Past as Prelude -Asteroids & the Origins of Life
World Map of Large Impact Craters
If the past is prelude, there's bound to be a massive collision event from a rogue asteroid at some point in the near future unless we successfully intervene.The map above shows most of the 160 impact craters that have been identified since 1950. The bulk of the terrestrial impact craters that were ever formed, however, have been obliterated by eons of geological processes.
Study the map at a glance you'll see major impacts in the major population centers of the U.S., Europe, Africa, and Australia. Keep in mind that only 65 million years ago (a wink of the eye in geological time) there was a mass extinction of the dinosaurs that was linked to global effects caused by a massive impact.
As reported in the world media this past week, NASA can find and track most of the nearby asteroids that could hit and damage the Earth, but there is not enough money in its budget to finish the project within a 15-year deadline mandated by Congress. 
NASA runs a program called the Spaceguard Survey to track the largest potentially hazardous objects of the 20,000 asteroids and comets orbiting relatively close to our planet greater than 3,300 feet in diameter that could devastate most life if they hit.
Donald K. Yeomans, director of the Spaceguard program, said that there were believed to be 1,100 of these larger objects and that the survey had cataloged about 73 percent of them. The initial goal of tracking 90 percent of them should be reached by 2010, more than a year later than originally planned.
In a note of cosmic irony, that which might eventually destroy us may also have been responsible for the origins of life on our planet.
In 2011, NASA will launch the OSIRIS mission to a menacing asteroid called RQ36,which would barely be noticed "except" says Joseph Nuth of NASA's Goddard Space Flight Center, "that It's a treasure trove of organic material, so it holds clues to how Earth formed and life got started, and it regularly crosses Earth's orbit, so it might impact us someday." RQ36 is roughly about two-fifths of a mile in diameter. It orbits between about 83 million and 126 million miles from the sun, swinging within about 280,000 miles of Earth orbit, or roughly 40,000 miles more distant than the moon.
"OSIRIS of Egyptian mythology is the god of life and fertility, the god who taught Egyptians agriculture," said Dante Lauretta, OSIRIS Deputy Principal Investigator. "There's an analogy to the proposed 21st century space mission. We're looking at the kind of object that we think brought life to Earth; that is, objects that seeded Earth with early biomolecules, the precursors of life."
The mission will also help to better track the orbits of asteroids that might hit Earth by accurately measuring the "Yarkovsky effect" for the first time. The Yarkovsky effect is a small push on an asteroid that happens when the asteroid absorbs sunlight and emits heat. The small push adds up over time, and it is uneven due to an asteroid's various surface materials, wobble, and rotation. There's no sure way to predict an Earth-approaching asteroid's orbit unless you can factor in how the Yarkovsky effect will change that orbit. Original post by Casey Kazan.
Ahh.. i think you will find that most aussies live on the east coast of our continent or the coastal fringe in other areas, and most cetainly not in the centre. We have one city in the north (Darwin) and numerous smaller outback towns. Only one event seems to have been near a major city and its Melbourne anyway so aussies wont care.(Just kidding) Once again, research is lacking.
Posted by: wayno | November 16, 2008 at 11:04 PM