Mars Express north polar plains
This image, taken in May 2014 by the Mars Express High Resolution Stereo Camera, captures many of the atmospheric and geologic processes at work on Amazonian Mars during a typical midsummer day in the Martian north polar plains. On this date, the seasonal ice cap is shrinking toward its summer minimum, fueling weather activity on the northern lowlands. At top center, a low-pressure system with water ice cirrus clouds was nearing peak intensity. The winds raised by seasonal polar storm systems, such as this one, are an important contributor to surface activity and the Martian geologic record. In particular, the polar winds sculpt the dark dune fields surrounding the northern ice cap and raise dust that may be deposited on the ice caps. During the winter months, that dust is buried by water ice condensing out of the atmosphere, creating alternating layers of dust and ice, preserving a record of deposition over seasonal, annual, decadal, and much longer timescales. Credit: ESA/DLR/FU Berlin/J. Cowart

In mid-June, approximately 30 Mars scientists and 17 students gathered in Lakewood, Colo., to outline science’s current understanding of active processes and environmental conditions occurring within the recent “Amazonian” and present-day Martian climate. Special emphasis was on the icy and rocky geologic records that those processes and conditions have created. This meeting was intended as a supplemental topical workshop between meetings in the International Conference on Mars Polar Science and Exploration series (the last one was held in 2016; the next one will be in 2020). Attendees came from a range of disciplines and presented on many different investigations, including analogue studies of glacial terrains, laboratory experiments of deliquescence, measurements of rocky and icy terrains and subsurface, and models and observations of the seasonal atmospheric cycles.

The mid-workshop fieldtrip took attendees into Rocky Mountain National Park, where Brian Hynek (University of Colorado Boulder) described examples of glacial and alpine terrain. This in situ exploration of records of terrestrial climate conditions (including conditions very different from those currently found within the Rockies) was a reminder of the scales and ways in which a climate (in particular, its volatiles) can leave marks on a planet’s surface.

From group discussion following each oral session, a consensus emerged that a top science objective for Mars Amazonian climate studies is “to identify, measure, and interpret the surface and subsurface record of Mars’ climate history.” In particular, it is important to establish if and how the polar layered deposits and other landforms and surface and subsurface materials record climate variations over annual to decadal, orbital (e.g., obliquity cycles), and/or longer timescales. Scientists can then begin to quantitatively read that record from high-resolution orbital images. Part of this work depends on gaining a strong understanding of current atmospheric processes and exchanges of volatiles with the surface and near surface; related major outstanding questions pertain to the global Martian thermal and volatile budgets. Specifically, characterizing volatile reservoirs that presently exchange with the atmosphere or have done so in the past and understanding how dust and clouds affect surface and atmospheric temperatures would place key constraints on environmental conditions and habitable regions during the recent past.

The final session of the workshop featured mission concept proposals. Engineers from Ball Aerospace and the Jet Propulsion Laboratory added to an animated discussion of the key measurements needed to address the top science objective and related outstanding Mars climate science questions. Discussion then turned to mission implementation, with many participants strongly recommending landing on the surface to enable access to the ice and from there characterizing in situ the atmospheric and subsurface composition and structure. However, such a mission would potentially need to be capable of surviving polar night, in addition to landing on and drilling into the Martian polar cap.

The meeting program and all abstracts are available here.

The meeting was convened by the Planetary Science Institute (Colorado), with student travel grants funded by NASA’s Mars Program Office and program organization assistance from the Universities Space Research Association’s Lunar and Planetary Institute.  The authors thank all attendees for contributing to the discussion, in particular those who engaged in note-taking and additional synthesis discussion.

—Serina Diniega ([email protected]), Jet Propulsion Laboratory, California Institute of Technology, Pasadena; Isaac Smith, York University, Toronto, Ontario, Canada; also at Planetary Science Institute, Lakewood, Colo.; and Ali Bramson, University of Arizona, Tucson

Citation:

Diniega, S.,Smith, I., and Bramson, A. (2019), Updates on understanding Mars’s recent and present-day climate, Eos, 100, https://doi.org/10.1029/2019EO114411. Published on 23 January 2019.

Text © 2019. The authors. CC BY-NC-ND 3.0
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