Nancy Merino, Heidi S Aronson, Diana Bojanova, Jayme Feyhl-Buska, Michael L Wong, Shu Zhang, Donato Giovannelli

Prokaryotic life has dominated most of the evolutionary history of our planet, evolving to
occupy virtually all available environmental niches. Extremophiles, especially those thriving
under multiple extremes, represent a key area of research for multiple disciplines, spanning
from the study of adaptations to harsh conditions, to the biogeochemical cycling of elements.
Extremophile research also has implications for origin of life studies and the search for life on
other planetary and celestial bodies. In this article, we will review the current state of
knowledge for the biospace in which life operates on Earth and will discuss it in a planetary
context, highlighting knowledge gaps and areas of opportunity.