An artificial impact on the asteroid (162173) Ryugu formed a crater in the gravity-dominated regime.
Masahiko ArakawaTakanao SaikiKoji WadaKazunori OgawaT KadonoKei ShiraiHirotaka SawadaK IshibashiRie HondaNaoya SakataniY IijimaC OkamotoHajime YanoY TakagiMasahiko HayakawaPatrick MichelMartin JutziYuri ShimakiS KimuraYuya MimasuT TodaH ImamuraSatoru NakazawaH HayakawaSeiji SugitaTomokatsu MorotaShingo KamedaEri TatsumiYuichiro ChoKazuo YoshiokaYasuhiro YokotaMoe MatsuokaManabu YamadaToru KouyamaChikatoshi HondaYuichi TsudaSei'ichiro WatanabeMakoto YoshikawaS TanakaFuyuto TeruiShota KikuchiT YamaguchiNaoko OgawaGo OnoKento YoshikawaT TakahashiYuto TakeiAtsushi FujiiHiroshi TakeuchiYukio YamamotoTatsuaki OkadaC HiroseSatoshi HosodaO MoriT ShimadaStefania SoldiniRyudo TsukizakiTakahiro IwataMasanobu OzakiMasanao AbeNoriyuki NamikiKohei KitazatoShogo TachibanaHitoshi IkedaNaru HirataNaoyuki HirataRina NoguchiAkira MiuraPublished in: Science (New York, N.Y.) (2020)
The Hayabusa2 spacecraft investigated the small asteroid Ryugu, which has a rubble-pile structure. We describe an impact experiment on Ryugu using Hayabusa2's Small Carry-on Impactor. The impact produced an artificial crater with a diameter >10 meters, which has a semicircular shape, an elevated rim, and a central pit. Images of the impact and resulting ejecta were recorded by the Deployable CAMera 3 for >8 minutes, showing the growth of an ejecta curtain (the outer edge of the ejecta) and deposition of ejecta onto the surface. The ejecta curtain was asymmetric and heterogeneous and it never fully detached from the surface. The crater formed in the gravity-dominated regime; in other words, crater growth was limited by gravity not surface strength. We discuss implications for Ryugu's surface age.