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Venus Exploration Analysis Group: Scientific Goals for Surface Exploration

Venus Exploration Analysis Group: Scientific Goals for Surface Exploration. Ellen R. Stofan, S. Mackwell, K. Baines, S. Atreya, J. Luhmann, J. Cutts, T. W. Thompson 14 November, 2006 VEP Landing Site Workshop. VEXAG.

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Venus Exploration Analysis Group: Scientific Goals for Surface Exploration

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  1. Venus Exploration Analysis Group:Scientific Goals for Surface Exploration Ellen R. Stofan, S. Mackwell, K. Baines, S. Atreya, J. Luhmann, J. Cutts, T. W. Thompson 14 November, 2006 VEP Landing Site Workshop

  2. VEXAG • Venus Exploration Analysis Group (VEXAG) established by NASA in July 2005 to identify scientific priorities and strategy for the exploration of Venus. • Provides NASA with community-based forum to provide scientific input and determine technology development requirements for planning and prioritizing the exploration of Venus over the next several decades. • Open to all interested scientists, • VEXAG will report its findings and provide input to NASA, but will not make recommendations

  3. Process • Chaired by Sushil Atreya (U. Michigan) and Janet Luhmann (U. California Berkeley) • 2 focus groups: atmosphere (lead Kevin Baines, JPL) and surface and interior (lead Steve Mackwell, LPI) • Website (www.lpi.usra.edu/vexag/) • 1st and 2nd meetings 11/05 and 5/06, Pasadena CA • 3rd meeting January 11-12, Washington DC (open to all)

  4. Aim • VEXAG will produce MEPAG-like document that will be a ‘living’document • Will outline Goals- Objectives-Investigations-Measurements • Draft early 2007 • Within each Goal, Objectives will be prioritized based on science and sequence. • Within each Objectives, series of Investigations collectively needed to achieve each objective. • Investigations may be addressed by single or multiple measurements/missions/instruments. • Significant technology development may be required for performing Investigations.

  5. Goals • Origin and Early Evolution of Venus: How did Venus originate and evolve, including the lifetime and conditions of habitable environments in solar systems? • Venus as a terrestrial planet: What are the processes that have and still shape the planet? • What does Venus tell us about the fate of Earth’s environment?

  6. Goal 1: Origin and Early evolution of Venus • Early periods with possible sustained surface oceans and climate more amenable to development and evolution of life not excluded based on present knowledge of Venus. • Sample surface investigations: • Determine atmospheric composition to seek chemical and isotopic signatures of earlier epochs of Venus’ history, and clues to Venus’ origin, formation and evolution through time. • Measure noble gases and isotopic composition with a precision sufficient to enable understanding of Venus origin, especially measurements of krypton, argon and xenon • Measure to high precision H/D, nitrogen (14N and 15N), oxygen, sulfur and carbon isotopes • Analyze trapped gases in rocks for evidence of relict atmosphere • Analyze stable isotopes for major and trace elements

  7. Goal 1 ctd. • Quantify the history of volatiles in the interior, surface and atmosphere of Venus, including degassing and atmospheric escape, to understand the planet’s geologic and atmospheric evolution. • Determine rock mineralogy and composition in multiple environments to constrain crustal and interior evolution. • Measure stable isotopes in minerals • Assess signature of crustal magnetization to constrain history of magnetic field • Determine rock ages to constrain geologic history. • Measure noble gas isotopic ratios (e.g., isotopic abundances of radiogenic argon generated by radioactive decay of potassium in the planet’s interior) to constrain interior and atmosphere evolution.

