Life et al.

a geodynamic perspective


The evolution of the Earth’s interior below our feet and the tectonic mode strongly impact the redox gradients and the composition of the atmosphere and the crust. The evolution of planet interiors and tectonics, therefore, impact the evolution of life and climate. On the other hand, life and climate impact mantle convection and plate tectonics through the water cycle and rheological modifications of the crust. My major goal is to unite geodynamics with biogeochemistry on land and in oceans in order to fully understand life and climate as a planetary global geophysical phenomenon. A beautiful part of this research is the close link between global and local geophysical modeling and Deep time observations on Earth - of geologic, paleontological, geochemical, and also phylogenetic nature - as well as the connection to planet habitability across the solar system and on exoplanets.








All Right Reserved, 2016 Vlada Stamenkovic.

  1. Bullet HIGHLIGHTS

  2. BulletEarth with much less water and desert or Dune worlds could be much more common and habitable than previously thought: We explore the minimum distance from a host star where an exoplanet could potentially be habitable in order not to discard close-in rocky exoplanets for follow-up observations. We find that the inner edge of the Habitable Zone for hot desert worlds can be as close as 0.38 AU around a solar-like star, if the greenhouse effect is reduced (∼ 1% relative humidity) and the surface albedo is increased. We consider a wide range of atmospheric and planetary parameters such as the mixing ratios of greenhouse gases (water vapor and CO2), surface albedo, pressure, and gravity. Intermediate surface pressure (∼1–10 bars) is necessary to limit water loss and to simultaneously sustain an active water cycle. We additionally find that the water loss timescale is influenced by the atmospheric CO2 level, because it indirectly influences the stratospheric water mixing ratio. If the CO2  mixing ratio of dry planets at the inner edge is smaller than 10−4, the water loss timescale is ∼ 1 billion years, which is considered here too short for life to evolve. We also show that the expected transmission spectra of hot desert worlds are similar to an Earth-like planet. Therefore, an instrument designed to identify biosignature gases in an Earth-like atmosphere can also identify similarly abundant gases in the atmospheres of dry planets. Our inner edge limit is closer to the host star than previous estimates. As a consequence, the occurrence rate of potentially habitable planets is larger than previously thought.

  3. BulletSerpentinization and Fischer-Tropsch type reactions are much more uncertain than what we assumed so far: Serpentinization and Fischer-Tropsch type (FTT) reactions (abbreviated to SFTT reactions) are crucial processes for understanding the origins of life, the limits of conditions for life, and the interactive dynamics of living and non-living systems, as they can provide hydrogen, methane, and other hydrocarbons to fuel life’s origin and its maintenance. However, there is a great lack of agreement on how the kinetics of SFTT reactions change with temperature and pressure, and hence how SFTT reactions vary with depth through a planet’s interior. Suggestions that early life that arose might have survived challenges such as the Late Heavy Bombardment by sustaining itself in the subsurface, make the exploration of the depth-dependent geophysical drivers for the emergence and maintenance of subsurface life through reduced gas production from water-rock reactions an important, but under-investigated aspect of life’s origins and planetary habitability. I aim to assess the depth-dependent kinetics of SFTT reactions along the geotherm by uniting local and global geophysical time-dependent 3D planet interior models with field work in both low-temperature and high-temperature SFTT regions with collaborators across the globe. This approach is novel in its interdisciplinarity and in its goal to not only model local processes but to embed them in a global 3D context of SFTT reactions - giving insight on whether the origin of life was fueled by low-temperature processes within or by high-temperature reactions deep below the “habitable zone”.


  1. Bullet FURTHER READING

  2. BulletStamenković, V., 2011, 2015. Serpentinization. In: Gargaud, M., et al., (Eds.), Encyclopedia of Astrobiology, Part 19. Springer, 1505-1506.

  3. BulletZsom, A., Seager, S., De Wit, J., Stamenković, V., 2013. Towards the minimum inner edge distance of the habitable zone. The Astrophysical Journal, 778, 109-126.