Year: 2024
Type: article
Abstract: Aims. We investigate the impact of CO2 on the distribution of water on TRAPPIST-1 e, f, and g during the magma ocean stage. These potentially habitable rocky planets are currently the most accessible for astronomical observations. A constraint on the volatile budget during the magma ocean stage is a key link to planet formation and also to judging their habitability. Methods. We expanded the MagmOc module of the VPLanet environment to perform simulations with 1-100 terrestrial oceans (TOs) of H2O with and without CO2 and for albedos 0 and 0.75. The CO2 mass was scaled with initial H2O by a constant factor between 0.1 and 1. Results. The magma ocean state of rocky planets begins with a CO2-dominated atmosphere but can evolve into a H2O dominated state, depending on initial conditions. For less than 10 TO initial H2O, the atmosphere tends to desiccate and the evolution can end with a CO2 dominated atmosphere. Otherwise, the final state is a thick (>1000 bar) H2O-CO2 atmosphere. Complete atmosphere desiccation with less than 10 TO initial H2O can be significantly delayed for TRAPPIST-1 e and f, when H2O has to diffuse through a CO2 atmosphere to reach the upper atmosphere, where photolysis due to extreme ultra violet irradiation occurs. As a consequence of CO2 diffusion-limited water loss, the time of mantle solidification for TRAPPIST-1 e, f, and g can be significantly extended compared to a pure H2O evolution by up to 40 Myrs for an albedo of 0.75 and by up to 200 Mys for an albedo of 0. The addition of CO2 further results in a higher water content in the melt during the magma ocean stage. Thus, more water can be sequestered in the solid mantle. However, only up to 6% of the initial water mass can be stored in the mantle at the end of the magma ocean stage. Our compositional model adjusted for the measured metallicity of TRAPPIST-1 yields for the dry inner planets (b, c, d) an iron fraction of 27 wt%. For TRAPPIST-1 e, this iron fraction would be compatible with a (partially) desiccated evolution scenario and a CO2 atmosphere with surface pressures of a few 100 bar. Conclusions. A comparative study between TRAPPIST-1 e and the inner planets may yield the most insights about formation and evolution scenarios by confronting, respectively, a scenario with a desiccated evolution due to volatile-poor formation and a volatile-rich scenario with extended atmospheric erosion.
Source: Astronomy and Astrophysics
Authors: L. Carone, R. Barnes, L. Noack, K. Chubb, P. Barth, B. Bitsch, A. Thamm, A. Balduin, R. Garcia, Ch. Helling
Institutions: Austrian Academy of Sciences, University of St Andrews, Space Research Institute, Max Planck Institute for Astronomy, University of Washington, Freie Universität Berlin, University of Bristol, University of Stuttgart, Stuttgart Center for Simulation Science, University College Cork, Graz University of Technology
Language: English
Subfield: Astronomy and Astrophysics
Field: Physics and Astronomy
Domain: Physical Sciences
SDG: Climate action
Open Access status: gold
Estimated APC paid: $1,732
