Near Earth Objects (NEOs)
23 August 2007Near-Earth Objects (NEOs) are asteroids, comets and large meteoroids whose orbits bring them close to Earth. One official classification of an NEO says that the object’s orbit must come closer to Earth than a (perihelion) distance of 1.3 Astronomical Units - 195 000 000 kilometres.
Scientists have discovered that many asteroids and comets have collided with the Earth throughout its 4.5 billion year history. The impact of these NEOs with our planet could be catastrophic and still represents a natural hazard today.
There are about 20 000 Near Earth Asteroids of 140 metres diameter and larger. Millions of other asteroids are in distant orbits in the "Asteroid Belt" between Mars and Jupiter. There is also an unknown number of comets classed as NEOs whose orbits might cross that of Earth's.
It must be remembered that the risk from a collision with an NEO is extemely small! The highest known risk to Earth is from an asteroid called Apophis which will pass close to Earth on 13 April 2036. Scientists have calculated that there is less than a 0.003% chance of it hitting our planet. Put another way, the chance of Apophis avoiding the Earth is over 99.997%. These are long odds!
However, for a few years now, the issue of NEOs has been given more and more attention from space agencies, institutions and working groups at national, regional and international levels.
NEOS were given special attention in 2007. In February 2007, the Association of Space Explorers presented a paper to the Scientific and Technical Subcommittee at 42nd session of the Committee on the Peaceful Uses of Outer Space (COPUOS).
From that paper came an initiative which has set up a series of meetings of experts and other interested people which will explore the subject of NEOs and possible means of diverting these objects from Earth before they would hit.
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