An investigation of solar wind effects on the evolution of the Martian atmosphere

Luhmann, Janet G.

This investigation concentrated on the question of how atmosphere escape, related to both photochemistry and the Mars solar wind interaction, may have affected the evolution of Mars' atmosphere over time. The principal investigator and postdoctoral researcher adopted the premise that contemporary escape processes have dominated the losses to space over the past 3.5 billion years, but that the associated loss rates have been modified by solar evolution. A model was constructed for the contemporary escape scenario based on knowledge gained from both Venus in-situ measurements from Pioneer Venus Orbiter and Mars measurements from Phobos-2. Venus provided a valuable second example of a weakly magnetized planet having a similar solar wind interaction where we have more knowledge from observations. The model included photochemical losses from recombining ionospheric molecular ions, scavenging Martian upper atmosphere ('pickup') ions by the solar wind, and sputtering of the atmosphere by reentering pickup ions. The existence of the latter mechanism was realized during the course of the supported investigation, and is now thought by Jakosky and Pepin to explain some of the Martian noble gas isotope ratios.

Document ID

19940032504

Acquisition Source

Legacy CDMS

Document Type

Contractor Report (CR)

Authors

Date Acquired

September 6, 2013

Publication Date

January 1, 1994

Subject Category

Report/Patent Number

Accession Number

94N37012

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Distribution Limits

Public

Work of the US Gov. Public Use Permitted.

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