Structure, dynamics, and seasonal variability of the Mars‐solar wind interaction: MAVEN Solar Wind Ion Analyzer in‐flight performance and science results

Abstract

We report on the in‐flight performance of the Solar Wind Ion Analyzer (SWIA) and observations of the Mars‐solar wind interaction made during the Mars Atmosphere and Volatile EvolutioN (MAVEN) prime mission and a portion of its extended mission, covering 0.85 Martian years. We describe the data products returned by SWIA and discuss the proper handling of measurements made with different mechanical attenuator states and telemetry modes, and the effects of penetrating and scattered backgrounds, limited phase space coverage, and multi‐ion populations on SWIA observations. SWIA directly measures solar wind protons and alpha particles upstream from Mars. SWIA also provides proxy measurements of solar wind and neutral densities based on products of charge exchange between the solar wind and the hydrogen corona. Together, upstream and proxy observations provide a complete record of the solar wind experienced by Mars, enabling organization of the structure, dynamics, and ion escape from the magnetosphere. We observe an interaction that varies with season and solar wind conditions. Solar wind dynamic pressure, Mach number, and extreme ultraviolet flux all affect the bow shock location. We confirm the occurrence of order‐of‐magnitude seasonal variations of the hydrogen corona. We find that solar wind Alfvén waves, which provide an additional energy input to Mars, vary over the mission. At most times, only weak mass loading occurs upstream from the bow shock. However, during periods with near‐radial interplanetary magnetic fields, structures consistent with Short Large Amplitude Magnetic Structures and their wakes form upstream, dramatically reconfiguring the Martian bow shock and magnetosphere.

Jets Downstream of Collisionless Shocks

“…5.2.1 and 5.2.3). Recently Halekas et al (2017) have shown using MAVEN data that SLAMS can occur upstream of the Martian bow shock for near-radial interplanetary magnetic fields, reconfiguring the Martian bow shock. Similarly, Collinson et al (2012) have observed SLAMS upstream of the bow shock of Venus.…”

On the response of Martian Ionosphere to the Passage of a Corotating Interaction Region: MAVEN Observations

“…The upstream solar wind parameters (density, dynamic pressure, and velocity) and IMF are computed from the SWIA onboard moments and MAG measurements (intensity and direction of the magnetic field) following the method by Halekas et al (2016). The SEP fluxes are obtained from the SEP instrument.…”

The Twisted Configuration of the Martian Magnetotail: MAVEN Observations

“…Periods of pristine solar wind were selected by implementing the algorithm developed by Halekas et al (2017), based on measurements of bulk flow speed, proton scalar temperature, spacecraft altitude, and normalized magnetic field fluctuation levels. Periods of pristine solar wind were selected by implementing the algorithm developed by Halekas et al (2017), based on measurements of bulk flow speed, proton scalar temperature, spacecraft altitude, and normalized magnetic field fluctuation levels.…”

“…For selection, we require that (1) MAVEN observed both the upstream solar wind and the magnetotail (X MSO ≤ À1 R M ) over the course of a single orbit and (2) upstream parameters met the criteria of the Halekas et al (2017) algorithm. For selection, we require that (1) MAVEN observed both the upstream solar wind and the magnetotail (X MSO ≤ À1 R M ) over the course of a single orbit and (2) upstream parameters met the criteria of the Halekas et al (2017) algorithm.…”