Editing Space Race (section)

== Human spaceflight, space treaties, interplanetary probes (1961–1968) ==
The period from 1961 to 1968 began with the first men sent to space, the first robotic explorations of other planets; with missions to Venus and Mars conducted by both the Soviet Union and the United States, robotic landings on the Moon, and the gestation of US ambition to land a man on the Moon. The 1960s saw significant advancements in crewed spaceflight by both Cold War adversaries, as well as the first nuclear detonation in space, research into anti-satellite technology, and the signing of historic international outer space treaties.

===First humans in space===
====Vostok====
{{Main|Vostok programme}}

[[File:Vostok spacecraft replica.jpg|thumb|upright=0.8|Replica of the [[Zenit (satellite)|Zenit]] and [[Vostok (spacecraft)|Vostok]] spacecraft bus]]

The Soviets designed their first human [[space capsule]] using the same [[spacecraft bus]] as their [[Zenit spy satellite]],<ref>{{Cite web|url=https://www.thespacereview.com/article/2844/1|title=Declassified documents offer a new perspective on Yuri Gagarin's flight|date=12 October 2015|author=[[Asif Siddiqi]]|archive-url=https://web.archive.org/web/20201213141408/https://www.thespacereview.com/article/2844/1|archive-date=13 December 2020|url-status=live}}</ref> forcing them to keep the details and true appearance secret until after the Vostok program was over. The craft consisted of a spherical descent module with a mass of {{convert|2.46|t|lb}} and a diameter of {{convert|2.3|m|ft|sp=us}}, with a cylindrical inner cabin housing the cosmonaut, instruments, and escape system; and a [[biconic]] instrument module with a mass of {{convert|2.27|t|lb}}, {{convert|2.25|m|ft|sp=us}} long and {{convert|2.43|m|ft|sp=us}} in diameter, containing the engine system and propellant. After reentry, the cosmonaut would eject at about {{convert|7000|m|ft|sp=us}} over the USSR and descend via parachute, while the capsule would land separately, because the descent module made an extremely rough landing that could have left a cosmonaut seriously injured.{{sfn|Hall|Shayler|2001|pp=149–57}} The "Vostok spaceship" was first displayed at the July 1961 [[Soviet air show|Tushino air show]], mounted on its launch vehicle's third stage, with the nose cone in place concealing the spherical capsule. A tail section with eight fins was added in an apparent attempt to confuse western observers. This also appeared on official commemorative stamps and a documentary.{{sfn|Gatland|1976|p=254}} The Soviets finally revealed the true appearance of their Vostok capsule at the April 1965 Moscow Economic Exhibition.<ref>{{Cite web |title=Soviet Space Deceptions - not so many after all! |url=http://www.svengrahn.pp.se/histind/Fakes/Fakes.htm |access-date=2024-12-08 |website=www.svengrahn.pp.se}}</ref>

[[File:The Soviet Union 1964 CPA 3014 stamp (Space Exploration. Gagarin and Vostok 1) small resolution.jpg|thumb|left|A 1964 Stamp with [[Yuri Gagarin]], and an intentionally inaccurate Vostok]]

On April 12, 1961, the USSR surprised the world by launching [[Yuri Gagarin]] into a single, 108-minute orbit around the Earth in a craft called [[Vostok 1]].{{sfn|Hall|Shayler|2001|pp=149–57}} They dubbed Gagarin the first [[cosmonaut]], roughly translated from Russian and Greek as "sailor of the universe". Gagarin's capsule was flown in automatic mode, since doctors did not know what would happen to a human in the weightlessness of space; but Gagarin was given an envelope containing the code that would unlock manual control in an emergency.{{sfn|Hall|Shayler|2001|pp=149–57}}

Gagarin became a national hero of the Soviet Union and the Eastern Bloc, and a worldwide celebrity. Moscow and other cities in the USSR held mass demonstrations, the scale of which was second only to the [[Moscow Victory Parade of 1945|World War II Victory Parade of 1945]].<ref>Pervushin (2011), [https://books.google.com/books?id=kMGlvz53P3cC&dq=%D0%B4%D0%B5%D0%BC%D0%BE%D0%BD%D1%81%D1%82%D1%80%D0%B0%D1%86%D0%B8%D0%B8+%D0%B2+%D0%B4%D0%B5%D0%BD%D1%8C+%D0%BA%D0%BE%D1%81%D0%BC%D0%BE%D0%BD%D0%B0%D0%B2%D1%82%D0%B8%D0%BA%D0%B8&pg=PT488 7.1 Гражданин мира]</ref> April 12 was declared [[Cosmonautics Day]] in the USSR, and is celebrated today in Russia as one of the official "Commemorative Dates of Russia."<ref name="32FZ">{{Cite Russian law
|ru_entity=Государственная Дума
|ru_type=Федеральный закон
|ru_number=32-ФЗ
|ru_date=13 марта 1995 г.
|ru_title=О днях воинской славы и памятных датах России
|ru_effective_date=со дня официального опубликования
|ru_published_in="Российская Газета", No. 52
|ru_published_date=15 марта 1995 г
|ru_url=http://ntc.duma.gov.ru/duma_na/asozd/asozd_text.php?code=22479
|ru_amendment_type=Федерального закона
|ru_amendment_number=59-ФЗ
|ru_amendment_date=10 апреля 2009 г
|ru_amendment_title=О внесении изменения в статью 1.1 федерального закона "О днях воинской славы и памятных датах России"
|en_entity=[[State Duma]]
|en_type=Federal Law
|en_number=32-FZ
|en_date=March 13, 1995
|en_title=On the Days of Military Glory and the Commemorative Dates in Russia
|en_effective_date=the day of the official publication
|en_url
|en_amendment_type=Federal Law
|en_amendment_number=59-FZ
|en_amendment_date=April 10, 2009
|en_amendment_title=On Amending Article&nbsp;1.1 of the Federal Law "On the Days of Military Glory and the Commemorative Dates in Russia"
}}</ref> In 2011, it was declared the International Day of Human Space Flight by the [[United Nations]].<ref>{{cite web |url=https://www.un.org/en/events/humanspaceflightday/ |title= UN Resolution A/RES/65/271, The International Day of Human Space Flight (12 April) |date=April 7, 2011 |access-date=January 19, 2015}}</ref>

The USSR demonstrated 24-hour launch pad turnaround and launched two piloted spacecraft, [[Vostok 3]] and [[Vostok 4]], in essentially identical orbits, on August 11 and 12, 1962.{{sfn|Hall|Shayler|2001|pp=183, 192}} The two spacecraft came within approximately {{convert|6.5|km|nmi|sp=us|abbr=off}} of one another, close enough for radio communication,{{sfn|Gatland|1976|pp=117–18}} but then drifted as far apart as {{convert|2850|km|nmi|sp=us|abbr=off}}. The Vostok had no maneuvering rockets to keep the two craft a controlled distance apart.{{sfn|Hall|Shayler|2001|pp=185–91}} Vostok 4 also set a record of nearly four days in space. The first woman, [[Valentina Tereshkova]], was launched into space on [[Vostok 6]] on June 16, 1963,{{sfn|Hall|Shayler|2001|pp=194–218}} as (possibly) a medical experiment. She was the only one to fly of a small group of female parachutist factory workers (unlike the male cosmonauts who were military test pilots),<ref>{{cite web|title=Kamanin diaries, April 16, 1965|url=http://www.astronautix.com/k/kamanindiaries.html|publisher=Astronautix.com|access-date=January 8, 2023}}</ref> chosen by the head of cosmonaut training because he read a tabloid article about the "[[Mercury 13]]" group of women wanting to become astronauts, and got the mistaken idea that NASA was actually entertaining this.{{sfn|Burgess|Hall|2009|p=229}}{{sfn|Hall|Shayler|2001|pp=194–218}} Five months after her flight, Tereshkova married [[Vostok 3]] cosmonaut [[Andriyan Nikolayev]],<ref>{{cite journal|first=Tamara|last=Eidelman|title=A Cosmic Wedding|journal=Russian Life|year=2013|volume=56|issue=6|pages=22–25}}</ref> and they had a daughter.<ref>{{cite book|title=The 'First Lady of Space': In Her Own Words|publisher=SpaceHistory101.com Press|year=2015|last1=Nikolaeva-Tereshkova|first1=Valentina Vladimirovna|isbn=978-1-887022-99-6|chapter=Preface|pages=4–7|location=Bethesda, MD|oclc=930799309|ref={{harvid|"Preface"|2003}}}}</ref>

====Mercury====
{{Main|Project Mercury}}

[[File:Mercury Spacecraft.png|thumb|left|Cutaway of the Mercury capsule]]

The US Air Force had been developing a program to launch the first man in space, named [[Man in Space Soonest]]. This program studied several different types of one-man space vehicles, settling on a [[space capsule|ballistic re-entry capsule]] launched on a derivative [[Atlas LV-3B|Atlas missile]], and selecting a group of nine candidate pilots. After NASA's creation, the program was transferred over to the civilian agency's [[Space Task Group]] and renamed Project Mercury on November 26, 1958. The Mercury spacecraft was designed by the STG's chief engineer [[Maxime Faget]]. NASA selected a new group of [[astronaut]] (from the Greek for "star sailor") candidates from [[United States Navy|Navy]], [[United States Air Force|Air Force]] and [[United States Marine Corps|Marine]] test pilots, and narrowed this down to [[Mercury Seven|a group of seven]] for the program. Capsule design and astronaut training began immediately, working toward preliminary suborbital flights on the [[Mercury-Redstone Launch Vehicle|Redstone missile]], followed by orbital flights on the Atlas. Each flight series would first start unpiloted, then carry a non-human primate, then finally humans.<ref>{{Cite web |date=2008-10-01 |title=In the Beginning: Project Mercury - NASA |url=https://www.nasa.gov/missions/project-mercury/in-the-beginning-project-mercury/ |access-date=2024-12-10 |language=en-US}}</ref>

The Mercury spacecraft's principal designer was [[Maxime Faget]], who started research for human spaceflight during the time of the NACA.{{sfn|Catchpole|2001|p=150}} It consisted of a conical capsule with a cylindrical pack of three solid-fuel [[retro-rocket]]s strapped over a [[beryllium]] or [[fiberglass]] [[heat shield]] on the blunt end. Base diameter at the blunt end was {{convert|6.0|ft}} and length was {{convert|10.8|ft}}; with the launch escape system added, the overall length was {{convert|25.9|ft}}.{{sfn|Catchpole|2001|p=131}} With {{convert|100|ft3|m3}} of habitable volume, the capsule was just large enough for a single astronaut.{{sfn|Swenson|Grimwood|Alexander|1966|p=47}} The first suborbital spacecraft weighed {{convert|3000|lb}}; the heaviest, Mercury-Atlas 9, weighed {{convert|3000|lb}} fully loaded.{{sfn|Swenson|Grimwood|Alexander|1966|p=490}} On reentry, the astronaut would stay in the craft through splashdown by parachute in the Atlantic Ocean.

