Kalmomin "baƙi" da "ƙasashen duniya" galibi ana haɗa su da haruffa a cikin ayyukan almara na kimiyya. Duk da haka, ko da yake hasashe ne, akwai wani reshe na ilmin halitta wanda yayi bincike kuma yayi la'akari da wanzuwar rayuwa ta waje: exobiology.
Amma ta yaya zai yiwu a yi nazarin halittun da ba a tabbatar da wanzuwarsu ba? Menene kuma a ina ya kamata masu binciken ilimin halittu su duba don fahimtar idan akwai rayuwa a cikin sararin samaniya?
Ldon drake equation
A shekara ta 1960, Frank Drake, wani masanin falaki dan kasar Amurka, ya gudanar da bincike na farko a gidan radiyon Falaki na kasa, don kokarin gano siginar rediyo daga wayewar da ke wuce gona da iri. Shekara guda bayan haka, Drake ya ƙirƙira wani ma'auni wanda har yanzu ake amfani da shi a fagen nazarin halittu, wanda aka ƙera don ƙididdige adadin wayewar duniya a cikin galaxy ɗinmu, wanda wasiƙar ta nuna. N.
Ma'aunin Drake yana ɗaukar sigogi da yawa cikin la'akari kuma an tsara shi kamar haka:
Ma'auni na Equation
Kimar farko ita ce R *, wanda shine adadin samuwar taurari a cikin Milky Way. Bayan haka, kawai taurari da ke da alaƙa da tsarin taurari ya kamata a yi la'akari da su; waɗannan dole ne su sami yanayin da ake buƙata don ɗaukar nauyin rayuwa, buƙatun da ba su da sauƙin gamsarwa kuma ana wakilta su bi da bi f p y n e . F l yayi dai-dai da juzu'in duniyoyin da ya kamata rayuwa ta bunkasa, yayin da fi es kaso daga cikin wadannan inda rayuwar da ke tasowa ta kasance mai hankali.
Ba wai kawai ya zama mai hankali ba, amma mai canzawa f cya ce dole ne waɗannan nau'ikan rayuwa su sami damar haɓaka fasahar da ke fitar da siginar rediyo zuwa sararin samaniya. Maɓalli na ƙarshe shine L, tsawon lokacin da ya kamata a aika da sigina. Kamar yadda ake iya gani, masu canji suna da yawa kuma yana da wuya a kafa daidai kowane ƙimar mutum, don haka muna magana game da yiwuwar. Duk da haka, akwai ƙididdiga da sakamako waɗanda zasu iya, aƙalla bisa ka'ida, ba da ƙima ga mai canzawa N da amsa tambayar.
Tafsiri da mafita
Tun farkon samar da Equation, masana kimiyya da yawa sun yi ƙoƙari su fayyace sakamakonsa. Daga shekarun 1960 zuwa yau, kayan aikin kimiyya da ake da su don sarrafa dabi'u sun samo asali, amma a gaskiya ma'auni shine, har yanzu hanya ce ta tattauna batun ta hanyar kimiyya, maimakon samar da tabbataccen amsoshi.
Ƙididdiga na baya-bayan nan sun ɗauka har zuwa wayewar waje guda 23 (exobiology)
Amma me ya sa ba mu taɓa samun tabbacin wanzuwarsa ba? Wannan shi ne ainihin matsalar da aka sani da Fermi ya saba, wanda ya ɗauki sunansa daga masanin ilimin lissafin Italiya wanda ya fara ba da shawara, Enrico Fermi. Tun da babu tabbas game da wannan, masana kimiyya da ke hulɗar da ilimin halittu a yau sun yi ƙoƙari su mai da hankali kan abubuwan da kwayoyin halitta dole ne su kasance don haɓakawa, ba tare da ware mafi yawan mahalli ba.
Exobiology: yanayin rayuwa don wanzuwa
Lokacin neman nau'ikan rayuwa a sararin samaniya, ana ɗauka cewa ana samun su akan taurari masu halaye masu kama da na duniya: yawan ruwa, hanyoyin makamashi da sauran muhimman kwayoyin halitta.
A cewar masana ilimin halittu, waɗannan su ne mafi ƙarancin buƙatun, amma dole ne mu tuna cewa ba za mu iya tabbatar da tabbacin cewa rayuwa koyaushe tana dogara ne akan kwayoyin halitta iri ɗaya ba.
Gabaɗaya, ba mu da tabbacin cewa zai iya zama yi hasashen kasancewar rayuwa idan duk abubuwan da muka saba la'akari da su ba makawa suna nan: wani ruwa mai ƙarfi, tushen makamashi da abin da ake kira asali sassa, wato, ainihin kwayoyin halitta, kwayoyin halitta da inorganic. , waɗanda suka haɗa da juna suna haifar da ƙarin hadaddun sifofi. Sauran sigogi masu canzawa sune pH, zazzabi, matsa lamba, salinity da radiation. Taurari masu sifofi masu kama da na Duniya ana kiransu da yawa kayan kwalliya.
