12-14 May, 2008SERENA, Santa Fe, NM 1 Compositional Relationships With the Surface and Crust The exosphere and related SERENA particle experiments

12-14 May, 2008SERENA, Santa Fe, NM 2 Ann L. Sprague Lunar and Planetary Laboratory, Tucson, AZ, USA With many, many collaborators over 2 decades: Exosphere studies-groundbased: Hunten, Hill, Kozlowski, Grosse, Wells, Domingue, Fink, Schneider, Killen, Potter, Morgan, Mendillo, Wilson, Baumgardner Exosphere studies-MESSENGER: MASCS--McClintock, Bradley, Vervak, Killen, Izenberg, Holsclaw, Kochte, Lankton, Mouawad FIPS--Raines, Gloeckler, Kabin, Krimigis, Andrews, Slavin, Koehn And the MESSENGER AMDG TEAM

12-14 May, 2008SERENA, Santa Fe, NM 3 What might we see with the neutral and ionised particle analyser SERENA (IFSI Italy) ? FIPS am I allowed to say WOW! exceeds expectations? Ions sputtered from surface and ionized from neutrals in atmosphere Neutrals in atmosphere Solar Wind ions—material delivered to surface which is implanted into surface

12-14 May, 2008SERENA, Santa Fe, NM 4 Pickup Ion Composition From Zurbuchen et al. 2008, EGU, Vienna, Austria

12-14 May, 2008SERENA, Santa Fe, NM 5 Height (Mer R) g (cm/sec 2 )HNaSKCaFe Geopotential Scale Heights (km) assumed temperature 1000 K

12-14 May, 2008SERENA, Santa Fe, NM 6 Near-surface measurements of Na and K

12-14 May, 2008SERENA, Santa Fe, NM 7 Credit: NASA/Joh ns Hopkins University Applied Physics Laboratory /Carnegie Institution of Washington

12-14 May, 2008SERENA, Santa Fe, NM 8 MDIS Color Three major units –Smooth plains –Average crustal material –Low albedo / relatively blue crustal material Minor units –Diffuse red material –High albedo / relatively blue crater floor and ray material –High albedo materials on crater floors and central peaks Adapted From Head et al. LPSC 2008

12-14 May, 2008SERENA, Santa Fe, NM 9 Atmospheric potassium, K (ionization time Na/K = 1.5 at 0.31 AU). Observations show it close to the surface. MASCS will determine if there is an extended component—or maybe Rosemary’s and Drew’s work. K emission Surface Reflection in band continuum Adapted from Potter and Morgan PSS (1997)

12-14 May, 2008SERENA, Santa Fe, NM 10 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 11 Credit: NASA/Johns Hopkins University Applied Physics Laboratory /Carnegie Institution of Washington looking north

12-14 May, 2008SERENA, Santa Fe, NM 12 Imaging the sources and full extent of the sodium tail of the planet Mercury Baumgardner, Wilson, Mendillo, GRL, 35, 2008

12-14 May, 2008SERENA, Santa Fe, NM m AEOS telescope on Maui, June 8, 2006 Baumgardner et al ~88 W long sub-earth not radar A and B Na + implant and subsequent release? Or….really Na-rich polar regions??

12-14 May, 2008SERENA, Santa Fe, NM 14 Ion Implantation Subsequent release to exosphere –High energy process Photo sputtering Charged particle sputtering –High energy coma –Low energy process Thermal desorption –Diurnal effect

12-14 May, 2008SERENA, Santa Fe, NM 15 – Impact distribution of Ca +11 on the surface of Mercury for specific solar wind conditions. Southern hemisphere impact sites dominate. Color bar--the number of parcels impacting per site. Each parcel represents ~10 17 Ca ions. Similar behavior, with more pronounced preference for southern hemisphere impacts is seen for O +6. (Patrick Koehn, 2006)

12-14 May, 2008SERENA, Santa Fe, NM 16 Observations of Ca High Resolution Spectrograph Keck I Mauna Kea Hawaii Bida et al Killen et al Radiance of emission ~ 2.5 k Ray High radial velocity (-2 km/s) indicates high energy

12-14 May, 2008SERENA, Santa Fe, NM 17 Strong Diurnal Effect Morning High/Afternoon Low Na K

12-14 May, 2008SERENA, Santa Fe, NM 18 Adapted from Raymond et al. 1997

12-14 May, 2008SERENA, Santa Fe, NM 19 Challenges for SERENA ●Sort out the true surface components from the solar implanted components ●Determine the fractional amount of recycling per pristine surface atom ●Observe impacts and measure exogenous components from first sight ●Discover new species and secular variation— eg. impacts, ecliptic variation, comet trails, other dust regions

12-14 May, 2008SERENA, Santa Fe, NM 20 This slide left intentionally empty end of presentation