Modelling Martian hydrous alteration from orbital and rover data

Lead Research Organisation: Open University
Department Name: Physical Sciences

Abstract

The Mars Science Laboratory rover Curiosity is currently exploring Gale Crater. It has found lake bed sediments, including conglomerates and mudstones (Grotzinger et al. 2014). The CheMin instrument - an XRD instrument - has revealed the basaltic mineralogy of those sediments, but also found up to 22 % clay minerals in the fine grained sediments (Vaniman et al. 2014). But Curiosity is not the only instrument on or around Mars to have found clay minerals. The first detection of clays was made by the OMEGA instrument aboard the European Mars Express orbiter (Bibring et al. 2005). Next, the CRISM instrument aboard the NASA Mars Reconnaissance Orbiter refined and extended those observations, leading to a detailed understanding of clay mineral occurrences on Mars (Ehlmann et al. 2011). With all the new observations, it has become clear that Mars has been a habitable place in the past - and it is critically important to understand alteration mineral formation pathways to assess the nature of those environments.
Thermochemical modeling is a powerful tool to understand alteration processes. It has the potential to provide insights into the nature of alteration environments that are otherwise inaccessible. For example, when the minerals are observed in a rock sequence, mineral formation usually has ceased and the fluids are gone. Thermochemical modeling allows to calculate fluid properties, e.g. pH, temperature, by assessing the path from a potolith to the observed alteration mineralogy. This technique has been used successfully by the supervisor team, for example to assess impact generated hydrothermal systems (Schwenzer and Kring 2009, Bridges and Schwenzer 2012) and alteration mineralogy observed by the Curiosity rover (Bridges et al. 2014). This project will build on the experience acquired and use the rapidly growing data base of rocks and alteration phases on Mars, to expand our understanding of the diversity of Martian alteration environments. The main objectives of the project are to
1. Provide a detailed mineralogical and geochemical account of the alteration in the different alteration settings, as described in the literature, to understand the alteration mineralogy.
2. Work closely with the supervisors and a PhD student at Leicester University to select Curiosity Rover data (APXS, ChemCam and CheMin instruments) as host rock chemistry and mineralogy proxies and to understand alteration mineralogy observed by the rover to date and in the future.
3. Set up and conduct models on a variety of host rock compositions and simulating pathways to re-create formation conditions of the observed alteration mineral assemblages.
This will allow to make significant progress in the understanding of Martian alteration conditions. It will further allow to assess the frequency with which such environments may have occurred on Mars and therefore better understand the overall planetary environmental conditions that have led to habitability of specific sites - and whether habitable sites were likely isolated or interconnected.

Publications

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Studentship Projects

Project Reference Relationship Related To Start End Student Name
ST/N50421X/1 01/10/2015 30/09/2020
1653314 Studentship ST/N50421X/1 01/10/2015 30/09/2018 Candice Bedford
 
