# Presentation: 302510

## Mars Aeronomy Science Themes and the NASA Exploration InitiativeReport from the NASA Mars Aeronomy Working Group

**Bruce Jakosky (Chair)**
**(bruce.jakosky@lasp.colorado.edu)**
**17 September 2004**

## Overview:  Mars Upper Atmosphere, Mars Science, and the Exploration Initiative

***Determining the history of the Martian climate, the chemical weathering and alteration of the surface, and the planet’s habitability requires understanding the roles of the solar wind and solar radiation inputs; the physics, chemistry, and dynamics of the upper atmosphere; and the escape of volatiles to space.***
***The upper atmosphere plays important roles in programmatic aspects of the Mars exploration program, including communications, energetic particle and radiation environments that can affect humans, the lifetimes of orbiting spacecraft, operational aspects of orbital missions, and aerobraking operations.***
***Some limited observations of the upper atmosphere are being made at present, and the Mars Telecommunications Orbiter has the potential to make further contributions, but the desired understanding can best be obtained from a dedicated upper-atmosphere mission.***

## Mars Aeronomy Working Group

**Chartered by NASA to explore science and programmatic issues related to the Mars upper atmosphere in light of recent discoveries and the new exploration program.**
**Combined effort of (then) Solar System Exploration Division and Sun-Earth Connection Division (both now part of the Science Mission Directorate).**
**Activity requested by the Directors of the two divisions.**
**Working group created to lead discussion, organize and run a workshop that would bring together the “aeronomy” community, the exploration initiative connections, and the rest of the Mars science community, and create a “white paper” reporting back on the results.  Workshop had nearly 90 participants.**
**Discussions of NASA Code S personnel with working group chair on 13 May 04, workshop held on 18-19 August 04, draft powerpoint report circulated within working group and then distributed to community for comments, and finalized on 17 September 04.**

## Mars Aeronomy Working Group (Steering Group) Membership:

**Bruce Jakosky, Univ. of Colorado (chair)**
**Stephen Bougher, Univ. of Michigan**
**Randy Gladstone, Southwest Research Inst.**
**Joe Grebowsky, NASA/GSFC**
**Rod Heelis, Univ. of Texas at Dallas**
**Jennifer Trosper, NASA HQ**
**Andrew Yau, Univ. of Calgary**
**Richard Zurek, NASA/JPL**
**Key NASA HQ participation:**
**Mary Mellott, SEC**
**Denis Bogan, SSED**
**Bill Peterson, SEC**

## Key Components of Working Group Charter

**Reexamine the upper-atmosphere science questions and determine whether and how they should be revised in response to the new vision.**
**Understand which operational requirements of the Exploration Systems Division involve this region and what further understanding is required.**
**Summarize the opportunities available for support of the study of this region, including those associated with the upcoming Mars Scout and Mars Telecommunications Orbiter opportunities.**

## MARS AERONOMY EXPLORATION WORKSHOP AGENDA, 18-19 August 2004

**(Agenda and powerpoint presentations available on web, at:**
**http://argyre.colorado.edu/life/aeronomy_workshop)**
***Wednesday, August 18***
- 8:00-8:30	Coffee
- 8:30-8:45	Workshop introduction				B. Jakosky
- 8:45-8:55	NASA HQ perspective, SEC division		M. Mellott
- 8:55-9:05	NASA HQ perspective, SSE division		D. Bogan
- 9:05-9:25	Mars program and NASA HQ			D. McCuistion
- 9:25-9:55	Status of the Mars Program			M. Meyer
- 9:55-10:20	Code T requirements and interest			J. Trosper
- 10:20-10:35	Break
- 10:35-10:50	Mars Telecommunications Orbiter			R. Zurek
- 10:50-11:05	Mars Scout opportunities				K. McBride
- 11:05-11:30	MEPAG Goals and Objectives for upper atmosphere	S. Bougher
- 11:30-11:45	Lessons learned from MGS and Odyssey aerobraking	S. Bougher
- 11:45-12:00	Lessons learned at Venus				A. Nagy
- 12:00-12:15	MGS Magnetometer results			D. Mitchell
- 12:15-1:30	Lunch						All
- 1:30-1:45	Lessons learned at Earth from Earth missions  	S. Yee
- 1:45-2:00	Preliminary results from Mars Express ASPERA 	J. Sharber