Duk da haka, godiya ga kwayoyin halitta da aka sani da extremophiles, mun san cewa rayuwa za ta iya bunƙasa ba kawai a kan exoplanets ba. amma duk inda mafi ƙarancin yanayi ya kasance.
exoplanets da haske shekara
Abin da muke kira Opasa Jikin sama ne waɗanda ke cikin tsarin hasken rana, a cikin namu ko a cikin wasu taurari. Suna kewaya ranansu a nesa wanda ke ba da damar kasancewar ruwa mai ruwa ko wasu abubuwan kaushi, ɗaya daga cikin mahimman buƙatun ci gaban rayuwa. Waɗannan taurari, kamar Duniya, suna iya samun mahalli da yawa waɗanda sinadarai da yanayin jiki ke da kyau don tallafawa rayuwa. Abin baƙin ciki shine, yawancin su suna da shekaru masu yawa da yawa daga tsarin hasken rana.
El ina luz ita ce tazarar da haske ke tafiya a cikin shekara guda. Hasken Rana yana riskar mu a cikin mintuna 8 da rabi, yana tafiyar kilomita miliyan 150. Tazarar da haske ya yi a cikin shekara daya (shekarar haske) ya kai kusan ninki 63.000 da Rana ta yi zuwa doron kasa. Don haka 63 sau dubu 150 km.
Exobiology: Proxima B
Mafi kusa shine na gaba b, wani bangare ne na tsarin Proxima Centauri a cikin galaxy mu, Milky Way. Proxima b yana da nisan shekaru 4,2 haske kuma shine na takwas mafi girman duniya kamar duniya bisa ga ma'aunin ESI, ma'aunin ma'auni na zahiri da ake amfani da shi don kwatanta sauran taurari da duniya. Darajar wannan fihirisar tana tsakanin 0 (babu kamanceceniya) da 1 (duniya mai kama da Duniya) kuma ana ƙididdige su bisa radius, yawa, saurin gudu da zafin jiki. Proxima b yana da ƙimar ESI na 0,87 kuma yana nuna cewa duniya tana kama da Duniya sosai. Koyaya, wannan bayanan baya ba da bayanai game da mazaunin sa.
Wata
Neman rayuwa a sararin samaniya bai iyakance ga exoplanets ba, amma kuma yana shafar tauraron su, watanni. Ana iya samun misali a cikin tsarin hasken rana kawai. An yi imani da cewa wata na Saturn, ciki, da wata na Jupiter, Turai, mai yuwuwar rayuwa ta tashar ruwa.
Nisa daga rana Enceladusba ya ba shi damar samun isassun hasken rana don zafi da kansa, don haka yanayin zafin samansa yana tsakanin -128 ° C da -240 ° C: tabbas ba wurin da za a nemi rayuwa ba. Duk da haka, godiya ga binciken Cassini ya yiwu a tabbatar da cewa ruwa da kwayoyin halitta suna nan akan wannan daskararren wata. Bincike ya nuna cewa nitrogen, carbon dioxide da methane suna cikin jiragen tururin ruwa da ke fitowa a saman. Saboda haka, an yi imani da cewa a karkashin daskararre surface akwai yalwataccen Layer na ruwa, a cikin abin da daban-daban kwayoyin suna narkar da, alhakin da hydrothermal aiki na substrate da kuma geysers a saman. Ana iya tunanin cewa wannan al'amari yana tasiri ne ta hanyar hasashe na kasancewar kwayoyin halittar methanogenic.
A cikin 2018, wasu masu bincike sun yi ƙoƙarin sake gina yanayin Enceladus tare da gwaji, yana nuna cewa ƙananan ƙwayoyin cuta. Methanothermococcus okinawensis zai sami kyawawan halaye don rayuwa da samar da methane a cikin madaidaicin Layer. Ƙarshen wannan binciken ya gaya mana cewa kwayoyin halitta iri ɗaya suna iya yin hakan, don haka a zahiri suna kan Enceladus.
Wadanne kwayoyin cuta ne zasu iya rayuwa a wasu duniyoyi?
An gano ƙananan ƙwayoyin cuta masu iyawa na musamman a matsayin extremophiles saboda sau da yawa suna rayuwa a cikin yanayin da ke da hani ga ƙwayoyin halitta masu rikitarwa. Ya kamata a lura cewa waɗannan kwayoyin halitta yawanci suna rayuwa ne a cikin waɗannan yanayi, don haka ana iya tunanin cewa suna rayuwa kuma ana samun su a cikin yanayi mai rikitarwa.
Mafi shahara a duniyar ilmin halitta shine tabbas Thermus aquaticus, iya girma a yanayin zafi na 75 ° C; godiya gareshi yana yiwuwa a inganta hanyar inganta DNA sosai. Akwai irin waɗannan ƙananan ƙwayoyin cuta da yawa, kowannensu ya dace da yanayi ɗaya ko fiye, don haka ya zama polyextremophilic.
