Related papers: Was Venus Ever Habitable? Constraints from a Coupl…
Present-day Mars is cold and dry, but mineralogical and morphological evidence shows that liquid-water existed on the surface of ancient Mars. In order to explain this evidence and assess ancient Mars's habitability, one must understand the…
The absence of plate tectonics and the young surface age (0.3-1 billion years) of Venus have led to diverse geodynamic models for Venus. The energetics of the Venusian interior drive these models; however, the lack of direct constraints on…
Terrestrial planets in the Habitable Zone of Sun-like stars are priority targets for detection and observation by the next generation of space telescopes. Earth's long-term habitability may have been tied to the geological carbon cycle, a…
Exoplanet exploration has revealed that many$\unicode{x2013}$perhaps most$\unicode{x2013}$terrestrial exoplanets formed with substantial H$_2$-rich envelopes, seemingly in contrast to solar system terrestrials, for which there is scant…
Life in the clouds of Venus, if present in sufficiently high abundance, must be affecting the atmospheric chemistry. It has been proposed that abundant Venusian life could obtain energy from its environment using three possible sulfur…
Earth has had oceans for nearly four billion years and Mars had lakes and rivers 3.5-3.8 billion years ago. However, it is still unknown whether water has ever condensed on the surface of Venus because the planet - now completely dry - has…
The TRAPPIST-1 system provides an extraordinary opportunity to study multiple terrestrial extrasolar planets and their atmospheres. Here we use the National Center for Atmospheric Research Community Atmosphere Model version 4 to study the…
A defining characteristic of the planet Venus is its thick, CO2-dominated atmosphere. Despite over fifty years of robotic exploration, including thirteen successful atmosphere probes and landers, our knowledge of N2, the…
The composition of an atmosphere has integrated the geological history of the entire planetary body. However, the long-term evolutions of the atmospheres of the terrestrial planets are not well documented. For Earth, there were until…
Nitrogen is the most common element in Earth's atmosphere and also appears to be present in significant amounts in the mantle. However, its long-term cycling between these two reservoirs remains poorly understood. Here a range of biotic and…
There are four different stable climate states for pure water atmospheres, as might exist on so-called "waterworlds". I map these as a function of solar constant for planets ranging in size from Mars size to 10 Earth-mass. The states are:…
It remains to be ascertained whether sub-Neptune exoplanets primarily possess hydrogen-rich atmospheres or whether a population of H$_2$O-rich "water worlds" lurks in their midst. Addressing this question requires improved modeling of…
The composition the atmosphere of Venus results from the integration of many processes entering into play over the entire geological history of the planet. Determining the elemental abundances and isotopic ratios of noble gases (He, Ne, Ar,…
During the post-main sequence phase of stellar evolution the orbital distance of the habitable zone, which allows for liquid surface water on terrestrial planets, moves out past the system's original frost line, providing an opportunity for…
Earth, Mars, and Venus, irradiated by an evolving Sun, have had fascinating but diverging histories of habitability. Although only Earth's surface is considered to be habitable today, all three planets might have simultaneously been…
Venus shares many similarities with the Earth, but concomitantly, some of its features are extremely original. This is especially true for its atmosphere, where high pressures and temperatures are found at the ground level. In these…
The climate of Mars likely evolved from a warmer, wetter early state to the cold, arid current state. However, no solutions for this evolution have previously been found to satisfy the observed geological features and isotopic measurements…
We present updated non-adiabatic and inhomogeneous evolution models for Uranus and Neptune, employing an interior composition of methane, ammonia, water, and rocks. Following formation trends of the gas giants, Uranus and Neptune formation…
The ability of a planet to maintain surface water, key to life as we know it, depends on solar and planetary energy. As a star ages, it delivers more energy to a planet. As a planet ages it produces less internal heat, which leads to…
The planetary mass and radius sensitivity of exoplanet discovery capabilities has reached into the terrestrial regime. The focus of such investigations is to search within the Habitable Zone where a modern Earth-like atmosphere may be a…