Editing Asteroid impact avoidance (section)

=== Nuclear explosive device ===
{{See also|Nuclear pulse propulsion|Nuclear bunker buster|Operation Fishbowl}}
[[File:Bravo secondary fireball.jpg|thumb|upright=1.5|In a similar manner to the earlier pipes filled with a [[partial pressure]] of helium, as used in the [[Ivy Mike]] test of 1952, the 1954 [[Castle Bravo]] test was likewise heavily instrumented with [[Nuclear weapon design#Light pipes|line-of-sight (LOS) pipes]], to better define and quantify the timing and energies of the x-rays and neutrons produced by these early thermonuclear devices.<ref>{{Cite web|url=http://archive.org/details/CastleCommandersReport1954|title=Operation CASTLE Commander's Report|date=May 21, 1954|website=Internet Archive}}</ref><ref>{{Cite web|url=https://www.youtube.com/watch?v=DFJ2MyWlXgs|title=Declassified U.S. Nuclear Test Film #34|date=31 October 2007 |website=www.youtube.com}}</ref> One of the outcomes of this diagnostic work resulted in this graphic depiction of the transport of energetic x-ray and neutrons through a vacuum line, some 2.3&nbsp;km long, whereupon it heated solid matter at the "station 1200" blockhouse and thus generated a secondary fireball.<ref>{{Cite web |url=http://permalink.lanl.gov/object/tr?what=info%3Alanl-repo%2Flareport%2FLA-UR-03-5462 |title=Data Contribute to Certification Fred N. Mortensen, John M. Scott, and Stirling A. Colgate |access-date=2016-12-23 |archive-url=https://web.archive.org/web/20161223223806/http://permalink.lanl.gov/object/tr?what=info%3Alanl-repo%2Flareport%2FLA-UR-03-5462 |archive-date=2016-12-23 |url-status=live }}</ref><ref>{{Cite web|url=http://la-science.lanl.gov/lascience28.shtml|title=LANL: Los Alamos Science: LA Science No. 28|date=June 12, 2007|archive-url=https://web.archive.org/web/20070612184310/http://la-science.lanl.gov/lascience28.shtml |archive-date=2007-06-12 }}</ref>]]

