Origins of Life

I investigate potential pathways for the origins of life where abiotically produced building blocks participate in self-propagating and increasingly complex systems that resemble life.

In Search of the RNA World on Mars

Zuber Lab, Szostak Lab, & James W. Head III

Latest publication: Mojarro et al. (2021) Geobiology, PDF, https://doi.org/10.1111/gbi.12433

Advances in origins of life research and prebiotic chemistry suggest that life as we know it may have emerged from an earlier RNA World. However, it has been difficult to reconcile the conditions used in laboratory experiments with real-world geochemical environments that may have existed on the early Earth and hosted the origins of life. This challenge is due to geologic resurfacing and recycling that have erased the overwhelming majority of the Earth’s prebiotic history. We therefore propose that Mars, a planet frozen in time, comprised of many surfaces that have remained relatively unchanged since their formation >4 Gya, is the best alternative to search for environments consistent with geochemical requirements imposed by the RNA world.

In this study we synthesize in situ and orbital observations of Mars and modeling of its early atmosphere into solutions containing a range of pHs and concentrations of prebiotically relevant metals (Fe2+, Mg2+, and Mn2+) spanning various candidate aqueous environments. We then experimentally determine RNA degradation kinetics due to metal-catalyzed hydrolysis (cleavage) and evaluate whether early Mars could have been permissive towards the accumulation of long-lived RNA polymers.

Extra-Terrestrial Organics

Sample Analysis at Mars - SAM

Summons Lab & the SAM Team

Latest publication: Mojarro et al. (2023) JGR Planets, PDF, https://doi.org/10.1029/2023JE007968

The Sample Analysis at Mars (SAM) instrument aboard the Curiosity Rover on Mars can detect and analyze organic molecules that might be used by life as we know it. SAM does this by heating scooped soil or drill samples in order to vaporize and uncover any organic content that might be present. In addition, SAM can detect different types of organics that have more direct similarities to those used by modern organisms by adding one of two different kinds of chemical reagents prior to heating. However, shortly after arriving at Mars, it was discovered that one type of reagent, called MTBSTFA, was leaking inside of SAM with the potential to eventually interfere with the other, called TMAH, whenever it might be utilized. This study therefore reports on the chemical interactions between the two reagents and how they might impact the detection of indigenous organics on Mars. We determined heating samples in the presence of both reagents produces a series of byproducts which obscure the identification of organic compounds of interest. Still, despite analytical challenges, it is possible SAM may detect different types of organics which have yet to be detected on Mars with TMAH despite interference from leaking MTBSTA.

OSIRIS-REx Sample Return

GSFC Astrochemitry Lab & the OSIRIS-REx Team

Latest publication: Mojarro et al. (2024) 55th Lunar and Planetary Science Conference (LPSC), PDF, https://www.hou.usra.edu/meetings/lpsc2024/pdf/1219.pdf

A longstanding question regarding the formation and evolution of the solar system concerns the potential sources and diversity of complex organic compounds which may have contributed to the origins of life on the early Earth. One possibility is that organics synthesized within the early formation of our solar system may fundamentally represent the most signiHcant source of building blocks (amino acids, sugars, nucleobases). Therefore, organic-rich asteroids and/or meteorites which have persisted with minimal alteration since their formation may serve as time capsules of the primordial solar system, which we can investigate to better understand our planetary and prebiotic origins.