Mars Atmosphere and Volatile EvolutioN (MAVEN) Mission

1. Mars Atmosphere and Volatile EvolutioN (MAVEN) Mission Particles and Fields Science Critical Design Review May 23 -25, 2011 Dave Mitchell SWEA Lead

2. MAVEN Science Questions MAVEN will determine the role that loss of volatiles to space has played through time, providing definitive answers about Mars climate history: • What is the current state of the upper atmosphere and what processes control it? • What is the escape rate at the present epoch and how does it relate to the controlling processes? • What has the total loss to space been through time?

3. MAVEN Mission Architecture In situ and semi-global remote sensing measurements are made from the MAVEN elliptical orbit. Measurements are obtained down to the well-mixed lower atmosphere through five “deep dip” campaigns. Coverage of all local solar times and most latitudes, along with broad geographical coverage, results from precession of the MAVEN high-inclination orbit.

4. MAVEN Measures Drivers, Reservoirs, and Escape Rates SWEA SWEA SEP EUV NGIMS MAG MAG IUVS IUVS Neutral Processes Solar Inputs Plasma Processes LPW LPW SWIA SWIA STATIC

5. The MAVEN Payload Makes the Essential Measurements NGIMS IUVS LPW integrated analysis integrated analysis STATIC MAG, SWEA, SWIA, LPW SEP LPW - EUV

6. STATIC Measurement Requirements STATIC measures low- and medium-energy ion composition, energy, and direction: Densities, velocities, and temperatures of suprathermal H+, O+, O2+, and CO2+ above the exobase with the ability to spatially resolve magnetic cusps Derived Level 3 measurement requirements:

7. SWEA Measurement Requirements SWEA measures properties of solar wind electrons that can drive escape: Energy distributions of solar wind, magnetosheath, and ionospheric electrons to determine the electron impact ionization rate, with an energy resolution sufficient to distinguish ionospheric photoelectrons from solar wind electrons Electron angular distributions to determine magnetic topology, with the ability to spatially resolve magnetic cusps. Derived Level 3 measurement requirements:

8. SWIA Measurement Requirements SWIA Measures properties of solar wind ions that can drive escape: Density and velocity distributions of solar wind and magnetosheath ions to determine the charge exchange rate and the bulk plasma flow from solar wind speeds down to stagnating magnetosheath speeds Derived Level 3 measurement requirements:

9. Cross Calibration of STATIC/SWEA/SWIA Response to RFAs 9 and 10 • The angular and energy responses and the geometric factor (minus detection efficiency) for all three instruments are determined on the ground to within ~10% by calibrations and electrostatic optics simulations. • Detection efficiency depends on MCP efficiency, which varies during the mission  need a procedure to measure and track this efficiency for all three instruments. New Level 3 Requirements

10. Cross Calibration of STATIC/SWEA/SWIA Response to RFAs 9 and 10 • Detection efficiency for STATIC: • Determine START and STOP efficiencies by measuring event ratios: (START with STOP)Validand (STOP with START)Valid STARTValidSTOPValid • This can be done anywhere that the ion composition is dominated by a single species (e.g., H+ in the outer sheath, O2+ in the ionosphere). • For cross calibration of SWIA and SWEA, efficiencies for H+ are needed. • STATIC can meet requirement without cross calibration. • Consistency check: Measure total plasma density near periapsis and compare with calibrated LPW measurements.

11. Cross Calibration of STATIC/SWEA/SWIA Response to RFAs 9 and 10 • Absolute sensitivity of SWIA determined by cross calibration with STATIC in the outer sheath • Instruments have the same analyzer optics and overlapping energy and angle ranges, so measurements of ion flux are sufficient for comparison. • Absolute sensitivity of SWEA determined by cross calibration with SWIA and STATIC in the outer sheath and with SWIA in the solar wind. • Modeling of total density needed in the sheath for all three. • Modeling of total density needed for SWEA in the solar wind.

12. SEP Measurement Requirements SEP Measures solar energetic particle input into upper atmosphere: Solar energetic particles that can interact with the upper atmosphere, with a time resolution sufficient to capture SEP events. Derived Level 3 measurement requirements:

13. MAG Measurement Requirements MAG measures solar-wind interactions and “mini-magnetospheres” Vector magnetic field in the unperturbed solar wind, magnetosheath, and crustal magnetospheres, with the ability to spatially resolve crustal magnetic cusps. Derived Level 3 measurement requirements:

14. LPW Measurement Requirements LPW shall measure electron temperature and number density measured in situ: Thermal electron density and temperature from the ionospheric main peak to the nominal ionopause with a vertical resolution of one O2+ scale height. LPW shall measure electric field wave power at frequencies important for ion heating. Derived Level 3 measurement requirements:

15. LPW/EUV Measurement Requirements EUV shall measure solar EUV input into upper atmosphere: Solar EUV irradiance at wavelengths important for ionization, dissociation, and heating of the upper atmosphere with a time resolution sufficient to capture solar flares. Derived Level 3 measurement requirements:

16. PF Instrument Backups PF

17. PF Measurement Resiliency If we lose any one instrument, do we lose any high-level objectives? (Y = Yes, S = Substantial, P = Partial, N = Not significant, - = Minimal contribution) PF