Titan under a red giant sun: A new kind of “habitable” moon
Abstract
We explore the response of Titan's surface and massive atmosphere to the change in solar spectrum and intensity as the sun evolves into a red giant. Titan's surface temperature is insensitive to insolation increases as the haze-laden atmosphere “puffs up” and blocks more sunlight. However, we find a window of several hundred Myr exists, roughly 6 Gyr from now, when liquid water-ammonia can form oceans on the surface and react with the abundant organic compounds there. The window opens due to a drop in haze production as the ultraviolet flux from the reddening sun plummets. The duration of such a window exceeds the time necessary for life to have begun on Earth. Similar environments, with ∼200K water-ammonia oceans warmed by methane greenhouses under red stars, are an alternative to the ∼300K water-CO2 environments considered the classic “habitable” planet.
- Publication:
-
Geophysical Research Letters
- Pub Date:
- November 1997
- DOI:
- 10.1029/97GL52843
- Bibcode:
- 1997GeoRL..24.2905L
- Keywords:
-
- Red Giant Stars;
- Exploration;
- Geophysics;
- Sun;
- Atmospheric Temperature;
- Atmospheric Chemistry;
- Greenhouses;
- Planetology: Solid Surface Planets: Surface materials and properties