Initiating a [[nuclear explosive]] device [[proximity fuze|above]], [[impact fuze|on]], or slightly [[Robust Nuclear Earth Penetrator|beneath]], the surface of a threatening celestial body is a potential deflection option, with the optimal detonation height dependent upon the composition and size of the object.<ref>{{cite book|author=Simonenko, V.|author2=Nogin, V.|author3=Petrov, D.|author4=Shubin, O.|author5=Solem, J. C.|date=1994|chapter-url=https://books.google.com/books?id=xXWZolI9NkUC&pg=PA929|chapter=Defending the Earth against impacts from large comets and asteroids|title=Hazards Due to Comets and Asteroids|editor=Geherels, T.|editor2=Matthews, M. S.|editor3=Schumann, A. M.|publisher=University of Arizona Press|isbn=9780816515059|pages=929–954}}</ref><ref>Solem, J. C. (1995). "[https://web.archive.org/web/20150909023233/https://e-reports-ext.llnl.gov/pdf/232015.pdf Interception and disruption]", in ''Proceedings of Planetary Defense Workshop, Livermore, CA, May 22–26, 1995'', CONF-9505266 (LLNL, Livermore, CA), pp. 219–228 (236–246).</ref><ref>{{cite journal|last=Solem|first=J. C.|year=1999|title=Comet and asteroid hazards: Threat and mitigation|journal=Science of Tsunami Hazards|volume=17|issue=3|pages=141–154|url=http://www.tsunamisociety.org/TitlesAuthors14to18.html}}</ref> It does not require the entire NEO to be vaporized to mitigate an impact threat. In the case of an inbound threat from a "rubble pile", the [[proximity fuze|stand off]], or detonation height above the surface configuration, has been put forth as a means to prevent the potential fracturing of the rubble pile.<ref name="defending Earth">{{cite book |url=http://www.nap.edu/openbook.php?record_id=12842&page=77 |title=Defending Planet Earth: Near-Earth Object Surveys and Hazard Mitigation Strategies ( 2010 ) National Academy of Sciences page 77|year=2010|doi=10.17226/12842|isbn=978-0-309-14968-6}}</ref> The energetic [[neutron]]s and [[soft X-rays]] released by the detonation, which do not appreciably penetrate matter,<ref>{{cite web|url=http://physics.nist.gov/cgi-bin/ffast/ffast.pl?Formula=H2O&gtype=5&range=S&lower=0.300&upper=2.00&density=1.00 |title=Physics.nist.gov |publisher=Physics.nist.gov |access-date=2011-11-08}}</ref> are converted into heat upon encountering the object's surface matter, [[radiation implosion|ablatively vaporizing]] all [[Line-of-sight propagation|line of sight]] exposed surface areas of the object to a shallow depth,<ref name="defending Earth"/> turning the surface material it heats up into [[ejecta]], and, analogous to the ejecta from a chemical [[rocket engine]] exhaust, changing the velocity, or "nudging", the object off course by the reaction, following [[Newton's third law]], with ejecta going one way and the object being propelled in the other.<ref name="defending Earth"/><ref name="flightglobal">{{cite web|first=Rob|last=Coppinger|date=August 3, 2007|url=http://www.flightglobal.com/articles/2007/08/03/215924/nasa-plans-armageddon-spacecraft-to-blast-asteroid.html|title=NASA plans 'Armageddon' spacecraft to blast asteroid|url-status=dead|archive-url=https://web.archive.org/web/20110905041237/http://www.flightglobal.com/articles/2007/08/03/215924/nasa-plans-armageddon-spacecraft-to-blast-asteroid.html|archive-date=2011-09-05|quote=The warheads would explode at a distance of one-third of the NEO's diameter and each detonation's X and gamma rays and neutrons would turn part of the NEO's surface into an expanding plasma to generate a force to deflect the asteroid.|website=Flightglobal.com}}<br />{{cite web|url=http://www.flightglobal.com/news/articles/nasa-plans-armageddon-spacecraft-to-blast-asteroid-215924/|title=NASA plans 'Armageddon' spacecraft to blast asteroid|access-date=2014-08-03}}</ref> Depending on the energy of the explosive device, the resulting [[reaction engine|rocket exhaust]] effect, created by the high velocity of the asteroid's vaporized mass ejecta, coupled with the object's small reduction in mass, would produce enough of a change in the object's orbit to make it miss the Earth.<ref name="Dillow"/><ref name="flightglobal"/>

A Hypervelocity Asteroid Mitigation Mission for Emergency Response (HAMMER) has been proposed.<ref>{{Cite web|url=https://phys.org/news/2018-03-scientists-asteroid-deflector-massive-potential.html|title=Scientists design conceptual asteroid deflector and evaluate it against massive potential threat |date=March 15, 2018 |website=[[Phys.org]] |archive-url=https://archive.today/20180423052949/https://phys.org/news/2018-03-scientists-asteroid-deflector-massive-potential.html |archive-date=April 23, 2018 |url-status=live}}</ref> While there have been no updates as of 2023 regarding the HAMMER, NASA has published its regular Planetary Defense Strategy and Action Plan for 2023. In it, NASA acknowledges that it is crucial to continue studying the potential of nuclear energy in deflecting or destroying asteroids. This is because it is currently the only option for defense if scientists were not aware of the asteroid within a few months or years, depending on the asteroid's velocity. The report also notes there needs to be research done into the legal implications as well as policy implications on the topic.<ref>{{Cite web |date=April 2023 |title=NASA Planetary Defense Strategy and Action Plan |url=https://www.nasa.gov/sites/default/files/atoms/files/nasa_-_planetary_defense_strategy_-_final-508.pdf |access-date=April 24, 2023}}</ref>