[[File:Alan Shepard during Mercury-Redstone 3.jpg|thumb|right|[[Alan Shepard]], the first American in space, 1961]]

On May 5, 1961, [[Alan Shepard]] became the first American in space, launching in a [[sub-orbital spaceflight|ballistic trajectory]] on [[Mercury-Redstone 3]], in a spacecraft he named ''Freedom 7''.{{sfn|Schefter|1999|pp=138–43}} Though he did not achieve orbit like Gagarin, he was the first person to exercise manual control over his spacecraft's [[Orientation (geometry)|attitude]] and [[retro-rocket]] firing.{{sfn|Gatland|1976|pp=153–54}} After his successful return, Shepard was celebrated as a national hero, honored with parades in Washington, New York and Los Angeles, and received the [[NASA Distinguished Service Medal]] from [[President of the United States|President]] [[John F. Kennedy]].<ref>{{cite AV media |year=1961 |title=As World Watched. Spaceman Hailed After U.S. Triumph, 1961/05/08 (1961) |medium=Motion picture |url=https://archive.org/details/1961-05-08_As_World_Watched|access-date=February 20, 2012 |publisher=[[Universal Newsreel|Universal-International Newsreel]] |oclc=709678549}}</ref>

American [[Gus Grissom|Virgil "Gus" Grissom]] repeated Shepard's suborbital flight in ''[[Mercury-Redstone 4|Liberty Bell 7]]'' on July 21, 1961.<ref>{{Cite news |last=Neuman |first=Scott |date=2021-07-22 |title=A New Analysis May Have Just Solved A Decades-Old Mystery Of The Space Race |language=en |work=NPR |url=https://www.npr.org/2021/07/22/1019254674/gus-grissom-liberty-bell-mercury-the-right-stuff |access-date=2022-12-13}}</ref> Almost a year after the Soviet Union put a human into orbit, astronaut [[John Glenn]] became the first American to orbit the Earth, on February 20, 1962.{{sfn|Schefter|1999|pp=156–164}} His [[Mercury-Atlas 6]] mission completed three orbits in the ''Friendship 7'' spacecraft, and splashed down safely in the Atlantic Ocean, after a tense reentry, due to what falsely appeared from the telemetry data to be a loose heat-shield.{{sfn|Schefter|1999|pp=156–164}} On February 23, 1962, President Kennedy awarded Glenn with the [[NASA Distinguished Service Medal]] in a ceremony at [[Cape Canaveral Air Force Station]].<ref>{{cite web|url=https://www.nasa.gov/image-feature/president-john-f-kennedy-pins-nasa-distinguished-service-medal-on-john-glenn|title=President John F. Kennedy Pins NASA Distinguished Service Medal on John Glenn|publisher=NASA|access-date=July 30, 2018 |date=May 13, 2015}}</ref> As the first American in orbit, Glenn became a national hero, and received a [[ticker-tape parade]] in New York City, reminiscent of that given for [[Charles Lindbergh]].

The United States launched three more Mercury flights after Glenn's: ''[[Aurora 7]]'' on May 24, 1962, duplicated Glenn's three orbits, ''[[Mercury-Atlas 8|Sigma 7]]'' on October 3, 1962, six orbits, and ''[[Faith 7]]'' on May 15, 1963, 22 orbits (32.4 hours), the maximum capability of the spacecraft. NASA at first intended to launch one more mission, extending the spacecraft's endurance to three days, but since this would not beat the Soviet record, it was decided instead to concentrate on developing Project Gemini.<ref>{{cite book|last=Catchpole|first=John|title=Project Mercury – NASA's First Manned Space Programme|date=2001|pages=385–386|publisher=Springer Praxis|location=Chichester, UK|isbn=1-85233-406-1|url-access=registration|url=https://archive.org/details/projectmercuryna0000catc}}</ref>

===Kennedy aims for a crewed Moon landing===
{{Main|Apollo program}}

{{see also|Moon landing}}

{{Quote box
| title = 
| quote = These are extraordinary times. And we face an extraordinary challenge. Our strength, as well as our convictions, have imposed upon this nation the role of leader in freedom's cause.

... if we are to win the battle that is now going on around the world between freedom and tyranny, the dramatic achievements in space which occurred in recent weeks should have made clear to us all, as did the Sputnik in 1957, the impact of this adventure on the minds of men everywhere, who are attempting to make a determination of which road they should take. ... Now it is time to take longer strides{{snd}}time for a great new American enterprise{{snd}}time for this nation to take a clearly leading role in space achievement, which in many ways may hold the key to our future on Earth.

... Recognizing the head start obtained by the Soviets with their large rocket engines, which gives them many months of lead-time, and recognizing the likelihood that they will exploit this lead for some time to come in still more impressive successes, we nevertheless are required to make new efforts on our own.

... I believe that this nation should commit itself to achieving the goal, before this decade is out, of landing a man on the Moon and returning him safely to the Earth. No single space project in this period will be more impressive to mankind, or more important for the long-range exploration of space, and none will be so difficult or expensive to accomplish.

... Let it be clear that I am asking the Congress and the country to accept a firm commitment to a new course of action—a course which will last for many years and carry very heavy costs: 531 million dollars in fiscal '62—an estimated seven to nine billion dollars additional over the next five years. If we are to go only half way, or reduce our sights in the face of difficulty, in my judgment it would be better not to go at all.
| source = John F. Kennedy,<br />Special Message to Congress on Urgent National Needs, May 25, 1961<ref name="Special Message">{{cite AV media |people=Kennedy, John F. |date=May 25, 1961 |title=Special Message to Congress on Urgent National Needs |medium=Motion picture (excerpt) |url=http://www.jfklibrary.org/Asset-Viewer/xzw1gaeeTES6khED14P1Iw.aspx |access-date=August 1, 2013 |publisher=John F. Kennedy Presidential Library and Museum |location=Boston, MA |id=Accession Number: TNC:200; Digital Identifier: TNC-200-2}}</ref>
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Before Gagarin's flight, US President [[John F. Kennedy#Space policy|John F. Kennedy]]'s support for America's piloted space program was lukewarm. [[Jerome Wiesner]] of MIT, who served as a science advisor to presidents Eisenhower and Kennedy, and himself an opponent of sending humans into space, remarked, "If Kennedy could have opted out of a big space program without hurting the country in his judgment, he would have."<ref>Quoted in John M. Logsdon, ''The Decision to Go to the Moon: Project Apollo and the National Interest'' (Cambridge, MA: MIT Press, 1970) p. 111.</ref> As late as March 1961, when NASA administrator James E. Webb submitted a budget request to fund a Moon landing before 1970, Kennedy rejected it because it was simply too expensive.<ref>[[David E. Bell]], Memorandum for the President, "National Aeronautics and Space Administration Budget Problem", March 22, 1961, NASA Historical Reference Collection; U.S. Congress, House, Committee of Science and Astronautics, ''NASA Fiscal 1962 Authorization'', ''Hearings'', 87th Cong., 1st. sess., 1962, pp. 203, 620; Logsdon, Decision to go to the Moon, pp. 94–100.</ref> Some were surprised by Kennedy's eventual support of NASA and the space program because of how often he had attacked the Eisenhower administration's inefficiency during the election.<ref>Wolfe, Tom. The Right Stuff. New York: Picador, 1979.(179)</ref>

Gagarin's flight changed this; now Kennedy sensed the humiliation and fear on the part of the American public over the Soviet lead. Additionally, the [[Bay of Pigs invasion]], planned before his term began but executed during it, was an embarrassment to his administration due to the colossal failure of the US forces.<ref>Roger D. Launius and Howard E. McCurdy, eds, Spaceflight and the Myth of Presidential Leadership (Champaign, IL: University of Illinois Press, 1997), 56.</ref> Looking for something to save political face, he sent a memo dated April 20, 1961, to Vice President [[Lyndon B. Johnson]], asking him to look into the state of America's space program, and into programs that could offer [[NASA]] the opportunity to catch up.<ref>Kennedy to Johnson,[http://www.hq.nasa.gov/office/pao/History/Apollomon/apollo1.pdf "Memorandum for Vice President,"] {{Webarchive|url=https://web.archive.org/web/20170131222858/http://www.hq.nasa.gov/office/pao/History/Apollomon/apollo1.pdf |date=January 31, 2017 }} April 20, 1961.</ref> The two major options at the time were either the establishment of an Earth orbital space station or a crewed landing on the Moon. Johnson, in turn, consulted with von Braun, who answered Kennedy's questions based on his estimates of US and Soviet rocket lifting capability.<ref>{{cite web|title=Memo, Wernher von Braun to the Vice President of the United States|last1=von Braun|first1=Wernher|url=http://www.hq.nasa.gov/office/pao/History/Apollomon/apollo3.pdf|date=April 29, 1961|publisher=NASA|access-date=January 8, 2023|archive-date=May 13, 2005|archive-url=https://web.archive.org/web/20050513043040/http://www.hq.nasa.gov/office/pao/History/Apollomon/apollo3.pdf}}</ref> Based on this, Johnson responded to Kennedy, concluding that much more was needed to reach a position of leadership, and recommending that the crewed Moon landing was far enough in the future that the US had a fighting chance to achieve it first.<ref name="lbjmemo">{{cite web|title=Memo, Johnson to Kennedy, Evaluation of Space Program |last1=Johnson|first1=Lyndon B.|url=https://www.hq.nasa.gov/office/pao/History/Apollomon/apollo2.pdf|date= April 28, 1961|access-date=January 8, 2023}}</ref>

