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The Holy Grail: A road map for unlocking the climate record stored within Mars' polar layered deposits

Smith, Isaac B. and Hayne, Paul O. and Byrne, Shane and Becerra, Patricio and Kahre, Melinda and Calvin, Wendy and Hvidberg, Christine and Milkovich, Sarah and Buhler, Peter and Landis, Margaret and Horgan, Briony and Kleinböhl, Armin and Perry, Matthew R. and Obbard, Rachel and Stern, Jennifer and Piqueux, Sylvain and Thomas, Nicolas and Zacny, Kris and Carter, Lynn and Edgar, Lauren and Emmett, Jeremy and Navarro, Thomas and Hanley, Jennifer and Koutnik, Michelle and Putzig, Nathaniel and Henderson, Bryana L. and Holt, John W. and Ehlmann, Bethany and Parra, Sergio and Lalich, Daniel and Hansen, Candice and Hecht, Michael and Banfield, Don and Herkenhoff, Ken and Paige, David A. and Skidmore, Mark and Staehle, Robert L. and Siegler, Matthew (2020) The Holy Grail: A road map for unlocking the climate record stored within Mars' polar layered deposits. Planetary and Space Science, 184 . Art. No. 104841. ISSN 0032-0633. doi:10.1016/j.pss.2020.104841.

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In its polar layered deposits (PLD), Mars possesses a record of its recent climate, analogous to terrestrial ice sheets containing climate records on Earth. Each PLD is greater than 2 ​km thick and contains thousands of layers, each containing information on the climatic and atmospheric state during its deposition, creating a climate archive. With detailed measurements of layer composition, it may be possible to extract age, accumulation rates, atmospheric conditions, and surface activity at the time of deposition, among other important parameters; gaining the information would allow us to “read” the climate record. Because Mars has fewer complicating factors than Earth (e.g. oceans, biology, and human-modified climate), the planet offers a unique opportunity to study the history of a terrestrial planet’s climate, which in turn can teach us about our own planet and the thousands of terrestrial exoplanets waiting to be discovered. During a two-part workshop, the Keck Institute for Space Studies (KISS) hosted 38 Mars scientists and engineers who focused on determining the measurements needed to extract the climate record contained in the PLD. The group converged on four fundamental questions that must be answered with the goal of interpreting the climate record and finding its history based on the climate drivers. The group then proposed numerous measurements in order to answer these questions and detailed a sequence of missions and architecture to complete the measurements. In all, several missions are required, including an orbiter that can characterize the present climate and volatile reservoirs; a static reconnaissance lander capable of characterizing near surface atmospheric processes, annual accumulation, surface properties, and layer formation mechanism in the upper 50 ​cm of the PLD; a network of SmallSat landers focused on meteorology for ground truth of the low-altitude orbiter data; and finally, a second landed platform to access ~500 ​m of layers to measure layer variability through time. This mission architecture, with two landers, would meet the science goals and is designed to save costs compared to a single very capable landed mission. The rationale for this plan is presented below. In this paper we discuss numerous aspects, including our motivation, background of polar science, the climate science that drives polar layer formation, modeling of the atmosphere and climate to create hypotheses for what the layers mean, and terrestrial analogs to climatological studies. Finally, we present a list of measurements and missions required to answer the four major questions and read the climate record. 1. What are present and past fluxes of volatiles, dust, and other materials into and out of the polar regions? 2. How do orbital forcing and exchange with other reservoirs affect those fluxes? 3. What chemical and physical processes form and modify layers? 4. What is the timespan, completeness, and temporal resolution of the climate history recorded in the PLD?

Item Type:Article
Related URLs:
URLURL TypeDescription
Buhler, Peter0000-0002-5247-7148
Horgan, Briony0000-0001-6314-9724
Stern, Jennifer0000-0002-0162-8807
Edgar, Lauren0000-0001-7512-7813
Ehlmann, Bethany0000-0002-2745-3240
Herkenhoff, Ken0000-0002-3153-6663
Additional Information:© 2020 Elsevier Ltd. Received 1 May 2019, Revised 26 December 2019, Accepted 9 January 2020, Available online 3 February 2020. We gratefully acknowledge the support of the Keck Institute of Space Studies who generously supported this meeting by hosting and facilitating all of our discussions. Work at the Jet Propulsion Laboratory, California Institute of Technology, is performed under contract with the National Aeronautics and Space Administration. We have no conflicts of interest.
Group:Keck Institute for Space Studies, Astronomy Department
Funding AgencyGrant Number
Keck Institute for Space Studies (KISS)UNSPECIFIED
Record Number:CaltechAUTHORS:20200204-093202879
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Official Citation:Isaac B. Smith, Paul O. Hayne, Shane Byrne, Patricio Becerra, Melinda Kahre, Wendy Calvin, Christine Hvidberg, Sarah Milkovich, Peter Buhler, Margaret Landis, Briony Horgan, Armin Kleinböhl, Matthew R. Perry, Rachel Obbard, Jennifer Stern, Sylvain Piqueux, Nicolas Thomas, Kris Zacny, Lynn Carter, Lauren Edgar, Jeremy Emmett, Thomas Navarro, Jennifer Hanley, Michelle Koutnik, Nathaniel Putzig, Bryana L. Henderson, John W. Holt, Bethany Ehlmann, Sergio Parra, Daniel Lalich, Candice Hansen, Michael Hecht, Don Banfield, Ken Herkenhoff, David A. Paige, Mark Skidmore, Robert L. Staehle, Matthew Siegler, The Holy Grail: A road map for unlocking the climate record stored within Mars’ polar layered deposits, Planetary and Space Science, Volume 184, 2020, 104841, ISSN 0032-0633, (
Usage Policy:No commercial reproduction, distribution, display or performance rights in this work are provided.
ID Code:101107
Deposited By: Tony Diaz
Deposited On:04 Feb 2020 18:51
Last Modified:16 Nov 2021 17:59

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