Kebolehdiaman planet: Perbezaan antara semakan

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KLITE789 (bincang | sumb.)
Teg: Suntingan sumber 2017
KLITE789 (bincang | sumb.)
Teg: Suntingan sumber 2017
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[[File:Earth poster.svg|thumb|Keratan rentas geologi Bumi]]
[[File:Simple model of the Earth's magnetic field.ogv|thumb|Gambaran mudah model [[medan magnet Bumi]].]]
Boleh dikatakan bahawa tumpuankepekatan [[radionuklid]] di mantel planet berbatu adalah penting untuk kebolehdiaman planet seakan Bumi, kerana planet yang melimpah-ruah kandungan radionuklidradionuklidnya mungkin tidak mempunyai [[Teori dinamo|dinamo yang berterusan]] untuk sebahagian signifikan dalam hayatnya, sementara yang kurang pula [[Jatah haba dalaman bumi#Haba radiogenik|mungkin lengai dari segi bentukan geologinya]]. Dinamo planet mewujudkan [[medan magnet]] kuat yang mungkin selalunya perlu untuk hidupan berkembang dan terus hidup kerana ia melindungi planet daripada [[angin suria]] dan [[sinaran kosmos]]. [[Spektrum pancaran]] elektronik bintang boleh digunakan untuk mengenal pasti bintang-bintang yang berkemungkinan menempatkan planet-planet yang boleh didiami seperti Bumi. Setakat tahun 2020, dipercayai bahawa radionuklid dihasilkan oleh proses-proses najam yang nadir seperti [[pergabungan bintang neutron]].<ref>{{cite news |last1=Woo |first1=Marcus |title=Stellar Smashups May Fuel Planetary Habitability, Study Suggests |url=https://www.scientificamerican.com/article/stellar-smashups-may-fuel-planetary-habitability-study-suggests/ |access-date=9 December 2020 |work=Scientific American |language=en}}</ref><ref>{{cite journal |last1=Nimmo |first1=Francis |last2=Primack |first2=Joel |last3=Faber |first3=S. M. |last4=Ramirez-Ruiz |first4=Enrico |last5=Safarzadeh |first5=Mohammadtaher |title=Radiogenic Heating and Its Influence on Rocky Planet Dynamos and Habitability |journal=The Astrophysical Journal |date=10 November 2020 |volume=903 |issue=2 |pages=L37 |doi=10.3847/2041-8213/abc251 |url=https://iopscience.iop.org/article/10.3847/2041-8213/abc251 |access-date=9 December 2020 |language=en |issn=2041-8213|arxiv=2011.04791|bibcode=2020ApJ...903L..37N |s2cid=226289878 }}</ref> Ciri-ciri geografi tambahan pula boleh dijadikan faktor utama dalam kebolehdiaman jasad samawi semula jadi, lebih-lebih lagi yang mungkin membentuk medan magnet dan haba jasad berkenaan, ada di antaranya yang tidak diketahui atau kurang difahami dan sedang dicerakin oleh penggiat-penggiat bidang [[sains planet]], [[geokimia]], dan lain-lain.<ref>{{cite news |title=The existence of a magnetic field beyond 3.5 billion years ago is still up for debate |url=https://phys.org/news/2020-04-magnetic-field-billion-years-debate.html |access-date=28 December 2020 |work=phys.org |language=en}}</ref>
 
==== Geokimia ====
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Terdapat satu pembatas yang penting terhadap kriteria kebolehdiaman, iaitu bahawa hanya sebahagian kecil sesebuah planet diperlukan untuk menampung kehidupan. Ahli-ahli astrobiologi sering memberikan penekanan terhadap "micropersekitaran" dengan hujah bahawa "kita tiada pemahaman asas tentang bagaimana penggerak-penggerak evolusi seperti [[mutasi]], [[Pemilihan semula jadi|pemilihan (semula jadi)]], dan [[hanyutan genetik]], beroperasi dalam mikroorganisma yang bertindak dan bertindak balas terhadap perubahan mikropersekitaran."<ref>{{cite web|url=http://astrobiology.arc.nasa.gov/roadmap/g5.html |title=Understand the evolutionary mechanisms and environmental limits of life |work=Astrobiology: Roadmap |publisher=[[NASA]] |date=September 2003 |access-date=6 August 2007 |url-status=dead |archive-url=https://web.archive.org/web/20110126083203/http://astrobiology.arc.nasa.gov/roadmap/g5.html |archive-date=26 January 2011 }}</ref> [[Ekstremofil]] merupakan organisma Bumi yang hidup dalam persekitaran yang dianggap melampau sehingga dianggap memudaratkan hidupan. Makhluk lasak sedemikian lazimnya (tetapi bukan semua) berbentuk unisel, antaranya termasuk organisma alkalifil (penggemar alkali) dan asidofil (penggemar asid) yang boleh hidup dalam suhu air melebihi 100&nbsp;°C dalam keadaan [[pengudaraan hidroterma]].
