21 Lutetia: Overview of Results 10/3/2017 21 Lutetia: Overview of Results from OSIRIS Images H. Sierks1, C. Barbieri2, D. Koschny3, P. Lamy4, H. Rickman5, R. Rodrigo6, and the OSIRIS team 1 Max-Planck-Institut für Sonnensystemforschung, Katlenburg-Lindau, Germany 2 CISAS, University of Padova, Padova, Italy 3 Research and Scientific Support Department, ESTEC, Noordwijk, The Netherlands 4 Laboratoire d’Astrophysique de Marseille, Marseille, France 5 Department of Astronomy and Space Physics, Uppsala, Sweden 6 Instituto de Astrofísica de Andalucía - CSIC, Granada, Spain 6 lead scientists, 9 contributing institutes to Osiris h/w, 35 CoIs, 15 associate scientists, 50 team scientists plus local scientists, post docs, phd students

Outline OSIRIS – Scientific Camera System 10/3/2017 Outline OSIRIS – Scientific Camera System Observation Geometry and Sequence Approach Sequence Opposition Images Closest Approach Shape Prediction & Observation Lutetia Map Projection & Coordinate System Surface Geomorphology Boulders and Landslides Ejecta Thickness from Craters Lutetia Reflectance Spectrum Summary Bridge from Rita intro and Sonia asteroid context talk to observations by Osiris Instrument, observation geometry, approach, opposition, CA, farewell, science: shape vs predict, map, geomorphology, boulders, ejecta, spectrum

OSIRIS - Scientific Camera System 10/3/2017 OSIRIS - Scientific Camera System NAC – Narrow Angle Camera FOV 2.2°, IFOV 18.6 µrad/px 2k x 2k BI E2V CCD, AB 60m px scale @ CA, f/8, 717mm 23 Filters 250 to 1000 nm (UV to IR) 2 high performance cameras, an optimized couple, both off axis imagers, optimized for comet observations WAC – Wide Angle Camera FOV 12°, IFOV 100 µrad/px 2k x 2k BI E2V CCD, AB 300m px scale @ CA, f/5.6, 140mm

Observation - Geometry and Sequence 10/3/2017 Observation - Geometry and Sequence OSIRIS fly-by sequence from closest approach (CA) -9h to CA +16 min 234 NAC images, 228 WAV images, total of 462 images with ~1 GB of image data show observation geometry and sequence of events, zero phase angle at 18 min before CA, got down to 0.15deg phase angle CA is at 3170km, so 10km off (plot courtesy ESA)

500.000 km -9:30h 400.000 km -7:30h 10/3/2017 300.000 km –5:30h 215.000 km -4:00h 81.000 km -1:30h 160.000 km -3:00h 40.000 km -0:46h 63.000 km -1:10h distances and time to CA, s/c flip is corrected for, see Lutetia rotation, upper left, 2 px dia, lower right 24px dia, disk 300px total

Opposition Images phase angles 4.1°, 2.0°, 0.6°, 0.15° 10/3/2017 Opposition Images 26.000 km -0:30h 20.000 km -0:22h Zero phase angle crossing 17.000 km -0:19h 16.000 km -0:18h phase angles 4.1°, 2.0°, 0.6°, 0.15° Work by Stefan Schroeder, MPS

Opposition Image Stretched 10/3/2017 Opposition Image Stretched Opposition Spot NAC image @ phase angle ~0.15° Albedo variation in landslide area ~7% Line features are visible Small impact feature Opposition spot crossing surface See opposition spot running over the surface No s/c shadow ;-) Features: fresh crater, land slide, stripes, small new crater ejecta Work by Stefan Schroeder, MPS

Closest Approach 10/3/2017 All NAC, all orange 3.600 km -0:02h 3.170 km CA All NAC, all orange Upper left at 15:42, 3604km, CA upper right at 15:44:48, mid from 3207 to 3667km. Low 3915, 4628, 6072, 6304 km, lower right 15:50:39, CA +5min CA –2min to CA +5min, 3604 to 3169 to 6304 km 6.300 km +0:06h

10/3/2017 Closest Approach Highest resolution image @ 60m px resolution, see large impact craters of size comparable to radius of the asteroid, smooth near craterless regions indicate recent impacts and ejecta. Regional units show craters, grabens, scarps, pits, ridges, contacts, large boulders. Craters with sharp and steep walls, some with land slides, some with irregular shape, and others almost filled with regolith are found. Add scale bar, add arrows 10 km

