Speaker
Description
The latest decadal planetary science survey recommended an orbiter and probe mission to Uranus [1]. Set to launch within the decade, now is an opportune moment to review kinetic data relevant for the design of this mission. The dissociation rates of molecular hydrogen are relevant for more accurate assessment of the convective heating experienced by an entry probe. Furthermore, in the last 20 years, several advancements on potential energy surfaces (PES) of systems relevant for giant planet entries have been published [2-5]. Simulations have estimated peak temperatures in the stagnation line to be around 27,000, 18,000, and 15,000 K for Jupiter [6] Saturn [7] and Uranus [7], respectively. Performing experiments at such high-temperatures is a challenging endeavor. The quasi-classical trajectory (QCT) method is useful to obtain kinetic data at such extreme temperatures [8] when quantum effects are negligible and as long as an accurate PES is available. The aim of this work is to propose state-to-state and global dissociation rates for molecular hydrogen by collisions with H and He. Additionally, a discussion on what remains to be accomplished for an updated global and state-to-state models for entry in Uranus is done.
[1] National Academies of Sciences, Engineering, and Medicine. 2022. Origins, Worlds, and Life: A Decadal Strategy for Planetary Science and Astrobiology 2023-2032. Washington, DC: The National Academies Press. doi.org/10.17226/26522 (2022)
[2] Mielke, S. L., Garrett, B. C. & Peterson, K. A. A hierarchical family of global analytic Born-Oppenheimer potential energy surfaces for the H+H2 reaction ranging in quality from double-zeta to the complete basis set limit. J. Chem. Phys. 116, 4142–4161 (2002).
[3] Mielke, S. L., Schwenke, D. W., Schatz, G. C., Garrett, B. C. & Peterson, K. A. Functional representation for the born-oppenheimer diagonal correction and born-huang adiabatic potential energy surfaces for isotopomers of H3. J. Phys. Chem. A 113, 4479–4488 (2009)
[4] Bakr, B. W., Smith, D. G. A. & Patkowski, K. Highly accurate potential energy surface for the He-H2 dimer. J. Chem. Phys. 139, (2013).
[5] Thibault, F. et al. Rovibrational line-shape parameters for H2 in He and new H2-He potential energy surface. J. Quant. Spectrosc. Radiat. Transf. 202, 308–320 (2017).
[6] Santos Fernandes, L., Lopez, B. & Lino Da Silva, M. Computational fluid radiative dynamics of the Galileo Jupiter entry. Phys. Fluids 31, (2019).
[7] Palmer, G., Prabhu, D. & Cruden, B. A. Aeroheating uncertainties in uranus and saturn entries by the Monte Carlo method. J. Spacecr. Rockets 51, 801–814 (2014).
[8] Jaffe, R. L., Schwenke, D. W. & Panesi, M. First Principles Calculation of Heavy Particle Rate Coefficients. Hypersonic Nonequilibrium Flows Fundam. Recent Adv. 103–158 (2015) doi:10.2514/5.9781624103292.0103.0158.
Summary
The latest decadal planetary science survey recommended an orbiter and probe mission to Uranus [1]. Set to launch within the decade, now is an opportune moment to review kinetic data relevant for the design of this mission. The dissociation rates of molecular hydrogen are relevant for more accurate assessment of the convective heating experienced by an entry probe. Furthermore, in the last 20 years, several advancements on potential energy surfaces (PES) of systems relevant for giant planet entries have been published [2-5]. Simulations have estimated peak temperatures in the stagnation line to be around 27,000, 18,000, and 15,000 K for Jupiter [6] Saturn [7] and Uranus [7], respectively. Performing experiments at such high-temperatures is a challenging endeavor. The quasi-classical trajectory (QCT) method is useful to obtain kinetic data at such extreme temperatures [8] when quantum effects are negligible and as long as an accurate PES is available. The aim of this work is to propose state-to-state and global dissociation rates for molecular hydrogen by collisions with H and He. Additionally, a discussion on what remains to be accomplished for an updated global and state-to-state models for entry in Uranus is done.
[1] National Academies of Sciences, Engineering, and Medicine. 2022. Origins, Worlds, and Life: A Decadal Strategy for Planetary Science and Astrobiology 2023-2032. Washington, DC: The National Academies Press. doi.org/10.17226/26522 (2022)
[2] Mielke, S. L., Garrett, B. C. & Peterson, K. A. A hierarchical family of global analytic Born-Oppenheimer potential energy surfaces for the H+H2 reaction ranging in quality from double-zeta to the complete basis set limit. J. Chem. Phys. 116, 4142–4161 (2002).
[3] Mielke, S. L., Schwenke, D. W., Schatz, G. C., Garrett, B. C. & Peterson, K. A. Functional representation for the born-oppenheimer diagonal correction and born-huang adiabatic potential energy surfaces for isotopomers of H3. J. Phys. Chem. A 113, 4479–4488 (2009)
[4] Bakr, B. W., Smith, D. G. A. & Patkowski, K. Highly accurate potential energy surface for the He-H2 dimer. J. Chem. Phys. 139, (2013).
[5] Thibault, F. et al. Rovibrational line-shape parameters for H2 in He and new H2-He potential energy surface. J. Quant. Spectrosc. Radiat. Transf. 202, 308–320 (2017).
[6] Santos Fernandes, L., Lopez, B. & Lino Da Silva, M. Computational fluid radiative dynamics of the Galileo Jupiter entry. Phys. Fluids 31, (2019).
[7] Palmer, G., Prabhu, D. & Cruden, B. A. Aeroheating uncertainties in uranus and saturn entries by the Monte Carlo method. J. Spacecr. Rockets 51, 801–814 (2014).
[8] Jaffe, R. L., Schwenke, D. W. & Panesi, M. First Principles Calculation of Heavy Particle Rate Coefficients. Hypersonic Nonequilibrium Flows Fundam. Recent Adv. 103–158 (2015) doi:10.2514/5.9781624103292.0103.0158.