 
ThePenemuan discoveryhidupan ofdi lifekeadaan in extreme conditions hasekstrem complicatedtelah definitionsmerumitkan ofdefinisi habitabilitykebolehdiaman, buttetapi alsojuga generatedmerangsang muchkalangan excitementpencerakin amongstuntuk researchersmemperluas inlagi greatlyjulat broadeningkeadaan theyang knowndiketahui rangedi ofmana conditionshidupan underberdaya which life can persisthidup. For exampleMisalnya, a planet thatyang mighttidak otherwisedapat bemenampung unableatmosfera tosemata-mata supportkerana ankeadaan atmospheresuria givendi the solar conditions in its vicinitylingkungannya, mightsebaliknya beboleh ableberbuat todemikian dodi sodalam withinrekahan aberbayang deepyang shadoweddalam riftataupun orgua volcanicgunung caveberapi.<ref>{{cite web |first=Stephen |last=Hart |url=http://www.space.com/scienceastronomy/astrobio_caves_030617-1.html |title=Cave Dwellers: ET Might Lurk in Dark Places |publisher=[[Space.com]] |date=17 June 2003 |archive-url=https://web.archive.org/web/20030620142504/http://www.space.com/scienceastronomy/astrobio_caves_030617-1.html |archive-date=20 June 2003 |access-date=6 August 2007 <!-- alternate copy: http://www.nasa.gov/vision/universe/solarsystem/cave_slime.html --> <!--}}</ref> SimilarlyBegitu juga, craterousrupa terrainbumi mightyang offerberkawah-kawah ajuga refugedapat formelindungi primitivehidupan lifeprimitif. The [[Kawah Lawn Hill crater]] hastelah beendikaji studiedsebagai asanalog an(kawasan astrobiologicalperbandingan) analoguntuk tujuan astrobiologi, withdi researchersmana suggestingpara rapidpenyelidik sedimentberpendapat infillbahawa createdsebuah amikropersekitaran protectedyang microenvironmentterlindung foruntuk microbialmikroorganisma organisms;terbentuk similardaripada conditionsisian maymendapan havederas; keadaan-keadaan occurredseumpanaya overtelah theterjadi geologicalsepanjang historysejarah ofgeologi [[MarsMarikh]].<ref>{{cite journal |last1=Lindsay |first1=J |last2=Brasier |first2=M |title=Impact Craters as biospheric microenvironments, Lawn Hill Structure, Northern Australia |journal=Astrobiology |volume=6 |issue=2 |date=2006 |pages=348–363 |doi=10.1089/ast.2006.6.348 |pmid=16689651 |bibcode=2006AsBio...6..348L |url=https://ora.ox.ac.uk/objects/uuid:c9796531-6943-4302-9733-8e8616adf78a }}</ref>
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The discovery of life in extreme conditions has complicated definitions of habitability, but also generated much excitement amongst researchers in greatly broadening the known range of conditions under which life can persist. For example, a planet that might otherwise be unable to support an atmosphere given the solar conditions in its vicinity, might be able to do so within a deep shadowed rift or volcanic cave.<ref>{{cite web |first=Stephen |last=Hart |url=http://www.space.com/scienceastronomy/astrobio_caves_030617-1.html |title=Cave Dwellers: ET Might Lurk in Dark Places |publisher=[[Space.com]] |date=17 June 2003 |archive-url=https://web.archive.org/web/20030620142504/http://www.space.com/scienceastronomy/astrobio_caves_030617-1.html |archive-date=20 June 2003 |access-date=6 August 2007 <!