Using Mars analog environments on Earth to understand what biological and geochemical cycling of carbon would look like on Mars.
About My Research
I use laboratory analysis, field work, and Curiosity rover data to understand the cycling of carbon and nitrogen on Mars, and whether life could have ever arisen elsewhere in our Solar System. I lead an experiment on the Sample Analysis at Mars (SAM) instrument on Curiosity to produce the first bulk carbon abundance and isotope measurements on Mars (Stern et al., PNAS, 2022). These measurements help us understand the sources and inventory of carbon on Mars, which in turn helps us understand whether complex organic chemistry (including life) ever evolved on Mars. I also use trace gas isotope measurements in Mars analog environments on Earth to understand what biological and geochemical cycling of carbon would look like on Mars. I also help develop instrumentation to measure stable isotopic composition of planetary materials in situ on other planetary surfaces.
How Picarro Analyzers Helped
The Picarro analyzer (specifically CO2/CH4 isotope analyzer) has been a very enabling instrument for my work in development of stable isotope instrumentation for spaceflight, as well as for making real-time (or simply rapid) C isotope measurements in remote locations as part of field campaigns to Earth environments that serve as analogs for Mars. Since 2011 I have been using Picarro analyzers as analogs for the tunable laser spectrometer (TLS) on the Sample Analysis at Mars (SAM) instrument on the Curiosity Rover. The TLS instrument measures high precision C, H, and O isotopes of CO2, CH4, and H2O. We measure the isotopic composition of gases both in the Mars atmosphere and evolved from the heating of Mars regolith. I have taken the Picarro in the field to remote laboratories (on research vessels in Svalbard, Norway) in order to measure the C isotopic composition of pyrolyzed carbonate samples to emulate the SAM instrument on Mars. In addition, I have used the Picarro to measure methane degassed from deep lake waters in Greenland lakes where active methanogenesis is occurring. We have also brought the instrument into the field (on a hunting carcass backpack) in Greenland to couple in a recirculating mode with homemade flux chambers, which allowed real time measurements of methane flux in permafrost wetlands. I have also used it to measure CO2 gradients in lava tubes on Mauna Loa to determine whether the the carbon isotopic composition of CO2 can be used to indicate biological activity in these environments. In the near future, I will bring the Picarro CH4/CO2 analyzer to Alaska to ground truth concentration measurements made during the demonstration of a very small multifunctional sensor in development for spaceflight. Bringing the Picarro into the field allows us to rapidly obtain isotope data and pinpoint samples of interest to take home for further analysis. It also allows us to characterize gradients in almost real time, and make sure we do not miss any important samples!
As part of method development of isotope instrumentation for spaceflight, I have also used the Water isotope analyzer to measure water evolved during the heating of clay minerals. This was performed on a glass line with a tube furnace, with water captured using a cold trap. This work allowed collection of different fractions of water evolved at different temperatures. This allowed us to better understand D/H measurement made in situ on Mars of clays in Mars materials.