Editing Asteroid impact avoidance (section)

=== Ongoing projects ===
[[File:NEA by survey.png|thumb|Number of NEOs detected by various projects.]]
[[File:PIA22419-Neowise-1stFourYearsDataFromDec2013-20180420.gif|thumb|[[NEOWISE]]{{Snd}} first four years of data starting in December 2013 (animated; April 20, 2018)]]
The [[Minor Planet Center]] in [[Cambridge, Massachusetts]] has been cataloging the orbits of asteroids and comets since 1947. It has recently been joined by surveys that specialize in locating the [[near-Earth object]]s (NEO), many (as of early 2007) funded by NASA's Near Earth Object program office as part of their Spaceguard program. One of the best-known is [[LINEAR]] that began in 1996. By 2004 LINEAR was discovering tens of thousands of objects each year and accounting for 65% of all new asteroid detections.<ref>{{cite conference|first = G.|last = Stokes|author2 = J. Evans|date = 18–25 July 2004|title = Detection and discovery of near-Earth asteroids by the linear program|conference = 35th COSPAR Scientific Assembly|location = Paris, France|pages = 4338|bibcode =2004cosp...35.4338S}}</ref> LINEAR uses two one-meter telescopes and one half-meter telescope based in New Mexico.<ref>{{cite web|url = http://neo.jpl.nasa.gov/programs/linear.html|archive-url = https://web.archive.org/web/20040114170809/http://neo.jpl.nasa.gov/programs/linear.html|url-status = dead|archive-date = 14 January 2004|title = Lincoln Near-Earth Asteroid Research (LINEAR)|publisher = National Aeronautics and Space Administration|date = 23 October 2007}}</ref>

The [[Catalina Sky Survey]] (CSS) is conducted at the [[Steward Observatory]]'s [[Catalina Station]], located near [[Tucson, Arizona]], in the United States. It uses two telescopes, a {{convert|1.5|m|in|adj=on|sp=us}} f/2 telescope on the peak of [[Mount Lemmon]], and a {{convert|68|cm|in|adj=on|sp=us}} f/1.7 [[Schmidt camera|Schmidt]] telescope near [[Mount Bigelow (Arizona)|Mount Bigelow]] (both in the Tucson, Arizona area). In 2005, CSS became the most prolific NEO survey surpassing [[Lincoln Near-Earth Asteroid Research]] (LINEAR) in total number of NEOs and potentially hazardous asteroids discovered each year since. CSS discovered 310 NEOs in 2005, 396 in 2006, 466 in 2007, and in 2008 564 NEOs were found.<ref>[https://web.archive.org/web/20040513230213/http://neo.jpl.nasa.gov/stats/ NEO discovery statistics] from JPL. Shows the number of asteroids of various types (potentially hazardous, size > 1&nbsp;km, etc.) that different programs have discovered, by year.</ref>

[[Spacewatch]], which uses a {{convert|90|cm|in|adj=on|sp=us}} telescope sited at the [[Kitt Peak Observatory]] in Arizona, updated with automatic pointing, imaging, and analysis equipment to search the skies for intruders, was set up in 1980 by [[Tom Gehrels]] and [[Robert S. McMillan (astronomer)|Robert S. McMillan]] of the Lunar and Planetary Laboratory of the [[University of Arizona]] in Tucson, and is now being operated by McMillan. The Spacewatch project has acquired a {{convert|1.8|m|in|adj=on|sp=us}} telescope, also at Kitt Peak, to hunt for NEOs, and has provided the old 90-centimeter telescope with an improved electronic imaging system with much greater resolution, improving its search capability.<ref>{{cite web|url = http://spacewatch.lpl.arizona.edu/index.html|title = The Spacewatch Project|access-date = 2007-10-23|url-status = dead|archive-url = https://web.archive.org/web/20110211071733/http://spacewatch.lpl.arizona.edu/index.html|archive-date = 2011-02-11}}</ref>