Kennedy ultimately decided to pursue what became the Apollo program, and on May 25 took the opportunity to ask for Congressional support in a Cold War speech titled "Special Message on Urgent National Needs". {{Cws |title=Full text |link=Special Message to the Congress on Urgent National Needs|nobullet=yes}}
He justified the program in terms of its importance to national security, and its focus of the nation's energies on other scientific and social fields.<ref name="wechoose">{{cite web
|last=Kennedy
|first=John F.
|url=http://www.jfklibrary.org/Historical+Resources/Archives/Reference+Desk/Speeches/JFK/003POF03SpaceEffort09121962.htm
|title=Address at Rice University on the Nation's Space Effort
|work=Historical Resources
|publisher=John F. Kennedy Presidential Library and Museum
|date=September 12, 1962
|access-date=August 16, 2010
|archive-date=May 6, 2010
|archive-url=https://web.archive.org/web/20100506113709/http://www.jfklibrary.org/Historical%2BResources/Archives/Reference%2BDesk/Speeches/JFK/003POF03SpaceEffort09121962.htm

}}</ref> He rallied popular support for the program in his "[[We choose to go to the Moon]]" speech, on September 12, 1962, before a large crowd at [[Rice University]] Stadium, in Houston, Texas, near the construction site of the new [[Lyndon B. Johnson Space Center]] facility.<ref name="wechoose" /> {{Cws |title=Full text |link=We choose to go to the moon|nobullet=yes}}

Khrushchev responded to Kennedy's challenge with silence, refusing to publicly confirm or deny the Soviets were pursuing a "Moon race".<ref>{{Cite web |last1=Magazine |first1=Smithsonian |last2=French |first2=Francis |title=Imagining a World Where Soviets and Americans Joined Hands on the Moon |url=https://www.smithsonianmag.com/history/imagining-world-where-soviets-and-americans-joined-hands-moon-180972692/ |access-date=2024-12-10 |website=Smithsonian Magazine |language=en}}</ref> As later disclosed, the Soviet Union secretly pursued [[Soviet crewed lunar programs|two competing crewed lunar programs]]. Soviet Decree 655–268, ''On Work on the Exploration of the Moon and Mastery of Space'', issued in August 1964, directed [[Vladimir Chelomei]] to develop a Moon flyby program with a projected first flight by the end of 1966, and directed Korolev to develop the Moon landing program with a first flight by the end of 1967.<ref name="Stabell2012">{{cite book|first1=Oddbjørn |last1=Engvold |first2=Bozena |last2=Czerny|first3=John|last3=Lattanzio |first4=Rolf |last4=Stabell|title=Astronomy and Astrophysics – Volume I|url=https://books.google.com/books?id=DXgvCwAAQBAJ&pg=PA228|date=30 November 2012|publisher=Encyclopedia of Life Support Systems (EOLSS)|isbn=978-1-78021-000-1|pages=228–}}</ref> In September 1965, Chelomei's flyby program was assigned to Korolev, who redesigned the cislunar mission to use his own [[Soyuz 7K-L1]] spacecraft and Chelomei's [[Proton (rocket)|Proton rocket]]. After Korolev's death in January 1966, another government decree of February 1967 moved the first crewed flyby to mid-1967, and the first crewed landing to the end of 1968.<ref name=":9">{{Cite web |title=THE SOVIET MANNED LUNAR PROGRAM |url=https://spp.fas.org/eprint/lindroos_moon1.htm |access-date=2024-12-10 |website=spp.fas.org}}</ref><ref>{{Cite web |title=Yes, There Was a Moon Race |url=https://www.airandspaceforces.com/article/0490moon/ |access-date=2024-12-10 |website=Air & Space Forces Magazine |language=en-US}}</ref>

====Proposed joint US-USSR program====
After a first US-USSR [[Hugh Dryden|Dryden]]-[[Anatoly Blagonravov|Blagonravov]] agreement and cooperation on the [[Project Echo|Echo II balloon satellite]] in 1962,<ref name="technology" /> President Kennedy proposed on September 20, 1963, in a speech before the [[United Nations General Assembly]], that the United States and the Soviet Union join forces in an effort to reach the Moon.<ref name="JFK Library 1963">{{cite web | title=Address before the 18th General Assembly of the United Nations, September 20, 1963 | website=JFK Library | date=1963-09-20 | url=https://www.jfklibrary.org/archives/other-resources/john-f-kennedy-speeches/united-nations-19630920 | access-date=2021-11-16 |quote="''Finally, in a field where the United States and the Soviet Union have a special capacity—in the field of space—there is room for new cooperation, for further joint efforts in the regulation and exploration of space. I include among these possibilities a joint expedition to the moon. Space offers no problems of sovereignty; by resolution of this Assembly, the members of the United Nations have foresworn any claim to territorial rights in outer space or on celestial bodies, and declared that international law and the United Nations Charter will apply. Why, therefore, should man's first flight to the moon be a matter of national competition? Why should the United States and the Soviet Union, in preparing for such expeditions, become involved in immense duplications of research, construction, and expenditure? Surely we should explore whether the scientists and astronauts of our two countries—indeed of all the world—cannot work together in the conquest of space, sending someday in this decade to the moon not the representatives of a single nation, but the representatives of all of our countries.''"}}</ref> Kennedy thus changed his mind regarding the desirability of the space race, preferring instead to ease tensions with the Soviet Union by cooperating on projects such as a joint lunar landing.<ref>Stone, Oliver and Peter Kuznick, "The Untold History of the United States" (Gallery Books, 2012), p. 320</ref> Soviet Premier [[Nikita Khrushchev]] initially rejected Kennedy's proposal.<ref name="spacedaily">{{cite web|last=Sietzen|first=Frank|title=Soviets Planned to Accept JFK's Joint Lunar Mission Offer|url=http://www.spacedaily.com/news/russia-97h.html|work="SpaceCast News Service" Washington DC|date=October 2, 1997 |access-date=February 1, 2011}}</ref> However, on October 2, 1997, it was reported that Khrushchev's son [[Sergei Khrushchev|Sergei]] claimed Khrushchev was poised to accept Kennedy's proposal at the time of [[assassination of John F. Kennedy|Kennedy's assassination]] on November 22, 1963. During the next few weeks he reportedly concluded that both nations might realize cost benefits and technological gains from a joint venture, and decided to accept Kennedy's offer based on a measure of rapport during their years as leaders of the world's two superpowers, but changed his mind and dropped the idea since he lacked the same trust for Kennedy's successor, Lyndon Johnson.<ref name="spacedaily" />

Some cooperation in robotic space exploration nevertheless did take place,<ref>{{cite web |author=Sagdeev, Roald |author2=Eisenhower, Susan |date=28 May 2008 |title=United States-Soviet Space Cooperation during the Cold War |url=http://www.nasa.gov/50th/50th_magazine/coldWarCoOp.html |access-date=19 July 2009 |archive-date=December 25, 2018 |archive-url=https://web.archive.org/web/20181225032051/https://www.nasa.gov/50th/50th_magazine/coldWarCoOp.html |url-status=dead }}</ref> such as a combined ''[[Venera 4]]''–''[[Mariner 5]]'' data analysis under a joint Soviet–American working group of [[COSPAR]] in 1969, allowing a more complete drawing of the profile of the [[atmosphere of Venus]].<ref>{{cite journal|doi=10.1016/0019-1035(69)90052-9|author=[[Carl Sagan]]|date=September 1969|title=The COSPAR Meetings in Prague|journal=[[Icarus (journal)|Icarus]]|volume=11|issue=2|pages=268–272|bibcode=1969Icar...11..268S}}</ref><ref>{{cite conference |title=Report on the Activities of the COSPAR Working Group VII |page=94 |date=11–24 May 1969 |location=Prague, Czechoslovakia |book-title=Preliminary Report, COSPAR Twelfth Plenary Meeting and Tenth International Space Science Symposium |publisher=[[National Academy of Sciences]]}}</ref> Eventually the [[Apollo–Soyuz mission]] was realized afterall, which furthermore laid the foundations for the [[Shuttle-Mir program]] and the [[ISS]].

As President, Johnson steadfastly pursued the Gemini and Apollo programs, promoting them as Kennedy's legacy to the American public. One week after Kennedy's death, he issued [[s:Executive Order 11129|Executive Order 11129]] renaming the Cape Canaveral and [[Kennedy Space Center|Apollo launch]] facilities after Kennedy.

