{"id":34938,"date":"2019-06-29T03:55:34","date_gmt":"2019-06-29T00:55:34","guid":{"rendered":"https:\/\/bilimvegelecek.com.tr\/?p=34938"},"modified":"2019-06-28T16:08:45","modified_gmt":"2019-06-28T13:08:45","slug":"allen-kusaklari","status":"publish","type":"post","link":"https:\/\/bilimvegelecek.com.tr\/index.php\/2019\/06\/29\/allen-kusaklari","title":{"rendered":"Allen Ku\u015faklar\u0131"},"content":{"rendered":"

Allen Ku\u015faklar\u0131 olarak bilinen ve D\u00fcnya\u2019y\u0131 halka \u015feklinde saran radyasyon alan\u0131, 1958 y\u0131l\u0131nda Dr. Van Allen taraf\u0131ndan Amerika\u2019n\u0131n ilk uydusu olan Explorer 1 f\u0131rlat\u0131ld\u0131ktan sonra ke\u015ffedilmi\u015ftir.1<\/sup> D\u00fcnya\u2019n\u0131n etraf\u0131nda i\u00e7 i\u00e7e ge\u00e7mi\u015f simitler \u015feklinde bulunurlar ve y\u00fcksek seviyede radyasyon i\u00e7erirler. Radyoaktiflik seviyeleri \u00e7e\u015fitli noktalarda de\u011fi\u015fkenlik g\u00f6stermekle birlikte baz\u0131 d\u0131\u015f etmenlerden etkilenebilirler. D\u00fcnya\u2019n\u0131n manyetik alan\u0131 y\u00fcz\u00fcnden olu\u015fan bu ku\u015faklar, G\u00fcne\u015f r\u00fczg\u00e2r\u0131ndan gelen enerji y\u00fckl\u00fc par\u00e7ac\u0131klar\u0131 i\u00e7ine hapsederler. Bu sayede D\u00fcnya\u2019y\u0131 hem G\u00fcne\u015f\u2019ten hem de di\u011fer y\u0131ld\u0131zlar\u0131n zararl\u0131 \u0131\u015f\u0131nlar\u0131ndan koruyan bir kalkan g\u00f6revi g\u00f6r\u00fcrler. Ayr\u0131ca Kuzey I\u015f\u0131klar\u0131\u2019n\u0131n olu\u015fmas\u0131nda Allen Ku\u015faklar\u0131\u2019n\u0131n b\u00fcy\u00fck oranda etkisi bulunur.<\/p>\n

Allen Ku\u015faklar\u0131\u2019n\u0131n y\u00fcksek radyasyona sahip olmas\u0131n\u0131n nedeni hapsetti\u011fi iki proton ve iki n\u00f6trondan olu\u015fan \u00e7ekirdeklerdir. Bu y\u00fczden Allen Ku\u015faklar\u0131, i\u00e7erisinde bulunan canl\u0131 ve cans\u0131z yap\u0131lara a\u015f\u0131r\u0131 derecede zarar verir. Bu nedene dayanarak 1969 y\u0131l\u0131nda Ay\u2019a insanl\u0131 ini\u015f yapan Apollo 11\u2019in Ay\u2019a gitmedi\u011fi ileri s\u00fcr\u00fclm\u00fc\u015ft\u00fcr. Ay\u2019a giderken bu ku\u015faklar\u0131n i\u00e7inden ge\u00e7ilmesi gerekti\u011fi ve bunun zarar g\u00f6rmeden yap\u0131lamayaca\u011f\u0131 \u00f6ne s\u00fcr\u00fclerek, Apollo 11\u2019in Ay\u2019a ini\u015f yapmad\u0131\u011f\u0131 iddia edilmi\u015ftir. Ancak bu do\u011fru de\u011fildir. \u00c7\u00fcnk\u00fc Allen Ku\u015faklar\u0131 1958 y\u0131l\u0131nda ke\u015ffedilmi\u015ftir, dolay\u0131s\u0131yla Apollo 11 yolculu\u011fa ba\u015flamadan \u00f6nce NASA\u2019n\u0131n bu radyasyon alanlar\u0131ndan haberi vard\u0131r. NASA bu radyasyonun etkisini en aza indirmek i\u00e7in Explorer 3, Pioneer 3 ve Luna 1 taraf\u0131ndan ku\u015faklardaki yo\u011fun ve hafif radyasyon b\u00f6lgelerini tespit etmi\u015f, olabilecek en az radyasyon maruziyetini sa\u011flayan bir g\u00fczerg\u00e2h se\u00e7mi\u015ftir. Bu y\u00fczden gidilecek mesafe uzam\u0131\u015ft\u0131r. Ayr\u0131ca radyasyondan korunmak i\u00e7in Apollo 11\u2019e \u00e7e\u015fitli maddeler ile kalkan yap\u0131lm\u0131\u015ft\u0131r. Yine de astronotlar bu b\u00f6lgeden ge\u00e7erken radyasyona maruz kalm\u0131\u015ft\u0131r, ancak bu radyasyon sa\u011fl\u0131\u011f\u0131 tehdit etmeyecek kadar azd\u0131r.2
\n<\/sup><\/p>\n