Other near-Earth object tracking programs include [[Near-Earth Asteroid Tracking]] (NEAT), [[Lowell Observatory Near-Earth-Object Search]] (LONEOS), [[Campo Imperatore Near-Earth Object Survey]] (CINEOS), [[Japanese Spaceguard Association]], and [[Asiago-DLR Asteroid Survey]].<ref>{{cite web|url = http://neo.jpl.nasa.gov/programs/|archive-url = https://web.archive.org/web/20040114063231/http://neo.jpl.nasa.gov/programs/|url-status = dead|archive-date = 14 January 2004|title = Near-Earth Objects Search Program|publisher = National Aeronautics and Space Administration|date = 23 October 2007}}</ref> [[Pan-STARRS]] completed telescope construction in 2010, and it is now actively observing.

The [[Asteroid Terrestrial-impact Last Alert System]], now in operation, conducts frequent scans of the sky with a view to later-stage detection on the collision stretch of the asteroid orbit. Those would be much too late for deflection, but still in time for evacuation and preparation of the affected Earth region.

Another project, supported by the [[European Union]], is '''NEOShield''', which analyses realistic options for preventing the collision of a NEO with Earth. Their aim is to provide test mission designs for feasible NEO mitigation concepts. The project particularly emphasises on two aspects.<ref name=neoshield>{{cite journal |title=Science and Technology for Near-Earth Object Impact Prevention |doi=10.3030/640351 |url=https://cordis.europa.eu/project/id/640351 |journal=CORDIS |access-date=21 May 2023|url-access=subscription }}</ref>

# The first one is the focus on technological development on essential techniques and instruments needed for guidance, navigation and control (GNC) in close vicinity of asteroids and comets. This will, for example, allow hitting such bodies with a high-velocity kinetic impactor spacecraft and observing them before, during and after a mitigation attempt, e.g., for orbit determination and monitoring.
# The second one focuses on refining Near Earth Object (NEO) characterisation. Moreover, NEOShield-2 will carry out astronomical observations of NEOs, to improve the understanding of their physical properties, concentrating on the smaller sizes of most concern for mitigation purposes, and to identify further objects suitable for missions for physical characterisation and NEO deflection demonstration.<ref>{{cite web|url = http://www.neoshield.net/science-technology-asteroid-impact/|title = NEOShield Project|publisher = European Union Consortium|date = 17 November 2016|access-date = 17 November 2016|archive-date = 4 March 2017|archive-url = https://web.archive.org/web/20170304190851/http://www.neoshield.net/science-technology-asteroid-impact/|url-status = dead}}</ref>

"[[Spaceguard]]" is the name for these loosely affiliated programs, some of which receive NASA funding to meet a U.S. Congressional requirement to detect 90% of near-Earth asteroids over 1&nbsp;km diameter by 2008.<ref>{{cite web|url = http://neo.jpl.nasa.gov/neo/report.html|archive-url = https://web.archive.org/web/20031001091527/http://neo.jpl.nasa.gov/neo/report.html|url-status = dead|archive-date = 2003-10-01|title = NASA Releases Near-Earth Object Search Report|publisher = National Aeronautics and Space Administration|access-date = 2007-10-23}}</ref> A 2003 NASA study of a follow-on program suggests spending US$250–450 million to detect 90% of all near-Earth asteroids {{convert|140|m|ft|sp=us}} and larger by 2028.<ref>{{cite web|url = http://impact.arc.nasa.gov/news_detail.cfm?ID=168|title = NASA NEO Workshop|author = David Morrison|publisher = National Aeronautics and Space Administration|url-status = dead|archive-url = https://web.archive.org/web/20080122123731/http://impact.arc.nasa.gov/news_detail.cfm?ID=168|archive-date = 2008-01-22}}</ref>