Awards: G1276317268, G2001806450, G2004165633, G2114958053, G2188020438, IN ORDER TO MODEL THE OXIDATION BEHAVIOR OF THE FIBERS IT IS CRUCIAL TO UNDERSTAND THE FLOW NEAR AND WITHIN THE TPS AT THE FIBER SCALE. ONE OF THE CHALLENGES OF ATTEMPTING TO MODEL THIS TYPE OF FLOW AT THIS SCALE IS THAT THE FIBERS ARE VERY SMALL ( 1 TO 10 M) THE MEAN FREE PATH OF THE MOLECULES AND ATOMS IN THE GAS IS OFTEN ON THE ORDER OF THE FIBERS THEMSELVES. WHEN THIS IS THE CASE THE NAVIER-STOKES EQUATIONS WHICH ARE BASED ON A CONTINUUM ASSUMPTION ARE NO LONGER VALID. FOR THIS KIND OF FLOW THE VALUE OF THE KNUDSEN NUMBER - THE RATIO BETWEEN THE MEAN FREE PATH OF THE GAS AND A RELEVANT LENGTH SCALE IN THIS CASE THE AVERAGE PORE DIAMETER - ENCOUNTERED BY THE MATERIAL IS>0.02. THIS SUGGEST THAT MODELING THESE FLOWS REQUIRES A METHOD WHICH CAN ACCOUNT FOR A RANGE OF KNUDSEN NUMBERS AND IS PARTICULARLY EFFECTIVE IN MORE RAREFIED REGIMES. ONE SUCH METHOD IS DIRECT SIMULATION MONTE CARLO (DSMC) WHICH CAN EFFICIENTLY BE USED TO MODEL THE GAS PHASE AND GAS-SURFACE INTERACTIONS PHENOMENA. DSMC IS A STOCHASTIC PARTICLE BASED METHOD WHICH IS VALID -- GIVEN SUFFICIENT COMPUTATIONAL RESOURCES -- FOR ALL KNUDSEN NUMBERS. ADDITIONALLY THE METHOD CAN HANDLE CONVECTION AS WELL AS MANY OTHER RELEVANT PHYSICAL PHENOMENA. WHEN THE HIGH TEMPERATURE FLOW INTERACTS WITH THE FIBERS CHEMICAL REACTIONS -- MAINLY OXIDATION -- TAKES PLACE. THIS TYPICALLY OCCURS IN A CHARACTERISTIC SURFACE CONSUMPTION MODE REFERRED TO AS PITTING. RATHER THAN CONSUMING THE SURFACE UNIFORMLY OXIDATION PROCEEDS PREFERENTIALLY THROUGH THE GROWTH IN DEPTH OF MULTIPLE CAVITIES SCATTERED ON THE ORIGINALLY SMOOTH SURFACE OF THE FIBER. THIS PHENOMENON RESULTS IN A NET INCREASE OF THE EXPOSED SURFACE WHICH IN ADDITION FORMS HIGHLY REACTIVE SITES. BOTH EFFECTS ACCELERATE THE RATE OF OXIDATION POTENTIALLY COMPROMISING THE STRENGTH OF THE FIBERS. THIS MAY LEAD TO THE EARLY BREAK-UP OF THE FIBERS REDUCING DRAMATICALLY THE PROTECTING PROPERTIES OF THE TPS. PITTING CAN BE TRACED TO THE MOLECULAR MECHANISM OF CARBON OXIDATION WHICH IS THE RESULT OF FOUR MAIN PROCESSES NAMELY OXYGEN ADSORPTION SURFACE DIFFUSION SURFACE REACTION AND PRODUCTS DESORPTION. CURRENTLY AVAILABLE KINETIC MECHANISMS ACCOUNT FOR THESE PROCESSES THROUGH EFFECTIVE GLOBAL REACTIONS RATES FITTED TO AVAILABLE EXPERIMENTAL DATA. THEY CAN PREDICT REASONABLY WELL THE MACROSCOPIC OVERALL BEHAVIOR OF CARBON MATERIALS ESSENTIALLY BECAUSE THEY ARE FINE-TUNED TO DO SO. HOWEVER NONE OF THEM ADDRESSES THE MICROSCOPIC NATURE OF OXIDATION AND THEREFORE CANNOT ACCOUNT FOR PITTING. ONCE THE FLOW AROUND THE FIBERS IS ACCURATELY MODELED AND THE GAS SURFACE INTERACTIONS APPROPRIATELY ACCOUNTED FOR IT IS POSSIBLE TO MODEL THE THERMO-MECHANICAL RESPONSE OF THE FIBERS. THIS IS ACHIEVED USING A MATERIAL RESPONSE CODE STRONGLY COUPLED TO A STEADYSTATE STRUCTURAL MECHANICS CODE. THE STRESS ACTING ON THE FIBER RESULTS FROM A COMBINATION OF THERMAL STRAIN INTERNAL PRESSURE AND EXTERNAL SHEAR STRESS COMING FROM BOTH THE NEAR SURFACE FLOW FIELD AND PYROLYSIS GAS BLOWING. TO CORRECTLY PREDICT THE LEADING FACTORS OF SPALLATION AND FAILURE OF THE TPS IT IS CRITICAL TO ACCURATELY MODEL BOTH THE DISTRIBUTIONS AND MAGNITUDES OF STRESSES WITHIN MATERIALS IN A STRONGLY COUPLED APPROACH., G3023719243, Virtual Laboratories for Exoplanets and Planet Forming Disks, G3345895242, G3967419199, G4937468798, G5392910068, G6281504974, G6838816059, G754140692, G7628805400, G7984235579, G8512683158, TO ENABLE AND ADVANCE NASA S SEARCH FOR LIFE BEYOND THE SOLAR SYSTEM THE VIRTUAL PLANETARY LABORATORY TEAM WILL FOCUS ON A COMPELLING SCIENTIFIC QUESTION: HOW DO WE RECOGNIZE WHETHER AN EXOPLANET CAN OR DOES SUPPORT LIFE? IN ADVANCE OF CHALLENGING OBSERVATIONS THE VPL WILL COMBINE SCIENTIFIC MODELS OBSERVATIONS AND FIELD AND LABORATORY DATA FROM MANY DISCIPLINES TO EXPLORE HOW A PLANET BECOMES AND REMAINS