{"id":820,"date":"2004-12-02T15:35:00","date_gmt":"2004-12-02T14:35:00","guid":{"rendered":"https:\/\/kids.esa.int\/gravity_assists\/"},"modified":"2026-10-08T00:32:39","modified_gmt":"2026-10-07T22:32:39","slug":"gravity_assists","status":"publish","type":"post","link":"https:\/\/kids.esa.int\/fi\/gravity_assists\/","title":{"rendered":"Painovoiman avustukset"},"content":{"rendered":"
\n

Kuten tied\u00e4tte, auto yleens\u00e4 hidastuu ajaessaan yl\u00e4m\u00e4keen ja kiihtyy ajaessaan alam\u00e4keen. Voidaan sanoa, ett\u00e4 auto saa \u2018painovoiman apua\u2019, sill\u00e4 maapallon painovoima auttaa sit\u00e4 hidastamaan tai kiihdytt\u00e4m\u00e4\u00e4n. Samalla tavalla avaruusalus voi saada ilmaisen kyydin ilman, ett\u00e4 se kuluttaa arvokasta polttoainetta.<\/p>\n<\/div>\n

Painovoimapys\u00e4hdykset tapahtuvat, kun avaruusalus lent\u00e4\u00e4 planeetan tai suuren kuun ohi. T\u00e4ll\u00f6in planeetan painovoima vet\u00e4\u00e4 avaruusalusta puoleensa ja muuttaa sen kiertorataa.<\/p>\n

Toisinaan avaruusalus kiihdytt\u00e4\u00e4 vauhtiaan, toisinaan taas hidastaa \u2013 riippuen siit\u00e4, kulkeeko se planeetan takaa vai edest\u00e4. Painovoimahyppy muuttaa my\u00f6s avaruusaluksen kulkusuuntaa.<\/p>\n

Yksi upeimmista painovoimahy\u00f6dynt\u00e4misist\u00e4 toteutettiin ESA:n Ulysses-luotaimen lennolla. Lent\u00e4m\u00e4ll\u00e4 Jupiterin pohjoisnavan yli Ulysses ohjattiin kiertoradalle, joka vei sen Auringon napojen yli.<\/p>\n

Cassini-Huygens-luotain hy\u00f6dynsi matkallaan Saturnukseen nelj\u00e4\u00e4 painovoimahyppy\u00e4 (yhden Maan, kaksi Venuksen ja yhden Jupiterin avulla).<\/p>\n

Painovoima vaikutti my\u00f6s ESA:n SMART-1-lentoon. Kun avaruusalus oli kiert\u00e4nyt spiraalimaisesti poisp\u00e4in Maasta 14 kuukauden ajan, se alkoi tuntea Kuun vetovoiman vaikutusta. Marraskuussa 2004 SMART-1 joutui Kuun painovoiman vaikutusalueelle ja siirtyi sen kiertoradalle.<\/p>","protected":false},"excerpt":{"rendered":"

As you know, a car tends to slow down when it goes up a mountain and to accelerate when it is going downhill. One can say that the car is […]<\/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\/2003\/08\/ulysses_and_the_heliosphere2\/17889541-2-eng-GB\/Ulysses_and_the_heliosphere.jpg","esa_banner_description":"Ulysses and the heliosphere","esa_banner_credit":"ESA (image by D. Hardy)","esa_banner_licence":"ESA Standard Licence","esa_banner_detail_url":"https:\/\/www.esa.int\/ESA_Multimedia\/Images\/2003\/08\/Ulysses_and_the_heliosphere2","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":[10,65,40],"tags":[2],"panel":[],"language":[],"age":[],"duration":[],"resource_type":[],"audience":[],"wf_post_folders":[],"class_list":["post-820","post","type-post","status-publish","format-standard","hentry","category-learn","category-mission-control","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\/820","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=820"}],"version-history":[{"count":1,"href":"https:\/\/kids.esa.int\/fi\/wp-json\/wp\/v2\/posts\/820\/revisions"}],"predecessor-version":[{"id":1963,"href":"https:\/\/kids.esa.int\/fi\/wp-json\/wp\/v2\/posts\/820\/revisions\/1963"}],"wp:attachment":[{"href":"https:\/\/kids.esa.int\/fi\/wp-json\/wp\/v2\/media?parent=820"}],"wp:term":[{"taxonomy":"category","embeddable":true,"href":"https:\/\/kids.esa.int\/fi\/wp-json\/wp\/v2\/categories?post=820"},{"taxonomy":"post_tag","embeddable":true,"href":"https:\/\/kids.esa.int\/fi\/wp-json\/wp\/v2\/tags?post=820"},{"taxonomy":"panel","embeddable":true,"href":"https:\/\/kids.esa.int\/fi\/wp-json\/wp\/v2\/panel?post=820"},{"taxonomy":"language","embeddable":true,"href":"https:\/\/kids.esa.int\/fi\/wp-json\/wp\/v2\/language?post=820"},{"taxonomy":"age","embeddable":true,"href":"https:\/\/kids.esa.int\/fi\/wp-json\/wp\/v2\/age?post=820"},{"taxonomy":"duration","embeddable":true,"href":"https:\/\/kids.esa.int\/fi\/wp-json\/wp\/v2\/duration?post=820"},{"taxonomy":"resource_type","embeddable":true,"href":"https:\/\/kids.esa.int\/fi\/wp-json\/wp\/v2\/resource_type?post=820"},{"taxonomy":"audience","embeddable":true,"href":"https:\/\/kids.esa.int\/fi\/wp-json\/wp\/v2\/audience?post=820"},{"taxonomy":"wf_post_folders","embeddable":true,"href":"https:\/\/kids.esa.int\/fi\/wp-json\/wp\/v2\/wf_post_folders?post=820"}],"curies":[{"name":"wp","href":"https:\/\/api.w.org\/{rel}","templated":true}]}}