Solar System

Dawn @ASDC

Dawn is a NASA mission designed to study the role of size and water in the evolution of the planets. It is directed to Vesta and Ceres, the most massive of the protoplanets, baby planets whose growth was interrupted by the formation of Jupiter.
Ceres may have active hydrological processes leading to seasonal polar caps of water frost, altering our understanding of the interior of these bodies. Vesta may have rocks more strongly magnetized than on Mars, altering our ideas of how and when dynamos arise with important lessons for Mars, Earth and Mercury. Ceres may have a thin, permanent atmosphere distinguishing it from the other minor planets.
Dawn was lauched in 2007, left Vesta after spending about 1 year orbiting around it, and at present is on its journey to Ceres, where the final orbit is expected to begin in 2015.

ASDC contribution

The only instrument onboard Dawn with Italian leadership is the Vis/NIR imaging spectrometer VIR (Visual and InfraRed Spectrometer). It produces spectral images in the 0.25-1 micron and 1-5 micron ranges.
VIR is a rebuild of the VIRTIS mapping spectrometer which is onboard the ESA Rosetta mission; it also benefits of the heritage from the Cassini VIMS spectrometer.

Principal Investigator: Maria Cristina De Sanctis, Istituto di Astrofisica e Planetologia Spaziali, Rome, Italy.

External sites: NASA, INAF-IAPS

VIR public data @ASDC

VIR raw (Level 1a) and calibrated (Level 1b) public data from all the Vesta phases are now freely available at ASDC.
In order to be able to access them please contact virdata@asdc.asi.it.
Observation geometries can be computed by using the SPICE toolkit and kernels.
We are currently working to integrate these data in MATISSE (Multi-purpose Advanced Tool for the Instruments of the Solar System Exploration).


VIR dataset characteristics
Target typeAsteroid
Target body4 Vesta
Time rangeStart: May 3, 2011End: Sept. 5, 2012
Raw dataset sizeIR: 19 GbVis: 20 Gb
Calibrated dataset sizeIR: 38 GbVis: 40 Gb
Please review the pending corrections before making use of these data

Note: The VIR level 1B data has had the 3 micron region set to zero (specifically, the range 2.534 - 3.272 microns). The calibration contained artifacts in this range which the VIR team believed made the calibrated data, in its current form, unusable. The VIR team is working on a new calibration for that region.
The raw Level 1A data is unmodified and covers the full wavelength range. The information for calibrating the level 1A data is available in the VIR Calibration Document.