KO ƘANANAN HALITTU A ENCELADUS ZA SU IYA RAYUWA DA TSOHON ABU MAI RAI?

Enceladus wani ƙaramin wata ne mai ƙanƙara na Saturn. Aikin Cassini na NASA ya bayyana cewa yana ɓoye teku ta ruwa da ta mamaye duka watan a ƙarƙashin ƙanƙararsa, kuma kumbon ya ratsa cikin maɓuɓɓugan da ke fitowa daga kudancinsa — karon farko da aka taɓa nazarin abu daga muhallin ruwa a wajen Duniya. Maɓuɓɓugan sun ƙunshi hydrogen (H₂) da methane (CH₄) masu yawa.

Babban bayanin ya shafi tsakiyar watan mai duwatsu. A Duniya, ruwan zafi da ke haɗuwa da wasu duwatsu — serpentinisation — yana fitar da hydrogen, kuma a maɓuɓɓugan ruwan zafi na ƙarƙashin teku (hydrothermal vents), ƙananan halittu da ake kira methanogens suna haɗa wannan hydrogen da carbon dioxide don samar da methane. Hakan zai iya faruwa a Enceladus ma.

Amma akwai matsala. Don ci gaba da samar da hydrogen ɗin da ke ɓacewa ta maɓuɓɓugan har tsawon biliyoyin shekaru, sinadarin dutsen zai buƙaci ya ci gaba da ƙarfi na dogon lokaci sosai — alhali ma’adinan da yake cinyewa wataƙila za su ƙare da wuri. Shin akwai wani abu dabam da ke ciyar da tekun?

Abinci tun daga farkon Tsarin Rana

Ana tunanin cewa abubuwan da ke can nesa a Tsarin Rana sun samu ne daga kayan da ke cike da abubuwa masu carbon na halitta (organic matter), kamar taurari masu wutsiya (comets) da duwatsun sama masu yawan carbon. Samfuran da aka dawo da su daga asteroid Bennu da Ryugu sun ƙunshi amino acid, sukari da sauran abubuwa masu carbon. Wataƙila tsakiyar Enceladus ma tana da irin wannan kaya, wanda ke narkewa a hankali cikin tekun.

A cikin teku da babu haske ko oxygen, wata hanya ta rayuwa da abu mai carbon ita ce fermentation, wadda ke fitar da makamashi ba tare da buƙatar oxygen ko wani sinadari na waje don “numfashi” ba. Sam Nasreldine da Régis Ferrière na Jami’ar Arizona, tare da abokan aiki a ETH Zurich, Queen Mary University of London, Natural History Museum a London, Jami’ar Aix-Marseille da National Museum of Natural History a Paris, sun zaɓi wani sauƙaƙan misali na gwaji: glycine, amino acid mafi sauƙi. Fermentation ɗinsa yana samar da hydrogen, acetate da ammonia. An san ƙananan halittu masu yin fermentation na glycine daga maɓuɓɓugan zurfin teku a Duniya.

Maɓuɓɓuga ta kwamfuta da nau’ikan ƙananan halittu uku

Ƙungiyar ta kwaikwayi wata ƙaramar al’umma da ke rayuwa a kusa da maɓuɓɓugar ruwan zafi a ƙasan tekun Enceladus, inda ruwa mai zafi ke haɗuwa da ruwan teku:

• masu yin fermentation na glycine, waɗanda ke samar da hydrogen da acetate;
• methanogens masu cin hydrogen, waɗanda ke mayar da hydrogen da CO₂ zuwa methane;
• methanogens masu cin acetate, waɗanda ke mayar da acetate zuwa methane.

Ƙirar tana bin diddigin makamashin da kowace ƙungiya za ta iya samu, girmanta, da yadda take canza ruwan ga sauran. Ƙungiyar ta gudanar da saitin yanayi 30,000 na bazata ga kowane cikin yanayi uku — kusan babu hydrogen ko methane daga duwatsu, ɗan ƙaramin adadi, ko mafi ƙarfi — kuma ta kwatanta iskar gas da aka fitar da abin da Cassini ya auna: kusan moles biliyan 1.2 zuwa 7.4 na hydrogen da moles biliyan 0.3 zuwa 1.6 na methane a kowace shekara.

Hasashen: ƙananan halittu masu yin fermentation na abu mai carbon na farko a ƙasan teku, suna ciyar da abokan aiki masu samar da methane (a); yadda aka haɗa ƙungiyoyin ƙananan halittu uku kuma aka tsara su a cikin ƙirar (b). — Figure 1, Nasreldine et al. (2026), arXiv:2610.13434.

Masu cin acetate sun yi nasara

• Da kusan babu taimako daga duwatsu, fermentation ita kaɗai ta sake samar da duka ma’aunan iskar gas biyu na Cassini — muddin isasshen kaya irin na glycine ya isa maɓuɓɓugar.
• Da ƙarancin samarwa daga duwatsu, gudu 91 da masu cin acetate, da 91 da dukan ƙungiyoyi uku, daga cikin 30,000, sun dace da iskar gas ɗin biyu. Babu ko ɗaya da ke da masu cin hydrogen kaɗai da ya dace. Wani kwatanci na ƙididdiga ya fifita al’ummomi masu cin acetate a fiye da kashi 90% na lokuta.

Dalilin mai sauƙi ne: masu cin hydrogen suna cinye ainihin hydrogen ɗin da ya kamata ya fita zuwa maɓuɓɓugan. Masu cin acetate suna samar da methane ba tare da taɓa shi ba. A yanayin ƙarancin samarwa, an kori masu cin hydrogen daga al’ummar ƙarshe a kowane gudu.

Ƙirar ta kuma nuna rayuwa tana canza muhallinta: fermentation ta buɗe sababbin wurare a kusa da maɓuɓɓugar inda methanogens za su iya girma, a cikin kashi biyu bisa uku na gudun yanayi na farko.

Abinci nawa ne akwai?

Wani ƙiyasi na sama mara cikakken daidaito ya sanya asalin ajiyar glycine na Enceladus zuwa kusan 1.3 × 10¹⁷ kilogram — wanda zai isa ya samar da hydrogen ɗin da aka gani na shekaru biliyan 0.2 zuwa 1.4, idan duka yana samuwa ga ƙananan halittu.

Matsalar: kwaikwayon da suka fi aiki suna buƙatar narkakken abu mai carbon fiye da abin da matakan glycine a samfuran Bennu suka yarda. Ko da duka ya narke, yawansa zai kasance ƙasa da abin da ƙirar ke buƙata. Saboda haka hasashen ya dogara ne kan kasancewar wasu sinadarai masu iya fermentation, ko kan wani ƙarin hydrogen da har yanzu ke fitowa daga duwatsu.

Hasashe da za a iya gwadawa

Marubutan sun gabatar da fermentation ba a matsayin shaidar rayuwa ba, sai dai a matsayin madadin da za a iya gwadawa. Idan tana faruwa, ya kamata maɓuɓɓugan su ɗauki acetate da ammonium ma, kuma isotope na carbon na methane su ɗauki alamarta. Sun jaddada iyakokin ƙirarsu: nau’in mai fermentation guda ɗaya kawai, babu kwaikwayon tafiya daga ƙasan teku zuwa maɓuɓɓugai, an ɗauka cewa abinci mai gina jiki ya isa — da kuma cewa sinadarai marasa rai za su iya samar da iskar gas iri ɗaya.