Editing Near-Earth object (section)

=== Projects to minimize the threat ===
{{main|Asteroid impact avoidance}}

{{multiple image
 |direction = vertical
 |align     = right
 |width1    = 350
 |width2    = 350
 |image1    = NEA by survey.svg<!-- The Wikimedia file, which is from the "neo-jpl-stats" source, should be updated (overwritten) annually, using the end-of-the-year version saved from the source at the start of the next year, simultaneously with the other three files & the stats in this article from the "neo-jpl-stats" source -->
 |image2    = NEA 1 km or more.svg<!-- The Wikimedia file, which is from the "neo-jpl-stats" source, should be updated (overwritten) annually, using the end-of-the-year version saved from the source at the start of the next year, simultaneously with the other three files & the stats in this article from the "neo-jpl-stats" source -->
 |footer    = Annual NEA discoveries by survey: all NEAs (''top'') and NEAs &gt; 1&nbsp;km (''bottom'')
}}
A year before the 1968 close approach of asteroid Icarus, [[Massachusetts Institute of Technology]] students launched Project Icarus, devising a plan to deflect the asteroid with rockets in case it was found to be on a collision course with Earth.<ref>{{cite news |first=Dwayne A. |last=Day |title=Giant bombs on giant rockets: Project Icarus |date=July 5, 2004 |work=The Space Review |url=http://www.thespacereview.com/article/175/1 |access-date=January 2, 2025 |url-status=live |archive-url=https://web.archive.org/web/20160415041026/http://www.thespacereview.com/article/175/1 |archive-date=April 15, 2016}}</ref> Project Icarus received wide media coverage, and inspired the 1979 disaster movie ''[[Meteor (film)|Meteor]]'', in which the US and the USSR join forces to blow up an Earth-bound fragment of an asteroid hit by a comet.<ref>{{cite news |title=MIT Course precept for movie |date=October 30, 1979 |work=[[The Tech (newspaper)|The Tech]] |publisher=MIT |url=http://tech.mit.edu/V99/PDF/V99-N43.pdf |access-date=November 15, 2017 |url-status=dead |archive-url=https://web.archive.org/web/20140811005933/http://tech.mit.edu/V99/PDF/V99-N43.pdf |archive-date=August 11, 2014}}</ref>

The first astronomical program dedicated to the discovery of near-Earth asteroids was the [[Palomar Planet-Crossing Asteroid Survey]]. The link to impact hazard, the need for dedicated survey telescopes and options to head off an eventual impact were first discussed at a 1981 [[interdisciplinary]] conference in [[Snowmass, Colorado]].<ref name="Chapman1998"/> Plans for a more comprehensive survey, named the Spaceguard Survey, were developed by NASA from 1992, under a mandate from the [[United States Congress]].<ref name="Vulcano1995"/><ref name="spaceguard-1998" /> To promote the survey on an international level, the International Astronomical Union (IAU) organised a workshop at [[Vulcano]], Italy in 1995,<ref name="Vulcano1995">{{cite conference |author=<!--Staff writer(s); no by-line.--> |title=Vulcano Workshop. Beginning the Spaceguard Survey |location=Vulcano, Italy |publisher=IAU |date=September 1995 |url=http://spaceguard.rm.iasf.cnr.it/SGF/Vulcano/booklet.ps |access-date=March 13, 2018 |url-status=dead |archive-url=https://web.archive.org/web/20131031042442/http://spaceguard.rm.iasf.cnr.it/SGF/Vulcano/booklet.ps |archive-date=October 31, 2013}}</ref> and set up [[The Spaceguard Foundation]] also in Italy a year later.<ref name="spaceguard-2004" /> In 1998, the [[United States Congress]] gave NASA a mandate to detect 90% of near-Earth asteroids over {{convert|1|km|mi|abbr=on}} diameter (that threaten global devastation) by 2008.<ref name="spaceguard-1998">{{cite web |first=Clark R. |last=Chapman |title=Statement on The Threat of Impact by Near-Earth Asteroids before the Subcommittee on Space and Aeronautics of the Committee on Science of the U.S. House of Representatives at its hearings on "Asteroids: Perils and Opportunities" |date=May 21, 1998 |publisher=Southwest Research Institute |url=http://www.boulder.swri.edu/clark/hr.html |access-date=January 2, 2025 |url-status=live |archive-url=https://web.archive.org/web/20241206153404/https://www.boulder.swri.edu/clark/hr.html |archive-date=December 6, 2024}}</ref><ref name="shigad" />
[[File:PIA22419-Neowise-1stFourYearsDataFromDec2013-20180420.gif|thumb|300px|{{center|Asteroids discovered in the first three years of the [[Wide-field Infrared Survey Explorer#NEOWISE (pre-hibernation)|Near-Earth Object WISE]] program, starting in December 2013, with green dots showing NEAs}}]]
Several [[astronomical surveys|surveys]] have undertaken "[[Spaceguard]]" activities (an umbrella term), including [[Lincoln Near-Earth Asteroid Research]] (LINEAR), [[Spacewatch]], [[Near-Earth Asteroid Tracking]] (NEAT), [[Lowell Observatory Near-Earth-Object Search]] (LONEOS), [[Catalina Sky Survey]] (CSS), [[Campo Imperatore Near-Earth Object Survey]] (CINEOS), [[Japanese Spaceguard Association]], [[Asiago-DLR Asteroid Survey]] (ADAS) and [[Wide-field Infrared Survey Explorer#NEOWISE (pre-hibernation)|Near-Earth Object WISE]] (NEOWISE). As a result, the ratio of the known and the estimated total number of near-Earth asteroids larger than 1&nbsp;km in diameter rose from about 20% in 1998 to 65% in 2004,<ref name="spaceguard-2004">{{cite web |title=NASA on the Prowl for Near-Earth Objects |date=May 26, 2004 |publisher=NASA/JPL |url=https://www.nasa.gov/vision/universe/watchtheskies/near_earth052104.html |access-date=March 6, 2018 |url-status=dead |archive-url=https://web.archive.org/web/20220813164957/https://www.nasa.gov/vision/universe/watchtheskies/near_earth052104.html |archive-date=August 13, 2022}}</ref> 80% in 2006,<ref name="shigad">{{cite news |last=Shiga |first=David |title=New telescope will hunt dangerous asteroids |date=June 27, 2006 |work=New Scientist |url=https://www.newscientist.com/article/dn9403-new-telescope-will-hunt-dangerous-asteroids/ |access-date=January 2, 2025 |url-status=live |archive-url=https://web.archive.org/web/20241203030816/https://www.newscientist.com/article/dn9403-new-telescope-will-hunt-dangerous-asteroids/ |archive-date=December 3, 2024}}</ref> and 93% in 2011. The original Spaceguard goal has thus been met, only three years late.<ref name="pia14734"/><ref name="WISE-asteroid-census"/> {{As of|2024|12}}, 867 NEAs larger than 1&nbsp;km have been discovered, of which one was discovered in 2024 and two in 2023.<ref name="neo-jpl-stats" />

