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Zenit (rocket family)
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<h2 id="history">History</h2> <p>The Zenit-2 was the first Zenit to be designed for use as an orbital carrier rocket. It consists of two stages. The first uses an <a href="/facts/RD-171/DVefcXeK">RD-171</a> engine, and an <a href="/facts/RD-120/5T8GX3en">RD-120</a> engine powers the second stage. It first flew on 13 April 1985, two years before the Energia, due to delays relating to the Energia's development. Zenit-2 would be certified for crewed launches and placed in specially built <a href="/facts/Launch_pad/6ePPb2ac">launch pad</a> at <a href="/facts/Baykonur/Axz7dYJq">Baykonur</a> spaceport, carrying the new crewed partially reusable <a href="/facts/Zarya_(spacecraft)/wjeEuEmh">Zarya</a> spacecraft that developed in end of the 1980s but was canceled. Also in the 1980s <a href="/facts/Vladimir_Chelomey/WlzNEcl2">Vladimir Chelomey</a>'s firm proposed never realised 15-ton Uragan spaceplane launched by Zenit-2. </p><p>Two launch facilities were constructed for the Zenit at Baikonour, however the second was only ever used twice. On October 4, 1990, an attempted launch of a Tselina-2 naval reconnaissance satellite ended in disaster as the booster suffered a first stage engine failure seconds into launch and fell back onto the pad, which was severely damaged in the ensuing explosion. The failure was traced to a leak in a LOX line that caused a fire in the thrust section of the booster. Estimated repair costs were about 45 million rubles, but the collapse of the Soviet Union meant that there were no funds available, so the pad was abandoned. </p><p>Following two failures in 1991–92 both caused by the second stage, the Zenit was on the verge of being cancelled entirely, but a successful flight in November 1992 saved the program. </p><p>The rate of Zenit launches slowed to a trickle during the 1990s due to the severely cash-strapped Russian Federation, and also because of Russia's reluctance to fly military payloads on a booster manufactured in now-independent Ukraine. On May 20, 1997, a launch of a Tselina-2 satellite failed when the first stage shut down 48 seconds into launch. The booster crashed downrange. </p><p>During the 2000s, Zenit would find a new lease on life as the basis of the international Sea Launch project whereby commercial flights would be undertaken from an offshore launch platform. The basic Zenit booster received several upgrades to the propulsion and avionics systems for Sea Launch as well as a third stage, and the first test with a dummy payload was carried out on March 27, 1999. In October, a Direct TV 1-R satellite was orbited successfully. An ICO F-1 comsat was lost in March 2000 due to a second stage guidance malfunction. There followed eight consecutive successful launches until Apstar 5 in 2004 suffered a premature third stage shutdown that left it in an incorrect orbit, but the satellite's onboard engines corrected it. </p><p>After nine successful launches, the Zenit produced a repeat performance of the 1990 disaster when on January 30, 2007, the first stage lost thrust and exploded. The flame deflector on the Sea Launch platform broke off and sank into the water. Loose debris had been sucked into a turbopump, resulting in engine failure. </p><p>By the late 2000s, the Zenit program at Baikonour was reviving and would see considerable success. </p><p>On February 1, 2013, an Intelsat satellite launched from the Sea Launch Odyssey platform in the equatorial Pacific. The nighttime launch performed nominally for about 20 seconds when the first stage abruptly lost thrust. Approximately 40 seconds after liftoff, all telemetry data ceased. Subsequent investigation showed that the Zenit had begun deviating from its flight path when the pitch and roll maneuver