Near earth object
Near Earth Objects ( English Near-Earth object , NEO ), also orbit cruisers are asteroids , comets and large meteoroids that, at the circulation around the sun , the earth's orbit intersect and therefore pose a collision danger. In order to be able to counter this danger, precise knowledge of such objects is necessary.
Classification of near-earth objects
According to type and size, the earth orbit cruisers are divided into:
Meteoroids are larger than interplanetary dust, but smaller than asteroids, although there is no clear and uniform boundary between the two types of objects in terms of size or composition.
The asteroids and meteoroids, together with the comets, belong to the small bodies of the solar system .
Sky surveillance
After the impact of the comet Shoemaker-Levy 9 on Jupiter in 1994 , NASA received an order from the American Congress in 1998 to catalog 90% of those earth orbit cruisers that are more than 1 km in diameter. This should be done through special programs for sky monitoring, such as B. LINEAR , LONEOS , NEAT , CSS , CINEOS , Spacewatch or ADAS can be achieved. The impact of an asteroid or comet of this magnitude could destroy an area the size of France and would also have global effects. The largest known near-Earth object - about 31 km in diameter - is (1036) Ganymede .
In 2005, the order to NASA was expanded to the effect of creating instruments and search programs by 2020 that make it possible to discover near-earth objects from a size of 140 m. Objects of this size could e.g. B. destroy the Washington DC area. After the second, no longer cryogenic observation phase of the Wide-Field Infrared Survey Explorer , which ended in early 2011, the researchers extrapolated that the 90% target in the size range over 1 km had already been exceeded, but that around 80% of the NEOs were still above 100 m are to be discovered (5,200 of probably around 20,000 were discovered). At the beginning of 2018 [obsolete] there were more than 8,000 (> 140 m) out of a likely 30,000.
With the more sensitive Large Synoptic Survey Telescope , currently under construction [out of date] , it will be possible to discover almost 90% in this area within a few years.
Risk assessment
There are two divisions for classifying the impact risk:
- the simple Turin scale
- the more complex Palermo scale
Turin scale
In 2003, a risk greater than zero was determined for the two near-earth asteroids (143649) 2003 QQ 47 and (433953) 1997 XR 2 , both of which are classified in danger level 1. After precise orbit measurements in 2005, the object (99942) Apophis (2004 MN 4 ) was the first to be assigned a risk level greater than 1, and for a short time the asteroid was even assigned to level 4. Between February and May 2006 (144898) 2004 VD 17 was rated 2 on the Turin scale, making it only the second asteroid to achieve a value of over 1 on this scale.
Palermo scale
So far, a near-earth object is known to have a risk greater than zero; for (29075) 1950 DA a close encounter is predicted in 2880. If this object were to be impacted, it could result in mass extinction with most life forms on earth wiped out. For (99942) Apophis, the impact risk rating on the Palermo scale briefly reached 1.80 in 2005.
Approximations
- The object with the closest known flyby so far - 6,500 km away - is 2004 FU 162 with a diameter of about 6 m. It could be observed by LINEAR for 44 minutes on March 31, 2004 and was deflected by 20 ° by the earth.
- On June 27, 2011, 2011 MD made the second closest approach to earth with a distance of around 12,000 km. The asteroid has a diameter of about 10 m, was discovered five days earlier by LINEAR and could be observed for six days after the flyby.
- On November 8, 2011, the 400 m large asteroid (308635) 2005 YU 55 passed the earth at about 0.85 times the lunar distance (325,000 km) and reached an apparent brightness of 11 mag, so that it could be measured with instruments from 80 mm aperture could be observed.
- On February 15, 2013, the approximately 46 m tall (367943) Duende passed the earth at a distance of about 28,000 km.
- On April 13, 2029, the 325 m tall (99942) Apophis will pass the earth at a distance of about 30,000 km.
First predicted meteor
- TC3 was discovered on October 6, 2008, while it was still outside the lunar orbit. The object exploded in the stratosphere about 20 hours later.
List of potentially dangerous objects
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Others
Many near-earth objects contain high concentrations of metals , such as B. platinum and rare earth metals , which could be important for raw material extraction in the future . In order to mine these resources in the future, there are theoretical considerations for asteroid mining .
