Editing Luna 3 (section)

===First gravity assist===
[[File:Luna3-trajectory-eng.svg|thumb|left|Luna 3 trajectory and the [[gravity assist]] maneuver]]

{{main|Gravity assist#Historical origins of the method}}
The [[gravity assist]] maneuver was first used in 1959 when Luna 3 photographed the far side of Earth's Moon. After launch from the [[Baikonur Cosmodrome]], Luna 3 passed behind the Moon from south to north and headed back to Earth. The gravity of the Moon changed the spacecraft's orbit; also, because of the Moon's own orbital motion, the spacecraft's orbital plane was also changed. The return orbit was calculated so that the spacecraft passed again over the Northern hemisphere where the Soviet ground stations were located. The maneuver relied on research performed under the direction of [[Mstislav Keldysh]] at the [[Steklov Institute of Mathematics]].<ref>{{cite web|url=http://www.keldysh.ru/events/fly|title=Mstislav Keldysh. Mechanics of the space flight|author=T. Eneev, E. Akim|website=Keldysh Institute of Applied Mathematics|language=ru}}</ref><ref>Egorov, Vsevolod Alexandrovich (1957) "Specific problems of a flight to the Moon", ''Physics – Uspekhi'', Vol. 63, No. 1a, pp. 73–117.

Egorov’s work is mentioned in:  Boris V. Rauschenbakh, Michael Yu. Ovchinnikov, and [[Susan McKenna-Lawlor|Susan M. P. McKenna-Lawlor]], ''Essential Spaceflight Dynamics and Magnetospherics'' (Dordrecht, Netherlands:  Kluwer Academic Publishers, 2002), pp. 146–147.   (The latter reference is available on-line at [https://books.google.com/books?id=s8FRVu0blhgC&pg=PA146 Google Books].)</ref><ref>{{cite web |last1=Berger |first1=Eric |title=All hail Luna 3, rightful king of 1950s space missions |url=https://arstechnica.com/science/2019/10/all-hail-luna-3-rightful-king-of-1950s-space-missions/ |website=Ars Technica |date=4 October 2019 |access-date=13 October 2023}}</ref>
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