started. The onboard computer sensed an abnormal situation and sent an automatic shutdown command to the first stage at T+23 seconds, and impact with the ocean occurred about one minute after liftoff. Ultimately, the failure was traced to a defective hydraulic pump that controlled gimbaling of the first stage engines. This resulted in the booster starting an uncontrolled rolling motion which caused the computer system to terminate all thrust. Although anomalous conditions began around T+11 seconds, the Zenit's flight computer was "locked" to prevent engine shutdown until at least 20 seconds after liftoff so the booster would not come down on or near the launch complex. Impact occurred about two miles downrange, but attempts to recover booster debris were unsuccessful. </p><p>In February 2015, following a year of strained relations as a result of a <a href="/facts/2014%E2%80%9315_Russian_military_intervention_in_Ukraine/kE7cHvoQ">Russian military intervention into Ukraine</a>, Russia announced that it would discontinue its "joint program with Ukraine to launch <a href="/facts/Dnepr_(rocket)/g3VIdEfT">Dnepr rockets</a> and [was] no longer interested in buying Ukrainian Zenit boosters, deepening problems for [Ukraine's] space program and its struggling <a href="/facts/Yuzhmash/lXU5z0xQ">Yuzhmash</a> factory."<a class="footnote-ref" id="fnref:6" href="#fn:6"><sup>6</sup></a> </p><p>Strained relations between Ukraine and Russia after 2014 have led to <a href="/facts/Russian_Federal_Space_Agency/GzWfae7U">Russian Federal Space Agency</a> intending to purchase no more of the Zenit first-stage boosters made by Yuzhmash (powered by Russian engines). However 2 Zenit rockets that have been delivered to Russia for <a href="/facts/Russian_Federal_Space_Agency/GzWfae7U">Russian Federal Space Agency</a> missions will still be used; another Zenit rocket for launching a Ukrainian satellite has been completed but without engines due to lack of funding for payments.<a class="footnote-ref" id="fnref:7" href="#fn:7"><sup>7</sup></a> The world market for Zenit launch vehicles has shriveled since Sea Launch suspended operations, and the future of Zenit is uncertain.<a class="footnote-ref" id="fnref:8" href="#fn:8"><sup>8</sup></a> </p><p>Despite the ongoing conflict between the two governments, a Zenit rocket was launched in December 2017, after a two-year hiatus, to deliver <a href="/facts/AngoSat_1/bGmjvkW6">AngoSat 1</a>.<a class="footnote-ref" id="fnref:9" href="#fn:9"><sup>9</sup></a> </p> <h2 id="production">Production</h2> <p>The first and the second stages of the Zenit were designed by Yuzhnoye and are manufactured by <a href="/facts/Yuzhmash/lXU5z0xQ">Yuzhmash</a>.<a class="footnote-ref" id="fnref:10" href="#fn:10"><sup>10</sup></a> </p> <h2 id="variants">Variants</h2> <h3>Zenit-2</h3> <p class="note">Main article: <a href="/facts/Zenit-2/DWGa0bN9">Zenit-2</a></p> <p>The Zenit-2 was the first member of the rocket family. It consists of two stages. The first uses an <a href="/facts/RD-171/DVefcXeK">RD-171</a> engine, and an <a href="/facts/RD-120/5T8GX3en">RD-120</a> engine powers the second stage. It first flew on 13 April 1985, carrying a <a href="/facts/Tselina-2/4BvLb2yT">Tselina-2</a> mass simulator. However the test flight was unsuccessful. The first successful flight occurred on 22 October 1985. </p> <h3>Energia booster</h3> <p class="note">For broader coverage of this topic, see <a href="/facts/Buran_programme/bN7KBBKG">Buran programme</a>.</p> <p>The Zenit first stage was used as a strap-on booster rocket for the <a href="/facts/Energia_(rocket)/snJSoyMA">Energia carrier rocket</a>.