Scientists in the USA are completing preparations for a unique operation of launching a missile to hit the nucleus of a comet. Another defensive effort to prevent the extinction of the human race
Dr. Noah Brosh
In about four years, in January 2004, a rocket will take off from the "Cape Kennedy" launch site in Florida to intercept, after a year and a half journey in space, the nucleus of a comet - and bombard it with a "smart projectile", made of copper.
This will be a first-of-its-kind experiment to examine the Earth's defenses against the impact of destructive comets - according to scenarios illustrated in the movies "Armageddon" and "Fatal Impact" - and the operation even received the name of the latest disaster and horror film (original name: Deep Impact). And this by the way: before the film itself is made...
The target comet is called "Temple", after its discoverer, a French astronomer from the mid-19th century. "Temple" orbits the sun once every 5.74 years. Its closest point to the sun is about twice the distance of the earth from the sun. Therefore, this comet does not threaten to harm the Earth, at least in the foreseeable future. This is one of the reasons we chose it as a target: its relative distance ensures that the fragments that will fly from it as a result of the bullet's impact - will not threaten the Earth.
The scientific goal of the operation: to study the material found deep within the comet's nucleus. Comet researchers think that the nucleus is mostly ice - a mixture of water and frozen gases - a remnant from the beginning of the solar system, that is, from more than five billion years ago.
Unlike the inner layers, the outer shell of a comet undergoes many changes over the ages - due to solar radiation and due to the collision of the comet with dust grains within the solar system. Therefore, although the study of comets from the earth and spacecraft that pass by them, provides a lot of knowledge, it is not possible to find out the nature of the comet's interior, but only in an experiment of the type planned.
The spacecraft intended for the interception mission will consist of two parts: a spacecraft carrying the projectile, and the projectile itself. The carrying spacecraft will be responsible for navigation during the flight to the comet, as well as for bringing the projectile to an almost collision course with the comet's nucleus. The flight to the comet will circle the Earth in December 2004 and the encounter with the comet is planned for July 4, 2005. A day before that the projectile will be released which will aim itself independently to hit the comet's nucleus.
At the time of the encounter with the comet, the two spacecraft will move at a speed of 30 km per second - and the comet, which catches up with the spacecraft - will then be at a speed of 40 km per second.
The comet's nucleus will collide with the projectile when the precision of the projectile's guidance will be about 300 meters. At the time of impact, the carrier spacecraft will be located approximately 500 km from the comet's nucleus. This is so that it will not itself be damaged by the impact fragments and to serve as a data relay system for the projectile, which will end its "life" upon impact.
With a relative speed of 10.2 km per second, and when the weight of the projectile is 500 kg, the energy will be fifty times greater than that produced by a large part of a Scud missile - the type that hit houses in Israel during the Gulf War 10 years ago.
According to the theoretical calculations, the impact will create a crater in the comet with a diameter of about 100 meters and a depth of about 30 meters. A large amount of material, which will be ejected from the crater during its formation, will be examined from the carrying spacecraft and also with ground telescopes. This is to investigate his composition.
To prevent contamination of the comet's material with the projectile materials, the scientists chose to construct the projectile from copper - a material that is not found in comets with high frequency and is not expected to disrupt the examination of the composition of the comet's materials.
As mentioned, this will be the first experiment to test the internal strength of a comet. The knowledge that will be gained in the operation will be essential for designing effective defense mechanisms on the Earth against possible impacts from comets.
The scientists will also closely monitor the projectile's performance because if it succeeds in its mission, it and others like it will be an essential part of future long-distance space interception missions.
Some believe that Operation Deep Impact will also advance the human race another step in its efforts to protect itself from possible extinction (and not as happened to dinosaurs and other primitive creatures that became extinct following the impact of a giant meteor or a comet that emerged from space).