=== Lunar probes and robotic landers ===

[[File:First Photo from the Surface of the Moon.jpg|thumb|First photo of the surface of the Moon, taken by Luna 9]]

The [[Ranger program]], started in 1959 by NASA's [[Jet Propulsion Laboratory]], aimed to conduct hard impacts on the Moon and had its first success in 1962, after three failures due to launch aborts ([[Ranger 1]] and [[Ranger 2]]) and a failure to reach the Moon ([[Ranger 3]]), when the {{convert|730|lb|kg|adj=on}} [[Ranger 4]] became the first US spacecraft to reach the Moon, but its [[photovoltaic module|solar panel]]s and navigational system failed near the Moon and it impacted the far side without returning any scientific data. [[Ranger 5]] ran out of power and missed the Moon by {{convert|725|km|nmi|sp=us}} on October 21, 1962. The first successful Ranger mission was the {{convert|806|lb|kg|adj=on}} Block III [[Ranger 7]] which impacted on July 31, 1964.{{sfn|Siddiqi|2018|p=41}} Ranger had three successful impacts out of nine attempts.<ref>{{cite web |title=National Space Science Data Center – Ranger 6 |url=https://nssdc.gsfc.nasa.gov/nmc/spacecraft/display.action?id=1964-007A |access-date=June 19, 2012 |publisher=National Air and Space Administration |ref=nssdc1964-007A}}</ref>

In 1963, the Soviet Union's "2nd Generation" Luna programme was less successful than the earlier Luna probes; [[Luna 4]], [[Luna 5]], [[Luna 6]], [[Luna 7]], and [[Luna 8]] were all met with mission failures. However, in 1966 the [[Luna 9]] achieved the first soft-landing on the Moon, and successfully transmitted photography from the surface.<ref>{{Cite web |title=Luna 9 |url=https://nssdc.gsfc.nasa.gov/nmc/spacecraft/display.action?id=1966-006A |website=nssdc.gsfc.nasa.gov}}</ref> [[Luna 10]] marked the first man-made object to establish an orbit around the Moon,<ref>{{Cite web |title=Luna 10 |url=https://nssdc.gsfc.nasa.gov/nmc/spacecraft/display.action?id=1966-027A |website=nssdc.gsfc.nasa.gov}}</ref> followed by [[Luna 11]], [[Luna 12]], and [[Luna 14]] which also successfully established orbits. [[Luna 12]] was able to transmit detailed photography of the surface from orbit.<ref>{{Cite web |title=Luna 12 |url=https://nssdc.gsfc.nasa.gov/nmc/spacecraft/display.action?id=1966-094A |website=nssdc.gsfc.nasa.gov}}</ref> Luna 10, 12, and [[Luna 14]] conducted [[Gamma ray spectrometry]] of the Moon, among other tests.

The [[Zond program]]me was orchestrated alongside the ''Luna'' programme with [[Zond 1]] and [[Zond 2]] launching in 1964, intended as flyby missions, however both failed.<ref>{{Cite web |title=Zond 1 |url=https://nssdc.gsfc.nasa.gov/nmc/spacecraft/display.action?id=1964-016D |website=nssdc.gsfc.nasa.gov}}</ref><ref>{{Cite web |title=Zond 2 |url=https://nssdc.gsfc.nasa.gov/nmc/spacecraft/display.action?id=1964-078C |website=nssdc.gsfc.nasa.gov}}</ref> [[Zond 3]] however was successful, and transmitted high quality photography from the far side of the moon.<ref>{{Cite web |title=Zond 3 |url=https://nssdc.gsfc.nasa.gov/nmc/spacecraft/display.action?id=1965-056A |website=nssdc.gsfc.nasa.gov}}</ref><ref>{{Cite web |title=Zond 3 photography |url=https://nssdc.gsfc.nasa.gov/nmc/experiment/display.action?id=1965-056A-01 |website=nssdc.gsfc.nasa.gov}}</ref>

[[File:Moon landing map.jpg|thumb|left|The near side of the Moon, showing Luna probe landing locations with red triangles, Surveyor in yellow, and the later Apollo landings in Green]]

Partly to aid the Apollo missions, the [[Surveyor program]] was conducted by NASA, with five successful soft landings out of seven attempts from 1966 to 1968. The [[Lunar Orbiter program]] had five successes out of five attempts in 1966–1967.<ref>{{Cite web |title=Lunar Orbiter to the Moon (1966 - 1967) |url=https://nssdc.gsfc.nasa.gov/planetary/lunar/lunarorb.html |access-date=2024-11-23 |website=nssdc.gsfc.nasa.gov}}</ref><ref>{{Cite web |title=Lunar Orbiter Program - NASA Science |url=https://science.nasa.gov/mission/lunar-orbiters-program/ |access-date=2024-11-23 |website=science.nasa.gov |date=September 11, 2023 |language=en-US}}</ref>

In late 1966, [[Luna 13]] became the third spacecraft to make a soft-landing on the Moon, with the American [[Surveyor 1]] having now taken second. Luna 13 made use of inflatable air-bags to soften it's landing.<ref name="Luna 13">{{Cite web |title=Luna 13 |url=https://nssdc.gsfc.nasa.gov/nmc/spacecraft/display.action?id=1966-116A |website=nssdc.gsfc.nasa.gov}}</ref><ref>{{Cite web |date=2016-12-24 |title=The Mission of Luna 13: Christmas 1966 on the Moon |url=https://www.drewexmachina.com/2016/12/24/the-mission-of-luna-13-christmas-1966-on-the-moon/ |access-date=2024-12-09 |website=Drew Ex Machina |language=en-US}}</ref><ref>{{Cite web |title=USSR - Luna 13 |url=https://www.orbitalfocus.uk/Diaries/Luna/Luna13.php |access-date=2024-12-09 |website=www.orbitalfocus.uk}}</ref> Surveyor 1 was a 995&nbsp;kg lander, notably larger than the 112&nbsp;kg Luna 13 E-6M lander.<ref name="Luna 13"/><ref>{{Cite web |title=Luna E-6M |url=http://www.astronautix.com/l/lunae-6m.html |access-date=2024-12-09 |website=www.astronautix.com}}</ref> Surveyor 1 was equipped with a [[Doppler velocity sensor|Doppler velocity sensing system]] that fed information into the spacecraft computer to implement a controllable descent to the surface. Each of the three landing pads also carried aircraft-type shock absorbers and strain gauges to provide data on landing characteristics, important for future Apollo missions.<ref>{{Cite web |title=Surveyor 1 - NASA Science |url=https://science.nasa.gov/mission/surveyor-1/ |access-date=2024-12-09 |website=science.nasa.gov |date=December 27, 2017 |language=en-US}}</ref><ref>{{Cite web |title=Surveyor 1 - Moon Missions - NASA's Jet Propulsion Laboratory |url=https://www.jpl.nasa.gov/missions/surveyor-1/ |access-date=2024-12-09 |website=NASA Jet Propulsion Laboratory (JPL) |language=en-US}}</ref>

[[Surveyor 3]], which successfully touched down on the Moon April 20, 1967, carried a 'surface sampler' which facilitated tests of the Lunar soil. Based on these experiments, scientists concluded that lunar soil had a consistency similar to wet sand, with a bearing strength of about 10 pounds per square inch (0.7 kilograms per square centimeter, or 98 kilopascals), which was concluded to be solid enough to support an Apollo Lunar Module.<ref>{{Cite web |title=Surveyor 3 - NASA Science |url=https://science.nasa.gov/mission/surveyor-3/ |access-date=2024-12-09 |website=science.nasa.gov |date=December 27, 2017 |language=en-US}}</ref> The Surveyor 3 lander would be later visited by [[Apollo 12]] astronauts.<ref>{{Cite web |title=Astronauts Pay a Visit to Surveyor 3 - NASA |url=https://www.nasa.gov/image-article/astronauts-pay-visit-surveyor-3/ |access-date=2024-12-09 |language=en-US}}</ref>

On Nov. 17, 1967, before mission termination, [[Surveyor 6]] fired its thrusters for 2.5 seconds, becoming the first spacecraft launched from the lunar surface. It rose about 10 feet (3 meters) before landing 8 feet (2.5 meters) west of its original spot. Cameras then examined the original landing site to assess the soil's properties.<ref>{{Cite web |title=Surveyor 6 - NASA Science |url=https://science.nasa.gov/mission/surveyor-6/ |access-date=2024-12-09 |website=science.nasa.gov |date=December 27, 2017 |language=en-US}}</ref><ref>{{Cite web |title=Surveyor 6 |url=https://nssdc.gsfc.nasa.gov/nmc/spacecraft/display.action?id=1967-112A |website=nssdc.gsfc.nasa.gov}}</ref>

=== First interplanetary probes ===
From the early 1960s both Cold War adversaries almost simultaneously initiated their own programmes which sought to reach other planets in the [[Solar System]] for the first time; namely Venus and Mars.

==== Venus ====
[[File:Mariner 2.jpg|thumb|Artist's impression of Mariner 2, the first successful interplanetary spacecraft]]

Venus was of great interest in the field of [[planetary science]] due to its thick and opaque atmosphere, the atmospheres of other planets being a novel area of research at the time.

In 1961 the [[Venera|Venera Programme]] was initiated by the Soviet Union, with the launch of [[Venera 1]]. The programme would go on to mark many firsts in the exploration of another planet. Despite the later successes however, [[Venera 1]] and [[Venera 2]], intended to flyby Venus, resulted in failure due to losses of contact.<ref>{{Cite web |title=Venus: Exploration - NASA Science |url=https://science.nasa.gov/venus/exploration/ |access-date=2024-12-10 |website=science.nasa.gov |date=November 9, 2017 |language=en-US}}</ref><ref>{{Cite web |title=Venera 1 |url=https://nssdc.gsfc.nasa.gov/nmc/spacecraft/display.action?id=1961-003A |website=nssdc.gsfc.nasa.gov}}</ref>

NASA would then initiate the [[Mariner program]] with the launch of [[Mariner 1]] and [[Mariner 2]]. Mariner 1 failed shortly after launch,<ref>{{Cite web |title=Mariner 1 - NASA Science |url=https://science.nasa.gov/mission/mariner-1/ |access-date=2024-11-21 |website=science.nasa.gov |date=December 8, 2017 |language=en-US}}</ref> however Mariner 2 would become the first man-made object to flyby another planet in December 1962 when the probe passed by Venus.<ref>{{Cite web |title=Mariner 2 - NASA Science |url=https://science.nasa.gov/mission/mariner-2/ |access-date=2024-11-21 |website=science.nasa.gov |date=December 20, 2017 |language=en-US}}</ref><ref>{{Cite web |title=Mariner 2 |url=https://www.jpl.nasa.gov/missions/mariner-2/ |access-date=2024-11-21 |website=NASA Jet Propulsion Laboratory (JPL) |language=en-US}}</ref>

Later in 1965/66, [[Venera 3]], marked the first time a man-made object made contact with another planet after it impacted Venus on March 1, 1966, despite operational difficulties resulting in loss of contact with the craft.<ref>{{Cite web |title=Venera 3 |url=https://nssdc.gsfc.nasa.gov/nmc/spacecraft/display.action?id=1965-092A |website=nssdc.gsfc.nasa.gov}}</ref>

In 1967, [[Mariner 5]] flew by Venus and conducted atmospheric analysis.<ref>{{Cite web |title=Mariner 5 - NASA Science |url=https://science.nasa.gov/mission/mariner-5/ |access-date=2024-12-10 |website=science.nasa.gov |date=December 20, 2017 |language=en-US}}</ref>

==== Mars ====
In 1964, NASA's [[Mariner 4]] became the first successful Mars flyby, transmitting 21 pictures of the planets surface. This was followed by [[Mariner 6 and 7]] in 1969.