Shape Prediction & Observation 10/3/2017 Shape Prediction & Observation 3.902 km distance size Carry @ Frascati: 134 x 102 x 94 km3, 1 sigma error 3 x 2 x 8 km B Carry volume 5.94 ± 0.90 x 10^20 cm^3 T Morley mass 1.62 10^18 kg -> density 3.6 (3.1 to 4.2) g/cm3 Excellent agreement with the predicted shape based on light curve inversion and AO observation with OSIRIS images. (see B. Carry et al., this conference) 26.178 km (top), 4.146 km distance (bottom)

Lutetia Coordinate System 10/3/2017 Lutetia Coordinate System Use Osiris/LAM shape by silhouette based on WAC limb images Project NAC highres images on shape Project grid of coordinates on shape to create coordinate system Identify features by latitude/longitude Will be improved by use of final shape from photo- clinometry (see Lamy et al., this conference) Work by Jean-Baptiste Vincent, MPS Use WAC images for coarse shape model (shape by silhouette) Move down to backup (tbc)

Lutetia Coordinate System 10/3/2017 Lutetia Coordinate System More than 50% seen by Osiris, we cover up to -10 to -20 deg Cylindrical projection, checkout Mercator JBV, redo psf deconvolved Work by JBV, MPS

Surface Geomorphology 10/3/2017 Surface Geomorphology Started to do cartography Work of Matteo Massironi, UPD Work by Matteo Massironi, UPD

Boulders and Landslides 10/3/2017 Boulders and Landslides Boulders in 2 regions (Montmatre and Trocadero) Total of 237 boulders identified of size of min 100m 3 landslides in Montmatre; gravitational talus in Trocadero Work by Richard Moissl, MPS Boulders not of size of Ayers Rock, but of impressive size up to 300m 5 km Work by Richard Moissl, MPS

10/3/2017 Regolith Thickness First estimation of d/D for different "old" regions between 0.13 and 0.3, similar to what has been measured on other planetary surfaces. "Young" region shows craters completely buried under the regolith blanket. If the region was similar to the rest of the asteroid before the resurfacing, these craters must be at least 600m deep, which gives a lower limit on the regolith thickness. Crater diameter: 70 pixels ~ 4.5 km Blanket thickness: ~600 m (for d/D = 0.13) Work by Jean-Baptiste Vincent, MPS Work by Jean-Baptiste Vincent, MPS

Lutetia Reflectance from OSIRIS 10/3/2017 Lutetia Reflectance from OSIRIS Distance 55000 km NAC ~100 px dia WAC ~20 px dia Disk integrated Phase angle 7.74° TNG spectrum from15/16 Nov 2004 (Belskaya et al. 2010) Match UV with ALICE Match IR with VIRTIS Want to match to UV with ALICE, IR to VIRTIS, to come Work by Sonia Fornasier, LESIA

Summary Asteroid fly-by was very successful 10/3/2017 Summary Asteroid fly-by was very successful Lutetia is a piece of rock, too dense for a rubble pile Old and young regions, young with ‘fresh’ blanket Blanket in North Pole region suggests a thick layer of regolith/ejecta Lutetia exposes fascinating morphology with many craters, grooves, ridges, graben, etc. that lead to speculations about Lutetia’s history Craters suggest Lutetia is very old (see Marchi et al., this conference) No satellites found, size limit 160m from WAC images (see Bertini et al., this conference) No exosphere found (Na) Nature paper in preparation M-type by mass C-type by X-type

Lutetia in Perspective 10/3/2017 Lutetia in Perspective Collection by E. Lakdawalla, APOD 26 July 2010 Collection by E. Lakdawalla, APOD 26 July 2010

Farewell Lutetia Thank you.

Talks to Come Martin Pätzold et al. on mass from radio tracking Nick Thomas et al. on surface geomorphology Simone Marchi et al. on age from crater counting Stubbe Hviid et al. on color variegation Philippe Lamy et al. on shape and physical properties

Backup Slides

Phase function ALBEDO UV375 0.15956 phase=0.15°

21 Lutetia Belskaya & Shevchenko 1999