Earth System Modeling, Comparative Planetary Climatologies and Remote Sensing

DESCRIPTION: We propose an unprecedented multi-pronged 3-D modeling approach to understand the habitability of Solar System rocky planets through time, and to use this foundation to inform the detection and characterization of habitable exoplanets in the future. 3-D modeling enables us to explore key dynamic components of planetary atmospheres.

Our prime science objective for this investigation is to address the following question: What is the history of planetary surface habitability in the Solar System, and what does this tell us about the potential habitability of planets orbiting other stars?

Our research will integrate four major innovative research components:

(1) Spin-orbit dynamical evolution of planets over Solar System history will be modeled to establish the probable ranges of variation of insolation patterns and rotation rates to which rocky planets with atmospheres have been subjected at various points in their history.

(2) The results will be used to drive 3-D simulations of planetary climates with a generalized General Circulation Model (GCM). We will focus on four planets/moons: (a) Earth, which has experienced various stages of habitability, documented by the geologic record; (b) Mars, now cold and dry but perhaps previously wet and possibly habitable; (c) Venus, an uninhabitable planet today but which may have had an ocean and been habitable in its early history; (d) Titan, too cold to be habitable but an analog to Earth’s and Venus’ past.

(3) Our Solar System planet simulations will be used as baselines for large ensembles of simulations with parameters perturbed from their a priori state that we will use to explore the range of habitable climates of exoplanets that may be detected by future spacecraft missions.

(4) From this database we will create synthetic hypothetical exoplanet visible-infrared spectra to use as inputs to planetary system spectral simulations that include both the planets and the interplanetary dust that obscures them. This will inform future exoplanet mission planning.

OUTCOMES: Resolving Orbital and Climate Keys of Earth and Extraterrestrial Environments with Dynamics (ROCKE-3D) is a three-dimensional General Circulation Model (GCM) developed at the NASA Goddard Institute for Space Studies for the modeling of atmospheres of solar system and exoplanetary terrestrial planets. Its parent model, known as ModelE2, is used to simulate modern Earth and near-term paleo-Earth climates. ROCKE-3D is an ongoing effort to expand the capabilities of ModelE2 to handle a broader range of atmospheric conditions, including higher and lower atmospheric pressures, more diverse chemistries and compositions, larger and smaller planet radii and gravity, different rotation rates (from slower to more rapid than modern Earth's, including synchronous rotation), diverse ocean and land distributions and topographies, and potential basic biosphere functions. The first aim of ROCKE-3D is to model planetary atmospheres on terrestrial worlds within the solar system such as paleo-Earth, modern and paleo-Mars, paleo-Venus, and Saturn's moon Titan. By validating the model for a broad range of temperatures, pressures, and atmospheric constituents, we can then further expand its capabilities to those exoplanetary rocky worlds that have been discovered in the past, as well as those to be discovered in the future.