====Stand-off approach====
If the object is very large but is still a loosely-held-together rubble pile, a solution is to detonate one or a series of nuclear explosive devices alongside the asteroid, at a {{convert|20|m|adj=on|sp=us|}} or greater stand-off height above its surface,{{Citation needed|date=August 2019}} so as not to fracture the potentially loosely-held-together object. Providing that this stand-off strategy was done far enough in advance, the force from a sufficient number of nuclear blasts would alter the object's trajectory enough to avoid an impact, according to computer simulations and experimental evidence from [[meteorite]]s exposed to the thermal X-ray pulses of the [[Z Pulsed Power Facility|Z-machine]].<ref>{{cite web |url=https://www.discovermagazine.com/the-sciences/how-to-stop-a-killer-asteroid |title=How to Stop a Killer Asteroid |magazine=Discover |first=Steve |last=Nadis |date=January 21, 2015}}<!-- {{webarchive |url=https://web.archive.org/web/20160827112933/http://discovermagazine.com/2015/march/15-how-to-stop-a-killer-asteroid |date=August 27, 2016 }} --></ref>

In 1967, graduate students under Professor Paul Sandorff at the [[Massachusetts Institute of Technology]] were tasked with designing a method to prevent a hypothetical 18-month distant impact on Earth by the {{convert|1.4|km|mi|adj=mid|-wide|sp=us}} asteroid [[1566 Icarus]], an object that makes regular close approaches to Earth, sometimes as close as 16 [[lunar distance (astronomy)|lunar distances]].<ref>{{Cite journal|last1=Goldstein |first1=R. M.|title=Radar Observations of Icarus|journal=[[Science (journal)|Science]]|year=1968|volume=162 |issue=3856 |pages=903–4|bibcode = 1968Sci...162..903G|doi=10.1126/science.162.3856.903|pmid=17769079|s2cid=129644095}}</ref> To achieve the task within the timeframe and with limited material knowledge of the asteroid's composition, a variable stand-off system was conceived. This would have used a number of modified [[Saturn V]] rockets sent on interception courses and the creation of a handful of nuclear explosive devices in the 100-megaton energy range—coincidentally, the same as the maximum yield of the Soviets' [[Tsar Bomba#Test|''Tsar Bomba'']] would have been if a uranium tamper had been used—as each rocket vehicle's [[payload]].<ref name="Time1967">[http://content.time.com/time/magazine/article/0,9171,843952,00.html "Systems Engineering: Avoiding an Asteroid"]  {{webarchive|url=https://web.archive.org/web/20130721110612/http://www.time.com/time/magazine/article/0%2C9171%2C843952%2C00.html |date=July 21, 2013 }}, ''[[Time (magazine)|Time]]'', June 16, 1967.</ref><ref name="Day">Day, Dwayne A., [http://www.thespacereview.com/article/175/1 "Giant bombs on giant rockets: Project Icarus"] {{webarchive |url=https://web.archive.org/web/20160415041026/http://www.thespacereview.com/article/175/1 |date=April 15, 2016 }}, ''The Space Review'', Monday, July 5, 2004</ref> The design study was later published as [[1566 Icarus#Project Icarus|Project Icarus]]<ref name="Icarus">Kleiman Louis A., [http://mitpress.mit.edu/catalog/item/default.asp?ttype=2&tid=6840 ''Project Icarus: an MIT Student Project in Systems Engineering''] {{webarchive |url=https://web.archive.org/web/20071017105104/http://mitpress.mit.edu/catalog/item/default.asp?ttype=2&tid=6840 |date=October 17, 2007 }}, Cambridge, Massachusetts : MIT Press, 1968</ref> which served as the inspiration for the 1979 film ''[[Meteor (film)|Meteor]]''.<ref name="Day"/><ref>{{Cite web|url=http://www.ips.gov.au/IPSHosted/neo/info/refers/Bk_Icarus_MIT.htm|archiveurl=https://web.archive.org/web/20160602104006/http://www.ips.gov.au/IPSHosted/neo/info/refers/Bk_Icarus_MIT.htm|url-status=dead|title=''Project Icarus''|archivedate=June 2, 2016}}</ref><ref name="Tech1979">[http://tech.mit.edu/archives/VOL_099/TECH_V099_S0470_P003.pdf "MIT Course precept for movie"] {{webarchive |url=https://web.archive.org/web/20161104102228/http://tech.mit.edu/archives/VOL_099/TECH_V099_S0470_P003.pdf |date=November 4, 2016 }}, ''The Tech'', MIT, October 30, 1979</ref>

