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Next Generation Adaptive Optics - Solar System Science Cases -

Next Generation Adaptive Optics - Solar System Science Cases -. SSC meeting - June 21-22 2006, Hawaii, USA. F. Marchis (UC-Berkeley) Members: A. Bouchez (Caltech), J. Emery (NASA-Ames), K. Noll (STSCI), M. Adamkovics (UC-Berkeley). General introduction.

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Next Generation Adaptive Optics - Solar System Science Cases -

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  1. Next Generation Adaptive Optics - Solar System Science Cases - SSC meeting - June 21-22 2006, Hawaii, USA F. Marchis (UC-Berkeley) Members: A. Bouchez (Caltech), J. Emery (NASA-Ames), K. Noll (STSCI), M. Adamkovics (UC-Berkeley)

  2. General introduction • AO expands the study of our solar system • Good temporal monitoring to observe variable phenomena (atmosphere and surface) • Short time scale to respond to transit and unpredictable events (impact of a comet on Jupiter) • Keck Observatory and planetary sciencesignificant contributions and dynamic sub-field.Since 2000: • 32% of Keck referee papers. • 42% of all Keck press releases • NASA (1/6 partner of Keck Obs) supports investigations mostly in Planetary science

  3. Science Cases A few science cases were chosen to illustrate the advanced capabilities of NGAO (with simulations) • A. Binary Minor Planets • Detection and orbits of asteroidal satellites • Spectroscopy of moonlets • Size and shape • B. Satellites of Giant Planets • Titan’s surface and its atmosphere • Io’s volcanism

  4. L5-Trojan Main-Belt L4-Trojan TNOs Centaurs Minor Planets • Building blocks of the Solar System linked to its formation • ~400,000 minor planets known • Small apparent size (largest 1 Ceres, Dapp=0.7arcsec  “seeing” limit)

  5. Diversity of shapes and sizes 25143 Itokawa “Like archaeologists working to translate stone carvings left behind by ancient civilizations, the collisional and dynamical clues left behind in or derived from the Main Belt, once properly interpreted, can be used to read the history of the inner Solar System.” Bottke et al 2005

  6. What are asteroids made of? (a) Shape of NEA* Toutatis observed with radar Internal structure? (b) Monolith (c) Contact Binary(d) Rubble Pile From E. Asphaug, 1999, “Survival of the weakest” * NEA= Near Earth Asteroid

  7. Binary Asteroids A Family Portrait MB 87 Sylvia and its 2 moons (VLT AO, 2005) MB - Ida and Dactyl (Galileo 1993) MB -45 Eugenia & Petit-Prince (CFHT AO, 1998) TNOs 2003EL61 (Keck AO, 2005) ~85 multiple asteroidal systems known Astronomical prize for astronomers and theorists Mass, density, constraints on formation of planets

  8. Multiple asteroidal systems and NGAO Considering 80 known multiple asteroidal systems: • + better angular resolution in visible (~15 mas) -> close doublet (sep. < 50 mas) can be also studied • + a better sensitivity as well…

  9. NGAO capabilities • Simulation context: • 87 Sylvia was discovered in 2005: Rprimary = 143 km, RRemus= 3.5 km, RRomulus=9 km • Insert 2 more moonlets. One closer (6 km) at 480 km and one smaller (1.75 km) at 1050 km Triple system 87 Sylvia with VLT/NACO Pseudo-Sylvia simulated

  10. Simulations • Better sensitivity • Detection of fainter moonlet & closer moonlets • More multiple systems • Better photometry • Better estimate of the size and shape of moonlet • Better astrometry • Reliable estimate of orbital parameters, small orders perturbations (e.g., precession, interactions between moonlets, …) 1.6” Simulation of pseudo- Sylvia observed with various AO systems

  11. Trans-Neptunian Object satellite systems K band -2” NGAO simulations K band -2” Hypothetical 3rd moon, 75 km diameter. Keck 2 LGS-AO 2003 EL61: A Charon-sized (~1500 km) TNO with 2 satellites in non-coplanar orbits (Brown et al. 2006). K band -1” 2003 EL61 at 51 AU • Most large TNOs may have multi-satellite systems, which record their formation and/or collisional history. • An NGAO survey of large TNOs would find all satellites >100 km diameter out to 100 AU. Identical system at 100 AU (mv=20), observed using an off-axis V=16.5 NGS. & 50” separation

  12. Low resolution spectroscopy • Better AO correction  higher SN on spectra of moons and primary (capture body, infant of primary, age, …) • Visible wavelength range  characterize the surface composition Silicate absorption bands centered at 1 and 2 m

  13. Summary Science case A • Keck NGAO will be the best tool for this scientific subject (no space mission scheduled, need for numerous observations,…) • Density & composition of minor planet is the key to understanding the formation of the solar system

