Evidence of Solar Wind Wave Power Propagating Deep into the Ionosphere of Mars

Fowler, Christopher

Evidence of Solar Wind Wave Power Propagating Deep into the Ionosphere of Mars

Thursday, October 1, 2015

Christopher M Fowler^1,2, Laila Andersson³, Robert Ergun¹, Michiko W Morooka², Gregory T Delory⁴, Tess McEnulty², Tristan David Weber^2,3, David J Andrews⁵, John E P Connerney⁶, Jared R Espley⁷, Jasper S Halekas⁸, James P McFadden⁴, David L Mitchell^4,9 and Davin E Larson^4,9, (1)Univ Colorado, Boulder, CO, United States, (2)LASP, University of Colorado, Boulder, CO, United States, (3)University of Colorado at Boulder, Boulder, CO, United States, (4)University of California Berkeley, Berkeley, CA, United States, (5)IRF Swedish Institute of Space Physics Uppsala, Uppsala, Sweden, (6)Goddard Space Flight Center, Greenbelt, MD, United States, (7)NASA Goddard Space Flight Center, Greenbelt, MD, United States, (8)University of Iowa, Physics and Astronomy, Iowa City, IA, United States, (9)Space Sciences Laboratory, Berkeley, CA, United States

Abstract:

Atmospheric loss at any planet is important for it’s evolution. In the past, Mars is expected to have had a magnetic dipole, be wet, and have had a thick atmosphere. Presently only surface crustal fields are left in the Southern hemisphere, the planet is much drier and has a thin atmosphere. To first order, the Martian ionosphere is very similar to that of Earth’s between ~70 km and 300 km, making the analysis and comparison of active physical processes between the two planets interesting.

The MAVEN mission allows the solar wind interaction with Mars to be studied all the way to well below an altitude of 200 km. The MAVEN spacecraft carries a full suite of plasma instruments capable of measuring many different quantities and dynamic behaviors essential in the solar wind interaction analysis.

There are many different paths to remove an atmosphere from a planet. In this study evidence is shown that solar wind wave power can reach to below 200 km and directly energize heavy ionospheric ions. This is the first time this type of measurement and study has been possible. The observations demonstrate that for some situations the solar wind has a direct path to drive atmospheric loss.

The presentation shows that the solar wind wave energy can propagate through the Martian ‘magnetosphere’ down to the ionosphere. The period of investigation occurs when the orbit apoapsis was located in the solar wind and the orbit periapsis was located in the night side ionosphere. The possibility that the solar wind can directly heat the ionosphere is a phenomenon that has been postulated [Ergun et al, 2006]. It is believed to be unique to small bodies with weak magnetic fields, compared to the solar wind magnetic field.