-- alternate copy: http://www.nasa.gov/vision/universe/solarsystem/cave_slime.html --> <!--}}</ref> Similarly, craterous terrain might offer a refuge for primitive life. The [[Lawn Hill crater]] has been studied as an astrobiological analog, with researchers suggesting rapid sediment infill created a protected microenvironment for microbial organisms; similar conditions may have occurred over the geological history of [[Mars]].<ref>{{cite journal |last1=Lindsay |first1=J |last2=Brasier |first2=M |title=Impact Craters as biospheric microenvironments, Lawn Hill Structure, Northern Australia |journal=Astrobiology |volume=6 |issue=2 |date=2006 |pages=348–363 |doi=10.1089/ast.2006.6.348 |pmid=16689651 |bibcode=2006AsBio...6..348L |url=https://ora.ox.ac.uk/objects/uuid:c9796531-6943-4302-9733-8e8616adf78a }}</ref>
 
EarthPersekitaran-persekitaran di environmentsBumi thatyang ''cannottidak dapat'' supportmenampung lifekehidupan aremasih stillmenimba instructivepengetahuan toahli astrobiologistsastrobiologi inuntuk definingmenentukan thehad-had limitsketahanan oforganisma. whatKehidupan organismsnampaknya cansukar endure.ditampung Thedi heart of thetengah-tengah [[Atacamagurun desertAtacama]], generallyyang consideredumum thedianggap driesttempat placepaling onkontang Earth,di appearsBumi; unableoleh toyang supportdemikianlah life,tempat anditu itmenjadi hasbahan beenkajian subjectoleh to study bypihak NASA and [[EuropeanAgensi SpaceAngkasa AgencyEropah|ESA]] forkeran thatia reason: it provides a Marsmenyediakan analog andMarikh, thedan moisturegradien-gradien gradientskelembapan alongdi itssepanjang edgespinggirnya areamat idealsesuai foruntuk studyingmengkaji thesempadan boundaryantara betweenketandusan sterilitydan andkesuburan habitability(kebolehdiaman).<ref>{{cite web|first=Christopher |last=McKay |date=June 2002 |url=http://quest.nasa.gov/challenges/marsanalog/egypt/AtacamaAdAstra.pdf |title=Too Dry for Life: The Atacama Desert and Mars |publisher=[[NASA]] |work=Ames Research Center |access-date=26 August 2009 |url-status=dead |archive-url=https://web.archive.org/web/20090826151945/http://quest.nasa.gov/challenges/marsanalog/egypt/AtacamaAdAstra.pdf |archive-date=26 August 2009 }}</ref> TheGurun Atacama wasdijadikan thebahan subjectkajian ofpada study intahun 2003 thatyang partlysedikit replicatedsebanyak experimentsmengulangi fromeksperimen-eksperimen thedari misi penjelajahan [[Viking (spacecraftkapal angkasa)|Viking]] landingsdi onMarikh Marspada in1970-an, thedi 1970s;mana notiadanya [[DNA]] couldyang bediperoleh recovereddaripada fromdua twosampel soil samplestanih, andmalah incubationeksperimen-eksperimen experimentspengeraman were also negative foruntuk [[biosignaturebiopenunjuk]]s tidak membuahkan hasil yang bermakna.<ref>{{cite journal |title=Mars-Like Soils in the Atacama Desert, Chile, and the Dry Limit of Microbial Life |journal=Science |date=7 November 2003 |first1=Rafael |last1=Navarro-González |first2=Christopher P. |last2=McKay |volume=302 |issue=5647 |pages=1018–1021 |doi=10.1126/science.1089143 |jstor=3835659 |pmid=14605363 |bibcode=2003Sci...302.1018N |s2cid=18220447 }}</ref>
 
