Mars Aeronomy Science Themes and the NASA Exploration Initiative Report from the NASA Mars Aeronomy

1
Mars Aeronomy Science Themes and the NASA
Exploration InitiativeReport from the NASA Mars
Aeronomy Working Group

• Bruce Jakosky (Chair)
• (bruce.jakosky_at_lasp.colorado.edu)
• 17 September 2004

2
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 planets 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.

3
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.

4
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

5
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.

6
MARS AERONOMY EXPLORATION WORKSHOP AGENDA, 18-19
August 2004 (Agenda and powerpoint presentations
available on web, at http//argyre.colorado.edu/l
ife/aeronomy_workshop) Wednesday, August
18 800-830 Coffee 830-845 Workshop
introduction B. Jakosky 845-855 NASA HQ
perspective, SEC division M. Mellott 855-905 NA
SA HQ perspective, SSE division D.
Bogan 905-925 Mars program and NASA HQ D.
McCuistion 925-955 Status of the Mars
Program M. Meyer 955-1020 Code T requirements
and interest J. Trosper 1020-1035 Break 1035-
1050 Mars Telecommunications Orbiter R.
Zurek 1050-1105 Mars Scout opportunities K.
McBride 1105-1130 MEPAG Goals and Objectives
for upper atmosphere S. Bougher 1130-1145 Lesson
s learned from MGS and Odyssey aerobraking S.
Bougher 1145-1200 Lessons learned at
Venus A. Nagy 1200-1215 MGS Magnetometer
results D. Mitchell 1215-130 Lunch All 1
30-145 Lessons learned at Earth from Earth
missions S. Yee 145-200 Preliminary results
from Mars Express ASPERA J. Sharber
7
Wednesday, August 18, continued 200-515 Discus
sion 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) 515-545 Integration and wrap-up B.
Jakosky
8
Thursday, August 19 800-830 Coffee 830-1200 C
ontinue 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 1200-115 L
unch 115-500 Closed session of steering group
to draft report 500 Adjourn
9
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.

10
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.

11
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.

12
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?

13
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.

14
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.

15
Influence on the atmosphere and climate via the
role of escape to space shown here.
16
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)
17
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

18
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.

19
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.

20
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.

21
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.

22
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.

23
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.

24
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.