===First crewed spacecraft===
Focused by the commitment to a Moon landing, in January 1962 the US announced Project Gemini, a two-person spacecraft that would support the later three-person Apollo by developing the key spaceflight technologies of [[space rendezvous]] and [[docking and berthing of spacecraft|docking of two craft]], flight durations of sufficient length to go to the Moon and back, and [[extra-vehicular activity]] to perform work outside the spacecraft.<ref>{{cite web
 |last1       = Loff
 |first1      = Sarah
 |title       = Gemini: Stepping Stone to the Moon
 |url         = http://www.nasa.gov/mission_pages/gemini/#.VKi1GsaWt78
 |website     = Gemini: Bridge to the Moon
 |publisher   = National Aeronautics and Space Administration
 |access-date  = 2015-01-04
 |archive-url  = https://web.archive.org/web/20141221151510/http://www.nasa.gov/mission_pages/gemini/
 |archive-date = 2014-12-21
 |location    = Washington, DC
 |date        = 2013-10-21
 
}}</ref>{{sfn|Siddiqi|2003a|p=383}}

Meanwhile, Korolev had planned further long-term missions for the Vostok spacecraft, and had four Vostoks in various stages of fabrication in late 1963 at his [[S.P. Korolev Rocket and Space Corporation Energia|OKB-1]] facilities.{{sfn|Siddiqi|2003a|pp=384–86}} The Americans' announced plans for Gemini represented major advances over the Mercury and Vostok capsules, and Korolev felt the need to try to beat the Americans to many of these innovations.{{sfn|Siddiqi|2003a|pp=384–86}} He had already begun designing the Vostok's replacement, the next-generation [[Soyuz (spacecraft)|Soyuz]], a multi-cosmonaut spacecraft that had at least the same capabilities as the Gemini spacecraft.{{sfn|Schefter|1999|p=149}} Soyuz would not be available for at least three years, and it could not be called upon to deal with this new American challenge in 1964 or 1965.{{sfn|Schefter|1999|p=198}} Political pressure in early 1964{{snd}}which some sources claim was from Khrushchev while other sources claim was from other Communist Party officials{{snd}}pushed him to modify his four remaining Vostoks to beat the Americans to new space firsts in the size of flight crews, and the duration of missions.{{sfn|Siddiqi|2003a|pp=384–86}}

====Voskhod====
{{Main|Voskhod programme}}

[[File:Vostok and Voskhod crew seating.png|thumb|Korolev modified the one-person Vostok capsule into carrying three people, or two plus an airlock for spacewalk capability.]]

Korolev's conversion of his surplus Vostok capsules to the [[Voskhod spacecraft]] allowed the Soviet space program to beat the Gemini program in achieving the first spaceflight with a multi-person crew, and the first "spacewalk". Gemini took a year longer than planned to make its first flight, so [[Voskhod 1]] became the first spaceflight with a three-person crew on October 12, 1964.<ref>{{cite news
| title = Space Troika on Target
| author = Special
| agency = UPI
| newspaper = [[The Toronto Star]]
| publisher = [[Torstar]]
| location = Toronto
| date = October 13, 1964
| page = 1}}</ref> The USSR touted another "technological achievement" during this mission: it was the first space flight during which cosmonauts performed in a shirt-sleeve-environment.{{sfn|Schefter|1999|pp=199–200}} However, flying without spacesuits was not due to safety improvements in the Soviet spacecraft's environmental systems; rather this was because the craft's limited cabin space did not allow for spacesuits. Flying without spacesuits exposed the cosmonauts to significant risk in the event of potentially fatal cabin depressurization.{{sfn|Schefter|1999|pp=199–200}} This was not repeated until the US [[Apollo Command Module]] flew in 1968; the command module cabin was designed to transport three astronauts in a low pressure, pure oxygen [[shirt-sleeve environment]] while in space.

On March 18, 1965, about a week before the first piloted Project Gemini space flight, the USSR launched the two-cosmonaut [[Voskhod 2]] mission with [[Pavel Belyayev]] and [[Alexei Leonov]].<ref name="NYT650319">{{cite news
| title = Russian Floats in Space for 10 Minutes; Leaves Orbiting Craft With a Lifeline; Moscow Says Moon Trip Is 'Target Now'
| first = Henry
| last = Tanner
| url = https://www.nytimes.com/learning/general/onthisday/big/0318.html?scp=2&sq=Voskhod%202&st=cse
| newspaper = [[The New York Times]]
| location = New York
| date = March 19, 1965
| page = 1}}</ref> Voskhod 2's design modifications included the addition of an inflatable airlock to allow for [[extravehicular activity]] (EVA), also known as a spacewalk, while keeping the cabin pressurized so that the capsule's electronics would not overheat.{{sfn|Siddiqi|2003a|p=448}} Leonov performed the first-ever EVA as part of the mission.<ref name="NYT650319" /> A fatality was narrowly avoided when Leonov's spacesuit expanded in the vacuum of space, preventing him from re-entering the airlock.{{sfn|Schefter|1999|p=205}} To overcome this, he had to partially depressurize his spacesuit to a potentially dangerous level.{{sfn|Schefter|1999|p=205}} He succeeded in safely re-entering the spacecraft, but he and Belyayev faced further challenges when the spacecraft's atmospheric controls flooded the cabin with 45% pure oxygen, which had to be lowered to acceptable levels before re-entry.{{sfn|Siddiqi|2003a|pp=454-460}} The reentry involved two more challenges: an improperly timed retrorocket firing caused the Voskhod 2 to land {{convert|386|km|mi|sp=us}} off its designated target area, the city of [[Perm, Russia|Perm]]; and the instrument compartment's failure to detach from the descent apparatus caused the spacecraft to become unstable during reentry.{{sfn|Siddiqi|2003a|pp=454-460}}

By October 16, 1964, [[Leonid Brezhnev]] and a small cadre of high-ranking Communist Party officials deposed Khrushchev as Soviet government leader a day after Voskhod 1 landed, in what was called the "Wednesday conspiracy".<ref>{{cite news
| title = Kremlin summit probably greased skids for Mr. K
| last = Gayn
| first = Mark
| newspaper = [[The Toronto Star]]
| publisher = [[Torstar]]
| location = Toronto
| date = October 16, 1964
| page = 11}}</ref>
The new political leaders, along with Korolev, ended the technologically troublesome Voskhod program, canceling Voskhod 3 and 4, which were in the planning stages, and started concentrating on reaching the Moon.{{sfn|Siddiqi|2003a|pp=510–11}} Voskhod 2 ended up being Korolev's final achievement before his death on January 14, 1966, as it became the last of the space firsts that the USSR achieved during the early 1960s. According to historian Asif Siddiqi, Korolev's accomplishments marked "the absolute zenith of the Soviet space program, one never, ever attained since."{{sfn|Siddiqi|2003a|p=460}} There was a two-year pause in Soviet piloted space flights while Voskhod's replacement, the Soyuz spacecraft, was designed and developed.{{Sfn|Schefter|1999|p=207}}

==== Gemini ====
{{Main|Project Gemini}}

[[File:Gemini 7 in orbit - GPN-2006-000035.jpg|thumb|Rendezvous of Gemini 6 and 7, December 1965]]

Though delayed a year to reach its first flight, Gemini was able to take advantage of the USSR's two-year hiatus after Voskhod, which enabled the US to catch up and surpass the previous Soviet superiority in piloted spaceflight. Gemini had ten crewed missions between March 1965 and November 1966: [[Gemini 3]], [[Gemini 4]], [[Gemini 5]], [[Gemini 6A]], [[Gemini 7]], [[Gemini 8]], [[Gemini 9A]], [[Gemini 10]], [[Gemini 11]], and [[Gemini 12]]; and accomplished the following:

* Every mission demonstrated the ability to adjust the crafts' inclination and apsis without issue.
* Gemini 5 demonstrated eight-day endurance, long enough for a round trip to the Moon. Gemini 7 demonstrated a fourteen-day endurance flight.
* Gemini 6A demonstrated rendezvous and [[orbital station-keeping|station-keeping]] with Gemini 7 for three consecutive orbits at distances as close as {{convert|1|ft|m|sp=us}}.<ref>{{cite web
 |title       = The World's First Space Rendezvous
 |work        = Apollo to the Moon; To Reach the Moon – Early Human Spaceflight
 |publisher   = Smithsonian National Air and Space Museum
 |url         = http://www.nasm.si.edu/exhibitions/attm/rm.ey.g7.3.html
 |access-date  = September 17, 2006
 
 |archive-url  = https://web.archive.org/web/20071116112847/http://www.nasm.si.edu/exhibitions/attm/rm.ey.g7.3.html
 |archive-date = November 16, 2007
 }}</ref> Gemini 9A also achieved rendezvous with an [[Agena Target Vehicle]] (ATV).
* Rendezvous and [[docking and berthing of spacecraft|docking]] with the ATV was achieved on Gemini 8, 10, 11, and 12. Gemini 11 achieved the first direct-ascent rendezvous with its Agena target on the first orbit.
*[[Extravehicular activity]] (EVA) was perfected through increasing practice on Gemini 4, 9A, 10, 11, and 12. On Gemini 12, [[Edwin Aldrin|Edwin "Buzz" Aldrin]] spent over five hours working comfortably during three (EVA) sessions, finally proving that humans could perform productive tasks outside their spacecraft.
* Gemini 10, 11, and 12 used the ATV's engine to make large changes in its orbit while docked. Gemini 11 used the Agena's rocket to achieve a crewed Earth orbit record [[apogee]] of {{convert|742|nmi|km|sp=us}}.