A [[NASA]] analysis of deflection alternatives, conducted in 2007, stated:

{{blockquote|Nuclear standoff explosions are assessed to be 10–100 times more effective than the non-nuclear alternatives analyzed in this study. Other techniques involving the surface or subsurface use of nuclear explosives may be more efficient, but they run an increased risk of fracturing the target NEO. They also carry higher development and operations risks.<ref name="nasa">{{cite web|url=http://neo.jpl.nasa.gov/neo/report2007.html |title=NEO Survey and Deflection Analysis and Alternatives |access-date=2015-11-20 |url-status=dead |archive-url=https://web.archive.org/web/20160305101217/http://neo.jpl.nasa.gov/neo/report2007.html |archive-date=2016-03-05 }} Near-Earth Object Survey and Deflection Analysis of Alternatives Report to Congress March 2007</ref>}}

In the same year, NASA released a study where the asteroid [[99942 Apophis|Apophis]] (with a diameter of around {{convert|300|m|disp=or|-2|sp=us}}) was assumed to have a much lower rubble pile density ({{cvt|1500|kg/m3|lb/cuft|disp=or|round=25}}) and therefore lower mass than it is now known to have, and in the study, it is assumed to be on an impact trajectory with Earth for the year 2029. Under these hypothetical conditions, the report determines that a "Cradle spacecraft" would be sufficient to deflect it from Earth impact. This conceptual spacecraft contains six [[B83 nuclear bomb|B83]] physics packages, each set for their maximum 1.2-megatonne yield,<ref name="flightglobal"/> bundled together and lofted by an [[Ares V]] vehicle sometime in the 2020s, with each B83 being [[proximity fuze|fuzed]] to detonate over the asteroid's surface at a height of {{convert|100|m|disp=or|sp=us}} ("1/3 of the objects diameter" as its stand-off), one after the other, with hour-long intervals between each detonation. The results of this study indicated that a single employment of this option "can deflect NEOs of [{{convert|100-500|m|disp=or|sp=us|-2}} diameter] two years before impact, and larger NEOs with at least five years warning".<ref name="flightglobal"/><ref name="nss.org">{{Cite web|url=http://www.nss.org/resources/library/planetarydefense/2007-NearEarthObjectMitigationOptionsUsingExplorationTechnologies.pdf|archiveurl=https://web.archive.org/web/20150701020407/http://www.nss.org/resources/library/planetarydefense/2007-NearEarthObjectMitigationOptionsUsingExplorationTechnologies.pdf|url-status=dead|title=Near Earth Object (NEO) Mitigation Options Using Exploration Technologies|archivedate=July 1, 2015}}</ref> These effectiveness figures are considered to be "conservative" by its authors, and only the thermal X-ray output of the B83 devices was considered, while neutron heating was neglected for ease of calculation purposes.<ref name="nss.org"/><ref>[https://web.archive.org/web/20170310002322/https://ntrs.nasa.gov/archive/nasa/casi.ntrs.nasa.gov/20090025983.pdf Towards Designing an Integrated Architecture for NEO Characterization, Mitigation, Scientific Evaluation, and Resource Utilization]</ref>

Research published in 2021 pointed out the fact that for an effective deflection mission, there would need to be a significant amount of warning time, with the ideal being several years or more. The more warning time provided, the less energy will be necessary to divert the asteroid just enough to adjust the trajectory to avoid Earth. The study also emphasized that deflection, as opposed to destruction, can be a safer option, as there is a smaller likelihood of asteroid debris falling to Earth's surface. The researchers proposed the best way to divert an asteroid through deflection is adjusting the output of neutron energy in the nuclear explosion.<ref name="auto">{{Cite journal |last1=Horan |first1=Lansing S. |last2=Holland |first2=Darren E. |last3=Bruck Syal |first3=Megan |last4=Bevins |first4=James E. |last5=Wasem |first5=Joseph V. |date=2021-06-01 |title=Impact of neutron energy on asteroid deflection performance |journal=Acta Astronautica |language=en |volume=183 |pages=29–42 |doi=10.1016/j.actaastro.2021.02.028 |bibcode=2021AcAau.183...29H |s2cid=233791597 |issn=0094-5765|doi-access=free }}</ref>