In 2005, the original USA Spaceguard mandate was extended by the [[George E. Brown, Jr.]] Near-Earth Object Survey Act, which calls for NASA to detect 90% of NEOs with diameters of {{convert|140|m|ft|abbr=on}} or greater, by 2020.<ref name="law-109-155">{{cite web |title=Public Law 109–155–DEC.30, 2005 |url=http://www.govinfo.gov/content/pkg/PLAW-109publ155/pdf/PLAW-109publ155.pdf |access-date=January 2, 2025 |url-status=live |archive-url=https://web.archive.org/web/20241206182016/https://www.govinfo.gov/content/pkg/PLAW-109publ155/pdf/PLAW-109publ155.pdf |archive-date=December 6, 2024}}</ref> In January 2016, NASA announced the creation of the [[Planetary Defense Coordination Office]] (PDCO) to coordinate an effective threat assessment, response and mitigation effort, which reinforced the goal to detect 90% of NEOs {{convert|140|m|ft|abbr=on}} or greater, but without a deadline.<ref name="ETech">{{cite news |first=Graham |last=Templeton |title=NASA is opening a new office for planetary defense |date=January 12, 2016 |work=[[ExtremeTech]] |url=http://www.extremetech.com/extreme/220745-nasa-is-opening-a-new-office-for-planetary-defense |access-date=March 2, 2025 |url-status=live |archive-url=https://web.archive.org/web/20170706223602/https://www.extremetech.com/extreme/220745-nasa-is-opening-a-new-office-for-planetary-defense |archive-date=July 6, 2017}}</ref><ref>{{cite web |title=Planetary Defense Coordination Office. Overview |date=8 September 2023 |publisher=NASA |url=https://science.nasa.gov/planetary-defense-overview |access-date=January 2, 2025 |url-status=live |archive-url=https://web.archive.org/web/20241226012441/https://science.nasa.gov/planetary-defense-overview/ |archive-date=December 26, 2024}}</ref> In September 2020, it was estimated that about half of these have been found, but objects of this size hit the Earth only about once in 30,000 years.<ref name="HarrisChodas2021">{{cite journal |first1=Alan W. |last1=Harris |first2=Paul W. |last2=Chodas |title=The population of near-earth asteroids revisited and updated |journal=Icarus |date=September 1, 2021 |volume=365 |at=section 114452 |doi=10.1016/j.icarus.2021.114452 |bibcode=2021Icar..36514452H}}</ref><!-- 30,000 impact interval for d=140 m = H=22 can be read from Figure 15 in the article.--> In December 2023, using a lower absolute brightness estimate for smaller asteroids, the ratio of discovered NEOs with diameters of {{convert|140|m|ft|abbr=on}} or greater was estimated at 38%.<ref name="Grav2023"/><!-- This article uses a H=23 cutoff for d>140, but states that in H terms, the estimate is consistent withe the earlier one--> The Chile-based [[Vera C. Rubin Observatory]], which will survey the southern sky for transient events from 2025, is expected to increase the number of known asteroids by a factor of 10 to 100 and increase the ratio of known NEOs with diameters of {{convert|140|m|ft|abbr=on}} or greater to at least 60%,<ref>{{cite web |title=Science Goals. What's in our Solar System? |publisher=Vera C. Rubin Observatory |url=https://rubinobservatory.org/explore/science-goals/solar-system |access-date=January 2, 2025 |url-status=live |archive-url=https://web.archive.org/web/20241219033206/https://rubinobservatory.org/explore/science-goals/solar-system |archive-date=December 19, 2024}}</ref> while the [[NEO Surveyor]] satellite, to be launched in 2027, is expected to push the ratio to 76% during its 5-year mission.<ref name="Grav2023">{{cite journal |last1=Grav |first1=Tommy |last2=Mainzer |first2=Amy K. |title=The NEO Surveyor Near-Earth Asteroid Known Object Model |journal=[[The Planetary Science Journal]] |volume=4 |issue=12 |at=part 228 |date=December 5, 2023 |doi=10.3847/PSJ/ad072e|doi-access=free |arxiv=2310.20149 |bibcode=2023PSJ.....4..228G}}</ref>

