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Wind enhanced planetary escape - Collisional modificationsEffects of collisions and finite winds characteristic of a highly perturbed atmosphere on the thermal escape of terrestrial hydrogen and helium are investigated using a Monte Carlo approach. The limiting cases of vertical and horizontal winds are considered, and the relaxation layer between the collisionless exosphere and the collision-dominated thermosphere is modeled as a plane-parallel slab of given column density, depth, and atmospheric density. For both gases, the upwardly injected flux at the base of the relaxation layer is compared with the returning downward flux distribution at the same location; the technique is also applied to the atmosphere of Titan. The results show that inclusion of collisions in the escape model for terrestrial hydrogen with winds effectively throttles the escape process, that collisional throttling is negligible for helium when the exobase temperature is at least 5000 K, and that the escape of a planetary-atmosphere constituent depends on the ratio of its gravitational and kinetic energies as well as on the ratio of its mass to that of the background gas.
Document ID
19770044476
Acquisition Source
Legacy CDMS
Document Type
Reprint (Version printed in journal)
Authors
Curtis, S. A.
(NASA Goddard Space Flight Center Greenbelt, MD, United States)
Hartle, R. E.
(NASA Goddard Space Flight Center Laboratory for Planetary Atmospheres, Greenbelt, Md., United States)
Date Acquired
August 8, 2013
Publication Date
March 1, 1977
Publication Information
Publication: Journal of Geophysical Research
Volume: 82
Subject Category
Lunar And Planetary Exploration
Accession Number
77A27328
Distribution Limits
Public
Copyright
Other

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