New research reveals that when NASA\u2019s DART (Double Asteroid Redirection Test) spacecraft intentionally impacted the asteroid moonlet Dimorphos in September 2022, it didn\u2019t just change the motion of Dimorphos around its larger companion, Didymos; the crash also shifted the orbit of both asteroids around the Sun. Linked together by gravity, Didymos and Dimorphos orbit each other around a shared center of mass in a configuration known as a binary system, so changes to one asteroid affect the other.<\/p>\n
As detailed in a study published <\/a>on Friday in the journal Science Advances, observations of the pair\u2019s motion revealed that the 770-day orbital period around the Sun changed by a fraction of a second after the DART spacecraft\u2019s<\/a> impact on Dimorphos. That change marks the first time a human-made object has measurably altered the path of a celestial body around the Sun.<\/p>\n \u201cThis is a tiny change to the orbit, but given enough time, even a tiny change can grow to a significant deflection,\u201d said Thomas Statler, lead scientist for solar system small bodies at NASA Headquarters in Washington. \u201cThe team\u2019s amazingly precise measurement again validates kinetic impact as a technique for defending Earth against asteroid hazards and shows how a binary asteroid might be deflected by impacting just one member of the pair.\u201d<\/p>\n When DART struck Dimorphos, the impact blasted a huge cloud of rocky debris<\/a> into space, altering the shape of the asteroid, which measures 560 feet (170 meters) wide. Because the debris carried its own momentum away from the asteroid, it gave Dimorphos an explosive thrust \u2014 what scientists call the momentum enhancement factor. More debris being kicked out means more oomph. According to the new research, the momentum enhancement factor for DART\u2019s impact was about two, meaning that the debris loss doubled the punch created by the spacecraft alone.<\/p>\n Earlier research showed that the smaller asteroid\u2019s 12-hour orbital period around the nearly half-mile-wide (805-meter-wide) Didymos shortened by 33 minutes<\/a>. The new study shows the impact ejected so much material from the binary system that it also changed the binary\u2019s orbital period around the Sun by 0.15 seconds.<\/p>\n \u201cThe change in the binary system\u2019s orbital speed was about 11.7 microns per second, or 1.7 inches per hour,\u201d said Rahil Makadia, the study\u2019s lead author at the University of Illinois Urbana-Champaign. \u201cOver time, such a small change in an asteroid\u2019s motion can make the difference between a hazardous object hitting or missing our planet.\u201d<\/p>\n Although Didymos was not on an impact trajectory with Earth and it was impossible for the DART mission to put it on one, that change in orbital speed underscores the role spacecraft \u2014 aka kinetic impactors in this context \u2014 could play if a potentially hazardous asteroid is found to be on a collision course in the future. The key is detecting near-Earth objects far enough in advance to send a kinetic impactor.<\/p>\n To that end, NASA is building the Near-Earth Object (NEO) Surveyor<\/a> mission. Managed by NASA\u2019s Jet Propulsion Laboratory in Southern California, this next-generation space survey telescope is the first to be built for planetary defense. The mission will seek out some of the hardest-to-find near-Earth objects, such as dark asteroids and comets that don\u2019t reflect much visible light.<\/p>\n To prove DART had a detectable influence on both asteroids \u2014 not just on the smaller Dimorphos \u2014 the researchers needed to measure Didymos\u2019 orbit around the Sun to exquisite precision. So, in addition to making radar and other ground-based observations of the asteroid, they tracked stellar occultations, which occur when the asteroid passes exactly in front of a star, causing the pinpoint of light to blink out for a fraction of a second. This technique provides extremely precise measurements of the asteroid\u2019s speed, shape, and position.