## Wednesday, August 18, continued

- 2:00-5:15	Discussion on these topics:
- 		-  Are the aeronomy science goals and objectives balanced,
- 			complete, appropriate, etc.?
- 							(S. Bougher)
- 		-  How do they relate to the rest of the Mars program?
- 							(R. Gladstone)
- 		-  Can MTO contribute to aeronomy science goals?
- 							(R. Zurek)
- 		-  What measurements/analyses are required prior to human
- 			missions?  Can they be obtained via a science-oriented
- 			Scout or do they require a dedicated mission?
- 							(J. Trosper)
- 5:15-5:45	Integration and wrap-up 			B. Jakosky

## Thursday, August 19

- 8:00-8:30	Coffee
- 8:30-12:00	Continue discussion from before, with these added topics:
- 		-  What actions/resources from HQ are required to further
- 			develop these topics?
- 		-  What are the recommendations from the group as a whole?
- 		-  Wrap-up of open workshop
- 12:00-1:15	Lunch
- 1:15-5:00	Closed session of steering group to draft report
- 5:00		Adjourn

## Long-Recognized Need for Upper-Atmosphere Measurements

**In-depth study of Mars’ upper atmosphere consistently has been judged necessary to understand the evolution of Mars and other planets.**
**Upper-atmosphere missions have been the subject of several advance mission studies and was a defining element of the ill-fated Japanese Nozomi mission.**
**COMPLEX (National Research Council Committee on Planetary and Lunar Exploration) has consistently given an aeronomy mission high value within planetary science.**
**NRC Decadal Survey (“New Frontiers in the Solar System: An Integrated Exploration Strategy”, 2003) includes Mars upper atmosphere studies as an important component of an overall program.**
**MEPAG (Mars Exploration Program Activity Group) 2004 prioritized ranking of science goals and objectives gives high priority to upper-atmosphere studies as they pertain to evolution and control of planetary habitability.**

## Ongoing and Planned Measurements From Orbit Relevant to the Upper Atmosphere

**Mars Global Surveyor (MGS) Magnetometer/Electron Reflectometer (MAG/ER) measurements (ongoing)**
**MGS radio occultation (ongoing)**
**Mars Express ASPERA (neutral particle imaging, neutral particle detection, electron spectrometer, ion mass analyzer; ongoing)**
**Mars Express SPICAM (atmospheric occultation; ongoing)**
**Mars Express MARSIS (long-wavelength radar; antenna not yet deployed)**
**Mars Reconnaissance Orbiter (MRO) aerobraking data**
**MRO radio occultations**
**Requires resoliciting the Radio Science investigation or implementing a funded Participating Scientist program in a timely manner.**
***While these will provide valuable science and operations data, they will not, taken together, provide the understanding of the upper atmosphere structure, composition, dynamics, and variability necessary to address the pertinent science questions.***

## Relevant Areas for Additional Study Other than from Spacecraft

**There is a need for new chemical rate coefficients and cross-section data; existing data are old, out of date, and inconsistent.**
**Some science issues can be addressed very effectively using telescopic observations from Earth; these are complementary to spacecraft measurements.  Ongoing and recent analyses include observations from HST, FUSE, and IRTF, as examples.**
**Studying stellar winds and UV output in Sun-like stars at various ages will help us infer the history of martian interactions with the Sun, and thereby its climate history and volatile evolution.**** **

## Key Areas Identified and Discussed:

**How do the Mars upper-atmosphere and aeronomy issues relate to the rest of the Mars science program?**
**Are the current aeronomy science goals and objectives balanced, complete, appropriate, etc.?**
**How can the Mars Telecommunications Orbiter contribute to aeronomy science goals?**
**What measurements/analyses are required prior to human missions?  Can they be obtained via a Scout mission designed to address science goals or do they require a dedicated mission or missions?**

