Laser Prevention of Earth Impact Disasters

Today we are seeing the geological data base constantly expanding as new evidence from past impacts with the Earth are discovered and investigated. It is now commonly believed that a hypervelocity impact occurring approximately 65 million years ago in the Yucatan Peninsula area was the disaster responsible for the extinction of almost 70% of the species of life on Earth including of course the dinosaurs. What is sobering is that we believe now that this was just one of several such disasters and that some of the others caused extinctions to even a greater extent. Preventing collisions with the Earth by hypervelocity asteroids, meteoroids, and comets is the most important problem facing human civilization. While there are many global problems facing our planet including overpopulation, pollution, disease, and deforestation; none of these offer the potential of rapid, total extinction. Rapid is the operative word here in that many of the global problems we face may indeed, if not sufficiently addressed, pose a similar long-term threat. However, with the impact threat, a single, almost unpredictable event could lead to a chain reaction of disasters that would end everything mankind has worked to achieve over the centuries. Our chances of being hit are greater than our chance of winning the lottery. We now believe that while there are only about 2000-earth orbit crossing rocks great than 1 kilometer in diameter, there may be as many as 100,000 rocks in the 100 m size range. The 1 kilometer rocks are difficult to detect and even harder to track. The 100 m class ones are almost impossible to find with today's technology. Can anything be done about this fundamental existence question facing us? The answer is a resounding yes. By using an intelligent combination of Earth and space based sensors coupled with high-energy laser stations in orbit, we can deflect rocks from striking the Earth. This is accomplished by irradiating the surface of the rock with sufficiently intense pulses so that ablation occurs. This ablation acts as a small rocket incrementally changing the shape of the rock's orbit around the Sun.