Survey programs aim to identify threats years in advance, giving humanity time to prepare a space mission to avert the threat.

{{blockquote|REP. STEWART: ... are we technologically capable of launching something that could intercept [an asteroid]? ...<br /> DR. A'HEARN: No. If we had spacecraft plans on the books already, that would take a year ... I mean a typical small mission ... takes four years from approval to start to launch ...|author=[[Chris Stewart (politician)|Rep. Chris Stewart (R, UT)]] and [[Michael A'Hearn|Dr. Michael F. A'Hearn]], April 10, 2013 |source=[[United States Congress]]<ref name="US-Congress-20130410">{{cite web |author=U.S.Congress |title=Threats From Space: a Review of U.S. Government Efforts to Track and mitigate Asteroids and Meteors (Part I and Part II) – Hearing Before the Committee on Science, Space, and Technology House of Representatives One Hundred Thirteenth Congress First Session |url=https://www.govinfo.gov/content/pkg/CHRG-113hhrg80552/pdf/CHRG-113hhrg80552.pdf |date=March 19, 2013 |page=147 |publisher=United States Congress |access-date=January 2, 2025 |url-status=live |archive-url=https://web.archive.org/web/20241206150309/https://www.govinfo.gov/content/pkg/CHRG-113hhrg80552/pdf/CHRG-113hhrg80552.pdf |archive-date=December 6, 2024}}</ref>}}

The [[Asteroid Terrestrial-impact Last Alert System|ATLAS]] project, by contrast, aims to find impacting asteroids shortly before impact, much too late for deflection maneuvers but still in time to evacuate and otherwise prepare the affected Earth region.<ref>{{cite news |title=ATLAS: The Asteroid Terrestrial-impact Last Alert System |date=February 18, 2013 |work=[[Astronomy (magazine)|Astronomy]] |publisher=University of Hawaii at Mānoa Institute for Astronomy |url=https://www.astronomy.com/science/atlas-the-asteroid-terrestrial-impact-last-alert-system/ |access-date=January 2, 2025 |url-status=live |archive-url=https://web.archive.org/web/20230604015435/https://www.astronomy.com/science/atlas-the-asteroid-terrestrial-impact-last-alert-system/ |archive-date=June 4, 2023}}</ref> Another project, the [[Zwicky Transient Facility]] (ZTF), which surveys for objects that change their brightness rapidly,<ref name="AT-20180207">{{cite news |last=Kulkarni |first= S.R. |display-authors=etal |title=The Zwicky Transient Facility (ZTF) begins |url=http://www.astronomerstelegram.org/?read=11266 |date=February 7, 2018 |work=[[The Astronomer's Telegram]] |number=11266 |access-date=January 2, 2025 |url-status=live |archive-url=https://web.archive.org/web/20180209062936/http://www.astronomerstelegram.org/?read=11266 |archive-date=February 9, 2018}}</ref> also detects asteroids passing close to Earth.<ref name="AT-20180208">{{cite news |last=Ye |first= Quan-Zhi|display-authors=etal|title=First Discovery of a Small Near Earth Asteroid with ZTF (2018 CL) |url=http://www.astronomerstelegram.org/?read=11274 |date=February 8, 2018 |work=The Astronomer's Telegram |number=11274 |access-date=January 2, 2025 |url-status=live |archive-url=https://web.archive.org/web/20180209002703/http://www.astronomerstelegram.org/?read=11274 |archive-date=February 9, 2018}}</ref>

{{further|List of near-Earth object observation projects}}

Scientists involved in NEO research have also considered options for actively averting the threat if an object is found to be on a collision course with Earth.<ref name="Chapman1998"/> All viable methods aim to deflect rather than destroy the threatening NEO, because the fragments would still cause widespread destruction.<ref name="TaskForceReport"/> Deflection, which means a change in the object's orbit months to years prior to the [[Asteroid impact prediction|predicted impact]], also requires orders of magnitude less energy.<ref name="TaskForceReport"/>