Asteroids approaching the earth from directions around the sun

We have estimated close asteroid encounters with the Earth by numerical integrations of a system with the Sun, 9 planets, and 188 near-earth-asteroids during the period 1994-4600. Asteroids approach the Earth from directions within 30 degrees around the Sun in more than 20% of encounters with the closest distance less than 0.01 AU. Since groundbased observations cannot detect these objects, we should develop space-borne and/or lunar observatories in a short time to allow enough warning time before a catastrophic collision.