How should humanity prepare for the danger of an asteroid hitting the Earth
Arthur Charles Clarke
The article was written in 1995 after the collision of Shoemaker Levi 9 with Jupiter
Colombo, Sri Lanka
"At 09:46 GMT on the morning of September 11, in the incredibly beautiful summer of 2077, most European residents saw a blinding fireball appear in the eastern sky... At a speed of 50 kilometers per second, 1,000 tons of rocks and metal landed on the plains of northern Italy and destroyed it in hot minutes Achievements achieved through centuries of hard work. The cities of Padua and Verona were wiped off the face of the earth, and the rest of the glory of Venice sank forever into the depths of the sea, when the waters of the Adriatic sea stormed the continent following the hammer blow that landed from space.
"After the initial shock, humanity reacted with a determination and unity not seen in any previous era... This was the beginning of the 'Space Guard' project" (intended to protect the Earth from invading space bodies). ("Encounter with Rama", 1973).
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Just after the last fragments of Comet Shoemaker-Levy crashed into Jupiter last month, the monsoonal waters above my house in Colombo cleared for a while, and I hurried to set up my sensitive 14-inch telescope. I didn't expect to see anything, so I almost couldn't believe my eyes when I clearly saw a line of dark bruises spreading across the star's southern hemisphere. Some imaginative souls have suggested that the comet could indeed collide with Jupiter with an enormous and disastrous force, but the result would be mainly cosmetic (since Jupiter is so massive and made of gas), and it would certainly have no effect on the Earth. But the spectacular collision between the recently discovered comet and the largest star in the solar system has brought new and sudden attention to a real threat: the possibility that a comet or an asteroid deviating from their orbit will hit the Earth and the possibility that they will wreak havoc.
Thus, the imaginary "Space Guard Project" that I described in my book in 1973 has now begun in reality, if Congress approves an amendment to the NASA Authorization Act of 1994 that requires it to identify and catalog within 10 years "the orbital characteristics of all comets and asteroids with a diameter greater than 1 kilometer of the holidays around the sun and crossing the orbit of the earth".
Although this correction porcupine by Comet Shoemaker-Levy, is actually a consequence of the "International Workshop for the Detection of Near-Earth Bodies", which was organized by NASA in 1992. With a nod to the "meeting with Rama", the official report of this workshop was called " Space Guard survey". I wonder what the resident Thomas Jefferson thought of these developments in light of his famous words when he heard of a meteorite falling in New England: "I'd rather believe that two Yankee professors lied than that rocks fell from the sky." No one would have imagined how quickly and dramatically a cosmic event, seemingly so far removed from everyday affairs, would turn into a primetime news item.
In view of the collisions that have occurred in this century alone - the most prominent case is that of the comet, or star, which exploded in 1908 in Siberia with the force of 20 hydrogen bombs - a very good argument can be made for the merit of a global survey on the possible danger, mainly because the expenses divided between nations would be null In sixty compared to most national defense budgets.
Most likely many would prefer not to know about an impending cosmic doomsday, if nothing can be done to prevent it. But with enough notice - and we hope the Space Guard will provide this extension - we will be able to provide the technology necessary to repel or even destroy such invaders from outer space.
There are at least three ways to deflect battle asteroids, or their cousins, the comets. The first approach is the language of force: drop a nuclear bomb on the monster. A large enough bomb – probably on the order of a few billion TNT tons – would be able to blow an invader to many pieces, but that would not necessarily prevent some of the pieces from continuing on their way straight to us. But at least instead of massive destruction in one area there may be minimal damage spread over many sites. Needless to say, such a pre-emptive strike has the support of enthusiastic bomb designers, who have recently been suffering from too little employment.
Perhaps a better solution would be the one I adopted in my other novel, The Corns of God, in which a deadly asteroid is located a year before it is due to collide with Earth, and thus the astronauts have enough time to deflect it into a harmless orbit by installing rocket thrusters on its surface.
If the world has enough warning time - at least a few years - it could be done with very modest amounts of energy. An initial deviation of only a few centimeters at the beginning of a path of many millions of kilometers can ensure that the asteroid will indeed make its way without harming us. Although it is possible to calculate the trajectory of a solid body such as an asteroid hundreds of years in advance (once the body was discovered!) the rocket thruster solution may be less successful with comets. These flying icebergs heat up as they approach the sun and begin to emit gas. The resulting "jet drive" makes their future location uncertain, so that if we ever have to divert a comet approaching us, we will have to do so while maintaining a significant margin of safety.
An even more elegant solution has been proposed by scientists at NASA and elsewhere: "solar sailing". The plan is to attach a huge, lightweight metal sail to the comet or asteroid, which will absorb the tiny but continuous pressure exerted by sunlight. Unfortunately, the acceleration caused by this weak pressure would be so minimal that to use it effectively would require years, perhaps decades, of advance warning.
All those solutions will require extensive investment in the development of new technology, and people say "why waste money on space?" We must remember the dinosaurs. The prevailing explanation about them today is that their destruction was caused, or at least accelerated, by the impact of a huge meteorite that landed on Earth about 65 million years ago. NASA's growing commitment to detecting threatening objects in space could have an additional benefit: It could breathe new life into America's faltering space program and bring back some of the lost magic of the Apollo era.
The author of the article, a science fiction writer who wrote, among other things, "2001: A Space Odyssey", is the father of the communication satellite
