Geoscience Reference
In-Depth Information
investigations must be considered as decisive to solve the apparent para-
doxes and shed some light on processes active during the early stages of
planetary growth. As explained above, a detailed assessment of the overall
composition of Ceres and Vesta has also deep implications for our under-
standing of the compositional gradient of the early protoplanetary disk.
For these reasons, Dawn has been conceived and is expected to be able
to provide answers to the most important open questions mentioned in
this Section. In particular, a crucial test of current ideas will be to find
evidence or not of the presence of large amounts of water in Ceres' com-
position. The presence of water, if not directly detected, will be evidenced
by the presence of hydrated minerals on the surface of Ceres. Moreover,
an accurate determination of the gravitational field of Ceres will allow us
to find evidence of the presence of a metallic core produced by thermal
differentiation. For what concerns Vesta, a detailed mineralogical map of
the surface, including layers at different depth exposed by the mentioned
hemispheric crater that is believed to characterize the surface of this aster-
oid, will be of paramount importance to really understand the composi-
tion gradient of Vesta and the connections with achondrite meteorites. In
what follows, we give a brief outline of the instrumental configuration of
the probe, that has been chosen with the aim of maximising the scientific
output of the mission.
3. Dawn: A General Outline
The Dawn mission is the result of the collaboration of the scientists and
agencies of these countries: the US, Germany, and Italy. In the US the mis-
sion is led by the University of California, Los Angeles (UCLA), funded
by NASA, managed by the Jet Propulsion Laboratory (JPL) with an
instrument provided by Los Alamos National Laboratory. In Germany, the
framing camera is being provided by the Max Planck Institut fur Sonnen-
systemforschung with assistance from the Deutsches Zentrum fur Luft-und
Raumfahrt (DLR). In Italy the mapping spectrometer is provided by the
Agenzia Spaziale Italiana (ASI), and oversight is provided by INAF. The
Principal and deputy Principal Investigators are C. T. Russell (UCLA) and
Carol Raymond (JPL). The UCLA is responsible for the overall direction
of the project, as well as management of science operations, data, products,
archiving, analysis and education and public outreach.
The space probe will be ion-propelled. The launch is now expected to
occur in 2007 using a Delta 2925H launcher. Independent of the exact
launch date Dawn uses a Mars gravity assist in 2009, and will reach Vesta