Gemini 8 experienced the first in-space mission abort on March 17, 1966, just after achieving the world's first docking, when a stuck or shorted thruster sent the craft into an uncontrolled spin. Command pilot [[Neil Armstrong]] was able to shut off the stuck thruster and stop the spin by using the re-entry control system.{{sfn|Gatland|1976|p=176}} He and his crewmate [[David Scott]] landed and were recovered safely.<ref name="Gemini 8 Crew and PJs">{{cite web |url=http://www.nasaimages.org/luna/servlet/detail/nasaNAS~7~7~32671~136538:Gemini-8-crew-stands-on-deck-of-rec |title=Gemini8 Crew and PJs |access-date=2010-06-15 |archive-url=https://web.archive.org/web/20110727151042/http://www.nasaimages.org/luna/servlet/detail/nasaNAS~7~7~32671~136538%3AGemini-8-crew-stands-on-deck-of-rec |archive-date=2011-07-27 }}</ref>

Most of the novice pilots on the early missions would command the later missions. In this way, Project Gemini built up spaceflight experience for the pool of astronauts for the Apollo lunar missions. With the completion of Gemini, the US had demonstrated many of the key technologies necessary to make Kennedy's goal of landing a man on the Moon, namely crewed spacecraft docking, with the exception of developing a large enough launch vehicle.<ref>{{Cite web |date=2023-03-27 |title=Gemini Pioneered the Technology Driving Today's Exploration - NASA |url=https://www.nasa.gov/missions/gemini/gemini-pioneered-the-technology-driving-todays-exploration/ |access-date=2024-11-26 |language=en-US}}</ref>

[[File:Space Race 1957-1975 black text.png|center|thumb|upright=2.0|Progress in the Space Race, showing the US passing the Soviets in 1965]]

===Soviet crewed Moon programs===
{{Main|Soviet crewed lunar programs}}

[[File:Manned Moon landers LK vs LM - to scale drawing.png|thumb|Soviet LK (Lunniy Korabl) and American [[Apollo Lunar Module]] lunar landers]]

Korolev's design bureau produced two prospectuses for circumlunar spaceflight (March 1962 and May 1963), the main spacecraft for which were early versions of his Soyuz design. At the same time, another bureau, [[OKB-52]], headed by [[Vladimir Chelomey]], was developing the [[LK-1]] lunar flyby spacecraft, which would be launched by Chelomey's [[Proton (rocket)|Proton UR-500]] rocket. The Soviet government rejected Korolev's proposals, opting to support Chelomey's project, who gained favor with Khrushchev by employing his son.<ref name="FAS 1997">{{cite web |last1=Lindroos |first1=Marcus |title=The Soviet Manned Lunar Program |url=https://fas.org/spp/eprint/lindroos_moon1.htm |date=1997 |website=FAS |publisher=Federation of American Scientists (FAS) |access-date=24 May 2024}}</ref>

Officially, the Soviet lunar program was established on August 3, 1964, with the adoption of Soviet Communist Party Central Committee Command 655-268 (''On Work on the Exploration of the Moon and Mastery of Space'').<ref name=":9" /> The circumlunar flights were planned to occur in 1967, and the landings to start in 1968, intending to land a person on the Moon before the Apollo flights.{{sfn|Portree|1995|p=3-5}} Both of the bureaus submitted their projects for a crewed lunar landing.<ref name=":9" />

Korolev's lunar landing program was designated N1/L3, for its [[N1 (rocket)|N1 super rocket]] and a more advanced [[Soyuz 7K-LOK|Soyuz 7K-L3]] spacecraft, also known as the lunar orbital module ("''Lunniy Orbitalny Korabl''", LOK), with a crew of two. A separate lunar lander ("''Lunniy Korabl''", [[LK (spacecraft)|LK]]), would carry a single cosmonaut to the lunar surface.{{sfn|Portree|1995|p=3-5}}

The N1/L3 launch vehicle had three stages to Earth orbit, a fourth stage for Earth departure, and a fifth stage for lunar landing assist. The combined space vehicle was roughly the same height and takeoff mass as the three-stage US [[Apollo spacecraft|Apollo]]-Saturn V and exceeded its takeoff thrust by 28% (45,400&nbsp;kN vs. 33,000&nbsp;kN.<ref>{{cite book|last1=Harford|first1=James|title=Korolev: how one man masterminded the Soviet drive to beat America to the moon |date=1997 |publisher=Wiley |location=New York; Chichester |isbn=978-0-471-32721-9|page=271}}</ref> The N1/3L was never successfully tested, the first flight suffered a fire in the first-stage Block A due to a loose bolt, leading to a catastrophic explosion 70 seconds into the flight. Further variations of the N1 had similar catastrophic results in testing.<ref name=":10"/> If successful, the N1 would have been capable of carrying a 95 metric tons payload into low earth orbit.<ref name=":10">{{Cite web |last=Avilla |first=Aeryn |date=2020-02-21 |title=N1: The Rise and Fall of the USSR's Moon Rocket |url=https://www.spaceflighthistories.com/post/n1-rocket |access-date=2024-12-11 |website=SpaceflightHistories |language=en}}</ref> The Saturn V comparatively used [[liquid rocket propellant#Hydrogen|liquid hydrogen fuel]] in its two upper stages, and carried a 140.6 metric tons payload to orbit,<ref name="svgiw">{{cite web|title=Ground Ignition Weights|url=https://history.nasa.gov/SP-4029/Apollo_18-19_Ground_Ignition_Weights.htm|website=NASA.gov|access-date=November 8, 2014}}</ref><ref name=":10" /> enough for a three-person [[Apollo Command and Service Module|orbiter]] and two-person [[Apollo Lunar Module|lander]].

Chelomey's program assumed using a [[direct ascent]] lander based on the LK-1, [[LK-700]], which would be launched using his proposed [[Universal Rocket#UR-700|UR-700]] rocket. Following Khrushchev's ouster from power, Chelomey lost his support in the Soviet government, and his proposal didn't receive any funding. Additionally, in August 1965, due to Korolev's opposition, work on the LK-1 was suspended, and later stopped completely. As a replacement, the circumlunar mission would use a stripped-down [[Soyuz 7K-L1]] "Zond", while still retaining the Proton UR-500 booster. To fit two crewmembers, the Zond had to omit the Soyuz orbital module, sacrificing equipment for habitable cabin volume.<ref name="FAS 1997" />{{sfn|Portree|1995|p=12-13}}

=== Outer space treaties ===

[[File:Starfish5.JPG|thumb|The debris fireball of [[Starfish Prime]] in space seen from [[Honolulu]]]]

The US and USSR began discussions on the peaceful uses of space as early as 1958, presenting issues for debate to the United Nations,<ref name="inesap">{{cite web|url=http://www.inesap.org/bulletin17/bul17art22.htm |publisher=International Network of Engineers and Scientists Against Proliferation |date=March 5, 1999|archive-url= https://web.archive.org/web/20080318143550/http://www.inesap.org/bulletin17/bul17art22.htm |archive-date=March 18, 2008| title=Peaceful Uses of Outer Space and International Law|first1=Hans-Joachim |last1=Heintze}}</ref><ref>[https://books.google.com/books?id=r2IfMEpPUIsC&dq=un+resolution+1148&pg=PA289 Google books] ''Nuclear Weapons and Contemporary International Law'' N. Singh, E. WcWhinney (p. 289)</ref><ref>[http://documents-dds-ny.un.org/doc/RESOLUTION/GEN/NR0/747/92/IMG/NR074792.pdf?OpenElement UN website] UN Resolution 1348 (XIII). {{Webarchive|url=https://web.archive.org/web/20151117022148/http://documents-dds-ny.un.org/doc/RESOLUTION/GEN/NR0/747/92/IMG/NR074792.pdf?OpenElement |date=November 17, 2015 }}</ref> which created a [[United Nations Committee on the Peaceful Uses of Outer Space|Committee on the Peaceful Uses of Outer Space]] in 1959.<ref>{{cite web | url = http://www.unoosa.org/oosa/COPUOS/copuos.html | title = United Nations Committee on the Peaceful Uses of Outer Space | publisher = United Nations Office for Outer Space Affairs}}</ref>

On May 10, 1962, Vice President Johnson addressed the Second National Conference on the Peaceful Uses of Space revealing that the United States and the USSR both supported a resolution passed by the Political Committee of the UN General Assembly in December 1962, which not only urged member nations to "extend the rules of international law to outer space," but to also cooperate in its exploration. Following the passing of this resolution, Kennedy commenced his communications proposing a cooperative American and Soviet space program.<ref>[http://www.jfklibrary.org/Asset-Viewer/Archives/JFKNSF-308-006.aspx Papers of John F. Kennedy. Presidential Papers. National Security Files. Subjects. Space activities: US/USSR cooperation, 1961–96]</ref>

In 1963, the [[Partial Nuclear Test Ban Treaty]] was signed by more than 100 signatories, including both the United States and the Soviet Union. This treaty followed the US test of a nuclear bomb detonated in outer space the year earlier called [[Starfish Prime]].

The UN ultimately created a ''[[Outer Space Treaty|Treaty on Principles Governing the Activities of States in the Exploration and Use of Outer Space, including the Moon and Other Celestial Bodies]]'', which was signed by the United States, the USSR, and the [[United Kingdom]] on January 27, 1967, and came into force the following October 10.<ref>[http://disarmament.un.org/treaties/t/outer_space/signature/asc Treaty on Principles Governing the Activities of States in the Exploration and Use of Outer Space, including the Moon and Other Celestial Bodies: Status of the Treaty] (UNODA)</ref>

{{Wikisource|Outer Space Treaty of 1967}}
This treaty:
* bars party States from placing [[weapons of mass destruction]] in Earth orbit, on the Moon, or any other celestial body;
* exclusively limits the use of the Moon and other celestial bodies to peaceful purposes, and expressly prohibits their use for testing weapons of any kind, conducting military maneuvers, or establishing military bases, installations, and fortifications;
* declares that the exploration of outer space shall be done to benefit all countries and shall be free for exploration and use by all the States;
* explicitly forbids any government from claiming a celestial resource such as the Moon or a planet, claiming that they are the [[common heritage of mankind]], "not subject to national appropriation by claim of sovereignty, by means of use or occupation, or by any other means". However, the State that launches a space object retains jurisdiction and control over that object;
* holds any State liable for damages caused by their space object;
* declares that "the activities of non-governmental entities in outer space, including the Moon and other celestial bodies, shall require authorization and continuing supervision by the appropriate State Party to the Treaty", and "States Parties shall bear international responsibility for national space activities whether carried out by governmental or non-governmental entities"; and
* "A State Party to the Treaty which has reason to believe that an activity or experiment planned by another State Party in outer space, including the Moon and other celestial bodies, would cause potentially harmful interference with activities in the peaceful exploration and use of outer space, including the Moon and other celestial bodies, may request consultation concerning the activity or experiment."

