Near Earth Objects (English Near-Earth object, NEO ), and Earth's orbit cruisers, are asteroids, comets and meteoroids large that the sun cross the Earth's orbit during its rotation and therefore pose a risk of collision. To counter this threat, an exact knowledge of such objects are necessary.
Near Earth Objects Classification
By type and size to that of the Earth divided cruiser in:
Meteoroids larger than the interplanetary dust, but smaller than asteroids, where there is a clear and consistent boundary between the two types of property but neither the size nor in composition.
The asteroids and meteoroids include along with the comet to the small bodies of the solar system.
After the impact of the comet Shoemaker- Levy 9 on Jupiter in 1994, NASA received in 1998 by the U.S. Congress commissioned to catalog 90 % of those Earth's orbit cruisers that have more than 1 km in diameter. This is due to special programs for sky monitoring, such as LINEAR, LONEOS, NEAT, CSS, CINEOS, Spacewatch or ADAS, are achieved. The impact of an asteroid or comet of this size could destroy an area the size of France and would have global implications. In 2005, the contract to NASA has been expanded to provide up to 2020 instruments and search programs that allow you to discover Near Earth objects of a size greater than 140 m. Objects of this magnitude could destroy on impact, for example, the Washington DC region.
More than 10,000 near-Earth objects (as of end of 2013 ) have been identified and katalogisiert.Mehr than 5000 have a diameter of 100m, a few up to several km, ( 1036 ) Ganymede is the largest near-Earth object with a diameter of about 31 km. every year are detected by the monitoring programs several hundred. Researchers estimate that up to 300m, more than 80 % of the objects with diameters still undiscovered.
There are two classifications for the classification of impact risk:
- The simple Torino Scale
- The complex Palermoskala
2003 was noted for the two near-Earth asteroid 2003 QQ47 and 1997 XR2 a risk greater than zero, both are classified in the security level 1. After precise orbit measurements in 2005, the object ( 99942 ) Apophis (2004 MN4 ) was assigned greater than 1 as the first risk levels in the short term, the asteroid had even been classified into stage 4. Between February and May 2006 2004 VD17 at the Turin scale was rated by 2, so he was only the second asteroid, which reached a value of about 1 at the Turin scale.
Previously, a low-earth orbit object with a risk greater than zero is known; for (29075) 1950 DA a close encounter in the year 2880 is predicted. Should there be an impact of this object, a mass extinction could result in the most life forms would extinguished on earth. For ( 99942 ) Apophis 2005, the risk assessment of the impact on the Palermo scale for a short time reached the value of 1.80.
- The object with the previously tightest flyby, in 6500 km distance is 2004 FU162 with about 6 m in diameter. It could be observed on 31 March 2004 for 44 minutes by LINEAR and was deflected by the Earth by 20 °.
- Took place on 27 June 2011 through 2011 MD is the second closest approach to the Earth at a distance of about 12,000 km. The asteroid has a diameter of about 10 m, was discovered five days in advance by LINEAR and could still be observed for six days after the flyby.
- On November 8, 2011 happened about 400 m wide asteroid ( 308635 ) 2005 YU55 the earth in about 0.85 -fold Moon distance, 325,000 km, reaching an apparent magnitude of this 11 likes, so he observed with instruments from 80 mm opening could be.
- On February 15, 2013, about 46 m wide ( 367943 ) Duende passed by the Earth at a distance of about 29,000 kilometers.
- On April 13, 2029 will pass the earth at a distance of about 30,000 km of the 270 m wide ( 99942 ) Apophis.
- On 6 October 2008, the first object was discovered in space that collided about 20 hours later with the earth. It was the asteroid 2008 TC3 4 m.
List of potentially dangerous objects
Many near-Earth objects containing metals in high concentrations, such as platinum and rare earth metals that might be in the future for the extraction of raw materials important. In order to reduce these resources in the future, there are theoretical considerations for asteroid mining.
Ethical Considerations of protection from impacts near-Earth objects relate to the demographic aspects. A successful defense against terrorist rocket attacks has hundreds of thousands of people a chance to survive. The prevention of an impact of a near-Earth object, for example, in the Pacific, which trigger a tsunami and cost as millions of people in California alone that life could, would, however, save many more lives. On the other hand, die each year approximately one million people from malaria and five men by shark attacks, whereas in the past, the number of people who are proven to have been killed by asteroids from scratch.