{"id":849,"date":"2010-02-25T13:30:00","date_gmt":"2010-02-25T12:30:00","guid":{"rendered":"https:\/\/kids.esa.int\/mars_express_and_the_mystery_of_phobos\/"},"modified":"2026-10-08T00:32:58","modified_gmt":"2026-10-07T22:32:58","slug":"mars_express_and_the_mystery_of_phobos","status":"publish","type":"post","link":"https:\/\/kids.esa.int\/fi\/mars_express_and_the_mystery_of_phobos\/","title":{"rendered":"Mars Express ja Phoboksen mysteeri"},"content":{"rendered":"<p>ESAn Mars Express -kiertolainen on l\u00e4hett\u00e4nyt upeita kuvia ja muuta dataa siit\u00e4 l\u00e4htien, kun se saapui Punaiselle planeetalle joulukuussa 2003. Vaikka Mars on sen ensisijainen kohde, avaruusaluksen napakierros vie sen toisinaan l\u00e4helle Phobosta, joka on planeetan kahdesta kuusta suurempi. Viimeisimm\u00e4n ohilentosarjan aikana, 16. helmikuuta ja 26. maaliskuuta v\u00e4lisen\u00e4 aikana, Mars Express rikkoo uuden enn\u00e4tyksen lent\u00e4m\u00e4ll\u00e4 3. maaliskuuta vain 50 kilometrin p\u00e4\u00e4h\u00e4n Phoboksen pinnasta. N\u00e4iden l\u00e4heisten ohilentojen aikana ker\u00e4tyt tiedot voivat auttaa ratkaisemaan joitakin t\u00e4m\u00e4n kiehtovan pienen kuun ymp\u00e4rill\u00e4 leijuvia mysteerej\u00e4.<\/p>\n<figure class=\"wp-block-image size-large\" data-width=\"2541\" data-credit=\"ESA\" data-detail-url=\"https:\/\/www.esa.int\/ESA_Multimedia\/Images\/2010\/01\/Mars_Express2\" data-licence=\"ESA Standard Licence\" data-licence-url=\"https:\/\/www.esa.int\/ESA_Multimedia\/Terms_and_conditions_of_use_of_images_and_videos_available_on_the_esa_website\"><img decoding=\"async\" loading=\"lazy\" style=\"max-width:100%;height:auto\" src=\"https:\/\/www.esa.int\/var\/esa\/storage\/images\/esa_multimedia\/images\/2010\/01\/mars_express2\/17902345-2-eng-GB\/Mars_Express.jpg\" alt=\"Mars Express\"><figcaption>Mars Express<\/figcaption><\/figure>\n<p>Mars Expressin ja muiden avaruusluotainten l\u00e4hett\u00e4m\u00e4t kuvat osoittavat, ett\u00e4 Phobos on kolhiintunut, perunanmuotoinen kivi, jonka halkaisija on alle 28 km. Se kiert\u00e4\u00e4 l\u00e4hes py\u00f6re\u00e4ll\u00e4, p\u00e4iv\u00e4ntasaajan suuntaisella radalla noin 6000 km:n korkeudella planeetan pinnasta. Jotta se ei t\u00f6rm\u00e4isi Marsiin, sen on liikkuttava kiertoradallaan eritt\u00e4in nopeasti. Yksi kierros kest\u00e4\u00e4 7 tuntia 39 minuuttia, joten planeetalla seisova ihminen n\u00e4kisi Phoboksen kulkevan taivaalla l\u00e4nnest\u00e4 it\u00e4\u00e4n kolme kertaa p\u00e4iv\u00e4ss\u00e4.<\/p>\n<p>Useimmat tutkijat uskovat, ett\u00e4 t\u00e4m\u00e4 pieni avaruuskivi on asteroidi, joka ajautui liian l\u00e4helle Marsia ja j\u00e4i sen painovoiman vangiksi. On kuitenkin eritt\u00e4in vaikeaa selitt\u00e4\u00e4, miten Phobos p\u00e4\u00e4tyi nykyiselle kiertoradalleen. Useimmat vangitut kuut kiert\u00e4v\u00e4t hyvin elliptisill\u00e4 (munanmuotoisilla) kiertoradoilla kaukana planeetastaan. Mars Express voi auttaa ratkaisemaan t\u00e4m\u00e4n mysteerin. Tutkimalla, miten Phoboksen painovoima vet\u00e4\u00e4 avaruusaluksen puoleensa ja muuttaa sen kiertorataa, tutkijat saavat lis\u00e4tietoa kuun sis\u00e4osista. Aiemmat tiedot ovat viitanneet siihen, ett\u00e4 Phobos saattaa olla huokoinen kivikasa, jossa on paljon tyhji\u00e4 tiloja.<\/p>","protected":false},"excerpt":{"rendered":"<p>ESA\u2019s Mars Express orbiter has been sending back remarkable images and other data since it reached the Red Planet in December 2003. Although Mars is its primary target, the spacecraft\u2019s [&hellip;]<\/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\/2009\/12\/phobos_up_close2\/17873150-2-eng-GB\/Phobos_up_close.jpg","esa_banner_description":"Phobos up close","esa_banner_credit":"ESA\/DLR\/FU Berlin (G. 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