12-14 May, 2008SERENA, Santa Fe, NM 1 Mid-IR observations of Mercury’s Surface as related to MERTIS and PEL and BED (and SERENA, of course)

12-14 May, 2008SERENA, Santa Fe, NM 2 Ann L. Sprague Lunar and Planetary Laboratory, Tucson, AZ, USA With many collaborators over 2 decades: Surface studies: GROUND-BASED--Kozlowski, Donaldson Hanna, Warell, Helbert, Maturilli, Russel, Lynch, Witteborn, Lebofsky, Wooden, Hora, Kasis, Cruikshank, Graps, Deutch MESSENGER--MASCS, GRNS, XRS: Domingue, Vilas, McClintock, Izenberg, Holsclaw, Blewett, Head, Helbert, McCoy, Murchie, Goldsten, Lawrence, Boynton, Feldman, Evans, Nittler, Schlemm, Rhodes, Starr, Robinson, Solomon and the MESSENGER TEAM

12-14 May, 2008SERENA, Santa Fe, NM 3 Ground-based and MESSENGER VIS NIR spectroscopy demonstrated no or very little FeO in Mercury’s regolith Ground-based summary: Vilas et al. (1994) A couple of detections of shallow Fe-bearing clinopyroxene at both N and S at high latitudes, 170º to 230º E Warell et al. (2006) MESSENGER MASCS McClintock et al. Submitted to Science, 2008

12-14 May, 2008SERENA, Santa Fe, NM 4 What might we see with the neutral and ionised particle analyser SERENA (IFSI Italy) coming directly from Mercury’s surface?

12-14 May, 2008SERENA, Santa Fe, NM 5 a.55N, 27S; b.6E, 354W radar spots B and A b. Same c. Same, also Kuiper-Murasaki craters d. Spots B and A e. Same f. Same g. Caloris Basin h. 65N, 155W 0, 125W 9S, 105W i. 35S, 43-73W Sprague et al. 1998

12-14 May, 2008SERENA, Santa Fe, NM 6 atmospheric K emission surface reflection in band continuum Adapted from Potter and Morgan PSS (1997)

12-14 May, 2008SERENA, Santa Fe, NM 7 The Mercury Radiometer and Thermal Infrared Spectrometer (MERTIS) H. Hiesinger, J. Helbert and the MERTIS Co-I Team

12-14 May, 2008SERENA, Santa Fe, NM 8 Plagioclase in some detail Data from PEL, Berlin Emissivity Database, (Helbert et al. 2006)

12-14 May, 2008SERENA, Santa Fe, NM 9 Credit: NASA/Johns Hopkins University Applied Physics Laboratory /Carnegie Institution of Washington New: There are composition differences between Caloris Basin, dark plains material, and radar bright region “C”

12-14 May, 2008SERENA, Santa Fe, NM 10 MDIS image of region measured in mid-infrared spectral imaging discussed in this paper. This region, also known as radar bright region "C" also has a prominent impact crater centered at 114°E, 11° N and its system of ejecta rays appearing brighter against the darker heavily cratered surface beneath.

12-14 May, 2008SERENA, Santa Fe, NM 11 (left) Goldstone-VLA X-band imaging showing radar-bright region "C" as the dark irregular patch--adapted from Butler et al. (1993). (right) Aricebo S-band dual polarization, delay-Doppler imaging showing same region as heavily cratered. Only the regions north of the "ambiguity line" approximately at the equator are relevant-- reproduced from Harmon et al. (2007). 210º to 270º W Longitude

12-14 May, 2008SERENA, Santa Fe, NM 12 Key to Mineral types on following slides Pyroxenes –(e) enstatite: Mg-rich (h) hypersthene: Mg,Fe –(diop) diopside: Ca,Mg (hed) hedenbergite Fe,Ca Plagioclase Na-rich ~90 down to 30 wgt% Na –(and) andesine Na (olig) oligiclase Na –(lab) labradorite Na,Ca (byt) bytownite Ca,Na Olivine –Mg-rich variety ~70 to 97 wgt% >>>FO(70), FO(97) Garnet –(p) pyrope Mg - variety –(g) grossular Ca-variety

12-14 May, 2008SERENA, Santa Fe, NM 13 bright region "C" data-- black models -- grey wide range of grain sizes 5 options for comparison 4 different opaque phases a) 90 spectral end members 180 spectral end members b) rutile (TiO 2 ) permitted, rutile chosen c) ilmenite permitted (FeTiO 3 ), but ilmenite not chosen d) perovskite (CaTiO 3 ) permitted, perovskite chosen e) troilite (FeS) permitted, troilite chosen

12-14 May, 2008SERENA, Santa Fe, NM 14 Enstatite.1 (Salisbury et al., 1988) SiO TiO Al 2 O Fe 2 O FeO4.79 MnO0.15 MgO35.25 CaO0.85 Na 2 O0.02 K2OK2O Total99.66 Hypersthene.1F (Salisbury et al., 1987) SiO Al 2 O FeO17.07 MgO26.09 CaO1.27 K2OK2O0.02 Na 2 O0.05 TiO MnO0.35 Total orthopyroxene

12-14 May, 2008SERENA, Santa Fe, NM 15 Labradorite.1F (Salisbury et al., 1987) SiO TiO Al 2 O Fe 2 O FeO0.17 MnOnot reported MgO0.05 CaO13.42 Na 2 O3.52 K2OK2O0.23 H2O0.04 Total99.89 Albite.1F (Salisbury et al., 1987) SiO Al 2 O FeO0.01 MgO0.02 CaO0.02 K2OK2O0.20 Na 2 O10.37 TiO MnO0.01 Total99.88 plagioclase feldspar