In October 2013, the [[United Nations Committee on the Peaceful Uses of Outer Space]] approved several measures to deal with terrestrial asteroid impacts, including the creation of an [[International Asteroid Warning Network]] (IAWN) to act as a clearinghouse for shared information on dangerous asteroids and for any future terrestrial impact events that are identified. [[Space Missions Planning Advisory Group]] (SMPAG) should coordinate joint studies of the technologies for deflection missions, and as well provide oversight of actual missions. This is due to deflection missions typically involving a progressive movement of an asteroid's predicted impact point across the surface of the Earth (and also across the territories of uninvolved countries) until the NEO has been deflected either ahead of, or behind the planet at the point their orbits intersect.<ref name="New Scientist-2013.10.28">Aron, Jacob. [https://www.newscientist.com/article/dn24478-un-sets-up-asteroid-peacekeepers-to-defend-earth.html#.U999lGPCeKJ  UN Sets Up Asteroid Peacekeepers to Defend Earth], ''[[New Scientist]]'' website, October 28, 2013.  Retrieved August 4, 2014.</ref><ref name="LA Times-2013.10.28">Netburn, Deborah. [http://www.latimes.com/science/sciencenow/la-sci-sn-un-asteroid-defense-plan-20131028-story.html#axzz2j5WHIgR1 UN Aims to Fight Asteroids, Creates a Global Warning Network], ''[[Los Angeles Times]]'', October 28, 2013.  Retrieved August 4, 2014.</ref><ref name="New York Times-2013.11.06">Chang, Kenneth. [https://www.nytimes.com/2013/11/07/science/space/more-large-asteroid-strikes-are-likely-scientists-find.html More Asteroid Strikes Are Likely, Scientists Say],   ''[[The New York Times]]'' website, November 6, 2013, and in print on November 7, 2013, p. A12 of the New York edition. Retrieved June 26, 2014.</ref> [[UN General Assembly]] endorsed the establishment of IAWN through its resolution 68/75 on 16 December 2023.<ref>{{cite web|url = https://iawn.net/about.shtml |title = About IAWN|publisher = IAWN}}</ref> IAWN’s main task is to warn of a possible impact threat, if the following criteria are reached: an impact probability of >1% within the next 20 years, for an object larger than about 10 meters in size.<ref>{{cite web|url = https://www.nature.com/articles/s41467-024-48600-x |title =About the International Asteroid Warning Network (IAWN) and the Space Mission Planning Advisory Group (SMPAG) |publisher = Nature}}</ref>  The number of known NEOs was 34,274 as of 30 January 2024, with 2,395 known asteroids whose orbits bring them within 8 million kilometers of Earth’s orbit and with diameters larger than about 140 m. Yet, it is estimated only about 44% of the NEOs of that size range have been found so far.<ref>{{cite web|url =https://www.unoosa.org/documents/pdf/copuos/stsc/2024/Statements/10_IAWN.pdf  |title = Statement by IAWN Representative to STSC 61th session|publisher = UN Office for Outer Space Affairs}}</ref>

[[NEODyS]] is an online database of known NEOs.

==== Sentinel mission ====
{{Main|B612 Foundation|Sentinel Space Telescope}}

The [[B612 Foundation]] is a private nonprofit [[Private foundation (United States)|foundation]] with headquarters in the United States, dedicated to protecting the Earth from [[Impact event|asteroid strikes]]. It is led mainly by scientists, former astronauts and engineers from the [[Institute for Advanced Study]], [[Southwest Research Institute]], [[Stanford University]], [[NASA]] and the [[space industry]].

As a non-governmental organization it has conducted two lines of related research to help detect NEOs that could one day strike the Earth, and find the technological means to divert their path to avoid such collisions. The foundation's goal had been to design and build a privately financed asteroid-finding [[Space observatory|space telescope]], [[Sentinel (space telescope)|Sentinel]], which was to be launched in 2017–2018. However the project was cancelled in 2015. Had the Sentinel's infrared telescope been parked in an orbit similar to that of [[Venus]], it would have helped identify threatening NEOs by cataloging 90% of those with diameters larger than {{convert|140|m|sp=us}}, as well as surveying smaller Solar System objects.<ref name="Discover-2013.09">Powell, Corey S. [http://discovermagazine.com/2013/september/17-hunting-season-for-asteroids "Developing Early Warning Systems for Killer Asteroids"] {{webarchive |url=https://web.archive.org/web/20161028014849/http://discovermagazine.com/2013/september/17-hunting-season-for-asteroids |date=October 28, 2016 }}, ''[[Discover (magazine)|Discover]]'', August 14, 2013, pp. 60–61 (subscription required).</ref><ref name="B612-Sentinel Mission" /><ref name="New York Times-2013.02.16" />

