| 1. |
- Ann, Sprague, et al.
(författare)
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Mercury: First Spectra from 0.7 to 5.5 mum Support Low FeO and Feldspathic Composition
- 2004
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Ingår i: 35th Lunar and Planetary Science Conference, March 15-19, 2004, League City, Texas, abstract no.1630.
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Konferensbidrag (populärvet., debatt m.m.)abstract
- Spectral measurements of Mercury's surface show an absence of absorptions centered near 0.9 and 1.2 micrometers. At the Moon these absorption bands are ubiquitous at varying depths. We have obtained spectra from the Moon for comparison. The lunar results are shown in a companion abstract.
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| 2. |
- Cremonese, Gabriele, et al.
(författare)
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The surface of Mercury as seen by Mariner 10
- 2007
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Ingår i: Space Science Reviews. - : Springer Science and Business Media LLC. - 0038-6308 .- 1572-9672. ; 132:2-4, s. 291-306
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Tidskriftsartikel (refereegranskat)abstract
- The Mariner 10 spacecraft made three fly by passes of Mercury in 1974 and 1975. It imaged a little under half of the surface and discovered Mercury had an intrinsic magnetic field. Here we briefly describe the surface of Mercury as seen by Mariner 10 as a back drop to the new discoveries made since those historic fly bys by ground-based observations and to the optimistic anticipation of new discoveries by MESSENGER and BepiColombo spacecraft that are scheduled for encounter in the next decade.
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| 3. |
- Mendillo, Michael, et al.
(författare)
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Imaging the surface of Mercury using ground-based telescopes
- 2001
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Ingår i: Planetary and Space Science. - : Elsevier Science Ltd. ; 49:14-15, s. 1501-1505
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Tidskriftsartikel (refereegranskat)abstract
- We describe and compare two methods of short-exposure, high-definition ground-based imaging of the planet Mercury. Two teams have recorded images of Mercury on different dates, from different locations, and with different observational and data reduction
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| 4. |
- Sprague, Ann, et al.
(författare)
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Mercury's Surface Composition and Character as Measured by Ground-based Observations
- 2007
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Ingår i: Space Science Series of ISSI.
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Bokkapitel (refereegranskat)abstract
- Mariner 10 made no measurements that directly measured the surface composition of Mercury. However, the 45% of the surface that was imaged is heavily cratered and in that sense resembles the Moon. Also the crater morphology and tectonic expression of fault scarps and ejecta rays give the strong impression that the surface is covered with silicates. This impression has been supported by ground-based observations that have identified key indicators in spectral measurements that appear similar to spectral measurments of silicates in the laboratory and on the Moon. Some spectra have been interpreted in terms Mercury's surface composition. These are summarized below and discussed in the context of the challenges and opportunities of future ground-based observations and orbital measurements by the MESSENGER and Bepi Colombo spacecrafts.
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| 5. |
- Sprague, Ann, et al.
(författare)
-
Mercury's Surface Composition and Character as Measured by Ground-based Observations
- 2007
-
Ingår i: Space Science Reviews. - : Springer Science and Business Media LLC. - 0038-6308 .- 1572-9672. ; 132:2-4, s. 399-431
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Tidskriftsartikel (refereegranskat)abstract
- Mercury’s surface is thought to be covered with highly space-weathered silicate material. The regolith is composed of material accumulated during the time of planetary formation, and subsequently from comets, meteorites, and the Sun. Ground-based observations indicate a heterogeneous surface composition with SiO2 content ranging from 39 to 57 wt%. Visible and near-infrared spectra, multi-spectral imaging, and modeling indicate expanses of feldspathic, well-comminuted surface with some smooth regions that are likely to be magmatic in origin with many widely distributed crystalline impact ejecta rays and blocky deposits. Pyroxene spectral signatures have been recorded at four locations. Although highly space weathered, there is little evidence for the conversion of FeO to nanophase metallic iron particles (npFe0), or “iron blebs,” as at the Moon. Near- and mid-infrared spectroscopy indicate clino- and ortho-pyroxene are present at different locations. There is some evidence for no- or low-iron alkali basalts and feldspathoids. All evidence, including microwave studies, point to a low iron and low titanium surface. There may be a link between the surface and the exosphere that may be diagnostic of the true crustal composition of Mercury. A structural global dichotomy exists with a huge basin on the side not imaged by Mariner 10. This paper briefly describes the implications for this dichotomy on the magnetic field and the 3 : 2 spin : orbit coupling. All other points made above are detailed here with an account of the observations, the analysis of the observations, and theoretical modeling, where appropriate, that supports the stated conclusions.
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| 6. |
- Warell, Johan, et al.
(författare)
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Moon: First Spectra from 0.7 to 5.5 mum
- 2004
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Ingår i: 35th Lunar and Planetary Science Conference, March 15-19, 2004, League City, Texas, abstract no.1624.
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Konferensbidrag (populärvet., debatt m.m.)abstract
- We present spectra of the Moon in the 0.7 - 5.5 micrometer wavelength region, obtained with SpeX on the IRTF. Spectra of Mercury were also obtained with the same instrument configuration and telescope during the observing period. Mercury spectra are discussed in a companion abstract.
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| 7. |
- Warell, Johan, et al.
(författare)
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The 0.7-5.3 mum IR spectra of Mercury and the Moon: : Evidence for high-Ca clinopyroxene on Mercury
- 2005
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Ingår i: Icarus.
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Tidskriftsartikel (refereegranskat)abstract
- We present infrared spectra of Mercury and the Moon in the wavelength range 0.7--5.3 $\mu$m obtained with the SpeX spectrograph at the NASA Infrared Telescope Facility. The spectra were acquired from pole and terminator locations of Mercury'ssurface and of Mersenius C and the Copernicus central peak on the Moon. Spectra of both bodies were measured in close temporal succession and were reduced in thesame manner with identical calibration stars to minimize differences in the reduction process. The Copernicus spectra display the expected absorption features dueto mafic minerals in the near infrared and show spectral features in the SiO combination/overtone vibrational band region above 4 $\mu$m. The spectra of Mercuryfrom longitude 170$^\circ$ and north and south midlatitudes display a 1-$\mu$m absorption band indicative of high-Ca clinopyroxene, while a spectrum from longitude 260$^\circ$ and northern midlatitudes does not. The Mercury spectra show a broad feature of low emittance over the full 3--5 $\mu$m thermal infrared region, butno narrow features in this spectral range. The longitude 260$^\circ$ spectrum shows excess thermal emission around 5 $\mu$m attributable to the existence of a thermal gradient in the insolated dayside regolith. The thermal-IR spectra suggesta significant difference in the compositional and/or structural properties of Mercury and the Moon that may be due to grain size, absorption coefficient, or the magnitude of near-surface thermal gradients. The results indicate that the composition of Mercury's surface is heterogeneous on regional scales, and that the nearinfrared wavelength range provides more discriminative information on the surfacecomposition than the 2--4 $\mu$m region, where the solar reflected and thermallyemitted radiation contribute approximately equally to the observed flux of thesebodies.
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