See also
- Near-Earth asteroid
- List of asteroids
- List of near-earth asteroids
- Orbit @ home
- B612 Foundation
- Planetary Defense
- Tunguska event
- Railway cruiser
literature
- Donald K. Yeomans: Near-earth objects - finding them before they find us. Princeton Univ. Press, Princeton 2013, ISBN 978-0-691-14929-5 .
- Andrea Milani: Near earth objects, our celestial neighbors - opportunity and risk. Cambridge Univ. Press, Cambridge 2007, ISBN 978-0-521-86345-2 .
- John L. Remo: Near-earth objects - the United Nations international conference. New York Acad. of Sciences, New York 1997, ISBN 1-57331-041-7 .
- Dale P. Cruikshank et al .: Determining the Physical Properties of Near-Earth Objects . ( Memento of February 8, 2012 in the Internet Archive ) (PDF; 315 kB; 9 S.) 2007 Planetary Defense Conference, March 2007, George Washington University, accessed October 10, 2009.
- Space Mission Priorities for Near-Earth Object Risk Assessment and Reduction . (PDF; 63 p.) ESA Near-Earth Object Mission Advisory Panel, 2004, accessed October 12, 2009.
- Near-Earth Object Surveys and Hazard Mitigation Strategies - Interim Report Executive Summary 08/2009. (PDF; 378 kB) National Research Council , ISBN 978-0-309-14361-5 , accessed August 13, 2009.
Web links
- Daily Minor Planet minorplanetcenter.net
- NEO Research Center NEORC - NEO Research Center Germany (German)
- NeoDys Near Earth Objects - Dynamic Site (English)
- Center for Near Earth Object Studies cneos.jpl.nasa.gov (English)
- The Spaceguard Central Node (English)
- Table of next close approaches to the Earth . TECA Sormano Astronomical Observatory (English)
- Small Asteroid Encounter List . SAEL Sormano Astronomical Observatory (English)
Individual evidence
- ↑ NEO GROUPS neo.jpl.nasa.gov (accessed on September 2, 2010)
- ↑ a b c Tad Friend: Vermin of the Sky . In: The New Yorker , February 28, 2011, pp. 22-29.
- ↑ Asiago DLR Asteroid Survey (ADAS) . jpl.nasa.gov, accessed July 16, 2011.
- ↑ Speech by Gen. Simon Worden: Military Perspectives on the Near-Earth Object (NEO) Threat . spaceref.com, accessed July 19, 2011.
- ^ The Threat to Earth from Asteroids & Comets . ( Memento of the original from December 29, 2008 in the Internet Archive ) Info: The archive link was automatically inserted and not yet checked. Please check the original and archive link according to the instructions and then remove this notice. pan-starrs.ifa.hawaii.edu, accessed July 26, 2011.
- ^ Amy Mainzer, et al .: NEOWISE observations of near-Earth objects: Preliminary results . In: The Astrophysical Journal . 743, 2011. arxiv : 1109.6400 . doi : 10.1088 / 0004-637X / 743/2/156 .
- ↑ Cumulative Totals: Near-Earth Asteroids Discovered. In: cneos.jpl.nasa.gov. Jet Propulsion Laboratory , accessed November 2, 2017 .
- ↑ Eva Schunová-Lilly, et al .: The size-frequency distribution of H> 13 NEOs and ARM target candidates detected by Pan-STARRS1 . In: Icarus . 284, 2017. arxiv : 1611.03095 . doi : 10.1016 / j.icarus.2016.11.010 .
- ^ R. Lynne Jones, et al .: The Large Synoptic Survey Telescope as a Near-Earth Object Discovery Machine . In: Icarus . accepted, 2017. arxiv : 1711.10621 .
- ^ Near-Earth Objects As Future Resources neo.jpl.nasa.gov; Part III: Near-Earth Objects - Resources of Near-Earth Space nss.org; The Role of Near-Earth Asteroids in Long-Term Platinum Supply . (PDF; 73 kB) nss.org; Retrieved March 1, 2011
- ^ John S. Lewis: Mining the sky - untold riches from the asteroids, comets, and planets. Addison-Wesley, Reading 1997, ISBN 0-201-32819-4
