{"id":820383,"date":"2026-08-20T23:24:13","date_gmt":"2026-08-20T23:24:13","guid":{"rendered":"https:\/\/www.newsbeep.com\/us\/820383\/"},"modified":"2026-08-20T23:24:13","modified_gmt":"2026-08-20T23:24:13","slug":"martian-moon-deimos-quirks-may-be-due-to-an-asteroid-strike","status":"publish","type":"post","link":"https:\/\/www.newsbeep.com\/us\/820383\/","title":{"rendered":"Martian moon Deimos\u2019 quirks may be due to an asteroid strike"},"content":{"rendered":"

\n Mars has two tiny moons that lack a confirmed origin story for how they came to orbit the red planet \u2014 but new research may explain some of the mysteries surrounding outermost satellite Deimos.\n <\/p>\n

\n Named for the son of the Greek god Ares, Deimos, which means dread in ancient Greek, is a small, lumpy rock shaped like a potato. Ares is also known as Mars in Roman mythology.\n <\/p>\n

\n The moon is about 14,913 miles (24,000 kilometers) from the Martian surface, and orbiters have observed it since the 1970s \u2014 including a recent flyby of the European Space Agency\u2019s Hera mission in March 2025. Hera is en route to study the aftermath of NASA\u2019s DART mission<\/a> that intentionally crashed a spacecraft into a small moon orbiting a larger asteroid.\n <\/p>\n

\n Orbital imagery has shown that unlike its heavily cratered sibling moon, Phobos, which means fear in ancient Greek, Deimos is much smoother \u2014 and covered in a perplexing layer of dust and rubble called regolith.\n <\/p>\n

\n Deimos, which is about 7.5 miles (12 kilometers) in diameter, also has an identifying feature, a 6.2-mile-wide (10-kilometer-wide) impact basin at its southern pole, which resembles a dramatic dip similar to those seen in mountain ranges. Scientists have long questioned what created the crater and led to the dust layer.\n <\/p>\n

\n By comparing Hera\u2019s flyby images with impact simulations, the authors of a new study published Tuesday in the journal Nature Astronomy<\/a> suggest that one large single asteroid impact reshaped Deimos, resulting in the moon\u2019s dramatic polar crater and global dust layer.\n <\/p>\n

\n The study offers a prediction that could be tested by the Japan Aerospace Exploration Agency\u2019s Martian Moons eXploration mission<\/a>, known as MMX, which is expected to launch by the end of the year. The mission aims to capture unprecedented, detailed observations of both moons to help determine how and when they formed and even return samples collected from Phobos to Earth.\n <\/p>\n

\n \u201cOur study provides important, concrete predictions for this Japanese MMX mission,\u201d said lead study author Dr. Sabina Raducan, science program manager at the International Space Science Institute and a senior fellow at the Free University of Brussels. \u201cThis gives MMX a clearer picture of what its instruments \u2014 and ultimately the sample collection \u2014 can expect.\u201d\n <\/p>\n

\"Deimos<\/p>\n

\n The researchers began by creating impact scenarios for Deimos using a computer code called the Bern Smoothed Particle Hydrodynamics, or SPH.\n <\/p>\n

\n This code, developed at Switzerland\u2019s University of Bern over two decades, is designed to simulate collisions between asteroids, comets and planets, and analyze the impact by looking at millions of individual particles involved in each scenario.\n <\/p>\n

\n This breakdown enables researchers to understand the different variations and factors at play during an impact, such as the density, gravity and compositional strength of the rocky bodies.\n <\/p>\n

\n \u201cWe carried out about a hundred simulations \u2014 each one took about a week,\u201d said Raducan, who is also one of the chairs of the Impact Physics Working Group for the Hera science team.\n <\/p>\n

\n The size, velocity and angle of impact for the asteroid that might have struck Deimos varied in each simulation, as did the moon\u2019s internal structure. Then, the team compared the data from its simulations with Hera\u2019s up-close observations of Deimos.\n <\/p>\n

\n The researchers zeroed in on the most likely scenario of an asteroid measuring about 1,050 feet (320 meters) across striking Deimos at a 45-degree angle, creating the south pole crater and the dust layer.\n <\/p>\n

\n The impact released a large amount of debris across Deimos\u2019 lumpy surface, effectively covering many of its surface features by as much as 656 feet (200 meters) \u2014 and making it appear much smoother than Phobos.\n <\/p>\n

\n \u201cOur simulation thus shows that a single impact was sufficient to decisively shape the current landscape of Deimos,\u201d said study coauthor Dr. Martin Jutzi, senior researcher at the University of Bern\u2019s Division of Space Research and Planetary Sciences.\n <\/p>\n

