Scot Rafkin Southwest Research Institute Boulder, CO Image Credit: MSSS/NASA/JPL

AMIII 2-4 Dec 2015S. Rafkin -- Atmospheric Science2 An affordable program is an activity that stakeholders are willing to support because it returns value commensurate with its cost. A sustainable campaign is one that is affordable with returned value sufficient to ensure stakeholder support over decades. Scientific Objectives for the Human Exploration of Mars Science Analysis Group (MEPAG HSO-SAG) Atmospheric Science Objectives enabled by proximal humans Stakeholders Science (Not Drawn to Scale) Engineering & Operations Atmospheric Science Others

AMIII 2-4 Dec 2015S. Rafkin -- Atmospheric Science3 An affordable program is an activity that stakeholders are willing to support because it returns value commensurate with its cost. A sustainable campaign is one that is affordable with returned value sufficient to ensure stakeholder support over decades. Scientific Objectives for the Human Exploration of Mars Science Analysis Group (MEPAG HSO-SAG) Atmospheric Science Objectives enabled by proximal humans The HSO-SAG output represents only those objectives identified under a relatively narrow Charter. Other relevant and important science objectives are most certainly possible! Stakeholders Science (Not Drawn to Scale) Engineering & Operations Atmospheric Science Others

Triaged and Reworked MEPAG Climate Objectives AMIII 2-4 Dec 2015S. Rafkin -- Atmospheric Science4 Science Objectives under each of the MEPAG Climate Objectives were evaluated against: 1) Scientific Value 2) Relevance for a human (landed) mission. 3) Value added by proximal humans. Ancient Mars: Wet era through desiccation Constrain past climate states and atmospheric composition through analysis of samples from the Noachian (ancient) and Hesperian (past), including trapped gases and inclusions. Recent Mars: Mostly dry with obliquity-driven climate cycles Infer previous climate states and atmospheric composition under different orbital configurations through chemical and isotopic analysis of sediments and water ice emplaced during the Amazonian (present era). Contemporary Mars: Weather and climate as observed today Quantify the atmospheric state and forcings near the surface at four or more locations supplemented by regular vertical atmospheric structure information. Identify and measure key parameters that determine local source/sinks of dust, water and CO 2 cycles. Quantify photo- and electrochemical cycles and potential subsurface trace gas sources. Provide context for near-surface measurements through global monitoring and quantification of the atmospheric state, forcings, and the distribution of airborne aerosols and trace gases.

Prioritized Objectives AMIII 2-4 Dec 2015S. Rafkin -- Atmospheric Science5 Ancient Mars: Wet era through desiccation Constrain past climate states and atmospheric composition through analysis of samples from the Noachian (ancient) and Hesperian (past), including trapped gases and inclusions. Recent Mars: Mostly dry with obliquity-driven climate cycles Infer previous climate states and atmospheric composition under different orbital configurations through chemical and isotopic analysis of sediments and water ice emplaced during the Amazonian (present era). Contemporary Mars: Weather and climate as observed today Quantify the atmospheric state and forcings near the surface at four or more locations supplemented by regular vertical atmospheric structure information. Identify and measure key parameters that determine local source/sinks of dust, water and CO 2 cycles. Quantify photo- and electrochemical cycles and potential subsurface trace gas sources. Provide context for near-surface measurements through global monitoring and quantification of the atmospheric state, forcings, and the distribution of airborne aerosols and trace gases. High Low Med High Low Prioritization is subjective: Based on scientific value, proximal human advantage, accessibility.

High Priority: Surface Station Network and Vertical Sounding  Scientific Motivation:  The fundamental data of meteorology, required to validate atmospheric models.  There has yet to be an adequate surface meteorology experiment on the surface of Mars, nor is one planned.  Needs to measure state and forcing.  Needs to be properly accommodated.  A long-standing Strategic Knowledge Gap (SKG) that needs to be achieved prior to human arrival.  Necessary for many Entry, Descent and Landing (EDL), Surface Operation, and Mars Ascent Vehicle (MAV) activities.. AMIII 2-4 Dec 2015S. Rafkin -- Atmospheric Science6  Specific Measurements:  pressure, air temperature, dust, 3D winds, turbulent heat and momentum fluxes, relative humidity, solar/IR fluxes, ground temperatures

