This software models the gas and dust dynamics of comet coma (the head region of a comet) in order to support the Microwave Instrument for Rosetta Orbiter (MIRO) project. MIRO will study the evolution of the comet
67P/Churyumov-Gerasimenko’s coma system. The instrument will measure surface temperature, gas-production rates and relative abundances, and velocity and excitation temperatures of each species along with their spatial temporal variability. This software will use these measurements to improve the understanding of coma dynamics.
The modeling tool solves the equation of motion of a dust particle, the energy balance equation of the dust particle, the continuity equation for the dust and gas flow, and the dust and gas mixture energy equation. By solving these equations numerically, the software calculates the temperature and velocity of gas and dust as a function of time for a given initial gas and dust production rate, and a dust characteristic parameter that measures the ability of a dust particle to adjust its velocity to the local gas velocity.
The software is written in a modular manner, thereby allowing the addition of more dynamics equations as needed. All of the numerical algorithms are added in-house and no third-party libraries are used.
This work was done by Paul A. Von Allmen and Seungwon Lee of Caltech for NASA’s Jet Propulsion Laboratory. For more information, download the Technical Support Package (free white paper) at www.techbriefs.com/tsp under the Software category.
This software is available for commercial licensing. Please contact Daniel Broderick of the California Institute of Technology at
This Brief includes a Technical Support Package (TSP).
Comet Gas and Dust Dynamics Modeling
(reference NPO-46507) is currently available for download from the TSP library.
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Overview
The document presents a technical support package detailing the modeling of gas and dust dynamics in comets, specifically in relation to the MIRO (Microwave Instrument for the Rosetta Orbiter) mission. Developed by NASA's Jet Propulsion Laboratory, MIRO is a dual-frequency heterodyne radiometer designed for the European Space Agency's Rosetta mission, which aims to study Comet 67P/Churyumov-Gerasimenko. The mission's primary objectives include understanding the cometary nucleus, the outgassing processes from the nucleus, and the development of the comet's coma, which are all interconnected aspects of cometary physics. A secondary goal is to explore the similarities and differences between comets and asteroids.
The modeling tool described in the document characterizes comet gas and dust dynamics using two key physical parameters: the dust-to-gas production rate ratio (M) and the dust characteristic parameter (beta). The parameter M indicates the momentum interaction between dust and gas, with different behaviors observed depending on its value. For M much less than 1, gas motion is minimally affected by dust, while dust is significantly influenced by gas motion. Conversely, for M much greater than 1, the opposite is true. When M is around 1, both gas and dust motions strongly influence each other.
The beta parameter measures how quickly a dust particle can adjust its velocity to match the local gas velocity. A low beta value indicates rapid equilibration, while a high beta value suggests a slower adjustment. The document highlights that the interactions between these parameters significantly affect the terminal velocities and temperatures of both dust and gas.
Key findings from the modeling include that as the ratio M increases for a fixed beta, both dust and gas terminal velocities decrease. An increase in beta leads to an increase in gas terminal velocity and a decrease in dust terminal velocity. The temperature dynamics of dust and gas are also influenced by these parameters, with varying outcomes based on their values.
Overall, the document emphasizes the importance of understanding the energy exchange and momentum interactions between gas and dust in cometary environments, which is crucial for advancing our knowledge of cometary physics and the broader implications for planetary science.