12-14 May, 2008SERENA, Santa Fe, NM 16 Radar Bright C region results Mineral Type Limited# end members Rutile TiO 2 Ilmenite FeTiO 3 Perovskite CaTiO 3 Troilite FeS Ortho- pyroxene 54 (e)33 (e) (h)17 (e)14 (e) (h)45 (e) (h) Clino- pyroxene 0037 (hed)20 (d)0 olivine5 Fo(91)5 Fo(66)025 Fo (88)6 Fo(79) plagioclase9 (lab)14 (lab) 00 orthoclase garnet5 (p) 2 (g) 0.7 (p) 0.9 (g) 3 (p) 0 (g) 02 (p) 0 (g) opaque0yes0

12-14 May, 2008SERENA, Santa Fe, NM 17 Color and albedo controlled by maturity and composition Map units statistically, next step is determine origin PC 2 interpreted to represent compositional variation Caloris Basin smooth plains Low albedo material Smooth plains Low albedo PC 2 MNF (minimum noise fraction, similar to PC) as R-G-B Low albedo material “streak” From Robinson et al. LPSC 2008

12-14 May, 2008SERENA, Santa Fe, NM 18 Next sequences from Donaldson Hanna et al 2008 EGU, Vienna, Austria

12-14 May, 2008SERENA, Santa Fe, NM 19 Caloris Basin Observations 8 April April

12-14 May, 2008SERENA, Santa Fe, NM 20 Best Fit Models – Caloris Basin 9 April April 2006 EM TM

12-14 May, 2008SERENA, Santa Fe, NM 21 Sanidine.3 (K,Na)Al 3 O 8 Salisbury et al. (1991) SiO Al 2 O FeO0.59 MgO0.03 CaO0.02 K2OK2O7.38 Na 2 O5.38 TiO MnO0.02 Total99.97 Orthoclase.3 KAlSi 3 O 8 Salisbury et al. (1991) SiO TiO Al 2 O MnO0.03 K2OK2O13.51 Na 2 O1.69 FeO0.02 MgO0.04 CaO0.04 Total99.34 Potassium feldspars: K-spars

12-14 May, 2008SERENA, Santa Fe, NM 22 Caloris Basin Results Merc0080Merc0070 Minerals K - Feldspar20% [sanidine]28% [sanidine] Plagioclase15% [labradorite]12% [labradorite] Orthopyroxene7% [enstatite] 5% [hypersthene] 10% [hypersthene] Clinopyroxene19% [augite]27% [augite] Olivine<3% [forsterite]<1% [forsterite] MISSINGMATERIALWHAT??

12-14 May, 2008SERENA, Santa Fe, NM 23 Dark Plains Observations 8 April April

12-14 May, 2008SERENA, Santa Fe, NM 24 Best Fit Models – Dark Plains 8 April April 2006 TM EM

12-14 May, 2008SERENA, Santa Fe, NM 25 Dark Plains Results Merc0098Merc0063 Minerals Plagioclase27% [labradorite]31% [labradorite] Orthopyroxene11% [hypersthene]6% [hypersthene] Clinopyroxene22% [augite]36% [augite] Olivine6% [forsterite]2% [forsterite] MISSINGMATERIALWHAT??

12-14 May, 2008SERENA, Santa Fe, NM 26 Rutile TiO 2

12-14 May, 2008SERENA, Santa Fe, NM 27 Perovskite CaTiO 3

12-14 May, 2008SERENA, Santa Fe, NM 28 Ilmenite FeTiO 3

12-14 May, 2008SERENA, Santa Fe, NM 29 Meteoritic troilite FeS

12-14 May, 2008SERENA, Santa Fe, NM 30 Observation Location: all E longitude Reported Result 1)Sprague et al. (1994) 338° to 348° 250° alkali basalt labradorite 2)Sprague et al. (1997) 240° to 250° 330° E labradorite, wgt. %SiO 2 ; 90% feldspar & 10% Mg- pyroxene 3)Emery et al. (1998) 295° to 350° 200° to 260° not modeled nepheline alkali syenite 4)Sprague et al. (1998) 240° to 250°90% labradorite & 10% enstatite 5)Cooper et al. (2001) 20° S to 20° N 275° ±10° 180° ±10°,170° ±10°,350° ±10° 215° ± 10° ~ 44 wgt% SiO wgt% SiO 2 ~50 and ~42 wgt. % SiO 2

12-14 May, 2008SERENA, Santa Fe, NM 31 6)Sprague et al. (2002) 20° S to 20° N 275° to 315° 252° to 292° wgt. %SiO 2 ; labradorite and clinopyroxene pyroxene (unspecified) 7)Warell et al. (2006) 50° to 75° N, 110° 50° to 75° S, 166° to 250° 50° to 75° N, 166° to 250° no FeO orthopyroxene wgt.%SiO 2 clinopyroxene wgt.%SiO 2 8)Sprague et al. (2008) EGU 0° to 30° N 100° to 140° enstatite, forsterite, orthoclase labradorite, Mg-garnet, rutile?/perovskite? 9) Donaldson Hanna et al. (2008) EGU Caloris Basin Dark Surrounding Plains K-spar, plagioclase, clinopyroxene, orthopyroxene

12-14 May, 2008SERENA, Santa Fe, NM 32 Challenges for SERENA ●Quantify neutral and ions sputtered Mg, Al, Ca, O, etc. from pyroxenes and feldspars ●Quantify Na, K, and if possible locate it ● Distinguish between solar Fe and Fe from surface materials—is it possible? ● Perhaps use knowledge of H, H 2 and He as a “boot strap” to distinguishing between solar wind and surface mineral partitioning??

12-14 May, 2008SERENA, Santa Fe, NM 33 This slide left intentionally empty end of presentation