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Table Of Contents
Introduction & Overview
Near-Earth Objects And Life On Earth
Near-Earth Objects As Future Resources
INTRODUCTION & OVERVIEW
Near-Earth Objects (NEOs) are comets and asteroids
that have been nudged by the
gravitational attraction of nearby planets into orbits that allow them to enter
the Earth's neighborhood. Composed mostly of water ice with embedded dust
particles, comets originally formed in the cold outer planetary system while
most of the rocky asteroids formed in the warmer inner solar system between the
orbits of Mars and Jupiter. The scientific interest in comets and asteroids is
due largely to their status as the relatively unchanged remnant debris from the
solar system formation process some 4.6 billion years ago. The giant outer
planets (Jupiter, Saturn, Uranus, and Neptune) formed from an agglomeration of
billions of comets and the left over bits and pieces from this formation
process are the comets we see today. Likewise, today's asteroids are the bits
and pieces left over from the initial agglomeration of the inner planets that
include Mercury, Venus, Earth, and Mars.
As the primitive, leftover building blocks of the solar system formation
process, comets and asteroids offer clues to the chemical mixture from which
the planets formed some 4.6 billion years ago. If we wish to know the
composition of the primordial mixture from which the planets formed, then we
must determine the chemical constituents of the leftover debris from this
formation process - the comets and asteroids.