===Faktor ekologi===
TheTerdapat twodua currentpendekatan ecologicalekologi approachessemasa foruntuk predictingmenduga thepotensi potentialkebolehdiaman habitabilityyang usemenggunakan 19 oratau 20 environmentalfaktor factorspersekitaran, withdengan emphasispenekanan onterhadap waterkehadiran availabilityair, temperaturesuhu, presencekehadiran of nutrientsnutrien, ansumber energy sourcetenaga, anddan protectionperlindungan fromdaripada solarsinaran ultravioletultraungu andsuria dan [[CosmicSinaran raykosmos|galactic cosmickosmos radiationgalaksi]].<ref name='D.C.Golden'>{{cite journal|last1=Schuerger|first1=Andrew C.|last2=Golden|first2=D.C.|last3=Ming|first3=Doug W.|title=Biotoxicity of Mars soils: 1. Dry deposition of analog soils on microbial colonies and survival under Martian conditions|journal=Planetary and Space Science|date=November 2012|volume=72|issue=1|pages=91–101|doi=10.1016/j.pss.2012.07.026|bibcode = 2012P&SS...72...91S }}</ref><ref name=Beaty>{{citation |first=David W. |last=Beaty |title=Findings of the Mars Special Regions Science Analysis Group |journal=Astrobiology |volume=6 |issue=5 |pages=677–732 |editor-last=the Mars Exploration Program Analysis Group (MEPAG) |date=14 July 2006 |url=http://mepag.jpl.nasa.gov/reports/MEPAG_SR-SAG_final1.pdf |access-date=6 June 2013 |display-authors=etal|bibcode=2006AsBio...6..677M |doi=10.1089/ast.2006.6.677 |pmid=17067257 }}</ref>
 
The two current ecological approaches for predicting the potential habitability use 19 or 20 environmental factors, with emphasis on water availability, temperature, presence of nutrients, an energy source, and protection from solar ultraviolet and [[Cosmic ray|galactic cosmic radiation]].<ref name='D.C.Golden'>{{cite journal|last1=Schuerger|first1=Andrew C.|last2=Golden|first2=D.C.|last3=Ming|first3=Doug W.|title=Biotoxicity of Mars soils: 1. Dry deposition of analog soils on microbial colonies and survival under Martian conditions|journal=Planetary and Space Science|date=November 2012|volume=72|issue=1|pages=91–101|doi=10.1016/j.pss.2012.07.026|bibcode = 2012P&SS...72...91S }}</ref><ref name=Beaty>{{citation |first=David W. |last=Beaty |title=Findings of the Mars Special Regions Science Analysis Group |journal=Astrobiology |volume=6 |issue=5 |pages=677–732 |editor-last=the Mars Exploration Program Analysis Group (MEPAG) |date=14 July 2006 |url=http://mepag.jpl.nasa.gov/reports/MEPAG_SR-SAG_final1.pdf |access-date=6 June 2013 |display-authors=etal|bibcode=2006AsBio...6..677M |doi=10.1089/ast.2006.6.677 |pmid=17067257 }}</ref>
 
{| class="wikitable"
|-
! style="align: center; background: lavender;" colspan="2" | '''SomeAntara habitabilityfaktor-faktor factorskebolehdiaman'''<ref name=Beaty/>
|-
