1. Laboratory data and modeling of Pluto’s spectra
Bernard Schmitt
Eric Quirico, Sylvain Douté et Olivier Brissaud
Laboratoire de Planétologie de Grenoble,
CNRS - Université J. Fourier

2. Optical properties of ices
Schmitt et al., 1998, Solar System Ices, p.199

3. Mesurement of spectral properties (0,4 – 200 µm) of molecular solids
Infrared Spectrometer with an optical cryogenic system ( K)
Solids :
- Ices
Clathrates, Hydrates,
Organics,
Minerals, …
Study effects of:
Temperature
Phases
Composition
Compounds
UV irradiations

4. Ices, organics, … Near and mid-infrared

5. Nitrogen 2n n 2 phases Transition : 35.6K - 2 very weak bands
- Very sensitive to phase
- Sensitive to temperature
Fundamental band sensitive to CO2, H2O
Spectral shape
 surface thermometer n
Grundy et al., 1993, Icarus, 105, 254
Schmitt et al., 1998, Solar System Ices, 199

6. Methane Vis Near-IR Mid-IR
Very large number of bands of various intensities, down to the visible range
- Band shape sensitive to temperature
Grundy et al., 2002, Icarus, 155, 486

7. Methane

8. CH4 – N2 mixtures
Spectra very sensitive on the way the molecular mixture is formed
Crystal growth from the liquid under thermodynamic equilibrium best represent the surface of Pluton and Triton !
Schmitt et al., 1998, Solar System Ices, 199

9. Diluted CH4 – N2 mixtures CH4 spectrum sensitive to :
- Pure vs diluted
- N2 phase and temperature
- CH4 abundance (> 2%)
Quirico & Schmitt 1997a Icarus, 127, 354

10. Rich CH4 – N2 mixtures
Spectrum = combination of the spectra of the saturated N2:CH4 solutions
Quirico et al; 1996 PSS, 44, 973
Schmitt et al., 1998, Solar System Ices, 199

11. Water ice Amorphous phase : Spectrum slightly depend on temperature
- Similar to high temperature crystalline
Crystalline phase :
Strong dependence with temperature, 1.65 µm band
 H2O ice thermometer
Schmitt et al., 1998, Solar System Ices, 199

12. Water ice : Phase and temperature
Grundy et al., 1998, JGR E, 103, 25809

13. Ammonia Pure ammonia : - Several phases Ammonia hydrates:
- 3 hydrate types + several phases
 Complex spectra and not yet well studied (in course …)
Schmitt et al., 1998, Solar System Ices, 199

14. Simple hydrocarbons
Quirico & Schmitt 1997a Icarus, 127, 354

15. Carbon monoxyde 2n 3n Quirico & Schmitt 1997a Icarus, 127, 354

16. Carbon dioxyde - Weakly sensitive to temperature
Quirico & Schmitt 1997a Icarus, 127, 354

17. Methanol, nitriles, oxydes, …
Many molecules measured or under study :
CH3OH, HC3N, C3H4, C2H5CN, C6H6, C3N3H3, …

18. Mesure de la réflectance spectrale (0,3 – 4,8 µm) bidirectionnelle des surfaces granulaires
Etude effets de la :
- Composition,
- Taille et forme des grains,
- Rugosité de surface,
Indices optiques, …
Mesure spectres et fonctions de diffusion :
- Glaces, minéraux,
- Organiques,
- Matériaux géophysiques,
Applications :
Spectro-imagerie spatiale

19. C-H-N compounds
Visible slope and near-IR band strength sensitive to composition and structure of the macromolecular solid
yellow tholins
poly-HCN
black tholins
Reflectance
Wavelength (nm)
Bernard et al. 2006, Icarus 185, 301
samples from LISA

20. surfaces par spectro-imagerie
Composition
Identification de molécules
Etat physique
Modes de coexistence
Abondances
Distribution spatiale
Variations temporelles
Origine - Evolutions
Origine chimique des molécules
Complexité de la matière organique
Microphysique échanges surface/atmosphère
Transports (cycles jour, saison, climat, …)
Liens avec géologie, topographie, …

21. Molecules identification
Quirico et al Icarus, 139, 159

22. Physical state
Quirico et al Icarus, 139, 159

23. Distribution, abundance, grain size
Different ways of mixing :
Molecular
Compounds
Granular
Spatial
Stratigraphy
(tholins)
Douté et al Icarus, 142, 421

24. Complete modeling
Comparison between objects

25. New-Horizon : spatial distribution
Quirico et al Icarus, 139, 159