A computational model calculates the excitation of water rotational levels and emission-line spectra in a cometary coma with applications for the Microwave Instrument for Rosetta Orbiter (MIRO). MIRO is a millimeter-submillimeter spectrometer that will be used to study the nature of cometary nuclei, the physical processes of outgassing, and the formation of the head region of a comet (coma). The computational model is a means to interpret the data measured by MIRO.

The model is based on the accelerated Monte Carlo method, which performs a random angular, spatial, and frequency sampling of the radiation field to calculate the local average intensity of the field. With the model, the water rotational level populations in the cometary coma and the line profiles for the emission from the water molecules as a function of cometary parameters (such as outgassing rate, gas temperature, and gas and electron density) and observation parameters (such as distance to the comet and beam width) are calculated.

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 email address is being protected from spambots. You need JavaScript enabled to view it.. Refer to NPO-46508.

This Brief includes a Technical Support Package (TSP).
MIRO Computational Model

(reference NPO-46508) is currently available for download from the TSP library.

Don't have an account? Sign up here.

NASA Tech Briefs Magazine

This article first appeared in the August, 2010 issue of NASA Tech Briefs Magazine.

Read more articles from this issue here.

Read more articles from the archives here.