|[[WaterAir ondi MarsMarikh|WaterAir]] || {{·}} ActivityAktiviti ofair liquid watercecair <br /> {{·}} PastSimpanan or future liquidcecair (iceais) inventoriesdahulu atau akan datang <br /> {{·}} [[SalinityKemasinan]], [[pH]], anddan [[ReductionKeupayaan potentialpenurunan|Eh]] ofair availableyang watertersedia
|-
|ChemicalPersekitaran environmentkimia || '''NutrientsNutrien:''' <br /> {{·}} [[Karbon|C]], [[Hidrogen|H]], [[Nitrogen|N]], [[Oksgien|O]], [[Fosforus|P]], [[Sulfur|S]], essentiallogam metalspati, essentialmikronutrien micronutrientspati <br /> {{·}}[[Nitrogen fixation|Fixed nitrogentetap]] <br /> {{·}}AvailabilityKetersediaan/mineralogymineralogi <br /> '''ToxinKelimpahan abundancesdan andkemautan lethalitytoksin:''' <br /> {{·}} [[HeavyLogam metal (chemistry)|Heavy metalsberat]] (e.gcth. [[Zink|Zn]], [[Nikel|Ni]], [[Kuprum|Cu]], [[Kromium|Cr]], [[Arsenik|As]], [[Kadmium|Cd]], etcdll.; someada areyang essentialpati, buttetapi toxictoksik atjika high levelsberlebihan) <br /> {{·}} GloballyTanih teroksida distributedtertabur oxidizingseluruh soilsbumi
|-
|EnergyTenaga foruntuk [[metabolismmetabolisme]] || '''SolarSuria''' (surfaceparas andpermukaan near-surfacedan onlydekat permukaan sahaja) <br /> '''GeochemicalGeokimia''' (subsurfacebawah permukaan) <br /> {{·}} [[OxidizingAgen agentpengoksida|OxidantsOksidan]] <br /> {{·}} [[ReducingAgen agentpenurun|ReductantsPenurun]] <br /> {{·}} [[RedoxGradien gradientredoks]]s
|-
|ConduciveKeadaan fizikal<br />yang physical conditionsmengizinkan || {{·}}TemperatureSuhu <br /> {{·}}ExtremeTurun naik diurnalsuhu temperatureharian fluctuationsketara <br /> {{·}}LowTekanan pressurerendah (isadakah thereterdapat aambang low-pressuretekanan thresholdrendah for terrestrialuntuk [[Anaerobicorganisma organismanaerob|anaerobesanaerob]] bumian?) <br /> {{·}}Strong [[ultravioletPenyinaran germicidalgermisid irradiationultraungu|Sinaran pembasmi kuman ultraungu]] yang kuat <br /> {{·}}[[CosmicSinaran raykosmos|GalacticSinaran cosmickosmos radiationgalaksi]] anddan [[SolarPeristiwa proton eventsuria|solarperistiwa particlezarah eventssuria]] (long-termkesan accumulatedterkumpul effectsjangka panjang) <br /> {{·}} SolarBahan UV-inducedpengoksidaan volatilemeruap oxidantsaruhan ultraungu suria, e.gcth. [[SuperoxideSuperoksida|O <sub>2</sub><sup>−</sup>]], O<sup>−</sup>, [[HydrogenHidrogen peroxideperoksida|H<sub>2</sub>O<sub>2</sub>]], [[Ozon|O<sub>3</sub>]] <br /> {{·}}ClimateIklim anddan itskeberubahan variabilityiklim (geographygeografi, seasons,peralihan diurnalmusim, andkitaran eventuallyharian, obliquitydan variasi variationskecondongan) <br /> {{·}}SubstrateSubstrat (soilproses processestanih, rockmikropersekitaran microenvironmentsberbatu, dustkomposisi compositiondebu, shieldingperlindungan angkasa) <br /> {{·}}HighKepekatan [[Carbon dioxide|CO<sub>2</sub>]] concentrationstinggi indalam theatmosfera global atmospheresegenap bumi<br /> {{·}}TransportAngkutan ([[AeolianProses processes|aeolian|angin]], ground waterair flowtanah, surfaceair waterpermukaan, glacialglasier)
|}
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== Catatan ==