Mars Science Orbiter (MSO) Science Definition Team (SDT) Report Overview

1. Mars Science Orbiter (MSO) Science Definition Team (SDT) Report Overview Michael Smith (NASA/GSFC) 18th MEPAG Meeting 20 February 2008

2. MSO SDT preceded by: • Science Analysis Group (SAG-1), chaired by C.B. Farmer • Science Analysis Group (SAG-2), chaired by W. Calvin • The purpose of the SDT effort was to define the: • Scientific objectives of an MSO mission building on the SAG-2 Plan A • Science requirements of likely instruments • Desired orbits and mission profile • Potential science synergies with future missions such as MSR • The SDT assumed an MRO-class spacecraft able to support telecommunications relay for 10 Earth years. • First telecon: 22 October 2007 • Face-to-face meeting: 12–13 November 2007 • Final draft of report: 15 December 2007

3. MSO SDT Membership: Michael Smith, Chair, NASA Goddard Space Flight Center Don Banfield, Cornell University Jeff Barnes, Oregon State University Phil Christensen, Arizona State University Todd Clancy, Space Science Institute Phil James, University of Toledo (retired) Jim Kasting, Pennsylvania State University Paul Wennberg, Caltech Daniel Winterhalter, JPL Michael Wolff, Space Science Institute Rich Zurek, JPL (Mars Program Office) Janis Chodas, JPL (MSO Project Manager) Tomas Komarek, JPL (MSO Mission Concept Manager)

4. The SDT identified five major objectives for MSO: • Atmospheric Composition • Sensitive and comprehensive survey of the abundance and temporal and seasonal distribution of atmospheric species and isotopologues • Atmospheric State • Provide new observations that constrain and validate models (winds), and extend the present record of martian climatology to characterize interannual variability and long-term trends • Surface Change Science • Investigate surface changes as recorded in surface properties and morphologies due to seasonal cycling, aeolian movement, mass wasting, small impact craters, action of present water • Site Certification Imaging • HiRISE-class imaging (~30 cm resolution) for certification of future landing sites • Telecommunications Support • Support relay of science data from, and commands to, landed assets

5. Atmospheric Composition • Atmospheric evidence for present habitability • Key measurement objectives: • Photochemistry (H2O2, O3, CO, H2O) • Transport (CO, H2O) • Isotopic Fractionation (isotopomers of H2O and CO2) • Surface exchange (CH4 and H2O) • Inventory (HO2, NO2, N2O, C2H2, C2H4, C2H6, H2CO, HCN, H2S, OCS, SO2, HCl) • Measurement goals: • Solar occultations to obtain sensitivity of 1–10 parts per trillion • Limb-geometry mapping at sensitivity of 1–10 parts per billion with latitude/longitude/altitude/local time coverage • Will significantly improve knowledge of atmospheric composition and chemistry • Could lead to identification of source regions

6. But, MSO is more than a “methane mission” • The SDT envisions a comprehensive survey of both known gases (H2O, H2O2, CO, etc.), as well as to improve by an order of magnitude or more detection limits on gases not yet observed. • Methane is still an important measurement goal, of course. MSO would be able to make a definitive statement about whether or not methane is present in the atmosphere, and what its distribution is. This is still a major finding whether or not methane is detected. • Plus, MSO has other major scientific objectives that would yield a major advance in our ability to understand and to simulate (for science and engineering) the Mars atmosphere…

7. Atmospheric State • Climate processes responsible for seasonal / interannual change • Key measurement objectives: • Wind velocity • Water vapor and atmospheric temperature without influence of dust • Diurnal coverage of all parameters • Vertical profiles of all parameters • Continue climatology monitoring • Measurement goals: • 2-D wind velocity, temperature, aerosol optical depth, water vapor at • 5 km vertical resolution over broad height range • diurnal coverage twice per martian season • 85% or better coverage along orbit • Extend record of climatology to characterize long-term trends • Validate and significantly improve models of transport and state

8. Surface Change Science • Recent processes of surface-atmosphere interaction • Key measurement objectives: • Polar layered terrain (“Swiss cheese”) • Aeolian features (dust devil tracks, streaks, dust storm changes) • Gullies, avalanches, dune motions • Formation of small impact craters over time • Measurement goals: • 1 meter resolution sufficient for these goals • Ability to image all areas (including poles) • Understanding of active processes and the role of volatiles in this activity • Exchange of volatiles between the polar surface and atmosphere, and the current evolution of the polar terrains

9. Sample “strawman” Payload • Solar occultation FTIR spectrometer • Atmospheric composition • Sub-millimeter spectrometer • Wind velocity through Doppler shift • Water vapor, temperatures, etc. without influence from dust • Wide-angle camera (MARCI-like) • Daily global view of surface and atmospheric dust and clouds • Thermal-IR spectrometer • Daily global observations of temperature, dust, ice, water vapor • Direct comparison to previous climatology record • High-resolution camera (HiRISE-class or TBD) • Imaging of active surface processes

10. Orbit characteristics: Near-circular at low altitude (300 km) Allows best global mapping Allows most solar occultation opportunities Near-polar inclination (82.5°) Lower inclination gives faster precession of local time and more uniform latitude distribution of solar occultation points Science requires full diurnal cycle in less than a Martian season Higher inclination favors polar surface imaging Desire to image rotational pole at airmass of two or less Orbit altitude increased to 400 km at some point for planetary protection

11. Orbit tracks for one day Good global mapping Solar occultations for one year Good latitude distribution

12. Summary: • MSO would enable significant new science and provide key infrastructure elements • MSO science objectives not covered by any other proposed mission (including MSR) • MSO science would have nice synergy with aeronomy Scout and would provide valuable feed-forward to MSR • 2016 is favored launch opportunity both to minimize gap in atmospheric monitoring and to provide needed telecom support for other future missions