MAVEN observations of the response of Mars to an interplanetary coronal mass ejection

Abstract

Coupling between the lower and upper atmosphere, combined with loss of gas from the upper atmosphere to space, likely contributed to the thin, cold, dry atmosphere of modern Mars. To help understand ongoing ion loss to space, the Mars Atmosphere and Volatile Evolution (MAVEN) spacecraft made comprehensive measurements of the Mars upper atmosphere, ionosphere, and interactions with the Sun and solar wind during an interplanetary coronal mass ejection impact in March 2015. Responses include changes in the bow shock and magnetosheath, formation of widespread diffuse aurora, and enhancement of pick-up ions. Observations and models both show an enhancement in escape rate of ions to space during the event. Ion loss during solar events early in Mars history may have been a major contributor to the long-term evolution of the Mars atmosphere.

Coronal mass ejections and their sheath regions in interplanetary space

“…At the dayside (small zenith angles) outward fluxes are strongly enhanced during the ICMEs. As stated in Jakosky et al (2015) this region is usually dominated by inward flows and the fluxes during this ICME were the strongest identified during the MAVEN lifespan so far. The results presented in Jakosky et al (2015) imply that ICMEs and the associated SEPs can dramatically alter the overall morphology and dynamics of the magnetosphere, ionosphere and upper atmosphere of Mars.…”

“…Space probes like Pioneer Venus Orbiter, Mars Express, Venus Express and the recent Mars Atmosphere and Volatile Evolution (MAVEN) spacecraft have revealed that ion losses from the ionosphere to space can be enhanced by an order of magnitude due to the ICME interaction (e.g., Luhmann et al 2007;Futaana et al 2008;Jakosky et al 2015). Figure 36, from Jakosky et al (2015) compares the outward and inward heavy (> 9 amu) ion fluxes from the Martian atmosphere as a function of solar zenith angle measured by MAVEN during an event on March 8-9, 2015 caused by two interacting ICMEs (red diamonds, blue diamonds give the median) to four-month median fluxes (solid curve, the dashed curves show the first and fourth quartiles).…”

“…Figure 36, from Jakosky et al (2015) compares the outward and inward heavy (> 9 amu) ion fluxes from the Martian atmosphere as a function of solar zenith angle measured by MAVEN during an event on March 8-9, 2015 caused by two interacting ICMEs (red diamonds, blue diamonds give the median) to four-month median fluxes (solid curve, the dashed curves show the first and fourth quartiles). We note that based on the solar wind data shown Jakosky et al (2015) these ICMEs were not merged into a complex ejecta, but their individual rotations can be distinguished. At the dayside (small zenith angles) outward fluxes are strongly enhanced during the ICMEs.…”

“…The fluxes of X-ray and UV emission, and SEPs were also much higher. These strong eruptions from the young Sun likely had a crucial role in the evolution of the atmospheres of the weakly magnetized planets, and could have even stripped away most of the atmosphere of Mars (e.g., Luhmann et al 2007;Jakosky et al 2015). The successive super-eruptions may have also affected significantly the atmosphere of the Earth.…”

Response of the Martian ionosphere to solar activity including SEPs and ICMEs in a two-week period starting on 25 February 2015

“…Since SEPs move much faster than the ICME shock they arrive earlier than the shock if the magnetic field lines are connected to the planet. SEP events have been shown to cause enhanced electron density in the ionosphere, which is seen from attenuation of the surface reflection during space weather events (see, e. g., Morgan et al, [2006], Nemec et al, [2014] Jakosky et al [2015] showed the response of Mars to the ICME on March 8, 2015, using data which provided information about the upstream solar wind from MAVEN solar wind monitors. Data from the MAVEN Solar Wind Ion Analyzer (SWIA) [Halekas et al, 2015] and the Magnetometer (MAG) [Connerney et al, 2015] were used to generate the escape rates in the regions affected by the ICMEs.…”