Biosignatures in ICY EnVIRONMENTS

MicroHabitable environments in ice

When Malaska et al (2020) looked at ice cores in Greenland, they observed patchy distributions of life and organics in ice. In sea ice on Earth, organics, including carbohydrates, influence the formation of brine channels in ice, which provide habitats for microorganisms within ice (Krembs et al., 2011).

This new project seeks to understand how organics influence the formation and maintenance of these microhabitable environments in ice under Enceladus and Europa-like conditions. At the end of the project, we will have quantified the potential habitable volume of ice in Ocean Worlds ice shells.

Stay tuned for updates on our research progress.

nutrient availability drives snow algae growth and biosignature formation

Snow algae and bacterial communities occur in icy environments on Earth. It has been suggested that they weather minerals to overcome nutrient limitation. My work examines these processes and how their dissolution of primary mineral phases and precipitation of secondary mineral phases results in the formation of mineral biosignatures. I also study how nutrient limitation influences organic compounds in snow algae, and therefore, potential organic biosignature formation.
The image here is of snow algae consortia associated with forsterite weathering. They gain iron from the olivine to support their growth. 

Biovermiculation Patterns in icy planetary environments  

Factors that influence habitability of icy planetary environments

Snow algae preferentially grow on Fe-phases and produce secondary Fe-phases

 

MARS ASTROBIOLOGY CAVES MISSION ANALOG SCIENCE

Subsurface environments may be the best astrobiological targets on Mars. Caves are accessible without costly drilling payloads. Caves also provide access to CHNOPS elements required for habitability, and provide shielding from UV radiation. For these reason, I’m studying the habitability and biosignature potential of caves and pit crater chains in order to eventually conduct an astrobiologically focused mission to Mars.

My early research focused on microbial colonization and weathering in lava tube caves at Craters of the Moon, a Mars analog environment:

Influences on Microbial Colonization in Lava Caves

Recently, my summer intern, Carole Lakrout evaluated microbial activity in lava tube caves and found that microbial activity increased in warmer caves. More importantly, in our incubated basalt chips, microbial activity increased with incubation time, even though microbial populations remained relatively static with time. Her GSA abstract will be posted here soon.

Influence of the Cave Environment on Habitability & Biosignatures: Implications for Finding Life on Mars

HABITABILITY OF ICY WORLDS: ScIENCE AND INstrumentation

At very cold temperatures, only salty waters (i.e. brines) are stable as liquids. Therefore, it is important for us to be able to characterize the composition of salty waters in the solar system as their composition will tell us about the types of microorganisms that may be able to live there. It’s very difficult to analyze brines, therefore we are developing new analytical techniques to determine the major and trace element chemistry of these solutions. We expect that these data will allow future space missions to remotely sample brines throughout the solar system, like the plume of salty liquid erupting on Enceladus. 

Measuring Perchlorate and Sulfate Concentrations in Brine

Measuring Carbonate and Perchlorate Concentrations in Brine

Raman Spectroscopy of Brines

Measuring Clathrate stability in the solar system

 My current project focuses on how amino acids, which are present in meteorites and potentially in the rocky cores of Ocean Worlds partition into ice during freezing. This is important for us to be able to detect and differentiate abiotic processes that occur naturally from biologically mediated processes that are indicators of life. Stay tuned for more updates.

MARS BRINES ATTACK: Chemical Weathering and HabitABility on LATE-State MArs

Finding unambiguous signs of past life is challenging because living organisms catalyze chemical reactions that could occur abiotically. Moreover, rock burial and diagenesis can alter biosignatures once they form. We have examined how high salinity brines influence weathering reactions on Mars, because these reactions control late-stage habitability.

The major volcanic minerals on Mars are olivine, pyroxene and plagioclase. These minerals are common in basaltic rocks. We examine their alteration in order to understand the weathering story on Mars’ surface, i.e. how long was liquid water present at the surface.

Pyroxene weathering in brines: Implications for Mar's meteorites

Pyroxene dissolution in brines: Implications for interpreting Mars' weathering history

Albite dissolution in brines: Implications for Mar's weathering history

Carbonate dissolution and preservation is extremely important for biosignature formation and preservation. The carbonate paper covers calcite and magnesite, two of the three carbonate minerals commonly detected on Mars. The second paper on siderite, covers Fe-carbonates, whose weathering is complicated by oxidation and reduction processes.

Carbonate weathering on Mars: Implications for biosignature preservation

Siderite dissolution in high salinity brines

Sulfate minerals, including anhydrite, alunite, and jarosite are common alteration phases on Mars. These weathering studies focus on how long alteration phases persist on Mars in the presence of liquid water to understand how long liquid water was present on Mars

Alunite weathering in Mars-relevant brines

Jarosite dissolution in perchlorate: Implications for late-stage weathering on Mars

Anhydrite Nucleation and Growth at Low-temperatures: Implications for Mars' weathering

Biosignature PReservation through geologic time

Finding unambiguous signs of past life is challenging because living organisms catalyze chemical reactions that could occur abiotically. Moreover, rock burial and diagenesis can alter biosignatures once they form. For this study we are examining carbonate springs that have been active for over 400 thousand years and determining what changes we see between the modern system and the most ancient samples. This will help us understand the types of processes that alter biosignatures through geologic time and help us better detect biosignatures in the rock record. 

Biosignature Preservation Through Geologic Time

Biosignatures in Acid-sulfate hydrothermal systems

After ~3 billion years, Mars experience what is thought to have been a global acid-sulfate weathering event. These studies examined microorganisms’ influence rock dissolution, clay mineral precipitation, and trace element distributions in acid-sulfate hot spring systems in order to determine whether microbial processes might be differentiated during this period of Mars’ history.

Microbial Weathering in Acid-Sulfate Hot Springs

I have recently submitted an article on how microorganisms and their biofilms influence trace metal distributions (including gold, silver, arsenic, copper, zinc, and nickel) in acid-sulfate hydrothermal systems.