\"\"
Apollo 11\u2019in rotas\u0131. NASA\u2019daki bilim insanlar\u0131 ku\u015faklardan m\u00fcmk\u00fcn olan en az seviye radyasyon maruziyeti ile ge\u00e7ebilmek i\u00e7in, resimde koyu renk ile g\u00f6sterilen radyoaktivite a\u00e7\u0131s\u0131ndan yo\u011fun olan b\u00f6lgeye fazla yakla\u015fmadan ilerleyecek bir rota \u00e7izdiler. (https:\/\/www.popsci.com\/sites\/popsci.com\/files\/styles\/655_1x_\/public\/import\/2014\/image-of-Apollo-11-and-van-allen-belts.gif)<\/figcaption><\/figure>\n

Ayr\u0131ca Sovyetler Birli\u011fi de Allen Ku\u015faklar\u0131\u2019ndaki radyasyonun etkilerini g\u00f6zlemek amac\u0131yla 1968 Eyl\u00fcl ay\u0131nda Zond 5\u2019i uzaya g\u00f6nderdi. Bu uzay arac\u0131n\u0131n i\u00e7erisinde 2 kaplumba\u011fa, meyve sinekleri, solucanlar, bakteri kolonisi ve bitki tohumlar\u0131 bulunuyordu. Ay\u2019a g\u00f6nderilen ara\u00e7 Ay\u2019\u0131n etraf\u0131nda bir tur att\u0131ktan sonra ba\u015far\u0131yla D\u00fcnya\u2019ya geri d\u00f6nd\u00fc. Yap\u0131lan inceleme sonucu uzay arac\u0131n\u0131n i\u00e7inde bulunan canl\u0131lar hayati bir zarar g\u00f6rmemi\u015fti. Art\u0131k uzaya insanl\u0131 bir uzay arac\u0131n\u0131n g\u00f6nderilebilece\u011fine ikna olunmu\u015ftu.3<\/sup><\/p>\n

Allen Ku\u015faklar\u0131 kutuplarda yok denecek kadar az iken ekvatorda olduk\u00e7a yo\u011fundur. Bunun sebebi d\u00fcnyan\u0131n manyetik alan\u0131n\u0131n kutuplarda \u00e7ok az iken ekvatorda fazla olmas\u0131d\u0131r. (https:\/\/www.nasa.gov\/sites\/default\/files\/thumbnails\/image\/van_allen_probes_discov_new_rad_belt_cal.jpg)<\/p>\n

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Allen Ku\u015faklar\u0131\u2019n\u0131n yap\u0131s\u0131 hakk\u0131nda biraz bilgi edinelim. Allen Ku\u015faklar\u0131, temelde i\u00e7 ve d\u0131\u015f olmak \u00fczere ikiye ayr\u0131l\u0131r.<\/figcaption><\/figure>\n

\u0130\u00e7 ku\u015fak<\/strong>: Allen Ku\u015faklar\u0131\u2019ndan i\u00e7te olan\u0131, yakla\u015f\u0131k olarak yery\u00fcz\u00fcnden bin km ile 6 bin km aras\u0131 bir uzakl\u0131kta bulunur. G\u00fcne\u015f etkinli\u011fi fazla oldu\u011funda veya G\u00fcney Atlantik Anomalisi gibi co\u011frafi b\u00f6lgelerde bu uzakl\u0131k yery\u00fcz\u00fcnden 200 km\u2019ye kadar d\u00fc\u015febilir.4<\/sup> Bu i\u00e7 ku\u015fak, \u00e7ok b\u00fcy\u00fck miktarlarda KeV enerjiye sahip elektron konsantrasyonlar\u0131 ve enerjileri 100 MeV ve daha fazla olan protonlar\u0131 i\u00e7erir. Bu par\u00e7ac\u0131klar g\u00fc\u00e7l\u00fc manyetik alan taraf\u0131ndan hapsedilmi\u015ftir. Kemerler bazen D\u00fcnya\u2019n\u0131n merkezinden biraz kayabilir, bu durum ger\u00e7ekle\u015fti\u011finde i\u00e7 ku\u015fak, G\u00fcney Atlantik Anomalisi\u2019nde y\u00fczeye en yak\u0131n duruma gelir.<\/p>\n

