The nature of Europa's dark non-ice surface material: Spatially-resolved high spectral resolution spectroscopy from the Keck telescope

• Published in: Icarus (New York, N.Y. 1962) Vol. 182; no. 1; pp. 202 - 210
• Main Authors: Spencer, John R., Grundy, William M., Dumas, Christophe, Carlson, Robert W., McCord, Thomas B., Hansen, Gary B., Terrile, Richard J.
• Format: Journal Article
• Language: English
• Published: San Diego, CA Elsevier Inc 01.05.2006; Elsevier
• Subjects: Astronomy; Earth, ocean, space; Europa; Exact sciences and technology; satellite; Satellites of Jupiter; Solar system; Spectroscopy; Surfaces; Satellites of Jupiter; Surfaces; Spectroscopy; Europa; Fine structure; Satellites of Jupiter; Europa; Surfaces; satellite; Spectroscopy; Mapping manifolds; Ice; Adaptive optics; Solar system; Jupiter satellite; Sulfuric acid
• ISSN: 0019-1035; 1090-2643
• DOI: 10.1016/j.icarus.2005.12.024

We present new 1.45–1.75 μm spectra of Europa's dark non-ice material with a spectral resolution ( λ / δ λ ) of 1200, obtained by using adaptive optics on the Keck telescope to spatially separate the spectrum of the non-ice material from that of the surrounding ice-rich regions. Despite the great increase in spectral resolution over the previous best spectra of the non-ice material, taken with Galileo's near-infrared mapping spectrometer (NIMS) with λ / δ λ = 66 , no new fine-scale spectral structure is revealed. The smoothness of the spectra is inconsistent with available laboratory spectra of crystalline hydrated salts at Europa temperatures, but is more consistent with various combinations of non-crystalline hydrated salts and/or hydrated sulfuric acid, as have been matched to the lower-resolution NIMS spectra.