Below, I have reproduced the content of a NASA news release, about a very small asteroid crashing into the atmosphere. In my opinion, this illustrates the impotence we would have, should this asteroid have been larger, a mile across, say. We would have likely detected this object earlier, because of its larger size, but we could have done nothing, in that case or now, to prevent this object from hitting the Earth. The larger object would not burn up, and, if it came at a time slightly different time from the one predicted, could hit a heavily populated area, with loss of life, and lots of other damage.
What is astounding is the fact that this very small object has been detected at all. Asteroids and meteorites intersect the Earth's orbit at an average speed of about 30 km/sec (20miles/sec), which translates into 108,000 km/hr (72,000 miles/hr). Nothing we can do to stop, or even to deflect an object like that from its pre-determined path. In the past, larger asteroids hitting the Earth have resulted in a wholesale extinction of species.
Here's NASA's press release:
DC Agle 818-393-9011Jet Propulsion Laboratory, Pasadena, Ca.firstname.lastname@example.org
Dwayne Brown 202-358-1726NASA Headquarters, Washington email@example.com
NEWS RELEASE: 2008-186 Oct. 6, 2008
Small Asteroid to Light Up Sky Over Africa
WASHINGTON -- An asteroid measuring several feet in diameter is expected to enter the atmosphere over northern Sudan before dawn Tuesday, setting off a potentially brilliant natural fireworks display.
It is unlikely any sizable fragments will survive the fiery passage through Earth's atmosphere. The event is expected to occur at 5:46 a.m. local time (10:46 p.m. EDT Monday).
"We estimate objects this size enter Earth's atmosphere once every few months," said Don Yeomans of the Near-Earth Object Office at NASA's Jet Propulsion Laboratory in Pasadena, Calif. "The unique aspect of this event is that it is the first time we have observed an impacting object during its final approach."
The small space rock, designated 2008 TC3, will be traveling on an eastward trajectory that will carry it toward the Red Sea.
"Observers in the region could be in for quite a show," Yeomans said. "When the object enters the atmosphere, it could become an extremely bright fireball."
The small space rock first was observed by the Mount Lemmon telescope of the NASA-funded Catalina Sky Survey early Monday and reported to the Minor Planet Center for initial orbit determination. The Minor Planet Center alerted NASA and JPL of the impact potential. NASA detects and tracks asteroids and comets passing close to Earth. The Near Earth Object Observation Program, commonly called "Spaceguard," plots the orbits of these objects to determine if any could be potentially hazardous to our planet.
For more information, visit: http://neo.jpl.nasa.gov/