Description my PhD research has involved distinguishing source region characteristics from the effects of mineral sorting, chemical weathering and aqueous alteration in the sedimentary rocks preserved in Gale crater, Mars. Understanding how water interacted with Gale's sedimentary record carries important paleoclimatic implications, while determining sediment source regions can develop our understanding about Mars' surface and crustal processes. My PhD research on the river and lake deposits of Gale crater identified that at least 5 distinct igneous source regions contributed to the geochemical variation therein and has been published in Geochimica et Cosmochimica Acta (Bedford et al., 2019). Mars has previously been thought to be a solely basaltic planet with little evidence of evolved magmatic assemblages. The results of this study supports others that have identified evolved magmatic endmembers at specific waypoints along Curiosity's traverse.
The NASA Curiosity rover is currently analysing the geological units within Gale crater and has so far encountered ancient (>3 Ga) lake, river and wind-blown deposits. Most of my research has been within the Chemistry and Camera (ChemCam) instrument team. ChemCam uses Laser-Induced Breakdown Spectroscopy to acquire rapid analyses of sample host rock or soil situated up to 7 m from the rover mast. As such, ChemCam has developed an extensive geochemical dataset ~750,000 spectral analyses to date of a variety of different geological targets (i.e., sedimentary rock, mineral veins and igneous float) spanning >500 m of Martian stratigraphy. The subject of my PhD thesis and Bedford et al. (GCA, 2019) has involved classifying and statistically analysing this large geochemical dataset for the entirety of the MSL mission in order to:
• Constrain endmember compositions relating to source region characteristics,
• Distinguish the effects of chemical weathering on sediment compositions, and
• Identify geochemical variation relating to diagenesis and mineral sorting as a result of ancient Mars' sedimentary processes.
My PhD research shows that alteration trends do not fully explain the observed geochemical differences between Gale's lake-deposited mudstone units, indicating that the dominant control on geochemical variation relates to sediment source region. This implies that chemical weathering was low throughout the formation of Gale's sedimentary units and post-depositional alteration occurred in a closed water-rock system at the scale of the stratigraphic units. Therefore, geochemical difference between and within the geologic units can be linked to four previously identified endmembers (subalkaline basalt, trachybasalt, trachyte and rhyolite), and one new endmember (silica-rich basalt). The identification of a new igneous compositional endmember contributing to Mt Sharp further extends the known geochemical complexity of the ancient highland crust around Gale crater. The results of my thesis and Bedford et al. (GCA, 2019) further supports that Martian river and lake deposits are more enriched in light-toned, felsic material relative to dark-toned, mafic material with distance from the sediment source. Meanwhile, wind-blown deposits become preferentially enriched in mafic materials. Geochemically identifying the ancient wind-blown mineral sorting trend in the ancient wind-blown deposits preserved in Gale crater has also constrained the wind direction at the time of deposition as SW-NE, which is opposite to the wind direction seen today in the modern dune deposits investigated by Curiosity in Gale.
Exploitation Route Now that I have constrained the bulk compositions of the main geologic groups in Gale crater, a collaboration is currently underway (e.g., Turner et al. LPSC, 2019) to use these values as starting compositions to model the alteration conditions that formed the high hematite abundance at the Vera Rubin Ridge, a key MSL mission target and the location of a recent campaign. This has important implications towards our understanding of the habitability of Gale crater after the deposition of the lake-deposited mudstone. The geochemical endmembers of the river and lake deposits from Bedford et al. (GCA, 2019) are also being used to help understand the origin of the young deposits in Gale crater such as the Stimson formation and Bimbe Blocky units.
Sectors Aerospace, Defence and Marine,Environment,Other

 
Description The findings of my research have been used to contribute towards active (i.e., NASA Mars Science Laboratory) and future (i.e., ESA/Roscosmos ExoMars 2020) mission planning and data interpretation of the Martian surface. My research has also been used to inspire a multitude of people, young and old, towards further education in a STEM subject through the many outreach talks I have given to geological societies across the country, outreach events I have assisted with (e.g., the Royal Society's summer of science) and interactions I have had with the media (co-authored a BBC article on Curiosity's main discoveries and was interviewed by BBC Look East). I have further participated in several ExoMars field trials (MURFI and ExoFiT 2) run by the UK Space Agency, European Space Agency and Airbus whereby the knowledge I have gained through this PhD has contributed to testing the technology and operations procedure that will be used in the 2020 ExoMars mission.
First Year Of Impact 2018
Sector Aerospace, Defence and Marine,Other
Impact Types Cultural

 
Description Department of Physical Sciences Equality and Diversity Team Member at the Open University
Geographic Reach Local/Municipal/Regional 
Policy Influence Type Participation in a advisory committee
URL http://www.open.ac.uk/science/physical-science/equality-and-diversity/equality-and-diversity-team
 
Description Department of Physical Sciences Public Outreach and Engagement Team member
Geographic Reach Local/Municipal/Regional 
Policy Influence Type Participation in a advisory committee
 
Description Royal Astronomical Society small grant
Amount £1,391 (GBP)
Organisation Royal Astronomical Society 
Sector Learned Society
Country United Kingdom
Start 10/2017 
End 11/2017
 
Description Santander funding for MetSoc conference attendance with supervisor
Amount £225 (GBP)
Organisation Santander Universities 
Sector Private
Country United Kingdom
Start 08/2016 
End 08/2016
 
