Hello fellow meteorite (and asteroid) aficionados,
Yes. There is a mapping spectrometer in the visual and infrared on board
the Dawn spacecraft:
VIR, the hyperspectral imaging
spectrometer onboard Dawn, with a spectral range
0.25-5.1 μm
http://www.hou.usra.edu/meetings/lpsc2015/pdf/1365.pdf
Don't worry; we all want to know about those mysterious bright spots on
Ceres. Yesterday I heard a talk by Matthew Izawa (U. of Winnipeg) on
this very topic. From the Planetary Sciences Institute website:
http://www.psi.edu/
Composition of Ceres’ Bright Spots
Wednesday, September 9, 2015
Matthew
Izawa
Abstract: The dwarf planet Ceres, located at a mean solar distance of
~2.8 Astronomical Units, is the largest (diameter ~950 km) object in
the main asteroid belt between Mars and Jupiter. Several evolution
models suggest a differentiated body with potential geologic activity.
One of the objectives of the Dawn mission during the Ceres encounter
is to search for signs of past or present geological activity,
including processes that might be linked to observations of transient
water vapour events. One of the most striking features of Ceres’
surface are localized bright areas, which are commonly associated with
impact craters. Of particular interest is a bright pit on the floor of
a 90.5 km diameter crater named Occator that shows signs of activity
in the form of water ice sublimation. I will present evidence that the
Ceres bright spots are hydrated salt deposits, using a combination of
Dawn Framing Camera (FC) multispectral observations, laboratory
spectroscopy, and geochemical data from carbonaceous chondrite
leaching experiments. Based on previous spectroscopic mineral
identifications, a range of candidate high albedo materials were
investigated including ice, Mg-carbonates, brucite, saponite and
ammonium saponite, (Mg,Na) sulphate salts, and (Mg,Na) halide salts.
Of these, the best matches are to mixtures of hydrated Mg sulfates
along with dark ‘average Ceres material’, which may be broadly
analogous to aqueously altered carbonaceous chondrite. The bright
spots may be forming as a result of sublimation of water from brines
exposed near the surface, leaving behind a chemical lag deposit of
former solutes, which are predicted on experimental and theoretical
grounds to be dominated by MgSO_4 hydrates.
Best regards,
Dolores Hill
UA-Lunar and Planetary Laboratory
https://www.lpl.arizona.edu/
http://www.asteroidmission.org/
On 9/11/2015 12:00 PM, Greg B. via Meteorite-list wrote:
There is now a very close up high resolution of the bright spots in
one of the craters. Why are we still
in the dark as to the composition of the bright material? Does NASA
have a spectrometer on the craft. If so why can't they determine what
the white substance is composed of. If they do not have a spectrometer
on the craft.
..what were they thinking!!
Greg B.
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--
Dolores H. Hill
Sr. Research Specialist
Lunar & Planetary Laboratory
Kuiper Space Sciences Bldg. #92
The University of Arizona
1629 E. University Blvd.
Tucson, AZ 85721
http://www.lpl.arizona.edu/
OSIRIS-REx Asteroid Sample Return Mission Communication & Public Engagement Team
Lead OSIRIS-REx Ambassadors program
Co-lead OSIRIS-REx Target Asteroids! citizen science program
Co-coordinator Target NEOs! observing program of the Astronomical League
http://osiris-rex.lpl.arizona.edu/
http://osiris-rex.lpl.arizona.edu/?q=target_asteroids
http://www.astroleague.org/files/u3/NEO_HomePage.pdf
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