Kule minyaka eyizigidi ezingu-500 edlule, kube khona okungenani iziqephu ezinhlanu ze ukushabalala okukhulu yezinhlobo zokuphila eMhlabeni lapho ngaphezu kwezingxenye ezintathu kwezine zezinhlobo ezikhona ziqedwa. Ukushabalala kokugcina kwempilo okukhulu kangaka kwenzeka ngenxa yomthelela weplanethi ewumkhathi cishe eminyakeni eyizigidi ezingama-65 edlule esikhathini saseCretaceous. Izimo eziwumphumela zaholela ekuqedweni kwezibankwakazi ebusweni be Emhlabeni.
I-Near-Earth objects (NEOs) njengama-asteroids kanye nenkanyezi enomsila, okungukuthi, izinto ezidlula eduze nomhlaba. i-orbit zingaba yingozi. Ukuzivikela kweplanethi imayelana nokuthola nokunciphisa izinsongo zomthelela ezivela kuma-NEO. Ukuchezukisa i-asteroid kude noMhlaba kungenye yezindlela zokwenza lokhu.
I-Double Asteroid Redirection Test (DART) kwaba umkhankaso wokuqala ngqa ozinikele ekuguquleni ukunyakaza kwe-asteroid isikhala ngomthelela we-kinetic. Bekuwukuboniswa kobuchwepheshe be-kinetic impactor okungukuthi, obuthinta i-asteroid ukuze ilungise isivinini nendlela yayo.
Inhloso ye-DART kwakuwuhlelo lwe-asteroid kanambambili oluhlanganisa i-asteroid Didymos enkulu kanye ne-asteroid encane, i-Dimorphos imizila i-asteroid enkulu. Bekuyikhandidethi elifaneleka kuqala ukuzivikela kweplanethi ukuhlola, nakuba ingekho endleleni yokungqubuzana noMhlaba futhi ingabambi usongo lwangempela.
Umkhumbi-mkhathi we-DART ube nomthelela we-asteroid Dimorphos ngomhla ka-26 Septhemba 2022. Wabonisa ukuthi i-kinetic impactor ingase isuse i-asteroid eyingozi endaweni yokushayisana noMhlaba.
Ucwaningo olushicilelwe ngomhla ka-19 Mashi 2024 lubika ukuthi umthelela ushintshe kokubili i-orbit kanye nesimo se-Dimorphos. I-orbit ayisekho isiyingi, futhi isikhathi se-orbital imizuzu engama-33 nemizuzwana engu-15 mfushane. Umumo ushintshile kusukela ku-“oblate spheroid” ehambisanayo kuya ku-“triaxial ellipsoid” njengekhabe eliyi-oblong.
Ithimba labacwaningi lisebenzise imithombo yedatha emithathu kumamodeli abo ekhompuyutha ukuze lithole imiphumela yomthelela ku-asteroid.
- Izithombe ezithwetshulwe umkhumbi-mkhathi we-DART: Izithombe ezithathwe umkhumbi-mkhathi njengoba usondela emkhathini futhi uzibuyisela eMhlabeni nge Inethiwekhi ye-Deep Space ye-NASA (DSN). Lezi zithombe zinikeze izilinganiso eziseduze zegebe phakathi kwe-Didymos ne-Dimorphos kuyilapho zikala nobukhulu bawo womabili ama-asteroid ngaphambi nje komthelela.
- Ukubhekwa kwe-radar: I-DSN's Goldstone Solar System Radar iqhumile radio amagagasi asuka womabili ama-asteroid ukuze alinganise ngokunembile indawo nesivinini se-Dimorphos ngokuhlobene ne-Didymos ngemva komthelela.
- Umthombo wesithathu wedatha wanikezwa izibonakude zomhlabathi emhlabeni wonke ezazikala “ijika elikhanyayo” lama-asteroids noma ukuthi ukukhanya kwelanga okuvela ezindaweni zama-asteroid kwashintsha kanjani ngokuhamba kwesikhathi. Ngokuqhathanisa amajika okukhanya ngaphambi nangemva komthelela, abacwaningi bangafunda ukuthi i-DART ikuguqule kanjani ukunyakaza kwe-Dimorphos.
Njengoba i-Dimorphos izungeza, idlula njalo ngaphambi nangemva kwe-Didymos. Kulokhu okubizwa ngokuthi “imicimbi ehambisanayo,” isibhakabhaka esisodwa singaphonsa isithunzi kwenye, noma sivimbele ukubuka kwethu eMhlabeni. Kunoma ikuphi, ukufiphala kwesikhashana - ukucwiliswa ejikeni lokukhanya - kuzorekhodwa ngezibonakude.
Ithimba labacwaningi lisebenzise isikhathi salolu chungechunge olunembile lokucwiliswa kwejika elikhanyayo ukuze lithole umumo we-orbit futhi lithole umumo we-asteroid. Ithimba elithole i-orbit ye-Dimorphos manje isinwetshiwe kancane, noma i-eccentric.
Abacwaningi baphinde babala ukuthi i-Dimorphos 'orbital period yavela kanjani. Ngokushesha ngemva komthelela, i-DART yehlisa ibanga elimaphakathi phakathi kwama-asteroids amabili, ifinyeza isikhathi sokuzungeza kwe-Dimorphos ngemizuzu engama-32 namasekhondi angu-42, kuya emahoreni angu-11, imizuzu engu-22, namasekhondi angu-37. Emasontweni alandelayo, isikhathi sokuzungeza kwe-asteroid saqhubeka siba mfishane njengoba i-Dimorphos ilahlekelwa impahla enamatshe kakhulu isikhala, ekugcineni ihlezi emahoreni angu-11, amaminithi angu-22, namasekhondi angu-3 nge-orbit ngayinye - imizuzu engu-33 namasekhondi angu-15 isikhathi esingaphansi kunomthelela wangaphambili.
I-Dimorphos manje inebanga eliqondile le-orbital ukusuka e-Didymos elingamamitha angu-3,780 (amamitha angu-1,152) - cishe amafidi angu-120 (amamitha angu-37) eduze kunangaphambili.
I-Hera mission ezayo (ezokwethulwa ngo-2024) ye-ESA izohambela ohlelweni lwe-asteroid kanambambili ukuze yenze ucwaningo oluningiliziwe futhi iqinisekise ukuthi i-DART imise kanjani kabusha i-Dimorphos.
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References:
- NASA. Izindaba - Ucwaningo lwe-NASA: I-Asteroid's Orbit, Umumo Ushintshile Ngemva Kokuthinta I-DART. Kuthunyelwe ngomhla ka-19 Mashi 2024. Itholakala e- https://www.jpl.nasa.gov/news/nasa-study-asteroids-orbit-shape-changed-after-dart-impact
- Naidu SP, et al 2024. I-Orbital and Physical Characterization ye-Asteroid Dimorphos Elandela Umthelela We-DART. The Planetary Science Journal, Volume 5, Number 3. Ishicilelwe 19 March 2024. DOI: https://doi.org/10.3847/PSJ/ad26e7
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