<\/p>\n Measuring stellar occultations is challenging: Astronomers have to be in the right place at the right time with several observing stations, sometimes miles apart, to track the predicted path of the asteroid in front of a specific star. The team relied on volunteer astronomers around the globe who recorded 22 stellar occultations between October 2022 and March 2025.<\/p>\n \u201cWhen combined with years of existing ground-based observations, these stellar occultation observations became key in helping us calculate how DART had changed Didymos\u2019 orbit,\u201d said study co-lead Steve Chesley, a senior research scientist at JPL. \u201cThis work is highly weather dependent and often requires travel to remote regions with no guarantee of success. This result would not have been possible without the dedication of dozens of volunteer occultation observers around the world.\u201d<\/p>\n Studying changes in Didymos\u2019 motion also helped the researchers calculate the densities of both asteroids. Dimorphos is slightly less dense than previously thought, supporting the theory that it formed from rocky debris shed by a rapidly spinning Didymos. This loose material eventually clumped together to form Dimorphos, a \u201crubble pile\u201d asteroid.<\/p>\n The DART spacecraft was designed, built, and operated by the Johns Hopkins Applied Physics Laboratory in Laurel, Maryland, for NASA\u2019s Planetary Defense Coordination Office, which oversees the agency\u2019s ongoing efforts in planetary defense. It was humanity\u2019s first mission to intentionally move a celestial object.<\/p>\n For more information about the DART mission visit:<\/p>\n https:\/\/science.nasa.gov\/mission\/dart\/<\/strong><\/a><\/p>\n Media Contacts<\/strong><\/p>\n Ian J. O\u2019Neill Karen Fox \/ Molly Wasser 2025-015<\/p>\n","protected":false},"excerpt":{"rendered":"New research reveals that when NASA\u2019s DART (Double Asteroid Redirection Test) spacecraft intentionally impacted the asteroid moonlet Dimorphos…\n","protected":false},"author":2,"featured_media":371478,"comment_status":"","ping_status":"","sticky":false,"template":"","format":"standard","meta":{"footnotes":"","_share_on_mastodon":"0"},"categories":[77],"tags":[9621,582,13082,171629,18,19,17,16032,171630,171631,133],"class_list":["post-371477","post","type-post","status-publish","format-standard","has-post-thumbnail","category-science","tag-asteroids","tag-astronomy","tag-dart-double-asteroid-redirection-test","tag-didymos-dimorphos","tag-eire","tag-ie","tag-ireland","tag-planetary-defense","tag-planetary-defense-coordination-office","tag-potentially-hazardous-asteroid-pha","tag-science"],"share_on_mastodon":{"url":"https:\/\/pubeurope.com\/@ie\/116183944723490099","error":""},"_links":{"self":[{"href":"https:\/\/www.europesays.com\/ie\/wp-json\/wp\/v2\/posts\/371477","targetHints":{"allow":["GET"]}}],"collection":[{"href":"https:\/\/www.europesays.com\/ie\/wp-json\/wp\/v2\/posts"}],"about":[{"href":"https:\/\/www.europesays.com\/ie\/wp-json\/wp\/v2\/types\/post"}],"author":[{"embeddable":true,"href":"https:\/\/www.europesays.com\/ie\/wp-json\/wp\/v2\/users\/2"}],"replies":[{"embeddable":true,"href":"https:\/\/www.europesays.com\/ie\/wp-json\/wp\/v2\/comments?post=371477"}],"version-history":[{"count":0,"href":"https:\/\/www.europesays.com\/ie\/wp-json\/wp\/v2\/posts\/371477\/revisions"}],"wp:featuredmedia":[{"embeddable":true,"href":"https:\/\/www.europesays.com\/ie\/wp-json\/wp\/v2\/media\/371478"}],"wp:attachment":[{"href":"https:\/\/www.europesays.com\/ie\/wp-json\/wp\/v2\/media?parent=371477"}],"wp:term":[{"taxonomy":"category","embeddable":true,"href":"https:\/\/www.europesays.com\/ie\/wp-json\/wp\/v2\/categories?post=371477"},{"taxonomy":"post_tag","embeddable":true,"href":"https:\/\/www.europesays.com\/ie\/wp-json\/wp\/v2\/tags?post=371477"}],"curies":[{"name":"wp","href":"https:\/\/api.w.org\/{rel}","templated":true}]}}
Jet Propulsion Laboratory, Pasadena, Calif.
818-354-2649
ian.j.oneill@jpl.nasa.gov<\/a><\/p>\n
NASA Headquarters, Washington
240-285-5155 \/ 240-419-1732
karen.c.fox@nasa.gov<\/a> \/ molly.l.wasser@nasa.gov<\/a><\/p>\n