It is almost certain that a big asteroid will one day land on Earth and provoke a huge catastrophe. This is why hundreds of scientists have attended the Planetary Defense Conference 2007, held this week in Washington, D.C., to try to develop plans to protect the Earth from such an asteroid. All these researchers have lots of ideas, some which look feasible, some not. Some of them want to destroy asteroids with nuclear weapons. Other scientists want to use a robotic tugboat to push a dangerous flying object out of the Earth's path. And others want to send unmanned robots to the asteroid, drill into it and send the debris into space to alter the course of the asteroid. And this is just a sample...
Before going further, below is an illustration showing one of the methods which could be used in the future to modify the orbit of an asteroid before it hits the Earth (Credit: "GN," for the Sunday Telegraph). Here is a link to the original -- and larger -- version.
In "Hollywood got it wrong, this is how you stop an apocalyptic asteroid," the Sunday Telegraph gives more details about this way to avoid a collision with one of these asteroids.
Now an engineering firm in Atlanta, Georgia, has been commissioned by NASA to develop a new kind of mission to land on an asteroid, drill through the surface and pump the debris into space. Anchoring several unmanned spacecraft, nicknamed Madmen, to an asteroid and ejecting material, would produce enough force in the opposite direction to push an asteroid slowly off its dangerous course.
"It is like throwing rocks out of a rowing boat on a lake. The rocks go in one direction and the boat is slowly pushed in the other under the laws of physics," said John Olds, the chief executive of SpaceWorks, the firm behind the scheme. "Over several months we think we can make the difference between a hit and a miss."
In "Big blasts or tiny tugs: how to stop an asteroid catastrophe, the Guardian gives describes other methods to avoid a collision with an asteroid.
"The collision of a moderately large asteroid or comet, also referred to as a near-Earth object (NEO), with Earth would have catastrophic consequences," writes Brent William Barbee of Emergent Space Technologies, Inc. in a discussion paper to be presented at the meeting. "Such events have occurred in the past and will occur again in the future. However, for the first time in known history, humanity may have the technology required to counter this threat."
Here is a link to this paper, "Optimal Deflection of Hazardous Near-Earth Objects by Standoff Nuclear Detonation and NEO Mitigation Mission Design" (PDF format, 11 pages). And Barbee wants to nuke the potentially dangerous asteroids.
Detonated at the correct position, a nuclear weapon could blast away a thin shell of material from the asteroid. "This virtually instantaneous blow-off of superheated mass imparts an impulsive thrust to the NEO in the opposite direction of the detonation coordinates, causing the NEO's subsequent trajectory to be altered slightly, which causes the NEO to miss Earth rather than collide."
This could be done today, but what about the consequences? As it was never been tried, nobody can predict if such a mission will do more harm than good Luckily, other scientists envision less radical solutions.
Piet Hut, of the Institute for Advanced Study in Princeton, has a less dangerous idea - a robotic tugboat that could attach itself to an asteroid and push it out of the Earth's path. "Based on early warning, provided by ground tracking and orbit prediction, it would be deployed 10 years or more before potential impact.
Here is a link to one of his papers, "Threat Mitigation: The Asteroid Tugboat" (PDF format, 9 pages).
There were many other ideas described during this conference. For more information, here is a link to some of the technical papers presented during the conference.
Sources: Alok Jha, The Guardian, UK, March 7, 2007; Richard Gray, The Sunday Telegraph, UK, February 25, 2007; and various websites
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