Will an airbag stop asteroids about to hit Earth?
Avi Blizovsky
Some scientists have already proposed launching atomic bombs at a large comet or asteroid that is about to collide with Earth. One researcher offers a more innovative idea - a giant airbag.
An atomic bomb may not move much to some types of asteroids - especially those made of a loose pile of debris and may absorb the energy without changing their trajectory, says Eric Espog of the University of California at Santa Cruz in an interview with CNN. According to him, simulations he conducted show that such an explosion may explode this type of asteroid or comet into many more pieces that will continue on the collision course and cause much more damage.
Herman Burchard of Oklahoma State University in Stillwater believes that a giant airbag could handle such a cosmic 'criminal'. Bouchard, a mathematician by profession, proposes that a spacecraft will reach the bone and inflate a giant air cushion several kilometers wide using chemical reactions to produce the necessary gas. The spacecraft will push the gas cushion against the asteroid or comet. The pillow will be able to distribute the pressure evenly and deflect the bone without breaking it into pieces. "It seems a simple, safe and realistic idea," he told the British magazine New Scientists.
Louis Friedman, formerly a rocket engineer at NASA and now the director of the Planetary Society claims that the idea is impossible. The order of magnitude needed for the air bag to gain momentum and change the trajectory of a 5 km wide solid rock moving at a speed of 180 thousand km/h is simply beyond our ability. " Of course, he adds, that in the long run of many hundreds of years, there might be a chance for that."
Other scientists received the idea with more enthusiasm. Dave Williams of NASA's Data Center says the basic idea makes sense, "provided the impact asteroid is detected well in advance."
Espog goes even further than Bouchard. He likes the idea of renouncing the need for nuclear power, but believes that it should be done without airbags, without splitting the bone into more parts, but by placing an engine on the asteroid's surface, and operating it so that it slightly changes the trajectory and eliminates the collision.
Just a collection of rock and ice fragments
New estimates of the nature of the asteroids were presented
at a scientific conference
Dr. Noah Brosh
A significant number of asteroids, which move around the edge of our solar system, are nothing more than a collection of fragments of rock and ice, and not solid bodies as previously thought. This assessment was presented last month in Berlin, at an international scientific conference that dealt with the riddle of asteroids, comets and meteors. Among other things, several Israeli research works were also presented there.
The findings that confirm the assumption that some asteroids are just a collection of fragments are based on the fact that the duration of their self-rotation is measured in a few hours, and is not particularly fast.
If an asteroid were just a block of solid rock - its parts would be held together by internal electrical forces between the atoms and molecules. The asteroid could then rotate at a fast rate, without the centripetal force (like the force that attaches the carousel passengers to the seats, when they rotate) succeeding in disintegrating the body. Also, the unifying force in the asteroid was its own gravity, which pulls each fragment towards the center of the body. But then there would be a limit to the maximum self-rotation rate, due to the centripetal force.
From this comes the conclusion: if the asteroids are nothing but collections of fragments - various plans to "eradicate" asteroids that threaten the earth, must change. A nuclear explosion in space, near such an asteroid, will scatter its parts and increase the danger from it, even more.
These days, astronomers are required not only to discover the threatening bodies - also to calculate their trajectories and assess the degree of danger, as well as to characterize, as much as possible, the nature of those bodies (based on the duration of the self-rotation, the composition of the materials on their surface, etc.).
One of the claims made recently on this topic links the research to discover the threatening asteroids with the "Gaia Theory" - according to which the Earth is "living" that develops and sustains itself. In this way of looking, the development of the human race took place to increase the protection of Gaia - on which we live - from possible harmful bodies and what is done for the purpose of eradicating the threatening asteroids, is intended to follow Gaia's will.
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