ULTRAVIOLET DISCOVERIES AT ASTEROID (21) LUTETIA BY THE ROSETTA ALICE ULTRAVIOLET SPECTROGRAPH

Journal Article · Wed Jun 15 00:00:00 EDT 2011 · Astronomical Journal (New York, N.Y. Online)

DOI:https://doi.org/10.1088/0004-6256/141/6/199· OSTI ID:21583097

Stern, S A; Parker, J Wm; Steffl, A; Birath, E; Graps, A ^[1]; Feldman, P D ^[2]; Weaver, H A ^[3]; A'Hearn, M F; Feaga, L ^[4]; Bertaux, J -L ^[5]; Slater, D C; Versteeg, M; Scherrer, J R ^[6]; Cunningham, N ^[7]

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1. Southwest Research Institute, 1050 Walnut St, Boulder, CO 80302 (United States)
2. Department of Physics and Astronomy, Johns Hopkins University, 3400 North Charles Street, Baltimore, MD 21218 (United States)
3. Applied Physics Laboratory, Johns Hopkins University, 11100 Johns Hopkins Road, Laurel, MD 20723 (United States)
4. Department of Astronomy, University of Maryland, College Park, MD 20742 (United States)
5. LATMOS/IPSL, CNRS/INSU, University of Versailles St-Quentin, 11 Bd d'Alembert, 78280 Guyancourt (France)
6. Southwest Research Institute, 6220 Culebra Rd, San Antonio, TX 78238 (United States)
7. Department of Physics, Nebraska Wesleyan University, 5000 Saint Paul Avenue, Lincoln, NE 68504 (United States)

The NASA Alice ultraviolet (UV) imaging spectrograph on board the ESA Rosetta comet orbiter successfully conducted a series of flyby observations of the large asteroid (21) Lutetia in the days surrounding Rosetta's closest approach on 2010 July 10. Observations included a search for emission lines from gas, and spectral observations of the Lutetia's surface reflectance. No emissions from gas around Lutetia were observed. Regarding the surface reflectance, we found that Lutetia has a distinctly different albedo and slope than both the asteroid (2867) Steins and Earth's moon, the two most analogous objects studied in the far ultraviolet (FUV). Further, Lutetia's {approx}10% geometric albedo near 1800 A is significantly lower than its 16%-19% albedo near 5500 A. Moreover, the FUV albedo shows a precipitous drop (to {approx}4%) between 1800 A and 1600 A, representing the strongest spectral absorption feature observed in Lutetia's spectrum at any observed wavelength. Our surface reflectance fits are not unique but are consistent with a surface dominated by an EH5 chondrite, combined with multiple other possible surface constituents, including anorthite, water frost, and SO{sub 2} frost or a similar mid-UV absorber. The water frost identification is consistent with some data sets but inconsistent with others. The anorthite (feldspar) identification suggests that Lutetia is a differentiated body.

• OSTI ID: 21583097
• Journal Information: Astronomical Journal (New York, N.Y. Online), Vol. 141, Issue 6; Other Information: DOI: 10.1088/0004-6256/141/6/199; ISSN 1538-3881
• Country of Publication: United States
• Language: English

Related Subjects

79 ASTROPHYSICS
COSMOLOGY AND ASTRONOMY
ABSORPTION
ALBEDO
ANORTHITE
ASTEROIDS
CHONDRITES
COMETS
EMISSION
ESA
FAR ULTRAVIOLET RADIATION
FROST
MOON
NASA
SPECTRA
WATER
ELECTROMAGNETIC RADIATION
FELDSPARS
HYDROGEN COMPOUNDS
ICE
INTERNATIONAL ORGANIZATIONS
METEORITES
MINERALS
NATIONAL ORGANIZATIONS
OXYGEN COMPOUNDS
RADIATIONS
SATELLITES
SILICATE MINERALS
SORPTION
STONE METEORITES
ULTRAVIOLET RADIATION
US ORGANIZATIONS