Ga wasu misalai masu ban sha'awa:
- Picrophilus oshimae yana rayuwa a cikin sulfate a cikin yanayin pH mai acidic tare da ƙimar 0,6 cikin 14, ya fi ƙarfin hydrochloric acid.
- Thermococcus piezophilus yana zaune a cikin abyss a matsa lamba na 125 Mpa, wanda yayi daidai da kusan kilogiram 1275 da aka yi amfani da shi zuwa yanki na santimita daya. An tabbatar da cewa wasu ƙananan ƙwayoyin cuta suna gudanar da ci gaba da aiki na rayuwa ko da a cikin matsi na 2000 Mpa;
- Halarsenatibacter silvermani yana zaune a cikin babban tafkin alkaline inda adadin gishiri na NaCl ya kasance 35% mg / L;
- Deinococcus radioduran s, har zuwa yau an yi la'akari da samfurin ƙananan ƙwayoyin cuta don nazarin juriya ga radiation da vacuum, polyextremophile mai iya tsira da yanayin duniyar Mars.
Akwai rayuwa a Mars?
Mars ita ce ta hudu mafi nisa daga rana ta mu, kafin ta kasance Duniya. An gudanar da ayyuka da yawa a cikin 'yan shekarun nan don gano shi da gudanar da bincike. Juriyar NASA ita ce sabuwar, har yanzu tana aiki kuma ana sa ran sake shiga cikin 2033.
Bayanan ƙasa da yanayi a duniyar Mars a halin yanzu ba su da alama ga ilimin halitta. A cikin 2003, ƙungiyar bincike ta gano wani wasa dangane da tsarin ƙasa tsakanin samfurin ƙasa da aka tattara ta manufa ta Viking da ƙasa daga wani yanki mai nisa na Desert Atacama a Chile, kuma bayan yunƙurin da yawa sun gano cewa ƙasa ba ta dace ba. ga kowane nau'in noman halitta. To, ina har yanzu zai yiwu a yi fatan samun alamun rayuwa a duniyar Mars?
rayuwar karkashin kasa
Wani bincike da aka yi a shekarar 2022 ya ba masana ilimin halin dan Adam kuzari a cikin binciken da suke yi na neman rayuwa ta waje. Waɗannan ƙananan lu'ulu'u ne da ke cikin abubuwan haɗin dutse a tsakiyar Ostiraliya, tun shekaru miliyan 830. A cikin waɗannan ƙananan lu'ulu'u, an gano mahaɗan kwayoyin halitta da kasancewar ƙwayoyin prokaryotic da eukaryotic waɗanda suka rayu a cikin wannan microenvironment. A cewar masana, wadannan nau'ikan kayan kwalliya, ko asalin yanayin ƙasa ko na asali, yakamata a yi la'akari da su azaman masu iya tallafawa don tsoffin microssiganisms da mahadi. Wannan yana nuna yuwuwar bincike da nemo shafi akan sauran taurari: ƙasan ƙasa.
Bugu da ƙari, a cikin ƙasan ƙasa abin da ya faru na maciji. Halin sinadaran-jiki wanda ke faruwa a ƙarƙashin yanayin pH na alkaline da kuma cewa, godiya ga hulɗar tsakanin ruwa da duwatsu, ya saki hydrogen, kwayoyin halitta da inorganic carbon mahadi. Serpentinization, a cewar masana ilimin halitta, ya yadu a cikin sararin samaniya na tsarin hasken rana, ciki har da watanni, kuma ana tunanin cewa watakila ya taka muhimmiyar rawa a duniya, yana fifita rayuwar wasu ƙananan ƙwayoyin cuta.
Ƙarshe game da exobiology
Har yanzu ana ci gaba da gudanar da bincike a cikin ilimin halin ɗan adam, a cikin Oktoba 2024 hukumar kula da sararin samaniya ta NASA za ta ƙaddamar da wani sabon manufa: CLIPPER. Manufar ita ce a nemo hanyoyin rayuwa daga jirage masu saukar ungulu da daya daga cikin dusar ƙanƙara ta watan Jupiter ke fitarwa: Turai.
A halin yanzu, ba a taɓa gano halittun da ke cikin ƙasa ba, amma ba za a iya kawar da yiwuwar wanzuwar su a cikin sararin samaniya ba. Duk da haka, dole ne mu yi la'akari da cewa rayuwa za ta iya tasowa a cikin yanayi daban-daban da na duniya, saboda haka yana daidaitawa kuma yana tasowa ta hanyoyi da ba a san mu ba. Gano nau'o'in rayuwa na waje zai kawo kulawa mai girma daga al'ummar kimiyya zuwa reshe na exobiology, bude hanyoyi har zuwa yanzu gaba daya ba a gano su ba.