Deep impact

If we are reading this post now, it means that last February 15th happened nothing as was expected. On this day the lowest perigee object ever recorded passes close to Earth, 2012_DA14 with 50 m diameter and 190.000 Tm of weight (see NASA video with characteristics). This doesn’t mean that they haven’t previously been objects that pass closer to Earth, more if we think that Earth is 4,500 years old, simply we haven’t recorded in the few hundred thousand years of human existence. But much of the ignorance about if it has never been closer objects is because we really can’t until last 50 years that we can detect objects of this size, so whenever you have a sufficiently close to Earth was a surprise and a concern, not so much if we were mistaken in calculating the trajectory of this particular, and the fact that if one day find some its trajectory that will clearly impact with Earth.

 

 

It may seem like a horror movie, but there really is an alien threat and it isn’t an extraterrestrial civilization who wants to become hamburgers us as happened in V. The ancient study of celestial world gave to this category of perfect and unchanging, and Astronomical Revolution of the S. XV didn’t take this condition. Although the discoveries until the twentieth century astronomy considered the universe in equilibrium and static, is to say the universe didn’t evolved logical consequence of his eternal immutability. The twentieth century was discovered that the universe has history and it isn’t in equilibrium, but the most important is that the solar system is considered concluded neither was entirely and still things happen.
The arrival of humanity to the moon brought, among many discoveries, confirm that interplanetary space is full of objects of any size which impact on it, creating all kinds of craters (some microscopic); but the moon has no atmosphere to disintegrate small objects or climate to erase the traces, becoming it in the reassuring conclusion that was so terribly riddled, Earth has saved. On the other hand satellites begin to discover, through zenithal photos, the existence of many craters on Earth's surface that had not recognized horizontally. This discovery not worries too much because they believed that these were isolated incidents and knowledge "exhaustive" that had the Solar System and the terrible distances that it’s covering* compared to the size of objects that it has, made impossible the impact of an object (comet or asteroid) with the earth, and the small does not pass the barrier of the earth's atmosphere.
But in July 1994, all this changed suddenly and for first time they see that there are things more troubling than nuclear proliferation. Two years progress was found that a comet was caught by Jupiter gravity and in addition it had a collision course with Jupiter. Preliminary collided with Jupiter it broke into several pieces of no more than 2 km in diameter which all ended up against the surface. The result was frightening: impacts, including those of smaller, produced flares clearly identifiable on the surface of the huge planet (1,000 times higher than Earth), with a flare taken by the Hubble two times as Earth (see down video), and impact marks remained visible in the clouds system beyond 1996. This impact showed that it still is occurring (until before people believe impossible) and power liberated is outside of the orders in which humans operate including thermonuclear bombs.

 

Flame of an impact on Jupiter, thing that is shining in right is Io a satellite of Jupiter

 

Although the official position until 1994 was that the collisions were not possible at present, this perception had changed in many scientific. Evidence of the impact that ended the Cretaceous age and incidents like the Tunguska indicated that the impacts must continue to take place, but there wasn’t historical evidence of impacts on Earth or in space seen. But the evidence was there. In the same way that evidence of the existence of Chicxulub had been collected by several teams working on different projects and therefore were not related, present impact evidence were also but the military had secretly hidden. We do not think they wanted to hide the fact the population, indeed they didn’t know that it was entries meteorites, just military powers trying to find nuclear tests in the atmosphere by the opponent, and They recorded an annual average of two to three blasts of the order of the pump of Nagasaky or 10 times higher that weren’t accompanied by its increased of radiation; as the tests were secret also monitoring this information was classified. Neither had access to detailed maps, especially submarines, of alterations magnetic, many of them associated recent craters, and other subtle details. All this shows that the land was subject to a real bombardment coming from space that we aren’t detectable simply because until the twentieth century we have not had a real geographical control, achieved thanks to the exigencies of the Cold War.
Where do objects come? Well they are living in the Solar System. Apart from the great clouds of comets at the edge of Solar S. (Kuiper and Oort), there are a lot of objects with stable orbits to the Sun. These objects called Asteroids what are rocky and Comets as if they are volatile have all kinds of sizes and are extremely difficult to detect. Most are located in called Asteroid Belt and these do not concern us, not care about those have orbits in inner our, asteroids concern us are those highly elliptical orbits which have points back (perihelion and aphelion) exterior and interior to points back of our orbit. In this case a disturbance as passing so close to another object can generate cutoffs between the orbit of the object and Earth orbit with the consequent danger of collision. In this sense some of the objects found until today have their orbits intersection points with our orbit but the calculations give no crash in sight. On the other hand we can consider that they are not dangerous until the opposite is proved; we can almost guarantee that asteroid with inner orbit and therefore less energy is unlikely to change its orbit except for dropping the Sun, but they are in belt can suffer a disturbance that throw it to areas most inner.

 

However the main difficulty is to detect objects which are estimated to have made about 10%. It's a small amount but recently has begun the search, which it began in the 90's years thanks to the impact on Jupiter. This impact blew alarms and apart assign budget, starting a trend that led to the production of two films about this thematic (both very pathetic although I used the title of one for the post). Today, the crisis has made us forget the issue and these days the passage of 2012_DA14 and impact on Russia has revived the issue. But the threat is real and the budget has been frozen as of any other investigation. Currently we have no way to stop a direct hit, although there are several ideas and tried one a while ago on an asteroid, All these projects and require a long preparation time that would in many cases impractical. So maybe better not to know if there is a sword of Damocles with date and time for fall on ours.

 

*To get an idea of the scale will advance the following distances. The Earth is 6,600 km in radius, 1,000 km up in the atmosphere but the sea air around us really is 50 km is to say 130 times smaller than the radius. The geostationary satellites (eg Meteosat) are 6 Earth radii to land surface (36,000 km altitude with round numbers), they can dig 3 Earths between the surface and Meteosat. From the Earth to the Moon is 390,000 km 10.5 times the distance between Earth and geosynchronous, is to say there 31 planets earth dug from the Earth and Moon. The Sun has a radius 100 times larger than the earth and obviously fit inside 1,000,000 Land, the distance that the earth is 150,000,000 miles a UA therefore fit 114 Sun or 11.400 Earth, and the distance to Jupiter is 6 AU (684 Sun or 68.400 Earth). As you can see the distances are far superior to command the sizes of objects that it’s just a bit to show what it mean.