Editing Spaceflight (section)

== History ==
{{Main|History of spaceflight}}
{{For timeline|Timeline of spaceflight}}

The first theoretical proposal of space travel using [[rocket]]s was published by Scottish astronomer and mathematician [[William Leitch (scientist)|William Leitch]], in an 1861 essay "A Journey Through Space".<ref>{{cite book|first=William |last=Leitch|title=God's Glory in the Heavens|url=https://archive.org/details/godsgloryinheave00leit|year=1867|publisher=A. Strahan}}</ref> More well-known is [[Konstantin Tsiolkovsky]]'s work, "{{lang|ru|Исследование мировых пространств реактивными приборами}}" (''The Exploration of Cosmic Space by Means of Reaction Devices''), published in 1903. In his work, Tsiolkovsky describes the fundamental rocket equation:

<math>\Delta v = v_e \ln \frac{m_0}{m_f}</math>

Where:

* (<math>\Delta v</math>) is the change in the rocket's velocity
* (<math>v_e</math>) is the exhaust velocity
* (<math>m_0</math>) and (<math>m_f</math>) are the initial and final masses of the rocket

This equation, known as the [[Tsiolkovsky rocket equation]], can be used to find the total <math>\Delta v</math>, or potential change in velocity. This formula, which is still used by engineers, is a key concept of spaceflight.

Spaceflight became a practical possibility with the work of [[Robert H. Goddard]]'s publication in 1919 of his paper ''[[Robert H. Goddard#A Method of Reaching Extreme Altitudes|A Method of Reaching Extreme Altitudes]]''. His application of the [[de Laval nozzle]] to [[liquid-propellant rocket|liquid-fuel rockets]] improved efficiency enough for interplanetary travel to become possible. After further research, Goddard attempted to secure an Army contract for a rocket-propelled weapon in the [[World War I|first World War]] but his plans were foiled by the [[Armistice of 11 November 1918|November 11, 1918 armistice with Germany]]. After choosing to work with private financial support, he was the first to launch a liquid-fueled rocket on March 16, 1926.

During [[World War II]], the first guided rocket, the [[V-2]], was developed and employed as a weapon by [[Nazi Germany]]. During a test flight in June 1944, one such rocket reached space at an altitude of {{convert|189|km|nmi|sp=us|abbr=off}}, becoming the first human-made object to reach space.<ref>{{cite book|first=Lucy |last=Rogers|title=It's ONLY Rocket Science: An Introduction in Plain English|url=https://books.google.com/books?id=75b84eC-ulsC&pg=PA25|year=2008|publisher=Springer Science & Business Media|isbn=978-0-387-75377-5|page=25}}</ref> At the end of World War II, most of the V-2 rocket team, including its head, [[Wernher von Braun]], surrendered to the United States, and were expatriated to work on American missiles at what became the [[Army Ballistic Missile Agency]], producing missiles such as [[Juno I]] and [[SM-65 Atlas|Atlas]]. The [[Soviet Union]], in turn, captured several V2 production facilities and built several replicas, with 5 of their 11 rockets successfully reaching their targets. (This was relatively consistent with Nazi Germany's success rate.)

The [[Soviet Union]] developed [[intercontinental ballistic missile]]s to carry [[nuclear weapon]]s as a counter measure to United States bomber planes in the 1950s. The Tsiolkovsky-influenced [[Sergey Korolev]] became the chief rocket designer, and derivatives of his [[R-7 Semyorka]] missiles were used to launch the world's first artificial Earth [[satellite]], [[Sputnik 1]], on October 4, 1957.

The U.S., after the launch of Sputnik and two embarrassing failures of [[Vanguard (rocket)|Vanguard rockets]], launched [[Explorer 1]] on February 1, 1958. Three years later, the USSR launched Vostok 1, carrying cosmonaut [[Yuri Gagarin]] into orbit. The US responded with the suborbital launch of [[Alan Shepard]] on May 5, 1961, and the orbital launch of [[Mercury-Atlas 6|John Glenn]] on February 20, 1962. These events were followed by a pledge from U.S. [[President John F. Kennedy]] to [[We choose to go to the Moon|go to the moon]] and the creation of the [[Gemini program|Gemini]] and [[Apollo program|Apollo]] programs. After successfully performing a rendezvous and docking and an [[Extravehicular activity|EVA]], the Gemini program ended just before the [[Apollo 1]] tragedy. Following multiple uncrewed test flights of the [[Saturn IB|Saturn 1B]] and the [[Saturn V]], the U.S. launched the crewed [[Apollo 7|Apollo 7 mission]] into [[Low Earth orbit|low Earth orbit]]. Shortly after its successful completion, the U.S. launched [[Apollo 8]] (first mission to orbit the Moon), [[Apollo 9]] (first Apollo mission to launch with both the [[Apollo CSM|CSM]] and the [[Lunar Excursion Module|LEM]]) and [[Apollo 10]] (first mission to nearly land on the Moon). These events culminated with the first crewed Moon landing, [[Apollo 11]], and six subsequent missions, five of which successfully landed on the Moon.

Spaceflight has been widely employed by numerous government and commercial entities for placing satellites into orbit around Earth for a broad range of purposes. Certain government agencies have also sent uncrewed spacecraft exploring space beyond the Moon and developed continuous crewed [[human presence in space]] with a series of [[space station]]s, ranging from the [[Salyut program|''Salyut'' program]] to the [[International Space Station]].