posted on Jul, 10 2006 @ 11:00 AM
www.spaceref.com...
According to this SOHO has discovered 500 comets so far so they can be detected and if they can be detected then their orbits can be tracked as well.
Since comets do have parabolic and periodic orbits.
In order for NASA to have conducted their latest mission they needed to track and predict the orbit of the comet for their 'Stardust' mission. Also
when comets begin to get closer to us and the sun they become more visable as the gasses begin to form a tail of vapour and gasses which really glow
bright.
We can't detect them all no but we can infact detect them and for the time being we here on Earth are quite safe. But yeah Asteroids are way easier
to track since they are generally larger and more dense then the loosly compact materials of a comet.
Your right when you say we can't get them all but I am still sure they keep an eye out for potentially dangerous NEO's.