Between October 2022 and March 2025, we captured 22 such stellar occultations of the Didymos system. Combined with a huge dataset publicly available at the Minor Planet Data Center that included nearly 6,000 ground-based astrometric measurements taken over 29 years, optical navigation data from the DART probe\u2019s approach, and ground-based radar measurements, researchers finally had all they needed.<\/p>\n
\u201cOnce we had enough measurements before and after the DART impact, we could discern how Didymos\u2019 orbit has changed,\u201d Makadia said.<\/p>\n
When the vending-machine-sized DART probe crashed into Dimorphos at over 22,000 kilometers per hour, it decreased the along-track velocity of the entire Didymos system by roughly 11.7 micrometers per second. But the team thinks it\u2019s still significant. \u201cWhen you do it early enough, even a small impulse can accumulate over years and cause a meaningful shift,\u201d Makadia explained.<\/p>\n
Also, the DART impact itself was not the only force that changed Didymos\u2019 orbit.<\/p>\n
The ejecta engine<\/p>\n
The pure kinetic energy of a 500-kilogram spacecraft hitting at hypersonic speeds is impressive, but on its own, it would not slow a huge asteroid that much. When DART struck Dimorphos, it blasted pulverized rock and dust out into the void. \u201cThe material kicked up off an asteroid surface acts like an extra rocket plume,\u201d Makadia said.<\/p>\n
Scientists call this effect the momentum enhancement factor, denoted by the Greek letter beta. If the spacecraft impact transferred exactly its own momentum and no debris was kicked up, beta would be exactly one.<\/p>\n
Because Dimorphos orbits Didymos, some of the ejecta remained trapped in the system, where it altered the mutual orbit between the two rocks. But a crucial fraction of the ejecta achieved escape velocity from the entire binary system. The momentum carried away by the system-escaping debris is what ultimately contributed to shoving the center of mass of the whole Didymos-Dimorphos pair. \u201cIn our case, we found that the beta parameter due to DART impact was around two,\u201d Makadia explained.<\/p>\n","protected":false},"excerpt":{"rendered":"Between October 2022 and March 2025, we captured 22 such stellar occultations of the Didymos system. Combined with…\n","protected":false},"author":2,"featured_media":316724,"comment_status":"","ping_status":"","sticky":false,"template":"","format":"standard","meta":{"footnotes":""},"categories":[23],"tags":[111,139,69,147,392],"class_list":["post-316723","post","type-post","status-publish","format-standard","has-post-thumbnail","category-space","tag-new-zealand","tag-newzealand","tag-nz","tag-science","tag-space"],"_links":{"self":[{"href":"https:\/\/www.newsbeep.com\/nz\/wp-json\/wp\/v2\/posts\/316723","targetHints":{"allow":["GET"]}}],"collection":[{"href":"https:\/\/www.newsbeep.com\/nz\/wp-json\/wp\/v2\/posts"}],"about":[{"href":"https:\/\/www.newsbeep.com\/nz\/wp-json\/wp\/v2\/types\/post"}],"author":[{"embeddable":true,"href":"https:\/\/www.newsbeep.com\/nz\/wp-json\/wp\/v2\/users\/2"}],"replies":[{"embeddable":true,"href":"https:\/\/www.newsbeep.com\/nz\/wp-json\/wp\/v2\/comments?post=316723"}],"version-history":[{"count":0,"href":"https:\/\/www.newsbeep.com\/nz\/wp-json\/wp\/v2\/posts\/316723\/revisions"}],"wp:featuredmedia":[{"embeddable":true,"href":"https:\/\/www.newsbeep.com\/nz\/wp-json\/wp\/v2\/media\/316724"}],"wp:attachment":[{"href":"https:\/\/www.newsbeep.com\/nz\/wp-json\/wp\/v2\/media?parent=316723"}],"wp:term":[{"taxonomy":"category","embeddable":true,"href":"https:\/\/www.newsbeep.com\/nz\/wp-json\/wp\/v2\/categories?post=316723"},{"taxonomy":"post_tag","embeddable":true,"href":"https:\/\/www.newsbeep.com\/nz\/wp-json\/wp\/v2\/tags?post=316723"}],"curies":[{"name":"wp","href":"https:\/\/api.w.org\/{rel}","templated":true}]}}