Asteroid Danger

> That is old news. We are fast approaching a 50% number. Also, NASA
> has committed to finding 90% of NEAs greater than 1 km by 2008. See
> http://impact.arc.nasa.gov/news/2000/August/1.html for more info.

Two problems:

One is that serious damage can be done by asteroids as small as 100m
(actually a bit larger than the likely size of the Tunguska
airbuster - place the Tunguska destruction an ellipse of around
2000km2 over just about anywhere in western Europe, eastern Asia or
South America; & watch your pocket calculator melt down doing the
body counts alone); & NASA has no plans to develop the technology to
systematically pick up even a small fraction of these objects.

Second is that Aten asteroids (asteroids which mostly orbit within
the Earth's orbit) are difficult to detect using NASA's 1km
technology plan; & those which don't cross significant past the the
Earth's orbit are almost totally undetectable. The Atens are the one
group of Earththreatening asteroids which really do need a space
telescope along the lines of NESS or Spaceguard-1.

Within the impactor research field, NASA's commitment is generally
considered more spin doctoring than real achievement; so while one
doesn't recommend running for the hills, being reassured about the
work currently being done is generally the best position to take.