Mart 2014\u2019te, i\u00e7 ku\u015fakta Van Allen Sondalar\u0131 taraf\u0131ndan zebra \u00e7izgilerine benzeyen \u015fekillere rastlanm\u0131\u015ft\u0131r. Daha sonra yap\u0131lan a\u00e7\u0131klamada, D\u00fcnya\u2019n\u0131n manyetik alan\u0131ndaki e\u011fim ve D\u00fcnya\u2019n\u0131n d\u00f6n\u00fc\u015f\u00fcn\u00fcn bir osilasyon \u00fcretmesi y\u00fcz\u00fcnden zay\u0131f bir elektrik alan\u0131n i\u00e7 ku\u015fak boyunca s\u0131zd\u0131\u011f\u0131 s\u00f6ylenmi\u015ftir. Asl\u0131nda, zebra \u00e7izgileri ionosferik r\u00fczg\u00e2rlar\u0131n ku\u015fak \u00fczerindeki izleriydi.5<\/sup><\/p>\n

D\u0131\u015f ku\u015fak<\/strong>: D\u0131\u015f ku\u015fak temelde D\u00fcnya\u2019n\u0131n manyetik alan\u0131 taraf\u0131ndan yakalanan y\u00fcksek enerjili (0.1 MeV – 10 MeV) elektronlar i\u00e7erir. D\u0131\u015f ku\u015fak i\u00e7 ku\u015faktan daha de\u011fi\u015fkendir ve G\u00fcne\u015f aktivitelerinden gelen etkilerden kolay bir \u015fekilde etkilenir. Yery\u00fcz\u00fcnden y\u00fcksekli\u011fi 13 bin km ile 60 bin km aras\u0131ndad\u0131r. D\u0131\u015f ku\u015fak elektronlar\u0131, D\u00fcnya atmosferi ile \u00e7arp\u0131\u015fmalar, manyetopozda kay\u0131plar ve d\u0131\u015far\u0131ya do\u011fru radyal dif\u00fczyondan dolay\u0131 s\u00fcrekli olarak uzakla\u015f\u0131r. D\u0131\u015f kemer i\u00e7 kemerden daha b\u00fcy\u00fckt\u00fcr ve par\u00e7ac\u0131k hareketleri b\u00fcy\u00fck oranda dalgal\u0131d\u0131r. Enerjili par\u00e7ac\u0131klar\u0131n ak\u0131lar\u0131, G\u00fcne\u015f\u2019in manyetik alan\u0131ndan veya plazmadaki bozukluklar taraf\u0131ndan harekete ge\u00e7irilen jeomanyetik f\u0131rt\u0131nalar y\u00fcz\u00fcnden \u00e7arp\u0131c\u0131 bir \u015fekilde art\u0131p azalabilir. Art\u0131\u015flar f\u0131rt\u0131na-kaynakl\u0131 enjeksiyonlar ve manyetosferin uzant\u0131s\u0131ndaki par\u00e7ac\u0131klar\u0131n ivmelenmesinden dolay\u0131 meydana gelebilir.4<\/sup><\/p>\n

Ku\u015faklar temelde iki tane olmas\u0131na kar\u015f\u0131n Nature Physics <\/em>dergisinde yay\u0131nlanan bir makaleye g\u00f6re, uzay tsunamisinin sebep oldu\u011fu \u00fc\u00e7\u00fcnc\u00fc bir Allen ku\u015fa\u011f\u0131 g\u00f6zlemlenmi\u015ftir. Bulgulara g\u00f6re ultra d\u00fc\u015f\u00fck frekanstaki yo\u011fun plazma dalgalar\u0131, d\u0131\u015f ku\u015faktaki radyasyonu belli bir miktarda gezegenler aras\u0131 uzaya ta\u015f\u0131yarak \u00fc\u00e7\u00fcnc\u00fc yeni bir ku\u015fak olu\u015fturuyor.6<\/sup><\/p>\n

\"\"
\u0130ki ku\u015fa\u011f\u0131n d\u0131\u015f\u0131nda \u00fc\u00e7\u00fcnc\u00fc bir ku\u015fak olu\u015fmu\u015ftur. (Resim: Yuri Shprits, Adam Kellerman, Dmitri Subbotin\/UCLA)<\/figcaption><\/figure>\n

