# Presentation: 046002

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

- Michael Smith (NASA/GSFC)
- 18th MEPAG Meeting
- 20 February 2008

## 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

## 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)

## 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

## 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

## 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...

## 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

## 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

## 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

## 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

## Orbit tracks for one day

- 	Good global mapping

- Solar occultations for one year
- 	Good latitude distribution

## 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