<a class="footnote-ref" id="fnref:11" href="#fn:11"><sup>11</sup></a> Four Zenit first stages were attached to the core vehicle to produce extra thrust at lift-off, in the same way that <a href="/facts/Shuttle_SRB/ETayF0Xh">Solid Rocket Boosters</a> were used on the US <a href="/facts/Space_Shuttle/7BoyetEv">Space Shuttle</a>. Energia made two flights (1987 and 1988) before the programme was abandoned. </p> <h3>Zenit 2M and 2SLB</h3> <p class="note">Main article: <a href="/facts/Zenit-2M/zKxwo7uc">Zenit-2M</a></p> <p>Zenit 2M is a new version of the Zenit 2 with an upgraded control system and modernized engines.<a class="footnote-ref" id="fnref:12" href="#fn:12"><sup>12</sup></a> The first Zenit 2M was launched on June 29, 2007, carrying a classified Russian military <a href="/facts/Tselina-2/4BvLb2yT">Tselina-2</a> satellite. The Zenit-2SLB designation applies to commercial launches through the <a href="/facts/Land_Launch/47w9dglI">Land Launch</a> subsidiary of Sea Launch, which began satellite launches from Baikonur Cosmodrome in 2008.<a class="footnote-ref" id="fnref:13" href="#fn:13"><sup>13</sup></a> </p> <h3>Zenit-3SL</h3> <p class="note">Main article: <a href="/facts/Zenit-3SL/g2gQntg4">Zenit-3SL</a></p> <p>Zenit-3SL is a three-stage <a href="/facts/Launch_vehicle/g1GCGFJB">carrier rocket</a> developed for and used by the Sea Launch consortium. </p><p>It combines:<a class="footnote-ref" id="fnref:14" href="#fn:14"><sup>14</sup></a> </p> <ul><li>two-stage Zenit-2S built by <a href="/facts/Ukraine/Qof0uqAj">Ukraine</a>'s SDO <a href="/facts/Yuzhnoye_Design_Bureau/euSxfxsR">Yuzhnoye</a>/PO <a href="/facts/Yuzhmash/lXU5z0xQ">Yuzhmash</a></li> <li><a href="/facts/Block_DM-SL/k5C7arlB">Block DM-SL</a> upper stage, provided by Russia's <a href="/facts/S.P._Korolev_Rocket_and_Space_Corporation_Energia/fThW3H3L">Energia</a></li> <li>nose-cone enclosure for protection of payload during launch, provided by <a href="/facts/Boeing/tF5sMe9F">Boeing</a>.</li></ul> <p>Rockets used by Sea Launch are assembled in <a href="/facts/Long_Beach,_California/rcmxRIXv">Long Beach, California</a>. Launches occur from the <i>Ocean Odyssey</i> offshore launch platform, situated at the equator. <i>Ocean Odyssey</i> is also used to transport rockets to the launch site. The <a href="/facts/List_of_Zenit_launches/YTTCK96P">most recent launch</a> of a Zenit-3SL occurred on 11 December 2015. The RD-171 engine of the Zenit-3SL first stage, and most of the control system of -3SL missiles were made in Russia.<a class="footnote-ref" id="fnref:15" href="#fn:15"><sup>15</sup></a> However, according to the same source, it is not clear if Russia's component suppliers are still working together with Yuzhmash as of this date. </p> <h3>Zenit 3M and 3SLB</h3> <p class="note">Main article: <a href="/facts/Zenit-3SLB/ewVWBXsz">Zenit-3SLB</a></p> <p>The Zenit-3M is a Zenit-2M with the <a href="/facts/Block-DM/k5C7arlB">Block-DM</a> upper stage used on the Zenit-3SL. It is launched from Baikonur. The maiden flight was launched on 28 April 2008. <a href="/facts/Land_Launch/47w9dglI">Land Launch</a> commercially market the Zenit-3M under the designation Zenit 3SLB.<a class="footnote-ref" id="fnref:16" href="#fn:16"><sup>16</sup></a> </p> <h3>Zenit-3F</h3> <p class="note">Main article: <a href="/facts/Zenit-3F/5HmxY0UX">Zenit-3F</a></p> <p>The Zenit-3F, also known as the Zenit-2SB/Fregat, is a 3-stage derivative of the Zenit-2M, using a <a href="/facts/Fregat/Sv4Ub6GJ">Fregat</a> upper stage, as already used on the <a href="/facts/Soyuz_(rocket_family)/cGMjYIPX">Soyuz</a>, to propel spacecraft to higher orbits. It made its maiden flight in January 2011, with the <a href="/facts/Elektro-L_No.1/GhhRnKpG">Elektro-L No.1</a> spacecraft for the Russian government. Later the same year, another launch carried <a href="/facts/Spektr-R/D6lgHW25">Spektr-R</a>, a 5,000-kilogram (11,000 lb) <a href="/facts/Space_telescope/BtI46sDX">space telescope</a>, into an orbit with a <a href="/facts/Perigee/VaL6ow9w">perigee</a> of 10,000 kilometres (6,200 mi) and an <a href="/facts/Apogee/VaL6ow9w">apogee</a> of 390,000 kilometres (240,000 mi).