  8. Goal 1 ctd. • Map rock mineralogy and elemental composition on a planetary scale to search for evidence of an earlier, cooler and wetter Venus. • Measure in situ mineralogy in multiple environments • Measure n situ bulk chemistry of rocks in multiple environments • Determine surface elemental abundances and mineralogy over broad areas • Assess petrology and petrography of surface rocks • Determine ages of and stratigraphic context of analyzed rocks

  9. Goal 1 ctd. • Seek evidence for biologic markers in Venusian environments, including sedimentary rock structures and/or fossil evidence of biological organisms, isotopic anomalies and disequilibrium. • Characterize sources of chemical disequilibrium in the atmosphere • Measure C, S, N and O isotopes in the atmosphere • Measure stable isotopes in the atmosphere and near the surface • Determine chemical alteration of surface as a function of depth • Perform in situ analysis of surface units • Microscopy of rocks including those below the surface • Search for fossils in surface rocks

  10. Goal 1 ctd. • Determine the ages of the various rock units on the surface, both absolute and relative, in order to unravel the past tectonic history of Venus. • Determine rock ages from multiple sites using appropriate dating schemes • Investigate alternative dating schemes • Characterize surface exposure ages

  11. Goal 2:Venus as Terrestrial Planet Exploring and characterizing processes on and in Venus can help us understand dynamical, chemical, and geologic processes on alien worlds throughout the universe. • Constrain the resurfacing history of Venus, including the current and past rates of volcanic activity, including outgassing and interior-surface-atmosphere coupling. • Constrain rate of interior activity and determine interior structure • Measure heat flow and surface temperature to constrain thermal structure. • Determine crustal and interior structure • Determine absolute ages of surface rock units to constrain surface evolution. • Characterize surface geologic units, mineralogically, compositionally and isotopically • Characterize the geochemical budgets and cycles including temporal changes

  12. Goal 3: Venus and Earth Understanding the interior dynamics and atmospheric evolution of Venus may provide insight into the ultimate fate of Earth • Search for evidence of past global climate change on Venus, including chemical and isotope evidence in the atmosphere, as well as rock chemistry and characteristics of surface weathering. • Characetrize the mineralogy of rocks • Measure trapped gases in rocks from earlier epochs • Assess paleoclimate indicators, stable isotopes (O, S, H …) • Search for geomorphological evidence of climate change • Search for evidence of past life, such as fossils

  13. Goal 3 ctd. • Search for evidence of past changes in interior dynamics and tectonics, including possible evolution from plate tectonics to stagnant-lid tectonics, which may have resulted in significant changes in the global climate pattern. • Measure chemical and isotopic composition • Search for paleomagnetic signatures • Constrain interior structure

  14. Goal 3 ctd. • Characterize the Venus Greenhouse effect, including its interaction with surface and interior, allowing a comparison to atmospheric evolution on Earth, Mars, Titan and extra-solar planets. • Obtain temperature profiles • Characterize surface geochemistry including alteration rind depth and composition • Constrain rate of volcanic outgassing and composition

  15. Summary • Detailed atmospheric chemistry including chemistry lower atmosphere and surface/atmosphere interactions • Surface mineralogy and bulk geochemistry • Descent imaging • “Biomarkers” Technological challenges: Seismology, surface age

  16. Decadal Survey/Strategic Roadmap NAS Decadal Survey- Venus lander (New Frontiers) plus future sample return • Strategic Roadmap for Solar System Exploration- New Frontiers reaffirmed, plus follow-on landed mission to highlands of Venus where the possibility exists to find more silicic crust (emphasis on mobility) • Focus on surface geochemistry, atmosphere analysis • Technologies for survival in extreme environments (seismic mission?)

  17. Where to go? • From VEXAG to my opinion! • Tessera, despite difficulties has to be top target • Possibility for older, silicic crust

  18. Other options • Combination of volcanic/stratigraphy sites • Hotspot flanks (geochemistry mantle) (Atla, Bell) • “young”/”older” plains boundary • Mixed volcanic field (Sedna/Guinevere) • Without mobility, all sites have scientific limitations (ex. MER)

  19. Conclusions • Participate in VEXAG process (www.lpi.usra.edu/vexag/) • Surface studies critical to all aspects of Venus studies- in particular understanding the mineralogy of surface rocks, their age, and interior structure • Descent imaging critical on any mission to allow ground truth for Magellan data, further information on surface age relationships • Tessera, despite landing difficulties, best target

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