Student Collaborator, University of Florida
    Gainesville, FL
  • Athanasios Klidaras
    Ph.D. Student, Purdue University
  • Rachel Kronyak
    Systems Engineer, NASA/JPL
    Pasadena, CA
  • Steven Lee
    Perseverance Deputy Project Manager, NASA/JPL
    Pasadena, CA
  • An Li
    Student Collaborator on PIXL, University of Washington
  • Justin Maki
    Imaging Scientist and Mastcam-Z Deputy Principal Investigator, NASA/JPL
  • Forrest Meyen
    MOXIE Science Team Member, Lunar Outpost
  • Sarah Milkovich
    Assistant Science Manager, NASA/JPL
    Pasadena, CA
  • Eleanor Moreland
    Ph.D. Student, Rice University
    Houston, Texas
  • Asier Munguira
    Ph.D. Student, University of the Basque Country
  • Matt Muszynski
    Vehicle Systems Engineer, NASA/JPL
    Pasadena, CA
  • Claire Newman
    Atmospheric Scientist, Aeolis Research
    Altadena, CA
  • Avi Okon
    Sampling Operations Deputy Lead, NASA/JPL
    Pasadena, CA
  • Pegah Pashai
    Vehicle Systems Engineer Lead, NASA/JPL
    Pasadena, CA
  • David Pedersen
    Co-Investigator, PIXL Instrument, Technical University of Denmark (DTU)
    Copenhagen, Denmark
  • Eleni Ravanis
    Student Collaborator, University of Hawaiʻi at Mānoa
    Honolulu, HI
  • Thirupathi Srinivasan
    Robotic Systems Engineer, NASA/JPL
  • Kathryn Stack
    Deputy Project Scientist, NASA/JPL
    Pasadena, CA
  • Vivian Sun
    Science Operations Systems Engineer, Staff Scientist, NASA/JPL
    Pasadena, CA
  • Iona (Brockie) Tirona
    Sampling Engineer, NASA/JPL
    Pasadena, CA
  • Jennifer Trosper
    Project Manager, NASA/JPL
    Pasadena, CA
  • Vandi Verma
    Chief Engineer for Robotic Operations, NASA/JPL
    Pasadena, CA
  • Rick Welch
    Deputy Project Manager, NASA/JPL
    Pasadena, CA
  • Roger Wiens
    Principal Investigator, SuperCam / Co-Investigator, SHERLOC instrument, Purdue University
    West Lafayette, IN

Tools on the Perseverance Rover+

The Perseverance rover has tools to study the history of its landing site, seek signs of ancient life, collect rock and soil samples, and help prepare for human exploration of Mars. The rover carries:


Where is the Rover?

Image of a rover pin-point at Perseverance's location on Mars, Jezero Crater

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