Description Mars Utah Rover Field Investigation 
Organisation UK Space Agency
Country United Kingdom 
Sector Public 
PI Contribution During the Mars Utah Rover Field Investigation mission simulation, I participated as a member of the mission science team in both the instrument scientist and mission planner roles. This mission simulation aimed to test the UK-developed PanCam instrument in an active mission enviornment similar to what is expected during the ExoMars 2020 rover campaign, as well as train UK scientists in active mission roles. I participated in the science discussions that constrained the science team's knowledge of the geology that the PanCam simulator was in (prior to and during the simulation the science team had no knowledge of the exact location of MURFI, just that it was somewhere in Utah). I also contributed to team debates as to our next moves, and how to best achieve our mission goal of completing a drill. I was involved in the 3 week simulation for a total of 4 days. After the simulation, I participated in a discussion on what could have been improved on, what was achieved, and how the next mission simulation should be conducted. I have also contributed to the conference abstract and paper publications that have resulted from this UK SA field trial. During the mission simulation, there was also extensive coverage from the media, in which I participated in a snapchat interview, and helped to write a blogpost for the MURFI science team blog.
Collaborator Contribution My collaborators in the MURFI organised, executed the mission simulation, and lead the publication and outreach efforts.
Impact This collaboration has culminated in one publication currently in review, and a conference abstract for the 2017 Lunar and Planetary Science Conference in Houston, Texas, USA. MURFI has also successfully provided training for myself and other UK-based scientists for active roles in the ExoMars space mission. This collaboration has also resulted in raising public awareness about the UK's involvement in the ExoMars 2020 space mission.
Start Year 2016
 
Description NASA Mars Science Laboratory mission 
Organisation National Aeronautics and Space Administration (NASA)
Country United States 
Sector Public 
PI Contribution I am a foreign collaborator on the NASA Mars Science Laboratory Science Team. I've contributed to; team science discussions, the Curiosity rover Vera Rubin ridge campaign, conference abstracts from other team members, and lead my own collaborative research effort within the team relating to my PhD subject area and culminating in a paper currently in review and one in prep.
Collaborator Contribution The members of the MSL engineering and rover operations teams have generated the data that form the basis of my research through the running the rover operations on Mars. Their work, target selection and ChemCam spectra analysis is what has built the target major element oxide dataset I analyse for my chemostratigraphic studies. Several science team members are also collaborators on my paper that is currently in review and many more have assisted in the development of my conference talks, abstracts and PhD research through telecon discussions.
Impact This collaboration has resulted in; a published paper "Diagenetic silica enrichment and late-stage groundwater activity in Gale Crater, Mars" lead by Dr. Jens Frydenvang, a science paper in review "Identifying alteration trends and geochemical source region characteristics preserved in the fluviolacustrine sedimentary record of Gale crater, Mars." lead by myself, and a paper in prep. Several conference abstracts have been published within this collaboration at both national and international conferences and science meetings such as the 1st British Planetary Science Congress in Glasgow, UK (3rd - 5th December, 2017), the 7th Astrobiology Society of Britain Conference in Milton Keynes, UK (13th - 14th September, 2017), the 4th International Conference on Early Mars, Flagstaff, USA (2nd - 6th October, 2017), and the 49th Lunar and Planetary Science conference, Houston, USA (19th - 23th March, 2018), with the abstracts selected for oral presentations for each of the meetings listed here. The MSL mission is is a multi-disciplinary collaboration with engineers, physicists, geologists, geochemists, astrobiologists and geomorphologists contributing to the on-going success of the mission.
Start Year 2016
 
Description BBC Look East TV interview 
Form Of Engagement Activity A press release, press conference or response to a media enquiry/interview
Part Of Official Scheme? No
Geographic Reach Regional
Primary Audience Public/other audiences
Results and Impact BBC Look East made a story about the Mars Rover simulations being conducted as part of the Open University S818 course on planetary geology. I was interviewed as an assistant PhD student who is assisting the project. This story was also featured on Twitter.
Year(s) Of Engagement Activity 2017
URL http://www.bbc.co.uk/news/live/uk-england-beds-bucks-herts-40462651
 
Description Curiosity rover outreach talk to the OU Geological Society in Milton Keynes 
Form Of Engagement Activity A talk or presentation
Part Of Official Scheme? No
Geographic Reach Local
Primary Audience Public/other audiences
Results and Impact I gave a 60 minute presentation on the Curiosity rover mission and its key findings to the Open University Geological Society members based in Walton Hall, Milton Keynes. Many of the members were Open University almuni who engaged me in a discussion after the presentation.
Year(s) Of Engagement Activity 2017
 