High Priority: Past Climate States and Atmospheric Composition  Scientific Motivation:  Evidence strongly suggests that liquid water flowed on the surface: ancient Mars had a very different climate than today.  Need mass and composition of the ancient atmosphere and a quantitative assessment of how much and how long water was present on the surface.  Models have been largely unsuccessful at reproducing a warm, wet Mars with weak, young sun. AMIII 2-4 Dec 2015S. Rafkin -- Atmospheric Science7  Added Human Value:  Enhanced sample selection: efficiency, quality, and quantity..  Enhanced in situ analyses to determine if the selected samples meet requirements, iterating if necessary.  Ability to quickly evaluate and better preserve rock samples.  Specific Measurements:  Trapped gases in rock: Absolute ages, isotopic composition, mineralogy.

Medium Priority: Local Sources and Sinks of the dust, Water and CO 2 cycles  Scientific Motivation:  Dust, water and CO 2 are critical driving components of the climate system.  Large uncertainties in how dust is lifted from the surface.  Must measure key parameters related to the exchange the surface and the atmosphere to quantify the processes that control the three climate cycles.  Added Human Value:  Proper siting, deployment and monitoring of instrument package is critical.  Real-time field studies (especially dust and water).  Specific Measurements:  Surface stress and roughness, dust lifting rates, dust lifting thresholds, dust accumulation rates, surface sand and dust properties, water and CO 2 sublimation and condensation rates, pressure, subsurface-to-atmosphere vapor diffusion rates. AMIII 2-4 Dec 2015S. Rafkin -- Atmospheric Science8

Medium Priority: Photo- and Electro-Chemical Cycles and Trace Gas Sources  Scientific Motivation:  Measurements of long- and short-lived photochemical species to study key reactions, rates, and pathways, and transport.  Electro-chemical effects and interactions between the atmosphere and surface are not well understood.  Heterogeneous chemical reactions may provide a crucial sink for trace gases such as methane, but these are poorly understood.  Added Human Value:  Ability to carefully and properly select substrates to test heterogeneous chemistry.  Specific Measurements:  Trace gas and dust abundances, electrical field strength, lab studies of heterogeneous chemistry on selected substrate material. AMIII 2-4 Dec 2015S. Rafkin -- Atmospheric Science9

Low Priority: Climate States and Atmospheric Composition Under Different Orbital Configurations  Scientific Motivation:  Evidence that surface ice was stable at low and middle latitudes in the recent past.  Chemical and isotopic measurements provide constraints on climate evolution.  Measurements to study volatile exchange for volatiles between atmosphere, surface and subsurface reservoirs.  Added Human Value:  Enhanced sample selection: efficiency, quality, and quantity.  Enhanced in situ analyses, iterating sample collection if necessary.  Ability to quickly evaluate and better preserve ice samples.  Specific Measurements:  Absolute ages, isotopic composition, mineralogy, trapped gases in ice and rock. AMIII 2-4 Dec 2015S. Rafkin -- Atmospheric Science10 Polar Layered Deposits

Low: Global Context for Surface Measurements  Scientific Motivation:  Observations of atmospheric phenomena provide regional and global context for local surface observations.  Winds have never been measured; would provide critical model validation.  Necessary for Mars weather prediction.  Scientific value will be significantly enhanced if the observations from orbit continue longer than the duration of the human mission. AMIII 2-4 Dec 2015S. Rafkin -- Atmospheric Science11  Added Human Value:  None!  If the “proximal human” filter is removed, becomes High priority.  Specific Measurements:  Atmospheric and surface temperatures, winds, dust, water ice, water vapor, CO 2 ice abundances, trace gas abundances.

Key Points* A human presence on Mars provides exceptional atmospheric science opportunities amplified by a sustained program. Human missions provide opportunity for high priority science that is not enabled by humans, but is unlikely to be done robotically. The U.S. Mars Atmosphere Science community is running on fumes. – Losing key resources and expertise. Will the people and infrastructure be there when we need it? Environmental monitoring prior to and during human presence is necessary for EDL, Surface Ops, and MAV. – Severe disconnect between data providers, engineers, Mars Program. – End goal is not observations, but validated models. I’ve got a lot of ideas, opinions and thoughts but not enough time on the floor. Come see me! Key Reference Documents: – MEPAG Science Goals, Strategic Knowledge Gaps, HSO-SAG – AMIII 2-4 Dec 2015S. Rafkin -- Atmospheric Science12 *Some of these points are my personal opinion.