In this era of space exploration, deep expeditions to the
ocean bottom and far viewing telescopes, the Earth's interior
has emerged as one of the most challenging frontier
areas for scientific investigation. Exploration of the
crust, by seismic and other means, is well underway but
our view of the underlying mantle and core is fuzzy.
Plate tectonic theory has revolutionized Earth Science but
we still do not understand the driving mechanism or why
global processes change with time. The origins of the
magnetic field, volcanism, earthquakes, mineral resources
and mountain building processes are related to processes
in the deep interior. Planetary exploration has opened up
the new science of comparative planetology and yet, the
most fundamental questions regarding the origin, evolution
and composition of the Earth are unresolved because of our
ignorance of the characteristics of most of our planet, the
interior.
The time is now ripe to make an integrated study of the
Earth as a Planet or, in space age jargon, to undertake a
mission to Planet Earth. There are several recent developments
which make this timely