The treaty remains in force, signed by 107 member states. – {{As of|July 2017}}

=== Anti-Satellite research ===

==== Istrebitel-sputnikov ====
[[File:IS anti satellite weapon.jpg|thumb|Artist's illustration of an Istrebitel Sputnikov [[Anti-satellite weapon|anti-satellite]] system]]
In November 1968, dismay gripped the United States Central Intelligence Agency when a successful satellite destruction simulation was successfully orchestrated by the Soviet Union.<ref name=":0">{{Cite web |title=THE HISTORY OF US ANTI-SATELLITE WEAPONS |url=https://man.fas.org/eprint/leitenberg/asat.pdf |website=man.fas.org}}</ref> As a part of the [[Istrebitel Sputnikov]] [[anti-satellite weapon]]s research programme, the Kosmos 248 Soviet satellite was successfully destroyed by Kosmos 252 which was able to intercept within the 5&nbsp;km 'kill radius' and destroyed Kosmos 248 by detonating its onboard warhead. This wasn't the beginning of the programme, years earlier intercept attempts had begun with maneuvering test of the [[Polyot (satellite)|Polyot]] satellites in 1964.<ref>{{Cite web |title=The Historic Beginnings Of The Space Arms Race |url=https://www.spacewar.com/reports/The_Historic_Beginnings_Of_The_Space_Arms_Race_999.html |access-date=2024-11-21 |website=www.spacewar.com}}</ref><ref>{{Cite web |last1=RBTH |last2=Novosti |first2=Yury Zaitsev, RIA |date=2008-11-01 |title=The historic beginnings of the space arms race |url=https://www.rbth.com/articles/2008/11/01/311008_space.html |access-date=2024-11-21 |website=Russia Beyond |language=en-US}}</ref><ref>{{Cite web |title=MilsatMagazine |url=http://www.milsatmagazine.com/story.php?number=701833149 |access-date=2024-11-21 |website=www.milsatmagazine.com}}</ref><ref>{{Cite web |date=2013-11-01 |title=The Hidden History of the Soviet Satellite-Killer |url=https://www.popularmechanics.com/space/satellites/a9620/the-hidden-history-of-the-soviet-satellite-killer-16108970/ |access-date=2024-11-21 |website=Popular Mechanics |language=en-US}}</ref>

==== SAINT ====
Possibly as a response to the Soviet programme, the United States began [[Project SAINT]], which was intended to provide anti-satellite capability to be used in the case of war with the Soviet Union.<ref>{{Cite web |title=istrebitel-sputnikov-is |url=https://weaponsandwarfare.com/2021/08/10/istrebitel-sputnikov-is/ |website=weaponsandwarfare.com|date=August 10, 2021 }}</ref><ref name=":0" /><ref name="SAINT">{{Cite web |date=2016-08-20 |title=SAINT |url=http://www.astronautix.com/s/saint.html |access-date=2024-11-21 |archive-url=https://web.archive.org/web/20160820134922/http://www.astronautix.com/s/saint.html |archive-date=August 20, 2016 }}</ref> However, less is known about the mission profiles of this project compared to the Soviet programme, and the project was cancelled early on due to budget constraints.<ref name="SAINT"/>

===Disaster strikes both sides===
In 1967, both nations' space programs faced serious challenges that brought them to temporary halts.

====Apollo 1====
{{Main|Apollo 1}}

[[File:Apollo 1 fire.jpg|thumb|Charred interior of the Apollo 1 spacecraft after the fire that killed the crew]]
On January 27, 1967, the same day the US and USSR signed the Outer Space Treaty, the crew of the first crewed Apollo mission, Command Pilot [[Gus Grissom|Virgil "Gus" Grissom]], Senior Pilot [[Ed White (astronaut)|Ed White]], and Pilot [[Roger Chaffee]], were killed in a fire that swept through their spacecraft cabin during a ground test, less than a month before the planned February 21 launch. An investigative board determined the fire was probably caused by an electrical spark and quickly grew out of control, fed by the spacecraft's atmosphere of pure oxygen at greater than one standard atmosphere. Crew escape was made impossible by inability to open the [[plug door]] hatch cover against the internal pressure.<ref name="sea5" /> The board also found design and construction flaws in the spacecraft, and procedural failings, including failure to appreciate the hazard of the pure-oxygen atmosphere, as well as inadequate safety procedures.<ref name="sea5" /> All these flaws had to be corrected over the next twenty-two months until the first piloted flight could be made.<ref name="sea5">{{cite book|first=Robert C. Jr.|last=Seamans|publisher=NASA History Office|title=Report of Apollo 204 Review Board|chapter=Findings, Determinations And Recommendations|chapter-url=http://www.hq.nasa.gov/pao/History/Apollo204/find.html|date=April 5, 1967|access-date=October 7, 2007|archive-date=November 5, 2015|archive-url=https://web.archive.org/web/20151105102355/http://www.hq.nasa.gov/pao/History/Apollo204/find.html|url-status=dead}}</ref>
Mercury and Gemini veteran Grissom had been a favored choice of [[Deke Slayton]], NASA's Director of Flight Crew Operations, to make the first piloted landing.<ref>{{cite book|last1=Slayton|first1=Donald K.|title=Deke!: U.S. Manned Space from Mercury to the Shuttle|author-link1=Deke Slayton|last2=Cassutt|first2=Michael|author-link2=Michael Cassutt|year=1994|page=223|publisher=Forge: St. Martin's Press|location=New York City|isbn=0-312-85503-6|lccn=94-2463|oclc=29845663|url=https://archive.org/details/dekeusmannedspac00slay|quote=It wasn't just a cut-and-dried decision as to who should make the first steps on the Moon. If I had to select on that basis, my first choice would have been Gus, which both [[Christopher C. Kraft, Jr.|Chris Kraft]] and [[Robert R. Gilruth|Bob Gilruth]] seconded.}}</ref>

==== Soyuz 1 ====
{{Main|Soyuz 1}}

[[File:Vladimir Komarov - body remains.jpg|thumb|The remains of Vladimir Komarov]]

On April 24, 1967, the single pilot of Soyuz 1, [[Vladimir Mikhaylovich Komarov|Vladimir Komarov]], became the first in-flight spaceflight fatality. The mission was planned to be a three-day test, to include the first Soviet docking with an unpiloted [[Soyuz 2]], but the mission was plagued with problems. Problems began shortly after launch when one solar panel failed to unfold, leading to a shortage of power for the spacecraft's systems. Further problems with the orientation detectors complicated maneuvering the craft. By orbit 13, the automatic stabilisation system was completely dead, and the manual system was only partially effective.<ref>{{Cite web |title=soyuz-1 |url=https://sma.nasa.gov/SignificantIncidents/assets/soyuz-1.pdf |website=sma.nasa.gov}}</ref> The mission was aborted, Soyuz 1 fired its [[retrorocket]]s and [[Atmospheric reentry|reentered]] the [[Atmosphere of Earth|Earth's atmosphere]]. During the emergency re-entry, a fault in the landing parachute system caused the primary chute to fail, and the reserve chute became tangled with the drogue chute, causing descent speed to reach as high as 40&nbsp;m/s (140&nbsp;km/h; 89&nbsp;mph). Shortly thereafter, [[Soyuz 1]] impacted the ground 3&nbsp;km (1.9&nbsp;mi) west of Karabutak, and was found on fire. The official autopsy states Komarov died of blunt force trauma on impact.<ref>{{Cite web |title=Vladimir Komarov's tragic flight aboard Soyuz-1 |url=https://www.russianspaceweb.com/soyuz1.html |access-date=2024-12-07 |website=www.russianspaceweb.com}}</ref><ref>{{Cite web |title=Soyuz 1 |url=https://nssdc.gsfc.nasa.gov/nmc/spacecraft/display.action?id=1967-037A |website=nssdc.gsfc.nasa.gov}}</ref><ref>{{Cite web |title=Spaceflight mission report: Soyuz 1 |url=http://www.spacefacts.de/mission/english/soyuz-1.htm |access-date=2024-12-07 |website=www.spacefacts.de}}</ref> In the US during subsequent years, stories began circulating that in his last transmissions Komarov cursed the engineers and flight staff as he descended, or even that he cursed the Soviet leadership, and that these transmissions were received by an [[National Security Agency|NSA]] listening station near [[Istanbul]].<ref>{{Cite web |date=2016-08-20 |title=Soyuz 1 |url=http://www.astronautix.com/s/soyuz1.html |access-date=2024-12-07 |archive-url=https://web.archive.org/web/20160820192411/http://www.astronautix.com/s/soyuz1.html |archive-date=August 20, 2016 }}</ref><ref>{{Cite web |last=Stilwell |first=Blake |date=2018-04-02 |title=The first man to die in the Space Race cursed the USSR the whole way down |url=https://www.wearethemighty.com/articles/first-man-die-space-race-cursed-command-whole-way/ |access-date=2024-12-07 |website=We Are The Mighty |language=en-US}}</ref><ref>{{Cite web |last=Harvey |first=Ian |date=2015-10-26 |title=US Analysts Heard Russian Astronaut Komarov cursing his superiors while he plunged to his death in 1967 {{!}} The Vintage News |url=https://www.thevintagenews.com/2015/10/26/us-analysts-heard-russian-astronaut-komarov-cursing-his-superiors-while-he-plunged-to-his-death-in-1967/ |access-date=2024-12-07 |website=thevintagenews |language=en}}</ref> This would contradict Soviet records of the radio transcripts, and historians such as [[Asif Azam Siddiqi]] and [[Robert Pearlman]] regard these claims to be fabrications.<ref>{{Cite web |date=2019-05-03 |title=A Cosmonaut's Fiery Death Retold : Krulwich Wonders... : NPR |website=[[NPR]] |url=https://www.npr.org/sections/krulwich/2011/05/03/135919389/a-cosmonauts-fiery-death-retold |access-date=2024-12-07 |archive-url=https://web.archive.org/web/20190503223325/https://www.npr.org/sections/krulwich/2011/05/03/135919389/a-cosmonauts-fiery-death-retold |archive-date=May 3, 2019 }}</ref><ref>{{Cite web |last=Margaritoff |first=Marco |date=2023-05-05 |title=The Tragic Death Of Vladimir Komarov, The Man Who Fell From Space |url=https://allthatsinteresting.com/vladimir-komarov |access-date=2024-12-07 |website=All That's Interesting |language=en-US}}</ref>

