|An American non-profit organisation has announced a space mission to map
the inner solar system for evidence of asteroids that could strike the
Earth. The five-and-a-half-year voyage, which the organisation describes
as the first privately funded deep-space mission, is due for launch in
2016 or 2017.
The ambitious plan is organised by the B612 Foundation. It aims to 'open
up the frontier to space exploration and protecting humanity on Earth'.
That protection focuses on mapping the orbits of the tens of thousands
of near-Earth asteroids with diameters of at least 140m that could
strike the Earth with an explosive force of at least 100 megatonnes of
TNT. That is 3.5 times the diameter of the object that struck Tunguska,
Siberia, in 1908, uprooting up to 80 million trees and shattering
windows hundreds of kilometres away.
According to B612, more than 98% of such asteroids remain totally
unknown to astronomers. The mission aims to find and track more than 90%
of them. The spacecraft, called Sentinel, will take off from NASA's
Kennedy Space Center in Florida. A gravitational slingshot manoeuvre off
Venus will put the craft into an orbit around the Sun close to that of
Venus. The craft will carry an infrared telescope to map the locations
and trajectories of Earth-crossing asteroids.
The telescope will scan the entire night half of the sky every 26 days
to identify every moving object. Repeated observations of individual
asteroids will permit astronomers to calculate their orbits and predict
their positions accurately for a century or more in the future.