HABITABLE AND IDENTIFY NEW BIOSIGNATURES IN THE CONTEXT OF THEIR ENVIRONMENTS. THIS RESEARCH WILL INFORM TARGET SELECTION FOR JWST FROM K2 TESS AND GROUND-BASED EXOPLANET DISCOVERIES; HELP OBSERVERS RECOGNIZE THE SIGNS OF PLANETARY HABITABILITY AND LIFE; AND INFORM UPCOMING NASA MISSIONS THAT WILL OBSERVE TERRESTRIAL EXOPLANETS SUCH AS JWST AND THE HABEX OST AND LUVOIR MISSION CONCEPTS. FIVE RESEARCH TASKS WILL ADDRESS OUR SCIENTIFIC QUESTION. TASKS A-D PROVIDE A SUITE OF SELF-CONSISTENT PLANETARY ENVIRONMENTS BASED ON DATA AND MODELS THAT ARE VALIDATED AGAINST SOLAR SYSTEM PLANETS. THESE PLANETARY ENVIRONMENTS ARE THEN INPUT TO TASK E TO SIMULATE PLANETARY OBSERVATIONS AND DETERMINE THE DETECTABILITY OF SIGNS OF HABITABILITY AND LIFE. TASK A: SOLAR SYSTEM ANALOGS FOR EXOPLANETS. WE WILL USE OBSERVATIONS AND ATMOSPHERIC MODELS OF EARTH AND VENUS AS WELL AS REALISTIC SIMULATIONS OF THE DISTANT SOLAR SYSTEM AND OTHER PLANETARY SYSTEMS TO EXPLORE PROCESSES AND REMOTE-SENSING DISCRIMINANTS RELEVANT TO HABITABLE ENVIRONMENTS BIOSIGNATURES AND FALSE POSITIVES. TASK B: THE EARTH THROUGH TIME. WE WILL UNDERTAKE AN INTERDISCIPLINARY SYNTHESIS OF FIELD LABORATORY AND MODELING EFFORTS TO CONSTRAIN ENVIRONMENTAL ECOLOGICAL AND REMOTELY OBSERVABLE PARAMETERS OF EARLY EARTH AND SIMILAR EXOPLANETS AROUND OTHER STARS AS A FUNCTION OF DOMINANT METABOLISM. TASK C: THE HABITABLE PLANET. WE WILL DEVELOP AND USE COUPLED STELLAR ORBITAL INTERIOR AND 1-D TO 3-D ATMOSPHERIC MODELS TO EXPLORE TERRESTRIAL EXOPLANET FORMATION DYNAMICS COMPOSITION ATMOSPHERIC EVOLUTION AND HABITABILITY. THESE ANALYSES WILL INFORM HABITABILITY ASSESSMENTS TO PRIORITIZE PROMISING EXOPLANETS FOR BIOSIGNATURE SEARCHES. TASK D: THE LIVING PLANET. WE WILL INTEGRATE FIELD AND LABORATORY RESEARCH WITH COUPLED CHEMICAL CLIMATE AND ECOSYSTEM MODELS TO EXPLORE THE NATURE AND DETECTABILITY OF BIOSIGNATURES FOR DIFFERENT GEOCHEMICAL AND STELLAR ENVIRONMENTS. WE WILL IDENTIFY NEW REMOTESENSING ATMOSPHERIC SURFACE AND TEMPORAL BIOSIGNATURES AND THEIR FALSE POSITIVES AND NEGATIVES AND QUANTIFY THE ENVIRONMENTAL LIMITS TO PHOTOSYNTHETIC PRODUCTIVITY. TASK E: THE OBSERVER. WE WILL COMBINE OBSERVATIONS ANALYSIS TECHNIQUES AND SIMULATIONS TO IMPROVE THE DETECTION AND CHARACTERIZATION OF POTENTIALLY HABITABLE EXOPLANETS. WE WILL IMPROVE RETRIEVAL OF PLANETARY PROPERTIES FROM EXOPLANET MAPPING AND FROM DIRECT IMAGING TRANSIT TRANSMISSION AND HIGH-RESOLUTION SPECTROSCOPY. OUR ANALYSES WILL DETERMINE OPTIMAL MEASUREMENTS AND OBSERVATION STRATEGIES FOR TERRESTRIAL EXOPLANET CHARACTERIZATION. THE PROPOSED EFFORT BENEFITS ASTROBIOLOGY AND THE NAI WITH A PROVEN PRODUCTIVE INTERDISCIPLINARY SCIENCE TEAM WHOSE RESEARCH ADDRESSES KEY ASTROBIOLOGY PROGRAM GOALS INCLUDING CONSTRUCTING HABITABLE WORLDS IDENTIFYING EXPLORING AND CHARACTERIZING ENVIRONMENTS FOR HABITABILITY AND BIOSIGNATURES AND THE COEVOLUTION OF LIFE AND THE PHYSICAL ENVIRONMENT. THE UW S ASTROBIOLOGY DUAL-TITLE PHD PROGRAM AND OUR ASTROBIOLOGY RESEARCH OPPORTUNITIES FOR MINORITY UNDERGRADUATES STRONGLY SUPPORT THE TRAINING OF THE NEXT GENERATION OF ASTROBIOLOGISTS. OUR TEAM MEMBERS WILL CONTINUE TO PROVIDE KEY SCIENTIFIC LEADERSHIP FOR RELEVANT NASA MISSIONS. THE VPL WILL LEVERAGE THE MASSIVELY INTERDISCIPLINARY COLLABORATION ENABLED BY THE NAI TO PROVIDE A UNIQUE SYNTHESIS OF NASA PLANETARY AND EARTH SCIENCE MISSION DATA MODELING AND RETRIEVAL TECHNIQUES THAT INFORM AND SUPPORT NASA ASTROBIOLOGY AND ASTROPHYSICS MISSION OBJECTIVES.
OpenAlex ID: W4405741762