skip to main content

SciTech ConnectSciTech Connect

Title: RAPID WATER LOSS CAN EXTEND THE LIFETIME OF PLANETARY HABITABILITY

Two habitable planetary states are proposed: an aqua planet like the Earth and a land planet that has a small amount of water. Land planets keep liquid water under larger solar radiation compared to aqua planets. Water loss may change an aqua planet into a land planet, and the planet can remain habitable for a longer time than if it had remained an aqua planet. We calculate planetary evolution with hydrogen escape for different initial water inventories and different distances from the central star. We find that there are two conditions necessary to evolve an aqua planet into a land planet: the critical amount of water on the surface (M{sub ml}) consistent with a planet being a land planet, and the critical amount of water vapor in the atmosphere (M{sub cv}) that defines the onset of the runaway greenhouse state. We find that Earth-sized aqua planets with initial oceans <10% of the Earth's can evolve into land planets if M{sub cv} = 3 m in precipitable water and M{sub ml} = 5% of the Earth's ocean mass. Such planets can keep liquid water on their surface for another 2 Gyr. The initial amount of water and M{sub cv} are shown to be importantmore » dividing parameters of the planetary evolution path. Our results indicate that massive hydrogen escape could give a fresh start as another kind of habitable planet rather than the end of its habitability.« less
Authors:
;  [1] ;  [2] ;  [3]
  1. Department of Earth and Planetary Science, The University of Tokyo, Tokyo 113-0033 (Japan)
  2. Earth-Life Science Institute, Tokyo Institute of Technology, Tokyo 152-8550 (Japan)
  3. Space Science and Astrobiology Division, NASA Ames Research Center, California 94035 (United States)
Publication Date:
OSTI Identifier:
22518740
Resource Type:
Journal Article
Resource Relation:
Journal Name: Astrophysical Journal; Journal Volume: 812; Journal Issue: 2; Other Information: Country of input: International Atomic Energy Agency (IAEA)
Country of Publication:
United States
Language:
English
Subject:
79 ASTROPHYSICS, COSMOLOGY AND ASTRONOMY; COMPARATIVE EVALUATIONS; DISTANCE; HYDROGEN; LIQUIDS; MASS; PLANETS; SATELLITE ATMOSPHERES; SATELLITES; SOLAR RADIATION; SOLAR SYSTEM EVOLUTION; STARS; WATER; WATER VAPOR