## Scientific Connections Between Studies of the Upper Atmosphere and the Rest of the Mars Program (1 of 2)

**Mars as an integrated system:  **The martian volatile, climate, and “habitability” system is an integrated one, from below the surface to above the exobase.  Atmospheric dynamics, surface-atmosphere volatile exchange, and the climate cannot be understood without determining the role of the upper atmosphere.
**Loss of martian water and volatiles:  **The history of the martian atmosphere and climate over time cannot properly be understood without knowing the role of loss of water and other volatiles to space.  These will affect our general understanding of the nature of planetary habitability in general and habitability of Mars in particular.
**Evolution of surface and atmospheric chemistry:  **Formation of surface weathering deposits (such as the sulfates at the Mars Exploration Rover (MER) Opportunity site, or carbonates there and elsewhere) depends on atmospheric composition and oxidation state; interpretation of chemical and isotopic composition requires understanding atmospheric effects.

## Scientific Connections Between Studies of the Upper Atmosphere and the Rest of the Mars Program (2 of 2)

**“****Follow the dust” theme:  **The lower and upper atmosphere are tightly coupled.  Atmospheric structure and change in the escape over time of volatiles to space may result from lower-upper atmosphere connections, electrodynamic response, and dust event heating in the lower atmosphere; potential importance for exploration missions (see below).
**Interpreting magnetic fields:  **Crustal magnetic field measurements are used to improve our understanding of the evolution of Mars' interior and crust.  Crustal magnetic fields and variations in external forcing all affect upper atmospheric processes, with plasma-neutral coupling a key player, and upper-atmospheric properties thereby affect our ability to measure and understand magnetic fields.
**Comparative planetology:  **By examining the same processes in the different environments of the three terrestrial planets, we can better understand how they work and better apply them to understanding planetary evolution.

## Influence on the atmosphere and climate via the role of escape to space shown here.

## Connections between loss of volatiles to space and other components of the Mars climate/surface/interior system

***(Arrows show which components of the system directly affect other components)***

## Are the Aeronomy Science Goals and Objectives Balanced, Complete, Appropriate, etc.? (1 of 2)

**The recent Mars Exploration Program Analysis Group (MEPAG) Science Goals and Objectives document describes the areas that should be addressed by upcoming missions.  Following discussion, the workshop participants concluded that:**
**The specific MEPAG goals and objectives articulated in the document:**
**Address key, high-priority issues in aeronomical science**
**Can frequently only be achieved by making measurements which are traditionally viewed as aeronomical in nature **
**The MEPAG investigations listed under the objectives should:**
**Note that several required aeronomical measurements can be made with Earth-based observations ( e.g., from earth-orbiting or ground-based platforms) and/or in situ measurements**
**Consider the potential role of atmospheric electrical properties **
**The MEPAG listed investigations should strengthen emphasis on:**
**Dust impact on the entire atmosphere (including aerosol charging) **
**Plasma-neutral coupling**
**External drivers at the top of the atmosphere (e.g., solar radiation and particle effects)**
**Implications of the crustal magnetic fields and their interaction with upper atmospheric processes over time**

## Are the Aeronomy Science Goals and Objectives Balanced, Complete, Appropriate, etc.? (2 of 2)

***What role do upper-atmosphere missions play in the “Pathways” architecture?***
**Concern was expressed over how an upper-atmosphere mission fits within the “Pathways” concept described in *****Mars Exploration Strategy, 2009-2020*****, published in 2003 by the Mars Science Program Synthesis Group**
**An aeronomy mission was called out in only one of the four pathways (“never any water”, in which it was a forced fit), and recent science results from MER appear to have rendered that pathway moot. **
***All need to be reminded that the pathways were examples to show the diversity of potential missions and mission architectures and the ability of the science program to respond to new discoveries.  It was not a menu of four options.***
***Aeronomy/upper-atmosphere studies address key science objectives for Mars, ensuring that a mission in this area is credible and appropriate within any actual architecture.***