====Surface and subsurface use====
[[File:Asteroid Capture.jpg|thumb|This early [[Asteroid Redirect Mission]] artist's impression is suggestive of another method of changing a large threatening celestial body's orbit by [[asteroid capture|capturing]] relatively smaller celestial objects and using those, and not the usually proposed small bits of spacecraft, as the means of creating a powerful [[kinetic energy|kinetic impact]],<ref>{{cite journal|last1=Asphaug|first1=E.|last2=Ostro|first2=S. J.|last3=Hudson|first3=R. S.|last4=Scheeres|first4=D. J.|last5=Benz|first5=W.|date=1998|title=Disruption of kilometre-sized asteroids by energetic collisions|journal=Nature|volume=393|issue=6684|pages=437–440|url=http://trs-new.jpl.nasa.gov/dspace/bitstream/2014/19541/1/98-0965.pdf|url-status=dead|archive-url=https://web.archive.org/web/20160306071546/http://trs-new.jpl.nasa.gov/dspace/bitstream/2014/19541/1/98-0965.pdf|archive-date=March 6, 2016|doi=10.1038/30911|bibcode=1998Natur.393..437A|s2cid=4328861}}</ref> or alternatively, a stronger faster acting [[gravitational tractor]], as some low-density asteroids such as [[253 Mathilde]] can [[crumple zone|dissipate impact energy]].]]

In 2011, the director of the Asteroid Deflection Research Center at [[Iowa State University]], Dr. Bong Wie (who had published kinetic impactor deflection studies<ref name="spacesailing.net"/> previously), began to study strategies that could deal with {{convert|50|to(-)|500|m|ft|adj=mid|-diameter|-2|sp=us}} objects when the time to Earth impact was less than one year. He concluded that to provide the required energy, a nuclear explosion or other event that could deliver the same power, are the only methods that can work against a very large asteroid within these time constraints.

This work resulted in the creation of a conceptual [[Hypervelocity Asteroid Intercept Vehicle]] (HAIV), which combines a [[Deep Impact (spacecraft)|kinetic impactor]] to create an initial [[Impact crater|crater]] for a follow-up subsurface nuclear detonation within that initial crater, which would generate a high degree of efficiency in the conversion of the nuclear energy that is released in the detonation into propulsion energy to the asteroid.<ref>{{cite web|url=http://www.space.com/21333-asteroid-nuke-spacecraft-mission.html |title=Nuking Dangerous Asteroids Might be the Best Protection, Expert Says |website=[[Space.com]] |date=29 May 2013 |access-date=2013-07-02 |url-status=live |archive-url=https://web.archive.org/web/20160401213420/http://www.space.com/21333-asteroid-nuke-spacecraft-mission.html |archive-date=2016-04-01 }} Nuking Dangerous Asteroids Might Be the Best Protection, Expert Says. Includes a supercomputer simulation video provided by [[Los Alamos National Laboratory]].</ref>

A similar proposal would use a surface-detonating nuclear device in place of the kinetic impactor to create the initial crater, then using the crater as a [[rocket nozzle]] to channel succeeding nuclear detonations.

Wie claimed the computer models he worked on showed the possibility for a {{convert|300|m|ft|adj=mid|-wide|abbr=off|sp=us}} asteroid to be destroyed using a single HAIV with a warning time of 30 days. Additionally, the models showed that less than 0.1% of debris from the asteroid would reach Earth's surface.<ref>{{Cite web |author1=Mike Wall |date=2014-02-14 |title=How Nuclear Bombs Could Save Earth from Killer Asteroids |url=https://www.space.com/24696-asteroid-strike-nuclear-bombs.html |access-date=2023-04-25 |website=Space.com |language=en}}</ref> There have been few substantial updates from Wie and his team since 2014 regarding the research.

