NASA Astrobiology Science and Technology for Exploring Planets (ASTEP) program

Subsurface Ice and Brine Sampling: Life Detection and Characterization in the McMurdo Dry Valleys Using an Ultrasonic Gopher

Principal Investigator:
Peter Doran, UIC

Co-investigotors:
Yoseph (Yosi) Bar-Cohen, JPL
Chris Fritsen, DRI
Fabien Kenig, UIC
Chris McKay, NASA Ames
Alison Murray, DRI

Collaborators:
John Priscu, Montana State University

Summary
Evidence for ice and fluids near the surface of Mars in both the distant and recent past is growing with each new mission to the Planet. One explanation for fluids forming spring-like features on Mars is the discharge of subsurface brines. Brines offer potential refugia for extant Martian life, and near surface ice could preserve a record of past life on the planet. Proven techniques to get underground to sample these environments, and get below the disruptive influence of the surface oxidant and radiation regime, will be critical for future astrobiology missions to Mars. We will develop and test a novel ultrasonic corer in a Mars analog environment, the McMurdo Dry valleys, Antarctica, and to detect and describe life in a previously unstudied extreme ecosystem.

Previous data from Lake Vida, one of the largest lakes in the McMurdo Dry Valleys of Antarctica, reveal that a NaCl brine with a salinity seven times sea water and temperature constantly below -10^oC lies beneath ~20 m of ice that is at least 2,800 radiocarbon years old. Microbial mats occur throughout the ice column and are viable upon thawing. Sediment layers in the ice effectively block incoming solar radiation. Ice below 16 m depth and the brine body have never been sampled directly due to logistical constraints. We will use the ultrasonic corer to make in situ ecosystem measurements, and acquire samples to be further analyzed upon retrieval.

Two general hypotheses will be tested:
H₁: Microbial communities within the brine (including brine pockets in the deep ice) and benthic sediments are currently viable, active and affect the present-day geochemistry of the lake.
H₂: Ice, brine and benthos of Lake Vida contain geochemical signatures of past microbiological activity.

Our research combines science, technology and a field campaign to further our understanding of the limits and constraints on life in extreme environments. Lake Vida provides the unique opportunity to investigate lake ecosystems on the edge of existence to determine what conditions may lead to the eventually complete freezing of a lake and the subsequent development/evolution of microbial communities and geochemical signatures. The combined hyper-saline, aphotic, atmospherically isolated and cold conditions in Lake Vida make it potentially among the most extreme aquatic environments on Earth. These conditions were likely to have been present during the last stages of purported lakes on Mars near the end of its water-rich past.

The technology developed and experience gained from the research will be directly applicable to future Mars missions. The ultrasonic gopher will be light-weight and low power, and our field campaign will test its operation through 20 m of sediment-laden ice in order to sample brine, analogous to Martian materials likely to be encountered. Application of our results to shallow coring on Europa should also be possible.

Schedule:
July 2005: Field test on glacier in Oregon
Late October through November 2005: Field season
March 2006: Samples and equipment return from field
All 2006: Sample analysis, data workup, writing

Links:

JPL Nondestructive Evaluation and Advanced Actuators (NDEAA) Technologies
Peter Doran's Web site