  14. Science Cases A few science cases were chosen to illustrate the advanced capabilities of NGAO (with simulations) • A. Binary Minor Planets • Detection and Orbits of asteroidal satellites • Spectroscopy of moonlets • Size and shape • B. Satellites of Giant Planets • Titan’s surface and its atmosphere • Io’s Volcanism

  15. Volcanism of Io • The most volcanically active place in the solar system • Only 5 successful flybys with Galileo (spatial resolution of global NIR observations 100-300 km) • Outstanding questions: • Internal composition linked to the highest temperature of magma • Evolution in the orbital resonance, constrained by the heat flow measurement and evolution

  16. Io observed with NGAO in NIR Keck NGAO - H Band Keck NGS - H Band 0.9” FWHM=33 mas FWHM=44 mas • Up to 0.9 m, thermal output of outburst can be detected (T>1450 K) • Up to 0.7 m -> mafic absorption band (centered at 1 m) • Thermal band imaging (3-5 m) capabilities are necessary

  17. Comparison with HST • + Better spatial resolution (~40 km) than Galileo spacecraft global NIR images • Surface Changes • Plumes No future mission (with imaging capabilities) planned toward Jupiter (brief flyby in 2007 by New Horizons)  NGAO on Keck is an highly competitive instrument!

  18. Why do we need NGAO? • Best angular resolution provided in visible and NIRDirectly image planetary surface and atmosphere, characterized by spectroscopy • Excellent and stable Strehl ratio in NIR Detect moonlets around asteroids & KBOs and determine their orbits and spectra. • A flexible AO system with service observingMaximize the scientific return and efficiency of the observatory and observe transient events or monitor regularly

  19. The End

  20. Other satellites Reminder: FWHM PSF(NGAO-R) = 14 mas

  21. Other satellites • Consider high resolution spectral analysis (R>1000) for atmospheric features. Example geysers on Enceladus • Problem due to giant planet halo contribution on the WFS? 80 mas Reminder: FWHM PSF(NGAO-R) = 12 mas

  22. Other satellites Insert here a figure showing which satellites can be observedconsidering the glare of the planet We should use Van Dam et al. measuremnts (sent to Mate) Reminder: FWHM PSF(NGAO-R) = 12 mas

  23. How many asteroids observable w/ NGAO?

  24. Mysterious Titan • Satellite of Saturn - D~5150 km • Surface mostly hidden by an opaque prebiotic atmosphere • Studied with Cassini spacecraft (4 flyby already) and Huygens lander (Jan. 2004) • Spatial resolution of global observations up to 9km in NIR

  25. Titan Surface and its Atmosphere • Goals:Observations of an extended object - imaging and spectroscopy of its atmosphere. Comparison with previous NGS AO systems. Illustration of the variability of solar system phenomena (volcanism, clouds) • Inputs from TCIS: Simulated short exposureﾊ On-Axis PSFs (~2-4s) (x10) at various wavelength (NOT YET DEFINED) in good seeing conditions for a bright reference (mv=8.5). Should we expect a degradation due to the angular size of Titan (D=0.8")ﾊ • Method:We will create a fake Titan observations considering also the haze component in visible and NIR and using global map (with R=30-200 km) of Cassini spacecraft.ﾊWe will focus on atmospheric windows for which the surface canﾊ be seen (tools are ready MA & FM). Wavelength not defined yet.- Deconvolution with AIDA may be included (algorithm 95% ready FM)- Comparison with Keck NGS AO, VLT AO, and Cassini will be included- Good temporal coverage from the ground vs spacecraft will be discussed and illustrated by surface changes due to a cryo-volcano (and/or clouds in the troposphere?)- Spectroscopy to detect N2+ species in the atmosphere (high R) and measure winds in Titan atmosphere at various altitudes (extremely high R).

  26. Titan Surface and its Atmosphere • First results - Comparison of H band observations 0.8” FWHM= 44 mas FWHM= 34 mas FWHM= 34 mas About the fake image of Titan based on Cassini map at 0.94 m, 600 pixels across, spatial resolution of 9 km (1 mas) near disk center, Minnaert function reflectivity, long=150W, lat=23S

  27. Titan Surface and its Atmosphere Prebiotic atmosphere Not completely transparent in visible-NIR • Multi-wavelength observations PSF used : NFAO - no blurring

  28. Titan Surface and its Atmosphere • Comparison HST-ACS/HRC & Keck NGAO Clear progress in angular resolution compared with HST

  29. Surface Changes on Titan HST/ACS R KNGAO-R Cryovolcanic-style surface change are detectable with KNGAO in J band. In R band morphology is better estimated -> volcano caldera, lava flow?

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