VISUAL INFRARED SPECTROMETERS THE ITALIAN SEARCH FOR THE ORIGIN OF THE SOLAR SYSTEM

Transcription

1 VISUAL INFRARED SPECTROMETERS THE ITALIAN SEARCH FOR THE ORIGIN OF THE SOLAR SYSTEM Rosetta Mario Salatti Unit «Exploration and Observation of the Universe» Agenzia Spaziale Italiana (ASI) 52nd STSC, UN-COPUOS, Vienna, February 5th 2015

2 VIS-NIR Spectrometers 2 VIMS-V Cassini Visual and Infrared Mapping Spectrometer(VIS Channel) Spectral range: nm (96 bands) VIRTIS-M Rosetta VIRTIS-M Venus Express VIR-MS Dawn Visible and Infrared Mapping Spectrometer Standalone realization of VIRTIS-M without-h channel Visible and Infrared Thermal Imaging Spectrometer (Mapping channel) SpectralrangeVIS nm, IR nm(432 bandseach) JIRAM Juno JIRAM Jovian InfraRed Auroral Mapper Spectralrange: : nm (432 bands) SIMBIO-SYS/VIHI BepiColombo Visible Infrared Hyperspectral Imager Spectral range nm (256 bands)

3 Unveil the secrets? Cometsand Asteroidsare minor bodiesof the Solar System, unchangedby geologicalprocesses, thus retaining the memory of the building blocks making up the proto-solar disk 4.6 Byrs ago Comets have abundant chemical compounds that vaporize when heated, e.g. water, and more elliptical orbits; they originate from the OortCloud or the Kluiper Belt Asteroids are essentially rocky, the majority of them liein the AsteroidBeltbetwenMars and Jupiter Both were responsible for taking water to Earth later on and maybelife 3

4 4 Asteroids and Comets for Rosetta ESA/Rosetta/OSIRIS/MPS/UPD/LAM/IAA/RSSD/INTA/UPM/DASP/IDA

5 Main Belt Asteroids for Dawn Dawn is a NASA Discovery mission A smaller mission, using fewer resources and shorter development times to allow scientist achieve outstanding results benefitting of new technologies Employing an innovative Solar Electric Propulsion System, Dawnisthe first spacecrafteverto orbitand extensivelystudytwoclestialbodiesof oursolar System Vesta Ceres NASA/JPL-Caltech/UCLA/MPS/DLR/IDA/PSI UCLA/ MPS/ DLR/ IDA 5

6 VIR Global Coverage on Vesta 6 The VIR nominal pixel resolution, during these phases, ranges from 1300 m to 70 m VIR covered about 90% of Vesta surface Data of high quality, from 0.2 to 5 microns, have been acquired in 864 spectral channels HAMOs

7 Vesta Mineralogy Spectral Diversity at Local Scale Vesta surface shows considerable local diversity at hundredmeters scale in terms of spectral reflectance and emission, band centers, depths and spectral slopes Stephan et al., JGR,

8 Vesta Mineralogy The Hemispherical and Regional Spectra Diversity 8 De Sanctis et al., Science, 2012

9 Vesta Mineralogy Mineralogy associated with geology and stratigraphy 9 Clear different material exposed on the slopes Lithological differences in the stratigraphy The scale of spectral variation indicates that Vesta scrust is compositionally variable at scales from a few tens meters to tens of km The differences at local scale were not foreseenbeforedawn observations Violet: deeper band depths Green : shallower band depths

10 Vesta Mineralogy OH Global Distribution 10 Observations of Vesta ssurface composition by Dawn revealed the presence of OH in surface materials [De Sanctiset al., 2012] and elemental hydrogen [Prettyman et al., 2012] The infallof OH-rich carbonaceous chondritemeteorites is the main hypothesis supported by this distribution

11 Vesta Mineralogy Vesta/HED Connection 11 Ammannito et al., Nature, 2013 Vesta spectra, on average, resemble those of howardites (breccia of eucrites and diogenites) indicating a surface highly reworked and well mixed De Sanctiset al., MAPS, 2013

12 Vesta Surface Temperature mapping To retrieve surface temperatures, we use the µm portion of the infrared spectrum as measured by VIR. No temperaturesbelow~180 K can be safelyretrieved by VIR. VIR data are strictlyreferredto the daysideof the asteroid and above this threshold. Thermal emission 12

13 13 Approach Local Solar Time PERMANENT SHADOWS Survey PERMANENT SHADOWS HAMO LAMO

14 Close-ups from the data VD7 (Numisia) Lat= 3.5 S Lon = E Diameter: 33 km FC clear filter, HAMO Solar incidence angle (i) µm (photom. corrected) Observed in Survey 683 m/pixel LST: 11.7 h r = 2.25 AU Composition: Eucrite (OH-enriched) Temperature Temperature / cos i 14

15 15 And now, Ceres! NASA/JPL-Caltech/UCLA/MPS/DLR/IDA NASA/JPL-Caltech/UCLA/ASI/INAF

16 16 To keepup with us: Wewillalwaysbe gratefulto Angioletta Coradini: a brilliant scientist who contributed deeply to Planetology, whose work isstillprovidingdata to be investigatedby new generationsof scientists-and willdo so for manyyearsto come THANK YOU FOR YOUR ATTENTION