Planet Modeling

1. Planet Modeling White Paper Authors: Amanda Brecht, Thomas Bristow, David Des Marais, EldarNoeDobrea, Jennifer Heldmann, Jeff Hollingsworth, Melinda Kahre, Alex Kling, Jeff Moore, Kathryn Steakley, Carol Stoker, OrkanUmurhan, Oliver White. • Overview and Objectives: • Computer simulations of planetary atmospheric, climatic, geological, and geochemical phenomena aim to constrain what processes and conditions are necessary for such phenomena to take place in the evolution of worlds. • A synergistic relationship exists amongst these modeling disciplines that strengthens each of them beyond what any one is capable of alone. • Atmospheric and Global Climate Modeling (GCM): Isolate, quantify, and understand the processes that control the current and past thermal and dynamical states of atmospheres of solid-surface bodies in our solar system and beyond. • Geochemical and Spectroscopic Modeling (GSM): Reconstruct ancient physiochemical conditions in near-surface environments to identify the characteristics and distribution (both temporally and spatially) of potentially habitable solar system environments. • Landform Evolution Modeling (LEM): Simulate the evolution of planetary landscapes through multiple, interacting geological processes acting simultaneously and/or sequentially at different rates upon the terrain.

2. 2018 Planet Modeling Summary • Atmospheric and Global Climate Modeling: • Pluto GCM development has been initiated (Bertrand et al., 2018, 2019). • Mars GCM legacy dynamical core (an Arakawa C-grid) has transitioned to the highly parallelized and scalable NOAA/GFDL cubed-sphere finite-volume dynamical core (Kahre et al., 2018; Haberle et al., 2019). • Venus thermospheric GCM now includes planetary waves and a non-uniform lower boundary (Brecht et al., 2018). • Geochemical and Spectroscopic Modeling (GSM): • Geochemical models of early Mars have been enhanced by mineralogical evidence for fluctuations in levels of Gale crater lake and atmospheric infiltration that, in turn, potentially affected nutrient redistribution and gases that help regulate climate (Bristow et al., 2018). • NoeDobrea has estimated water ice abundance in Martian regolith from color imaging. • Initiation of development of advanced radiative transfer reflectance code that includes emission by fluorescence and Raman scattering. • Landform Evolution Modeling: • Studies published on deciphering the nature and origins of landforms in the Pluto system: Pluto’s bladed terrain (Moore et al., 2018), Pluto’s washboard terrain (White et al., 2019), Charon’s smooth plains (Beyer et al., 2019). • Moore and Umurhan have published on penitentes on Europa, a study of significance for any future lander targeted there (Hobley et al., 2018). • The Ames Stereo Pipeline is being used to generate stereo topography for the Kuiper belt object UltimaThule, which will feed into LEM studies of it.

3. Alignment with NASA Goals and Future Missions • Benefit to and alignment with NASA goals: • The goals of the planet modeling group are directly relevant to the 2018 NASA Strategic Plan objective 1.1 to “understand the Sun, Earth, Solar System, and Universe”. • Our objectives address requested capabilities in the Science Modeling goal (11.2.4) of the 2015 TA 11 NASA Technology Roadmap for Modeling, Simulation, Information Technology, and Processing. • Our modeling directly pertains to the topic in the 2015 NASA Astrobiology Strategy of ‘identifying, exploring, and characterizing environments for habitability and biosignatures’. • How planet modeling supports relevant NASA missions: • Planet modeling constrains the probable range of conditions and materials (surface and atmospheric) that prevail at target sites based on existing remote sensing observations. • This provides guidance for future missions by allowing instrumentation and observation planning to be designed accordingly, e.g. Mars 2020 rover / Next Mars Orbiter (GCM, LEM, GSM) & Europa Clipper (LEM, GSM). • In anticipation of forthcoming NASA-related lunar missions (e.g. CLPS), LEM and GSM will yield results on the transport and stability of lunar volatilesthat are highly relevant to in situ resource utilization and associated exploration, as well lunar science.

4. Milestones, Year 1 • Milestones, Year 1 (2019): • Test and validate the new Mars GCM capabilities and incorporation of physics packages for early Mars climates into the new dynamical core framework. • Provide active modeling support to the Mars community: Update the engineering-level MARS-GRAM and perform cutting-edge Mars research (e.g. in prep: Bertrand et al.; Wilson et al.; Kling et al.). • Develop radiative transfer modules to establish the theoretical framework and tools needed to support SSW, PDART, and Mars 2020 proposals and laboratory investigations into the geochemical evolution of the surfaces of Mars, the Moon, and Europa.  • Update spectroscopic and analytical capabilities of the existing geochemical laboratory in preparation for these investigations. • Adapt existing LEM modules (in particular cratering processes) to model exhumation, transport, and re-burial of volatile constituents on the Moon, especially at the poles where cold trapping can occur. • Develop new LEM modules that are applicable to fluid behavior (e.g. dissolution, plastic deformation, glacial erosion) on Mars, Titan, and Pluto. • Begin/continue synergistic relationship between Pluto and Mars GCM and LEM.

5. Milestones, Years 2-5 & 6-10 • Milestones, Years 2-5 (2020-2024): • Develop and test an exoplanet GCM. • Advance the Venus thermospheric GCM in support of proposed Venus missions. • Establish a framework and infrastructure for consolidating and publishing web-based, model-relevant databases and libraries. • Maintain a consistent funding and hiring regime for the GCM, LEM, and GSM groups and their staffs (now only GCM) so as to permit meaningful integration of them and to bolster the yield of high-impact science that they can produce. • Guarantee support for existing Ames facilities (procurements are critical) that directly benefit the planetary modeling work, including the Ames Stereo Pipeline and spectroscopic lab equipment. • Establish a standing working group to gauge how the skills and interests of our research groups complement and feed into those of others, for groups both within and outside of Ames. • Milestones, Years 6-10 (2025+): • Provide a path towards tenure for promising scientists as civil servants, while concurrently hiring recognized civil servants from elsewhere (succession). • Tackle complex issues related to climate history and valley formation on Mars and Titan, and atmosphere-surface interactions on Pluto. • Develop a quantitative model framework to characterize the environmental conditions and habitability of past planetary environments using observations of the chemistry and mineralogy of crustal materials.