=== Both programs recover ===

[[File:ZOND.jpg|thumb|Soyuz 7K-L1 Zond spacecraft, artist view]]

The United States recovered from the Apollo 1 fire, fixing the fatal flaws in an improved version of the [[Apollo Command and Service Module#Major differences between Block I and Block II|Block II command module]]. The US proceeded with unpiloted test launches of the Saturn V launch vehicle ([[Apollo 4]] and [[Apollo 6]]) and the Lunar Module ([[Apollo 5]]) during the latter half of 1967 and early 1968.{{sfn|Cadbury|2006|pp=310–12, 314–16}} The first Saturn V flight was an unqualified success, and although the second suffered some non-catastrophic engine failures, it was considered a partial success and the launcher achieved human rating qualification. Apollo 1's mission to check out the Apollo Command and Service Module in Earth orbit was accomplished by Grissom's backup crew on [[Apollo 7]], launched on October 11, 1968.<ref>Burrows (1999), p. 417</ref> The eleven-day mission was a total success, as the spacecraft performed a virtually flawless mission, paving the way for the United States to continue with its lunar mission schedule.{{sfn|Murray|Cox|1990|pp=323–24}}

The Soviet Union also fixed the parachute and control problems with Soyuz, and the next piloted mission [[Soyuz 3]] was launched on October 26, 1968.{{sfn|Hall|Shayler|2003|pp=144-47}} The goal was to complete Komarov's rendezvous and docking mission with the un-piloted Soyuz 2.{{sfn|Hall|Shayler|2003|pp=144-47}} Ground controllers brought the two craft to within {{convert|200|m|ft|sp=us}} of each other, then cosmonaut [[Georgy Beregovoy]] took control.{{sfn|Hall|Shayler|2003|pp=144-47}} He got within {{convert|40|m|ft|sp=us}} of his target, but was unable to dock before expending 90 percent of his maneuvering fuel, due to a piloting error that put his spacecraft into the wrong orientation and forced Soyuz 2 to automatically turn away from his approaching craft.{{sfn|Hall|Shayler|2003|pp=144-47}} The first docking of Soviet spacecraft was finally realized in January 1969 by the [[Soyuz 4]] and [[Soyuz 5]] missions. It was the first-ever docking of two crewed spacecraft, and the first transfer of crew from one space vehicle to another.<ref>{{cite web |title=Soyuz 4 & 5: The First Crew Exchange in Space |url=https://www.drewexmachina.com/2019/01/17/soyuz-4-5-the-first-crew-exchange-in-space/ |website=drewexmachina |date=January 17, 2019 |access-date=24 July 2022}}</ref>

[[File:NASA-Apollo8-Dec24-Earthrise.jpg|alt=A small blue-white semicircle of Earth, almost glowing with color in the blackness of space, rising over the limb of the desolate, cratered surface of the Moon|thumb|left|''[[Earthrise]]'', as seen from Apollo&nbsp;8, December 24, 1968 (photograph by astronaut [[William Anders]])]]

The Soviet [[Soyuz 7K-L1|Zond spacecraft]] was not yet ready for piloted [[circumlunar]] missions in 1968, after six unsuccessful automated test launches: [[Kosmos 146]] on March 10, 1967; [[Kosmos 154]] on April 8, 1967; [[Zond 1967A]] on September 28, 1967; [[Zond 1967B]] on November 22, 1967; [[Zond 1968A]] on April 23, 1968; and [[Zond 1968B]] in July 1968.<ref name="tent">{{cite web |url=http://nssdc.gsfc.nasa.gov/planetary/tent_launch.html |title=Tentatively Identified Missions and Launch Failures|publisher=NASA NSSDC|first=David R.|last=Williams|access-date=July 30, 2010|date=January 6, 2005}}</ref> [[Zond 4]] was launched on March 2, 1968, and successfully made a circumlunar flight,{{sfn|Siddiqi|2003b|pp=616-618}} but encountered problems with its Earth reentry on March 9, and was ordered destroyed by an explosive charge {{convert|15000|m|ft|sp=us}} over the [[Gulf of Guinea]].{{sfn|Hall|Shayler|2003|p=25}} The Soviet official announcement said that Zond 4 was an automated test flight which ended with its intentional destruction, due to its recovery trajectory positioning it over the Atlantic Ocean instead of over the USSR.{{sfn|Siddiqi|2003b|pp=616-618}}

During the summer of 1968, the Apollo program hit another snag: the first pilot-rated Lunar Module (LM) was not ready for orbital tests in time for a December 1968 launch. NASA planners overcame this challenge by changing the mission flight order, delaying the first LM flight until March 1969, and sending [[Apollo 8]] into lunar orbit without the LM in December.{{sfn|Kraft|2001|pp=284–97}} This mission was in part motivated by intelligence rumors the Soviet Union might be ready for a piloted Zond flight in late 1968.{{sfn|Chaikin|1994|pp=57–58}} In September 1968, [[Zond 5]] made a circumlunar flight with [[tortoises]] on board and returned safely to Earth, accomplishing the first successful water landing of the Soviet space program in the Indian Ocean.{{sfn|Siddiqi|2003b|pp=654–56}} It also scared NASA planners, as it took them several days to figure out that it was only an automated flight, not piloted, because voice recordings were transmitted from the craft en route to the Moon.{{sfn|Turnhill|2004|p=134}} On November 10, 1968, another automated test flight, [[Zond 6]], was launched. It encountered difficulties in Earth reentry, and depressurized and deployed its parachute too early, causing it to crash-land only {{convert|16|km|mi|sp=us}} from where it had been launched six days earlier.{{sfn|Siddiqi|2003b|pp=663–66}} It turned out there was no chance of a piloted Soviet circumlunar flight during 1968, due to the unreliability of the Zonds.{{sfn|Cadbury|2006|pp=318–19}}

On December 21, 1968, [[Frank Borman]], [[Jim Lovell|James Lovell]], and [[William Anders]] became the first humans to ride the Saturn V rocket into space, on Apollo 8. They also became the first to leave low-Earth orbit and go to another celestial body, entering lunar orbit on December 24.{{sfn|Poole|2008|pp=19–34}} They made ten orbits in twenty hours, and transmitted one of the most watched TV broadcasts in history, with their [[Apollo 8 Genesis reading|Christmas Eve program]] from lunar orbit, which concluded with a reading from the biblical [[Book of Genesis]].{{sfn|Poole|2008|pp=19–34}} Two and a half hours after the broadcast, they fired their engine to perform the first [[trans-Earth injection]] to leave lunar orbit and return to the Earth.{{sfn|Poole|2008|pp=19–34}} Apollo 8 safely landed in the Pacific Ocean on December 27, in NASA's first dawn splashdown and recovery.{{sfn|Poole|2008|pp=19–34}}

The American Lunar Module was finally ready for a successful piloted test flight in low Earth orbit on [[Apollo 9]] in March 1969. The next mission, [[Apollo 10]], conducted a "dress rehearsal" for the first landing in May 1969, flying the LM in lunar orbit as close as {{convert|47400|ft|km}} above the surface, the point where the powered descent to the surface would begin.<ref name="chariots12-7">{{cite book |last1=Brooks |first1=Courtney G. |last2=Grimwood |first2=James M. |last3=Swenson |first3=Loyd S. Jr. |others=Foreword by [[Samuel C. Phillips]] |title=Chariots for Apollo: A History of Manned Lunar Spacecraft |url=http://www.hq.nasa.gov/office/pao/History/SP-4205/cover.html |access-date=January 29, 2008 |series=NASA History Series |year=1979 |publisher=Scientific and Technical Information Branch, NASA |location=Washington, D.C. |isbn=978-0-486-46756-6 |oclc=4664449 |lccn=79001042 |id=NASA SP-4205 |chapter=''Apollo 10:'' The Dress Rehearsal |chapter-url=http://www.hq.nasa.gov/office/pao/History/SP-4205/ch12-7.html |archive-date=October 20, 2015 |archive-url=https://web.archive.org/web/20151020095653/http://www.hq.nasa.gov/office/pao/History/SP-4205/cover.html }}</ref> With the LM proven to work well, the next step was to attempt the landing.

Unknown to the Americans, the Soviet Moon program was in deep trouble.{{sfn|Cadbury|2006|pp=318–19}} After two successive launch failures of the N1 rocket in 1969, Soviet plans for a piloted landing suffered delay.{{sfn|Siddiqi|2003b|pp=665, 832–34}} The launch pad explosion of the N-1 on July 3, 1969, was a significant setback.{{sfn|Siddiqi|2003b|pp=690–93}} The rocket hit the pad after an engine shutdown, destroying itself and the launch facility.{{sfn|Siddiqi|2003b|pp=690–93}} Without the N-1 rocket, the USSR could not send a large enough payload to the Moon to land a human and return him safely.{{sfn|Parry|2009|pp=178–79}}