{"id":805,"date":"2011-07-05T08:12:00","date_gmt":"2011-07-05T06:12:00","guid":{"rendered":"https:\/\/kids.esa.int\/communications\/"},"modified":"2026-10-08T00:32:27","modified_gmt":"2026-10-07T22:32:27","slug":"communications","status":"publish","type":"post","link":"https:\/\/kids.esa.int\/fi\/communications\/","title":{"rendered":"Viestint\u00e4"},"content":{"rendered":"
\n

1960-luvun tv-sarjan fanit Star Trek<\/i> olivat h\u00e4mm\u00e4styneit\u00e4, kun he n\u00e4kiv\u00e4t kapteeni Kirkin avaavan pienen k\u00e4dess\u00e4 pidett\u00e4v\u00e4n puhelimen puhuakseen avaruusaluksensa miehist\u00f6lle. Nyky\u00e4\u00e4n matkapuhelimet eiv\u00e4t ole en\u00e4\u00e4 tieteiskirjallisuutta. Miss\u00e4 tahansa maapallolla liikutkin, napa-alueilta keskelle merta, on mahdollista pit\u00e4\u00e4 yhteytt\u00e4 puhelimitse. Uusimmilla malleilla on my\u00f6s mahdollista l\u00e4hett\u00e4\u00e4 s\u00e4hk\u00f6posteja ja tehd\u00e4 hakuja internetiss\u00e4.<\/p>\n<\/div>\n

T\u00e4m\u00e4 viestinn\u00e4n vallankumous on tullut mahdolliseksi satelliittiteknologian k\u00e4ytt\u00f6\u00f6noton ansiosta. 1960-luvun puoliv\u00e4liin asti puhelinviestit v\u00e4litettiin maalla sijaitsevien radioyhteyksien ja kaapeleiden kautta. Viestien k\u00e4sittelykapasiteetilla oli kuitenkin rajansa.<\/p>\n

Sitten tulivat ensimm\u00e4iset tietoliikennesatelliitit. Geostationaarisella kiertoradalla, noin 36 000 km p\u00e4iv\u00e4ntasaajan yl\u00e4puolella, satelliitit pystyiv\u00e4t toimimaan ilman kallista l\u00e4hetin- ja kaapeliverkkoa. Ne pystyiv\u00e4t helposti yhdist\u00e4m\u00e4\u00e4n soittajia meren tai vuorijonon molemmin puolin. Vuonna 1965 laukaisun saanut Early Bird pystyi k\u00e4sittelem\u00e4\u00e4n 240 puhelua kerrallaan. Nyky\u00e4\u00e4n suuri viestint\u00e4satelliitti pystyy k\u00e4sittelem\u00e4\u00e4n satoja tuhansia puheluita.<\/p>\n

Viime vuosina on tapahtunut uusi mullistus, kun pienien satelliittien laivastot on otettu k\u00e4ytt\u00f6\u00f6n matalilla tai keskikorkeilla maankiertoradoilla. Koska kymmeni\u00e4 satelliitteja lent\u00e4\u00e4 eri reiteill\u00e4, horisontin yl\u00e4puolella on aina useita satelliitteja, jotka voivat vastaanottaa puheluita mobiililaitteista. Jokainen puhelu l\u00e4hetet\u00e4\u00e4n sitten maassa sijaitsevaan \u2018yhdysasemaan\u2019, joka v\u00e4litt\u00e4\u00e4 sen edelleen vastaanottajalle. N\u00e4it\u00e4 satelliitteja k\u00e4ytet\u00e4\u00e4n my\u00f6s henkil\u00f6iden seurantaan, viestint\u00e4\u00e4n ja h\u00e4t\u00e4tilanteiden paikantamiseen.<\/p>","protected":false},"excerpt":{"rendered":"

