Editing Outer space (section)

== Exploration ==
{{Main|Space exploration|Human presence in space}}
{{See also|Astronautics|Spaceflight|Human spaceflight}}
[[File:As08-16-2593.jpg|thumb|left|South is up in the [[first image of Earth]] taken by a person,<ref name="Apollo8FlightJournalDay1"/> probably by [[Bill Anders]] (during the 1968 [[Apollo 8]] mission)]]

For most of human history, space was explored by observations made from the Earth's surface—initially with the unaided eye and then with the telescope. Before reliable rocket technology, the closest that humans had come to reaching outer space was through balloon flights. In 1935, the American ''[[Explorer II]]'' crewed balloon flight 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 uncrewed 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 low Earth orbit were [[Frank Borman]], [[Jim Lovell]] and [[William Anders]] in 1968 on board the American [[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}}

The first spacecraft to reach escape velocity was the Soviet ''[[Luna 1]]'', which performed a fly-by of the Moon in 1959.{{sfn|Hardesty|Eisman|Krushchev|2008|pp=89–90}} In 1961, ''[[Venera 1]]'' became the first planetary probe. It revealed the presence of the solar wind and performed the first fly-by of [[Venus]], although contact was lost before reaching Venus. The first successful planetary mission was the 1962 fly-by of Venus by [[Mariner 2]].{{sfn|Collins|2007|p=86}} The first fly-by of Mars was by [[Mariner 4]] in 1964. Since that time, uncrewed spacecraft have successfully examined each of the Solar System's planets, as well their moons and many [[minor planet]]s and comets. They remain a fundamental tool for the exploration of outer space, as well as for observation of the Earth.{{sfn|Harris|2008|pp=7, 68–69}} In August 2012, ''[[Voyager 1]]'' became the first man-made object to leave the Solar System and enter [[interstellar space]].<ref name="mike_wall"/>