Thank you VERY MUCH for posting this article, Antipatros.Antipatros wrote:Gregory L. Matloff, Deflecting Asteroids
A solar sail could use light to nudge an earthbound rock into an orbit we could live with
http://spectrum.ieee.org/aerospace/spac ... steroids/0
Sixty-five million years ago, a Manhattan-size meteorite traveling through space at about 11 kilometers per second punched through the sky before hitting the ground near what is now Mexico’s Yucatán Peninsula. The energy released by the impact poured into the atmosphere, heating Earth’s surface. Then the dust lofted by this impact blocked out the sun, bringing years of wintry conditions everywhere, wiping out many terrestrial species, including the nonfeathered dinosaurs. Birds and mammals thus owe their ascendancy to the intersection of two orbits: that of Earth and that of a devastating visitor from deep space.
We humans need not wait, like dinosaurs, for the next big rock to drop. We have an advanced understanding of the heavens and a spacefaring technology that could soon enable us to alter the orbits of any celestial object on a collision path with us. That capability just might come in handy.
We got a taste of the challenge in December 2004, when scientists at NASA and the Jet Propulsion Laboratory (JPL), in Pasadena, Calif., estimated there was a nearly 3 percent chance that a 30-billion-kilogram rock called 99942 Apophis would slam into Earth in 2029, releasing the energy equivalent of 500 million tons of TNT. That’s enough to level small countries or raise tsunamis [PDF] that could wash away coastal cities on several continents. More recent calculations have lowered the odds of a 2029 impact to about 1 in 250 000. This time around, Apophis will probably miss us—but only by 30 000 km, less than one-tenth of the distance to the moon.
But let’s not rejoice too quickly. We know next to nothing about that asteroid’s porosity, composition, and tensile strength. It’s possible that tidal stresses during its 2029 approach could cause it to break apart, adding to the odds of an Earth impact during another rendezvous further down the line.
There is some disagreement about the best course of action. In the United States, experts tend to want to experiment with various deflection techniques by first sending robots or even astronauts to asteroids that do not threaten Earth. But in Russia, many asteroid watchers believe the risk of a collision between Apophis and Earth has been underestimated. These analysts contend that we should therefore concentrate our experiments on this particular asteroid.
To be sure of diverting any interplanetary intruder, we would need several strings to our bow. A method that could swiftly deflect a hunk of iron might blow an icy rock into several parts, each of which could then become a danger. And the gentler method now being discussed—to vaporize part of the surface of the asteroid, creating an outpouring of gas that would generate a propulsive force—would do no more than warm a meteorite made of iron. So we’ll doubtless need to devise several strategies for dealing with threatening asteroids.
So I have proposed a new tool, one that would use the pressure of light to nudge threatening objects into safe trajectories. That I’ve been asked to explain it at all in a magazine article shows that there’s indeed one thing we can rejoice in: the enhanced awareness of the problem. The mention of killer asteroids no longer raises jeering comparisons to the cries of Chicken Little, now that we know celestial impacts are far more common than once thought....
This is a topic of great concern to me.
IMVHO need to be working on this faster....
FWIW, I remember reading about another technique: painting a dangerous asteroid to alter solar energy absorption and alter the orbit.
But we need a good way to get off this rock to the other rocks......... my favorite is the Orion rocket which uses mini-nukes as propulsion.....
http://en.wikipedia.org/wiki/Project_Or ... pulsion%29
Since we've got nukes, we might as well do something useful with them......