Fans of the 1960s TV series Star Trek were amazed when they saw Captain Kirk flip open a tiny hand-help phone to speak to the crew of his starship. Today, […]<\/p>\n","protected":false},"author":5,"featured_media":0,"comment_status":"closed","ping_status":"closed","sticky":false,"template":"","format":"standard","meta":{"_jetpack_newsletter_access":"","_jetpack_dont_email_post_to_subs":false,"_jetpack_newsletter_tier_id":0,"_jetpack_memberships_contains_paywalled_content":false,"esa_banner_image":"https:\/\/www.esa.int\/var\/esa\/storage\/images\/esa_multimedia\/images\/2010\/10\/hylas-1_serving_europe2\/17876924-2-eng-GB\/Hylas-1_serving_Europe.jpg","esa_banner_description":"","esa_banner_credit":"ESA","esa_banner_licence":"ESA Standard Licence","esa_banner_detail_url":"https:\/\/www.esa.int\/ESA_Multimedia\/Images\/2010\/10\/Hylas-1_serving_Europe2","esa_external_url":"","esa_external_new_window":false,"_jetpack_feature_clip_id":0,"_jetpack_memberships_contains_paid_content":false,"footnotes":"","jetpack_post_was_ever_published":true},"categories":[10,54,40],"tags":[2],"panel":[],"language":[],"age":[],"duration":[],"resource_type":[],"audience":[],"wf_post_folders":[],"class_list":["post-805","post","type-post","status-publish","format-standard","hentry","category-learn","category-space-technologies-on-earth","category-technology","tag-background-article"],"jetpack_sharing_enabled":true,"jetpack_featured_media_url":"","_links":{"self":[{"href":"https:\/\/kids.esa.int\/fi\/wp-json\/wp\/v2\/posts\/805","targetHints":{"allow":["GET"]}}],"collection":[{"href":"https:\/\/kids.esa.int\/fi\/wp-json\/wp\/v2\/posts"}],"about":[{"href":"https:\/\/kids.esa.int\/fi\/wp-json\/wp\/v2\/types\/post"}],"author":[{"embeddable":true,"href":"https:\/\/kids.esa.int\/fi\/wp-json\/wp\/v2\/users\/5"}],"replies":[{"embeddable":true,"href":"https:\/\/kids.esa.int\/fi\/wp-json\/wp\/v2\/comments?post=805"}],"version-history":[{"count":1,"href":"https:\/\/kids.esa.int\/fi\/wp-json\/wp\/v2\/posts\/805\/revisions"}],"predecessor-version":[{"id":1948,"href":"https:\/\/kids.esa.int\/fi\/wp-json\/wp\/v2\/posts\/805\/revisions\/1948"}],"wp:attachment":[{"href":"https:\/\/kids.esa.int\/fi\/wp-json\/wp\/v2\/media?parent=805"}],"wp:term":[{"taxonomy":"category","embeddable":true,"href":"https:\/\/kids.esa.int\/fi\/wp-json\/wp\/v2\/categories?post=805"},{"taxonomy":"post_tag","embeddable":true,"href":"https:\/\/kids.esa.int\/fi\/wp-json\/wp\/v2\/tags?post=805"},{"taxonomy":"panel","embeddable":true,"href":"https:\/\/kids.esa.int\/fi\/wp-json\/wp\/v2\/panel?post=805"},{"taxonomy":"language","embeddable":true,"href":"https:\/\/kids.esa.int\/fi\/wp-json\/wp\/v2\/language?post=805"},{"taxonomy":"age","embeddable":true,"href":"https:\/\/kids.esa.int\/fi\/wp-json\/wp\/v2\/age?post=805"},{"taxonomy":"duration","embeddable":true,"href":"https:\/\/kids.esa.int\/fi\/wp-json\/wp\/v2\/duration?post=805"},{"taxonomy":"resource_type","embeddable":true,"href":"https:\/\/kids.esa.int\/fi\/wp-json\/wp\/v2\/resource_type?post=805"},{"taxonomy":"audience","embeddable":true,"href":"https:\/\/kids.esa.int\/fi\/wp-json\/wp\/v2\/audience?post=805"},{"taxonomy":"wf_post_folders","embeddable":true,"href":"https:\/\/kids.esa.int\/fi\/wp-json\/wp\/v2\/wf_post_folders?post=805"}],"curies":[{"name":"wp","href":"https:\/\/api.w.org\/{rel}","templated":true}]}}