Dimorphos is a small moon that orbits the asteroid Didymos, and the target of NASA’s DART mission in September 2022. <\/p>
Many small asteroids, such as Dimorphos, Ryugu and Bennu, have quite low densities compared to moons or terrestrial planets. Known as \u2018rubble-pile\u2019 asteroids, they appear to be composed of loose conglomerations of rocks, small grains and dust, and are not \u2018solid\u2019 at all. Planetary scientists believe that rubble-pile asteroids are formed by material coalescing after the destruction of larger asteroids.<\/p>\n
The Japanese spacecraft Hayabusa2<\/a> visited asteroid Ryugu<\/a> in 2018 and revealed that about 50 per cent of its volume is empty space! Meanwhile, measurements have revealed that Bennu<\/a> has a density only slightly greater than that of water. It is likely that Bennu has hollow cavities in its interior, some of which are probably filled with water. NASA\u2019s OSIRIS-REx<\/a> probe, which collected a sample from Bennu in 2020, would almost certainly have sunk into Bennu\u2019s surface had it not fired its rockets on contact.<\/p>\n Just like other celestial bodies, it is gravity<\/a> that keeps these asteroids together \u2013 as long as the centrifugal force due to their rotation is not strong enough to overcome gravity. Research has shown that, for many asteroids, \u2018cohesive\u2019 and \u2018adhesive\u2019 forces \u2013 the tendency of materials to attract each other and \u2018stick together\u2019\u2013 are also required to prevent rotation from tearing these asteroids apart. In fact, the ratio of the gravitational to centrifugal forces on a rubble-pile asteroid determines not only the maximum size of boulders on its surface, but also the minimum mass at which the asteroid can remain intact.<\/p>\n So a boulder on the surface of Dimorphos is easily held there by gravity because the asteroid\u2019s rotation is not sufficient to overcome gravity and throw it off into space.<\/p>\n Read more:<\/strong><\/p>\n Asked by: Roger Jordan, via email<\/strong><\/p>\n To submit your questions email us at questions@sciencefocus.com (don\u2019t forget to include your name and location)<\/em><\/p> <\/body><\/html>\n Dimorphos is a small moon that orbits the asteroid Didymos, and the target of NASA’s DART mission in September 2022. <\/p>\n","protected":false},"author":24,"featured_media":27474,"template":"","categories":[30],"acf":{"readingTimeMinutes":"2"},"uagb_featured_image_src":{"full":["https:\/\/c01.purpledshub.com\/uploads\/sites\/42\/2023\/05\/space-oddities-the-surprising-science-of-hollow-rubble-pile-asteroids-scaled.jpg",2560,1090,false],"thumbnail":["https:\/\/c01.purpledshub.com\/uploads\/sites\/42\/2023\/05\/space-oddities-the-surprising-science-of-hollow-rubble-pile-asteroids-150x150.jpg",150,150,true],"medium":["https:\/\/c01.purpledshub.com\/uploads\/sites\/42\/2023\/05\/space-oddities-the-surprising-science-of-hollow-rubble-pile-asteroids-300x128.jpg",300,128,true],"medium_large":["https:\/\/c01.purpledshub.com\/uploads\/sites\/42\/2023\/05\/space-oddities-the-surprising-science-of-hollow-rubble-pile-asteroids-768x327.jpg",768,327,true],"large":["https:\/\/c01.purpledshub.com\/uploads\/sites\/42\/2023\/05\/space-oddities-the-surprising-science-of-hollow-rubble-pile-asteroids-1024x436.jpg",800,341,true],"1536x1536":["https:\/\/c01.purpledshub.com\/uploads\/sites\/42\/2023\/05\/space-oddities-the-surprising-science-of-hollow-rubble-pile-asteroids-1536x654.jpg",1536,654,true],"2048x2048":["https:\/\/c01.purpledshub.com\/uploads\/sites\/42\/2023\/05\/space-oddities-the-surprising-science-of-hollow-rubble-pile-asteroids-2048x872.jpg",2048,872,true]},"uagb_author_info":{"display_name":"importmanagerhub@sprylab.com","author_link":"https:\/\/c01.purpledshub.com\/bbcsciencefocus\/author\/importmanagerhubsprylab-com\/"},"uagb_comment_info":0,"uagb_excerpt":"Dimorphos is a small moon that orbits the asteroid Didymos, and the target of NASA's DART mission in September 2022.","_links":{"self":[{"href":"https:\/\/c01.purpledshub.com\/bbcsciencefocus\/wp-json\/wp\/v2\/rss_feed\/27473"}],"collection":[{"href":"https:\/\/c01.purpledshub.com\/bbcsciencefocus\/wp-json\/wp\/v2\/rss_feed"}],"about":[{"href":"https:\/\/c01.purpledshub.com\/bbcsciencefocus\/wp-json\/wp\/v2\/types\/rss_feed"}],"author":[{"embeddable":true,"href":"https:\/\/c01.purpledshub.com\/bbcsciencefocus\/wp-json\/wp\/v2\/users\/24"}],"wp:featuredmedia":[{"embeddable":true,"href":"https:\/\/c01.purpledshub.com\/bbcsciencefocus\/wp-json\/wp\/v2\/media\/27474"}],"wp:attachment":[{"href":"https:\/\/c01.purpledshub.com\/bbcsciencefocus\/wp-json\/wp\/v2\/media?parent=27473"}],"wp:term":[{"taxonomy":"category","embeddable":true,"href":"https:\/\/c01.purpledshub.com\/bbcsciencefocus\/wp-json\/wp\/v2\/categories?post=27473"}],"curies":[{"name":"wp","href":"https:\/\/api.w.org\/{rel}","templated":true}]}}
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