Methane on Mars and Habitability:
Challenges and Responses
Yuk L. Yung,
1,2
Pin Chen,
2
Kenneth Nealson,
3
Sushil Atreya,
4
Patrick Beckett,
2
Jennifer Blank
5
Bethany Ehlmann,
1,2
John Eiler,
1
Giuseppe Etiope,
6
James G. Ferry,
7
Francois Forget,
8
Peter
Gao,
5
Renyu Hu,
2
Armin Kleinböhl,
2
Ronald Klusman,
9
Franck Lefèvre,
10
Charles Miller,
2
Michael
Mischna,
2
Michael Mumma,
11
Sally Newman,
1
Dorothy Oehler,
12
Mitchio Okumura,
1
Ronald
Oremland,
13
Victoria Orphan,
1
Radu Popa,
3
Michael Russell,
2
Linhan Shen,
1
Barbara Sherwood
Lollar,
14
Vlada Stamenković,
1,2
Robert Staehle,
2
Daniel Stolper,
15
Alexis Templeton,
16
Ann C.
Vandaele,
17
Sébastien Viscardy,
17
Chris Webster,
2
Paul O. Wennberg,
1
Michael Wong,
1
John
Worden
2
1
California Institute of Technology, Pasadena, California, USA
2
NASA Jet Propulsion Laboratory, California Institute of Technology, Pasadena, California, USA
3
University of Southern California, Los Angeles, California, USA
4
University of Michigan, Ann Arbor, Michigan, USA
5
NASA Ames Research Center, Moffett Field, California, USA
6
Istituto Nazionale di Geofisica e Vulcanologia, Sezione Roma, Catania, Italy and Faculty of
Environmental Science and Engineering, Babes-Bolyai University, Cluj-Napoca, Romania
7
The Pennsylvania State University, University Park, Pennsylvania, USA
8
Laboratoire de Météorologie Dynamique, Institut Pierre Simon Laplace, CNRS, Paris, France
9
Colorado School of Mines, Golden, Colorado, USA
10
Laboratoire Atmospheres, Milieux, Observations Spatiales (LATMOS), IPSL, Paris, France
11
NASA Goddard Space Flight Center, Greenbelt, Maryland, USA
12
Planetary Science Institute, Tucson, Arizona, USA
13
U.S. Geological Survey, Menlo Park, California, USA
14
University of Toronto, Toronto Ontario, Canada
15
University of California, Berkeley, California, USA
16
University of Colorado, Boulder, Colorado, USA
17
The Royal Belgian Institute for Space Aeronomy (BIRA-IASB), Brussels, Belgium
We dedicate this report to JPL scientist Mark Allen, whose spirit of generosity inspired many of
the conversations and much of the work that brought us together. We thank the Director of the
Keck Institute for Space Studies, Tom Prince, the Executive Director, Michele Judd, and the
fantastic KISS staff for hosting our workshop and providing a wonderful environment for these
discussions.
Address Correspondence to:
Pin Chen
JPL/Caltech
Science Division
4800 Oak Grove Dr.
M/S 183-301
Pasadena CA, 91109 USA
E-mail: pin.chen@jpl.nasa.gov
Study Report prepared for the Keck Institute for Space Studies (KISS)
Cover Image: Chuck Carter/Keck Institute for Space Studies (KISS)
Editing and Formatting: Meg Rosenburg
©
January, 2018
. All rights reserved.
Contents
List of Figures
. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 6
Abstract
. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 9
1
Introduction
. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 11
2
MSL Measurements
. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 15
3
Lifetime of CH
4
. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 17
4
Geology and Geochemistry Relevant to Life on Mars
. . . . . . . . . . . . . 21
5
Detection of CH
4
Seepage
. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 27
6
ExoMars Trace Gas Orbiter (TGO)
. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 29
7
Habitability and Biosignatures
. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 33
8
Atmospheric Transport and Measurement Strategies
. . . . . . . . . . . . . 37
9
Conclusions
. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 45
Appendix
. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 47
Bibliography
. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 49
List of Figures
1 Summary of TLS measurements of CH
4
. . . . . . . . . . . . . . . . . . . . . . . 16
2 Mixing ratios of minor species in the Martian atmosphere and a CH
4
simulation . . 18
3 Global chemical trends of basalt degassing . . . . . . . . . . . . . . . . . . . . . . 22
4 Free-energy profile of a hydrothermal pathway to methane . . . . . . . . . . . . . . 23
5 Models of water abundance . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 38
6 Dust in the Martian atmosphere . . . . . . . . . . . . . . . . . . . . . . . . . . . 39