As of 2015, Wie has collaborated with the Danish [[Emergency Asteroid Defence Project]] (EADP), which intends to [[crowdsource]] sufficient funds to design, build, and store a non-nuclear HAIV spacecraft as planetary insurance. For threatening asteroids too large or close to Earth impact to effectively be deflected by the non-nuclear HAIV approach, nuclear explosive devices (with 5% of the explosive yield than those used for the stand-off strategy) are intended to be used, under international oversight, when conditions arise that necessitate it.<ref>{{Cite web|url=http://asteroiddefence.com/|title=EADP|date=May 5, 2015|archive-url=https://web.archive.org/web/20150505181554/http://asteroiddefence.com/ |archive-date=2015-05-05 }}</ref>

A study published in 2020 pointed out that a non-nuclear kinetic impact becomes less effective the larger and closer the asteroid. However, researchers ran a model that suggested a nuclear detonation near the surface of an asteroid designed to cover one side of the asteroid with x-rays would be effective. When the x-rays cover one side of an asteroid in the program, the energy would propel the asteroid in a preferred direction.<ref>{{Cite journal |last1=Dearborn |first1=David S. P. |last2=Bruck Syal |first2=Megan |last3=Barbee |first3=Brent W. |last4=Gisler |first4=Galen |last5=Greenaugh |first5=Kevin |last6=Howley |first6=Kirsten M. |last7=Leung |first7=Ronald |last8=Lyzhoft |first8=Joshua |last9=Miller |first9=Paul L. |last10=Nuth |first10=Joseph A. |last11=Plesko |first11=Catherine S. |last12=Seery |first12=Bernard D. |last13=Wasem |first13=Joseph V. |last14=Weaver |first14=Robert P. |last15=Zebenay |first15=Melak |date=2020-01-01 |title=Options and uncertainties in planetary defense: Impulse-dependent response and the physical properties of asteroids |journal=Acta Astronautica |language=en |volume=166 |pages=290–305 |doi=10.1016/j.actaastro.2019.10.026 |bibcode=2020AcAau.166..290D |s2cid=208840044 |issn=0094-5765|doi-access=free }}</ref> The lead researcher with the study, Dave Dearborn, said a nuclear impact offered more flexibility than a non-nuclear approach, as the energy output can be adjusted specifically to the asteroid's size and location.<ref>{{Cite web |title=Nuclear impulse could deflect massive asteroid |url=https://www.llnl.gov/news/nuclear-impulse-could-deflect-massive-asteroid |access-date=2023-04-25 |website=Lawrence Livermore National Laboratory |language=en}}</ref>

====Comet deflection possibility====
[[File:Comet-Hale-Bopp-29-03-1997 hires adj.jpg|thumb|right|"Who knows whether, when a comet shall approach this globe to destroy it&nbsp;... men will not tear rocks from their foundations by means of steam, and hurl mountains, as the giants are said to have done, against the flaming mass?"<br />— [[Lord Byron]]<ref>As quoted in ''Conversations of Lord Byron with Thomas Medwin'' (1832).</ref>]]