\n \u201cThe impact was violent enough to redistribute material globally, but not so strong that it would have shattered the moon.\u201d\n <\/p>\n

\n Outlines of ancient craters can still be seen beneath Deimos\u2019 dust layer in the Hera images. If Deimos were more solid, shock waves from the impact would have resonated through the moon and disrupted or even erased surface features. Instead, Deimos\u2019 fractured interior dampened the force of the impact, according to the study authors.\n <\/p>\n

\n The authors did not include a suggestion of when this ancient impact occurred on Deimos, only that it must have happened well after the moon formed.\n <\/p>\n

\"An<\/p>\n

\n Scientists have long questioned whether Phobos and Deimos are rocky chunks that an impact blasted away from Mars, or if they are space rocks that the red planet\u2019s gravity captured.\n <\/p>\n

\n The observations and computer models suggest that Deimos\u2019 internal structure is highly porous, making it more like rubble-pile asteroids \u2014 groups of space rocks loosely held together by gravity \u2014 than like Earth\u2019s moon.\n <\/p>\n

\n \u201cBut that doesn\u2019t necessarily mean that Deimos is actually an asteroid. It could also have formed from material ejected during impacts on Mars,\u201d Raducan said.\n <\/p>\n

\n The MMX mission is expected to collect data that could definitively solve the mystery of Phobos and Deimos\u2019 origins, as well as provide a window into the early history of our solar system when the gravity of the largest planets caused space rocks to crash into planets as well as one another.\n <\/p>\n

\n The mission will arrive at the moons in 2027, spend two years mapping Phobos and selecting a landing site for sampling before backing away to observe Deimos. A sample from Phobos is expected to be dropped off on Earth in 2031.\n <\/p>\n

\"Deimos<\/p>\n

\n Interest in Deimos and Phobos is growing as more orbiters capture imagery of the enigmatic moons, said Dr. Terik Daly, planetary scientist at the Johns Hopkins University Applied Physics Laboratory. Daly was not involved in the study but is a member of the Science Working Team for MMX.\n <\/p>\n

\n \u201cThe paper outlines a viable model for Deimos\u2019 unusual shape, building on longstanding questions about its origin and evolution,\u201d Daly wrote in an email. \u201cLike many modeling studies, there are assumptions that future observations will need to test and Japan\u2019s Martian Moons eXploration mission is expected to make observations that could provide an opportunity to evaluate ideas presented in the paper.\u201d\n <\/p>\n

\n Sign up for CNN\u2019s Wonder Theory science newsletter<\/a>. Explore the universe with news on fascinating discoveries, scientific advancements and more.<\/p>\n","protected":false},"excerpt":{"rendered":"Mars has two tiny moons that lack a confirmed origin story for how they came to orbit the…\n","protected":false},"author":2,"featured_media":820384,"comment_status":"","ping_status":"","sticky":false,"template":"","format":"standard","meta":{"footnotes":""},"categories":[32],"tags":[79],"class_list":["post-820383","post","type-post","status-publish","format-standard","has-post-thumbnail","category-science","tag-science"],"_links":{"self":[{"href":"https:\/\/www.newsbeep.com\/us\/wp-json\/wp\/v2\/posts\/820383","targetHints":{"allow":["GET"]}}],"collection":[{"href":"https:\/\/www.newsbeep.com\/us\/wp-json\/wp\/v2\/posts"}],"about":[{"href":"https:\/\/www.newsbeep.com\/us\/wp-json\/wp\/v2\/types\/post"}],"author":[{"embeddable":true,"href":"https:\/\/www.newsbeep.com\/us\/wp-json\/wp\/v2\/users\/2"}],"replies":[{"embeddable":true,"href":"https:\/\/www.newsbeep.com\/us\/wp-json\/wp\/v2\/comments?post=820383"}],"version-history":[{"count":0,"href":"https:\/\/www.newsbeep.com\/us\/wp-json\/wp\/v2\/posts\/820383\/revisions"}],"wp:featuredmedia":[{"embeddable":true,"href":"https:\/\/www.newsbeep.com\/us\/wp-json\/wp\/v2\/media\/820384"}],"wp:attachment":[{"href":"https:\/\/www.newsbeep.com\/us\/wp-json\/wp\/v2\/media?parent=820383"}],"wp:term":[{"taxonomy":"category","embeddable":true,"href":"https:\/\/www.newsbeep.com\/us\/wp-json\/wp\/v2\/categories?post=820383"},{"taxonomy":"post_tag","embeddable":true,"href":"https:\/\/www.newsbeep.com\/us\/wp-json\/wp\/v2\/tags?post=820383"}],"curies":[{"name":"wp","href":"https:\/\/api.w.org\/{rel}","templated":true}]}}