## How Can the Mars Telecommunications Orbiter (MTO) Contribute to Aeronomy Science Goals? (1 of 2)

**The theme recommended by the MTO Science Definition Team, of “Mars environmental monitoring” is supported.**
**It appropriately takes advantage of the expected long lifetime of MTO, potentially to observe the behavior of components of the upper atmosphere over a full 11-yr. solar cycle.**
**It could provide the “solar cycle” context in which a shorter-lived upper-atmosphere mission could provide the detailed coverage of physical and chemical processes related to volatile evolution and therefore climate change.**
***Example***** candidate instruments for long-term monitoring include:**
**Radiation fields, including Solar Energetic Particles (SEPs) and Solar UV irradiance;**
**Atmospheric emissions from which composition can be inferred;**
**Solar-wind interactions at the 4000-km MTO orbital altitude;**
**Atmospheric dust and temperature structure to high altitudes;**
**Ionosphere electron density profiles.**

## How Can the Mars Telecommunications Orbiter (MTO) Contribute to Aeronomy Science Goals? (2 of 2)

**Notes with regard to MTO:**
**MTO radiation measurements would enhance similar and contemporaneous measurements on the Mars surface.**
**Spacecraft-to-spacecraft radio occultations would broaden coverage of atmospheric neutral and ionospheric structure beyond that attainable by MTO alone.**
**Magnetic field measurements can significantly enhance interpretation of the SEP and pick-up-ion distribution measurements that would address the proposed Mars space environment monitoring.**
**The measurements obtainable within the constraints imposed by MTO (instrument mass, power, available funding, viewing geometry, s/c orbit, etc.) are such that no plausible instrument selection would allow us to “check the box” that MTO has made the aeronomy measurements necessary to understand key volatile escape processes and their current rates.**

## Human Exploration Program Considerations:(1 of 2)

**Upper-atmosphere studies have the potential to play important roles in the following areas:**
**Understanding the human-related radiation environment and the relationship between the radiation incident on the upper-atmosphere and the surface radiation hazard.**
**The role of the ionosphere in communications links.**
**Lifetime of orbital instruments and platforms and related planetary protection concerns, and operational aspects of orbital missions at moderate altitudes that still feel the effects of the upper atmosphere (such as reaction wheel desaturation operations).**
**Aerobraking operations and hazards associated with upper-atmosphere structure and variability including dust influence, variability, and evolution.**

## Human Exploration Program Considerations:(2 of 2)

**Understanding the influence of the upper atmosphere in these areas requires knowledge (observation and modeling) of the:**
**Diurnal variability**
**Seasonal variability**
**Solar-cycle variability**
**Spatial (geographical) variability**
**Altitude variability (including effects from the lower atmosphere)**
**It is necessary to establish measurement requirements in terms of a well-defined risk and mitigation strategy (i.e., whether the system can handle the potential variations vs. simultaneous observations to allow optimization and control).**
**Upper-atmosphere studies do support aerobraking of robotic missions, but may not be needed for aerocapture due to the low altitude of primary deceleration (30-50 km) expected for human missions.**

## Ongoing Participation and Responsibility of the Aeronomy Community

**Making the scientific connections between the Mars upper atmosphere and the broad Mars science goals via a science traceability matrix is the responsibility of any proposer for instruments or missions.**
**Mars Express results are relevant to the upper atmosphere and to evolution processes, and need to be incorporated into any discussion of science results and proposals for future instruments or missions.**
**Generally, the Mars aeronomy/upper-atmosphere community has not been heavily engaged in MEPAG activities, and as a result the potential contributions of aeronomical science to achieving high-priority Mars science goals and objectives have not been incorporated as thoroughly as they could be.**
**The discussion represented by this workshop and white paper needs to be the first of an ongoing dialog and integration of the community, not a one-time activity.**

## Summary Recommendations and Conclusions

**The upper atmosphere is an important part of the martian climate system.  Understanding the behavior of the key components of the system (such as surface habitability or geochemical evolution) will require understanding the entire system from the interior to the exobase.**
**Important aspects of the upper-atmosphere can be observed from the unique perspective of MTO, especially with observations potentially made over an entire solar cycle.**
**Although some notable observations of the upper atmosphere are being made at present, they are limited in scope and coverage and do not provide the detailed information necessary to address the major science and programmatic issues.**
**The necessary observations can be made from a dedicated s/c mission with appropriate orbit, lifetime, and instrumentation.  The necessary observations are thought to be possible within the constraints of a Scout mission, although detailed analysis of this opportunity has not been done.**