EGU General Assembly 2021
© Author(s) 2022. This work is distributed under
the Creative Commons Attribution 4.0 License.

Venus, an Astrobiology Target

Sanjay Limaye1, Rakesh Mogul2, Kevin Baines3, Mark Bullock4, Charles Cockell5, James Cutts3, Diana Gentry6, James Head7, Kandis-Lea Jessup8, Vladimir Kompanichenko9, Yeon Joo Lee10, Richard Mathies11, Tetyana Milojevic12, Rosalyn Pertzborn1, Lynn Rothschild6, Dirk Schulze-Makuch13, David Smith6, and Michael Way14
Sanjay Limaye et al.
  • 1University of Wisconsin-Madison, Space Science and Engineering Center, Madison, Wisconsin, United States of America (
  • 2Cal Poly, Pomona, California, USA
  • 3Jet Propulsion Laboratory, California Institute of Technology, Psadena, California, USA
  • 4Science and Technology Corp., Hampton, Virgninia, USA
  • 5University of Edinburgh, Edinburg, UK
  • 6NASA Ames Research Center, Mountain View, California, USA
  • 7Planetary Science Institute, Tucson, Arizona, USA
  • 8Brown University, Providence, Rhode Island, USA
  • 9Southwest Research Institute, Boulder, Colorado, USA
  • 10ICARP, Russian Academy of Science, Birobidzhan, Russia
  • 11Technical University of Berlin, Berlin, Germany
  • 12University of California, Berkeley, California, USA
  • 13University of Vienna, Vienna, Austria
  • 14Tokyo University of Technology, Tokyo, Japan

The interest in the possibility of life on Venus is driven not just by curiosity about life originating in another Earth-like environment, but because of the possibility that life may be playing a critical role in the planet’s present, and possibly its past, atmospheric state. The brilliance of Venus in the night sky (as viewed from Earth) is due to its highly reflective cloud cover, about 28 km thick at the equator.  Its spectral albedo is about 90% at wavelengths > 500 nm, but it drops gradually to about 40% around 370 nm before rising slightly at shorter wavelengths.  This albedo drop is due to the presence of several absorbers in the atmosphere and the cloud cover.  A very large fraction of the energy absorbed by Venus is at ultraviolet wavelengths with sulfur dioxide above the clouds contributing to the absorption below 330 nm; however, the identities of the other absorbers remain unknown.  The inability to identify the absorbers that are responsible for determining the radiative energy balance of Venus over the last century is a major impediment to understanding how the planet “works”, a major component of NASA’s efforts in planetary exploration.  Limaye et al. (Astrobiology 18, 1181-1198, 2018) presented a hypothesis suggesting that cloud-based microbial life could be contributors to the spectral signatures of Venus’ clouds, building upon previous suggestions of the possibility of life in the clouds of Venus.

Four interconnected themes for the exploration of Venus as an astrobiology target are: – (i) investigations focused on the likelihood that liquid water existed on the surface in the past leading to the potential for the origin and evolution of life, (ii) investigations into the potential for habitable zones within Venus’ clouds and Venus-like atmospheres, (iii) theoretical investigations into how active aerobiology may impact the radiative energy balance of Venus’ clouds and Venus-like atmospheres, and (iv) application of these investigative themes towards better understanding the atmospheric dynamics and habitability of exoplanets. These themes can serve as a basis for proposed Venus Astrobiology Objectives and suggestions for measurements for future missions, as per the goals and objectives developed by the Venus Exploration Analysis Group (VEXAG), which is sponsored by NASA to plan for the future exploration of Venus.  

A Venus Collection to be published in Astrobiology journal in 2021 will include papers from the  “Habitability of the Venus Cloud Layer”, Moscow (October 2019) workshop. 

How to cite: Limaye, S., Mogul, R., Baines, K., Bullock, M., Cockell, C., Cutts, J., Gentry, D., Head, J., Jessup, K.-L., Kompanichenko, V., Lee, Y. J., Mathies, R., Milojevic, T., Pertzborn, R., Rothschild, L., Schulze-Makuch, D., Smith, D., and Way, M.: Venus, an Astrobiology Target, EGU General Assembly 2021, online, 19–30 Apr 2021, EGU21-5999,, 2021.

Display materials

Display link Display file

Comments on the display material

to access the discussion