အပြင်ဖက်အာကာသ: တည်းဖြတ်မှု မူကွဲများ

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==စူးစမ်းလေ့လာခြင်းနှင့်အသုံးချခြင်း==
{{Main|အာကာသစူးစမ်းလေ့လာခြင်း|အာကာသကိုသိမ်းပိုက်ခြင်း|Space manufacturing}}
 
[[File:Convert ru kosmos080.jpg|thumb|Soviet stamp depicting Yuri Gagarin, first human in space|alt=At left is the bust of a man in a spacesuit. To the right is a brown-green planet with a white atmosphere against the black background of a starry sky.]]
For the majority of human history, space was explored by remote observation; initially with the unaided eye and then with the telescope. Prior to the advent of reliable rocket technology, the closest that humans had come to reaching outer space was through the use of balloon flights. In 1935, the U.S. ''[[Explorer II (balloon)|Explorer II]]'' manned balloon flight had reached an altitude of {{Convert|22|km|mi|abbr=on}}.<ref name=ssr13_2_199/> This was greatly exceeded in 1942 when the third launch of the German [[V-2 rocket|A-4 rocket]] climbed to an altitude of about {{Convert|80|km|mi|abbr=on}}. In 1957, the unmanned satellite ''[[Sputnik 1]]'' was launched by a Russian [[R-7 Semyorka|R-7 rocket]], achieving Earth orbit at an altitude of {{Convert|215|-|939|km|mi}}.{{sfn|O'Leary|2009|pp=209–224}} This was followed by the first human spaceflight in 1961, when [[Yuri Gagarin]] was sent into orbit on [[Vostok 1]]. The first humans to escape Earth orbit were [[Frank Borman]], [[Jim Lovell]] and [[William Anders]] in 1968 on board [[Apollo 8]], which achieved lunar orbit{{sfn|Harrison|2002|pp=60–63}} and reached a maximum distance of {{Convert|377349|km|mi|abbr=on}} from the Earth.{{sfn|Orloff|2001}}