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Early on the morning of 30 June 1908 an alien object streaks across the cloudless sky, 8 km above the surface it explodes flattening an area over 2000 square km. Despite the huge detonation, equivalent to a 10 megaton nuclear warhead, there are few casualties. If this object had exploded over a major city like London, the devastation and loss would be unthinkable.
Fortunately, objects of this size collide with the Earth only every few centuries. Objects around one km in size typically collide every few hundred thousand years, such impacts may cause climate change and even mass extinctions. This cosmic game of Russian roulette has increased awareness and pushed efforts to detect, categorise and reduce the threat from NEOs.
In July 2002 the general studies programme of ESA provided funding for preliminary studies on six space missions that could provide significant contributions to our knowledge of NEOs.
The six missions under study were:
Don Quijote: The launch of two spacecraft (Hidalgo and Sancho) to
investigate technologies required to deflect an asteroid heading towards Earth.
Hidalgo will be targeted to impact a 500-metre-diameter
asteroid. Its companion, �Sancho�
will deliver sensors to the surface of the asteroid and
observe from a safe distance what happens during and after the high speed
collision.
Earthguard 1: Proposes to mount a �hitchhiker� telescope on a
spacecraft en route to the inner Solar System, e.g. ESA�s BepiColombo
Mercury orbiter. The telescope would detect Earth-crossing asteroids
larger than about 100 metres, which are very difficult or impossible to
detect with ground-based telescopes.
EUNEOS: A medium-sized telescope mounted on a dedicated spacecraft
platform that would search for the most dangerous NEOs from inside the
orbit of Venus. Its main goal is to detect 80% of the potentially
hazardous objects down to a few hundreds of metres in size.
ISHTAR (Internal Structure High-resolution Tomography by Asteroid Rendezvous): In addition to measuring the mass, density and surface
properties of an NEO, this spacecraft would probe by using radar tomography the interior of an NEO
in order to study its structure and internal strength.
SIMONE( Smallsat Intercept Missions to Objects Near Earth): A fleet of five low-cost micro-satellites that would each fly by
and/or rendezvous with a different type of NEO. Each spacecraft would
carry a suite of scientific instruments that would provide valuable
insights into the nature of large asteroids.
Remote observation from a space-based observatory that would carry out remote sensing and detect physical and compositional characteristics of NEOs.
With these mission proposals feasible and affordable, a valuable framework of studies by industry and academia will be provided for developing future missions. Each mission will be discussed by ESA and its international Partners to determine how best to proceed.
More info: ESA NEO space mission preparation
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