Data gathered by Sentinel would have helped identify [[asteroid]]s and other NEOs that pose a risk of collision with Earth, by being forwarded to scientific data-sharing networks, including [[NASA]] and academic institutions such as the Minor Planet Center.<ref name="B612-Sentinel Mission">{{cite web|title=The Sentinel Mission |publisher=B612 Foundation |url=http://b612foundation.org/media/sentinelmission/ |access-date=September 19, 2012 |url-status=dead |archive-url=https://web.archive.org/web/20120910234035/http://b612foundation.org/media/sentinelmission/ |archive-date=September 10, 2012 }}</ref><ref name="New York Times-2013.02.16">Broad, William J. [https://www.nytimes.com/2013/02/17/science/space/dismissed-as-doomsayers-advocates-for-meteor-detection-feel-vindicated.html Vindication for Entrepreneurs Watching Sky: Yes, It Can Fall] {{webarchive |url=https://web.archive.org/web/20141104050747/http://www.nytimes.com/2013/02/17/science/space/dismissed-as-doomsayers-advocates-for-meteor-detection-feel-vindicated.html |date=November 4, 2014 }}, ''[[The New York Times]]'' website, February 16, 2013 and in print on February 17, 2013, p. A1 of the New York edition. Retrieved June 27, 2014.</ref><ref name="Space.com-2012.07.10">{{cite web| first=Mike | last=Wall| title=Private Space Telescope Project Could Boost Asteroid Mining| work=[[Space.com]]| date=July 10, 2012 | access-date=September 14, 2012| url=http://www.space.com/16501-private-space-telescope-asteroid-mining.html}}</ref> The foundation also proposes asteroid deflection of potentially dangerous NEOs by the use of [[gravity tractor]]s to divert their trajectories away from Earth,<ref name="Discover-2013.10">Powell, Corey S. [http://discovermagazine.com/2013/oct/16-how-to-dodge-a-cosmic-bullet How to Deflect a Killer Asteroid: Researchers Come Up With Contingency Plans That Could Help Our Planet Dodge A Cosmic Bullet] {{webarchive |url=https://web.archive.org/web/20160828054622/http://discovermagazine.com/2013/oct/16-how-to-dodge-a-cosmic-bullet |date=August 28, 2016 }},  ''[[Discover (magazine)|Discover]]'' website, September 18, 2013  (subscription required), and in print as "How to Dodge a Cosmic Bullet", October 2013. Retrieved July 15, 2014.</ref><ref name="B612-2002">{{cite web|title=PROJECT B612: Deflecting an Asteroid using Nuclear-Powered Plasma Drive Propulsion (home page) |publisher=Project B612 (now B612 Foundation) |date=November 26, 2002 |url=http://b612.boulder.swri.edu/ |access-date=April 15, 2012 |url-status=dead |archive-url=https://web.archive.org/web/20110712085255/http://b612.boulder.swri.edu/ |archive-date=July 12, 2011 }}</ref> a concept co-invented by the organization's CEO, physicist and former NASA astronaut [[Ed Lu]].<ref name="Nature-Vol. 438 No. 7065-Lu, Love">{{cite journal | last1 = Lu | first1 = Edward T. | last2 = Love | first2 = Stanley G. | year = 2005 | title = Gravitational Tractor For Towing Asteroids | journal = Nature | volume = 438 | issue = 7065| pages = 177–178 | doi = 10.1038/438177a | pmid = 16281025 | arxiv = astro-ph/0509595 |bibcode = 2005Natur.438..177L | s2cid = 4414357 }}</ref>