<a class="footnote-ref" id="fnref:17" href="#fn:17"><sup>17</sup></a> The most recent launch occurred on 26 December 2017 from Baikonur Cosmodrome when the rocket lifted off with the Angolian Angosat 1 spacecraft.<a class="footnote-ref" id="fnref:18" href="#fn:18"><sup>18</sup></a> </p> <h2 id="specifications">Specifications</h2> <h3>Overview</h3> <table><tbody><tr><th></th><th>Zenit-2</th><th>Zenit-3SL</th></tr><tr><th>Stages</th><td>2</td><td>3</td></tr><tr><th>Total length</th><td>57 <a href="/facts/Meters/hPhzc1CV">m</a></td><td>59.6 m</td></tr><tr><th>Total empty mass</th><td>37,600 <a href="/facts/Kilogram/lU2zbPk8">kg</a></td><td>40,320 kg</td></tr><tr><th>Total gross mass</th><td>444,900 kg</td><td>462,200 kg</td></tr><tr><th>Payload</th><td>13.74 <a href="/facts/Tonne/gMymLmWv">tonne</a> to <a href="/facts/Low_Earth_orbit/rq1TwayJ">LEO</a></td><td>≈6 tonne to <a href="/facts/Geostationary_transfer_orbit/1WwL0SPz">GTO</a></td></tr><tr><th>Launch site</th><td><a href="/facts/Baikonur_Cosmodrome/sk16LwcH">Baikonur Cosmodrome</a></td><td><a href="/facts/Sea_Launch/7LbLz348">Sea Launch</a> ocean platform</td></tr><tr><th>Launches</th><td>21 (6 failed) as of 10 June 2004</td><td>31 (3 failed, 1 partial success)as of 1 February 2013</td></tr><tr><th>Success ratio</th><td>71.4%</td><td>91.1%</td></tr><tr><th>Price per launch</th><td>~$45 million</td><td>~$90 million</td></tr></tbody></table> <h3>Payload capacities</h3> <h4>Two stage version (Zenit-2)</h4> <table><tbody><tr><th colspan="2"><a href="/facts/Payload_(air_and_space_craft)/wb7m7LLV">Payload</a> to <a href="/facts/Low_Earth_orbit/rq1TwayJ">LEO</a></th><td>13,740 kg</td></tr><tr><th colspan="2">Payload to <a href="/facts/Polar_orbit/JLUlIPlq">PEO</a></th><td>5,000 kg</td></tr><tr><th colspan="2">Payload to <a href="/facts/Geostationary_orbit/VBq1v5Kr">GEO</a></th><td>Not designed for GEO</td></tr></tbody></table> <h4>Three stage version (Zenit-3SL)</h4> <table><tbody><tr><th colspan="2">Payload to LEO</th><td>6,100 kg, 3rd stage structural limitation</td></tr><tr><th colspan="2">Payload to <a href="/facts/Medium_Earth_orbit/7Qmz5XxG">MEO</a></th><td>3,965 kg (10,000 km, 45°)</td></tr><tr><th colspan="2">Payload to GEO</th><td>1840 kg</td></tr><tr><th colspan="2">Payload to <a href="/facts/Geostationary_transfer_orbit/1WwL0SPz">GTO</a></th><td>5,250 kg (upgraded to 6,000+ kg)</td></tr></tbody></table> <h2 id="launches">Launches</h2> <p class="note">Main article: <a href="/facts/List_of_Zenit_launches/YTTCK96P">List of Zenit launches</a></p> <h2 id="see-also">See also</h2> <ul><li><a href="/facts/Comparison_of_orbital_launcher_families/w5HG4Juq">Comparison of orbital launcher families</a></li> <li><a href="/facts/Tsyklon-4/5PfNGs8f">Tsyklon-4</a></li> <li><a href="/facts/State_Space_Agency_of_Ukraine/aR8mUIXj">State Space Agency of Ukraine</a></li></ul> <h2 id="external-links">External links</h2> Wikinews has related news: <ul><li> Zenit rocket explodes on launch pad</li></ul> <ul><li><a href="http://www.boris-lux.de/04_types/61_lv/sp_ru/14_zen/spze.php">Zenit Family</a></li> <li><a href="https://web.archive.org/web/20061018183306/http://www.astronautix.com/lvs/zenit3sl.htm">Information at Encyclopedia Astronautica</a></li> <li><a href="https://web.archive.org/web/20070927012634/http://www.nkau.gov.ua/nsau/catalogNEW.nsf/0/EFB7A4C2121BE0F6C2256E8B0044EBA8?OpenDocument&Lang=E">Information at National Space Agency of Ukraine</a></li> <li><a href="http://www.buran-energia.com/energia/zenith-zenit-desc.php">Information at Buran web site</a></li> <li><a href="https://web.archive.org/web/20061029193722/http://www.orbireport.com/Launchers/Zenit_3SL/">Information at Orbital Report News Agency</a></li></ul> Wikimedia Commons has media related to Zenit (rocket). <h2 id="references">References</h2> <ol> <li