Description Invited Speaker (Huddersfield Geology Group) 
Form Of Engagement Activity A talk or presentation
Part Of Official Scheme? No
Geographic Reach Local
Primary Audience Public/other audiences
Results and Impact Gave a talk titled "To the Ridge! - An update on the Mars Science Laboratory mission and the new discoveries made since 2017" which was intended to update the geological society on Curiosity's most recent discoveries since the talk I gave in 2017. Over 20 people attended. Every member of the audience engaged in the discussion relating to the talk and the society expressed an interest in asking that I return in 2020.
Year(s) Of Engagement Activity 2019
 
Description Invited speaker (Royal Holloway, University of London Geosciences department) 
Form Of Engagement Activity A talk or presentation
Part Of Official Scheme? No
Geographic Reach National
Primary Audience Undergraduate students
Results and Impact Gave an undergraduate guest lecture to the third year planetary geology students (and any other interested student/staff member who wished to attend) on my research within the MSL science team alongside an introduction to Mars geology and exploration. I also discussed my experience working as a PhD student within an active planetary mission and gave advice on how to get involved with planetary science with the aim of pursuing it as a career. The organisers also asked me to return as a regular guest speaker for the third year planetary science students over the years to come.
Year(s) Of Engagement Activity 2019
 
Description Outreach talk to the Huddersfield Geology Group 
Form Of Engagement Activity A talk or presentation
Part Of Official Scheme? No
Geographic Reach Regional
Primary Audience Public/other audiences
Results and Impact Roughly 30 amateur geologists attended from West Yorkshire, Lancashire and the Greater Manchester area to learn more about the NASA Mars Science Laboratory mission, my role within it and what the mission and my research has uncovered about the geological history of Gale crater, Mars. The talk was 60 minutes long followed by a discussion, with the Huddersfield Geology Group inviting me back for another talk in May, 2018.
Year(s) Of Engagement Activity 2016
URL http://www.huddersfieldgeology.org.uk/talks/
 
Description Outreach talk to the OU Geological Society in Milton, Cambridge 
Form Of Engagement Activity A talk or presentation
Part Of Official Scheme? No
Geographic Reach Regional
Primary Audience Public/other audiences
Results and Impact Presented the current progress that the Curiosity rover has made with its science goals, as well as the new scientific discoveries relating to our understanding of Mars' past and current geological processes. I also presented my role in the mission, and what my research entails. A lengthy discussion followed after the debate about the differences between Mars' geology and that of the Earth's as well as why planetary protection is important, and how corporations such as SpaceX may threaten future science relating to possible extraterrestrial life. Roughly 40 amateur geologists attended the "day of talks" for which my presentation was one of three. The organisers relayed to me that it my talk was "eye-opening" and informative, and expressed and interest in inviting me back in the future.
Year(s) Of Engagement Activity 2018
 
Description Royal Society Summer of Science exhibitor 
Form Of Engagement Activity Participation in an activity, workshop or similar
Part Of Official Scheme? No
Geographic Reach International
Primary Audience Public/other audiences
Results and Impact I was an exhibitor on The Open University's ExoMars Trace Gas Orbiter stand. I engaged the public with our interactive exhibit to teach them more about Mars, the research we are doing there with emphasis placed on ExoMars, and to inspire them into STEM subjects. Our exhibit was open for a week and had a constant flow of people stopping to ask questions and learn more about Mars and the ExoMars mission.
Year(s) Of Engagement Activity 2018
 
Description Voice of the Future 
Form Of Engagement Activity A formal working group, expert panel or dialogue
Part Of Official Scheme? No
Geographic Reach National
Primary Audience Policymakers/politicians
Results and Impact Representatives from the learned scientific bodies convened at Parliament to discuss the issues within UK science policy, and how to improve on them. These issues were discussed with multiple MP's such as Jo Johnson who was the Minister for Universities and Science at the time. The debate was televised on the BBC Parliament channel and I was one of the representatives of the Open University. During the discussion where I was on the panel, I managed to raise the issue of female role models in science, and the unconscious gender bias that still faces science today.
Year(s) Of Engagement Activity 2016