\u00d6zetle, Allen Ku\u015faklar\u0131 yery\u00fcz\u00fcnden uzakl\u0131\u011f\u0131 bin km ile 60 bin km aras\u0131nda de\u011fi\u015fen ve s\u0131n\u0131rlar\u0131n\u0131n zaman zaman d\u0131\u015f etkilerle esneyebildi\u011fi, D\u00fcnyam\u0131z\u0131 hem G\u00fcne\u015f\u2019in hem de di\u011fer y\u0131ld\u0131zlar\u0131n zararl\u0131 radyasyonundan koruyan yap\u0131lard\u0131r. Temelde iki ku\u015fak olsa da son bulgulara g\u00f6re baz\u0131 ko\u015fullarda \u00fc\u00e7\u00fcnc\u00fc yeni bir ku\u015fak da olu\u015fabilmektedir. \u0130lk ke\u015ffedildiklerinde insano\u011flunun uzaya gitme hayalleri \u00f6n\u00fcnde engel gibi dursalar da sonradan onlar\u0131 a\u015fman\u0131n bir yolu bulunmu\u015ftur. \u00d6te yandan Allen Ku\u015faklar\u0131 olmasayd\u0131 kim bilir belki de D\u00fcnya\u2019da ya\u015fam asla var olmayacakt\u0131.<\/p>\n

Kaynaklar:
\n<\/strong>1) https:\/\/www.space.com\/33948-van-allen-radiation-belts.html
\n2) https:\/\/www.bilgeyik.com\/van-allen-kusagi-319
\n3) https:\/\/en.wikipedia.org\/wiki\/Zond_5
\n4) https:\/\/en.wikipedia.org\/wiki\/Van_Allen_radiation_belt
\n5) Lejosne, S., & Roederer, J. (2016). The \u201czebra stripes\u201d: An effect of F region zonal plasma drifts on the longitudinal distribution of radiation belt particles. Journal Of Geophysical Research: Space Physics, 121(1), 507-518. doi: 10.1002\/2015ja021925.
\n6) Mann, I., Ozeke, L., Murphy, K., Claudepierre, S., Turner, D., & Baker, D. et al. (2016). Explaining the dynamics of the ultra-relativistic third Van Allen radiation belt.\u00a0Nature Physics<\/em>,\u00a012<\/em>(10), 978-983. doi: 10.1038\/nphys3799.<\/p>\n","protected":false},"excerpt":{"rendered":"

Allen Ku\u015faklar\u0131 olarak bilinen ve D\u00fcnya\u2019y\u0131 halka \u015feklinde saran radyasyon alan\u0131, 1958 y\u0131l\u0131nda Dr. Van Allen taraf\u0131ndan Amerika\u2019n\u0131n ilk uydusu olan Explorer 1 f\u0131rlat\u0131ld\u0131ktan sonra ke\u015ffedilmi\u015ftir.1 D\u00fcnya\u2019n\u0131n etraf\u0131nda i\u00e7 i\u00e7e ge\u00e7mi\u015f simitler \u015feklinde bulunurlar ve y\u00fcksek seviyede radyasyon i\u00e7erirler. Radyoaktiflik seviyeleri \u00e7e\u015fitli noktalarda de\u011fi\u015fkenlik g\u00f6stermekle birlikte baz\u0131 d\u0131\u015f etmenlerden etkilenebilirler. D\u00fcnya\u2019n\u0131n manyetik alan\u0131 y\u00fcz\u00fcnden olu\u015fan […]<\/p>\n","protected":false},"author":2039,"featured_media":34939,"comment_status":"closed","ping_status":"closed","sticky":false,"template":"","format":"standard","meta":{"_acf_changed":false,"footnotes":""},"categories":[19],"tags":[4957,249,1600,743,4956],"class_list":["post-34938","post","type-post","status-publish","format-standard","has-post-thumbnail","hentry","category-bilim-gundemi","tag-allen-kusaklari","tag-atmosfer","tag-radyasyon","tag-radyoaktivite","tag-von-allen"],"acf":[],"aioseo_notices":[],"aioseo_head":"\n\t\t\n\t\n\t\n\t\n\t\n\t\t\n\t\t\n\t\t\n\t\t\n\t\t\n\t\t\n\t\t\n\t\t\n\t\t\n\t\t\n\t\t\n\t\t\n\t\t\n\t\t\n\t\t\n\t\t\n\t\t\n\t\t\n\t\t