Following the 1994 [[Shoemaker-Levy 9]] comet impacts with Jupiter, [[Edward Teller]] proposed, to a collective of U.S. and Russian ex-[[Cold War]] weapons designers in a 1995 planetary defense workshop meeting at [[Lawrence Livermore National Laboratory]] (LLNL), that they collaborate to design a [[Nuclear weapon design#Arbitrarily large multi-staged devices|one-gigaton nuclear explosive device]], which would be equivalent to the kinetic energy of a {{convert|1|km|mi|adj=mid|-diameter|spell=in|sp=us|sigfig=1}} asteroid.<ref name="e-reports-ext.llnl.gov">[https://web.archive.org/web/20150909023233/https://e-reports-ext.llnl.gov/pdf/232015.pdf Planetary defense workshop LLNL 1995]</ref><ref name="Jason Mick">{{cite web|url=http://www.dailytech.com/Russia+US+Eye+Teamup+to+Build+Massive+Nuke+to+Save+Planet+from+an+Asteroid/article33569.htm#sthash.rQvVzS6m.dpuf|title=The mother of all bombs would sit in wait in an orbitary platform|date=October 17, 2013|author=Jason Mick|access-date=October 6, 2014|archive-url=https://web.archive.org/web/20141009190305/http://www.dailytech.com/Russia+US+Eye+Teamup+to+Build+Massive+Nuke+to+Save+Planet+from+an+Asteroid/article33569.htm#sthash.rQvVzS6m.dpuf|archive-date=October 9, 2014|url-status=dead|df=mdy-all}}</ref><ref name="publicintegrity.org">{{Cite web|url=http://publicintegrity.org/national-security/a-new-use-for-nuclear-weapons-hunting-rogue-asteroids/|archiveurl=https://web.archive.org/web/20160320055111/http://www.publicintegrity.org/2013/10/16/13547/new-use-nuclear-weapons-hunting-rogue-asteroids|url-status=dead|title=A new use for nuclear weapons: hunting rogue asteroids|first=Douglas|last=Birch|date=October 16, 2013|archivedate=March 20, 2016|website=Center for Public Integrity}}</ref> The theoretical one-gigaton device would weigh about 25–30 tons, light enough to be lifted on the [[Energia (rocket)|Energia]] rocket. It could be used to instantaneously vaporize a one-kilometer asteroid, divert the paths of [[Global catastrophic risk|ELE-class asteroids]] (greater than {{convert|10|km|disp=or|sp=us}} in diameter) within short notice of a few months. With one year of notice, and at an interception location no closer than [[Jupiter]], it could also deal with the even rarer [[List of periodic comets|short period comets]] that can come out of the [[Kuiper belt]] and transit past Earth orbit within two years.{{clarify|is it 1 year or 2?|date=May 2019}} For comets of this class, with a maximum estimated diameter of {{convert|100|km|sp=us|sigfig=1}}, [[2060 Chiron|Chiron]] served as the hypothetical threat.<ref name="e-reports-ext.llnl.gov"/><ref name="Jason Mick"/><ref name="publicintegrity.org"/>

In 2013, the related National Laboratories of the [[United States Department of Energy national laboratories|US]] and [[Rosatom|Russia]] signed a deal that includes an intent to cooperate on defense from asteroids.<ref>{{Cite web|url=https://www.energy.gov/articles/united-states-russia-sign-agreement-further-research-and-development-collaboration-nuclear|archiveurl=https://web.archive.org/web/20160304125747/http://energy.gov/articles/united-states-russia-sign-agreement-further-research-and-development-collaboration-nuclear|url-status=dead|title=United States, Russia Sign Agreement to Further Research and Development Collaboration in Nuclear Energy and Security|archivedate=March 4, 2016|website=Energy.gov}}</ref> The deal was meant to complement [[New START]], but Russia suspended its participation in the treaty in 2023.<ref>{{Cite news |last=Chappell |first=Bill |date=February 22, 2023 |title=What happens now after Russia suspends the last nuclear arms treaty with the U.S.? |work=NPR |url=https://www.npr.org/2023/02/22/1158529106/nuclear-treaty-new-start-putin |access-date=April 24, 2023}}</ref> As of April 2023, there has not been an official update from the White House or Moscow on how Russia's suspended participation will affect adjacent treaties.

====Present capability====
As of late 2022, the most likely and most effective method for asteroid deflection does not involve nuclear technology. Instead, it involves a kinetic impactor designed to redirect the asteroid, which showed promise in the NASA [[DART mission]].<ref>{{Cite web |title=DART |url=https://dart.jhuapl.edu/Mission/index.php |access-date=2023-04-25 |website=dart.jhuapl.edu |language=en}}</ref> For nuclear technology, simulations have been run analyzing the possibility of using neutron energy put off by a nuclear device to redirect an asteroid. These simulations showed promise, with one study finding that increasing the neutron energy output had a notable effect on the angle of the asteroid's travel.<ref name="auto"/> However, there has not been a practical test studying the possibility as of April 2023.