id="fn:1"><p>Bodner, Matthew (June 6, 2016). "How Crimea's annexation hurt Ukraine's space program". SpaceNews. Retrieved 2024-04-02. <a href="https://spacenews.com/from-the-archives-how-crimeas-annexation-hurt-ukraines-space-program/" target="_blank">https://spacenews.com/from-the-archives-how-crimeas-annexation-hurt-ukraines-space-program/</a> <a href="#fnref:1" class="footnote-back-ref">↩</a></p></li> <li id="fn:2"><p>Pultarova, Tereza (2023-08-27). "Lost partnerships destroying Ukraine's space sector faster than Russian missiles, former space chief says". Space.com. Retrieved 2024-04-02. <a href="https://www.space.com/ukraine-space-sector-threatened-lost-partnerships" target="_blank">https://www.space.com/ukraine-space-sector-threatened-lost-partnerships</a> <a href="#fnref:2" class="footnote-back-ref">↩</a></p></li> <li id="fn:3"><p>"Land Launch User's Guide Revision B" (PDF). Space International Services. 1 October 2014. Archived from the original (PDF) on 25 June 2016. Retrieved 8 February 2015. <a href="https://web.archive.org/web/20160625025453/http://www.landlaunch.ru/download/llug_eng.pdf" target="_blank">https://web.archive.org/web/20160625025453/http://www.landlaunch.ru/download/llug_eng.pdf</a> <a href="#fnref:3" class="footnote-back-ref">↩</a></p></li> <li id="fn:4"><p>Harvey, Brian (2007). The Rebirth of the Russian Space Program. Chichester, UK: Praxis. pp. 167–175. <a href="#fnref:4" class="footnote-back-ref">↩</a></p></li> <li id="fn:5"><p>Bergin, Chris (1 February 2013). "Sea Launch Zenit 3SL with Intelsat 27 fails during first stage flight". NASASpaceflight.com. Retrieved 1 February 2013. <a href="http://www.nasaspaceflight.com/2013/02/sea-launch-zenit-3sl-launch-intelsat-27/" target="_blank">http://www.nasaspaceflight.com/2013/02/sea-launch-zenit-3sl-launch-intelsat-27/</a> <a href="#fnref:5" class="footnote-back-ref">↩</a></p></li> <li id="fn:6"><p>Messier, Doug (6 February 2015). "Russia Severing Ties With Ukraine on Dnepr, Zenit Launch Programs". Parabolic Arc. Archived from the original on 15 February 2015. Retrieved 8 February 2015. <a href="https://web.archive.org/web/20150215052356/http://www.parabolicarc.com/2015/02/06/russia-severing-ties-ukraine-dnepr-zenit-launch-programs/" target="_blank">https://web.archive.org/web/20150215052356/http://www.parabolicarc.com/2015/02/06/russia-severing-ties-ukraine-dnepr-zenit-launch-programs/</a> <a href="#fnref:6" class="footnote-back-ref">↩</a></p></li> <li id="fn:7"><p>"Russia No Longer Interested In Ukrainian Built Launch Vehicles". SatNews. 3 February 2015. Retrieved 10 February 2015. <a href="http://www.satnews.com/story.php?number=1637484549" target="_blank">http://www.satnews.com/story.php?number=1637484549</a> <a href="#fnref:7" class="footnote-back-ref">↩</a></p></li> <li id="fn:8"><p>"How Crimea fractured Ukraine's space program". SpaceNews.com. 7 June 2016. <a href="https://spacenews.com/from-the-magazine-ukraines-untethered-orbital-manuevers-how-crimea-hurt-ukraines-space-program/" target="_blank">https://spacenews.com/from-the-magazine-ukraines-untethered-orbital-manuevers-how-crimea-hurt-ukraines-space-program/</a> <a href="#fnref:8" class="footnote-back-ref">↩</a></p></li> <li id="fn:9"><p>Zak, Anatoly. "Zenit delivers Angosat-1, but the spacecraft breaks contact with ground control". Russian Space Web. Retrieved 28 December 2017. <a href="http://www.russianspaceweb.com/zenit-angosat-launch.html" target="_blank">http://www.russianspaceweb.com/zenit-angosat-launch.html</a> <a href="#fnref:9" class="footnote-back-ref">↩</a></p></li> <li id="fn:10"><p>"Sea Launch: the Twenty-Fifth Launch of Zenit-3SL". Yuzhnoye. 2008-01-21. Archived from the original on 2013-11-11. <a href="https://web.archive.org/web/20131111054341/http://www.yuzhnoye.com/index.php?idD=48&id=124&path=News/News_e&lang=en" target="_blank">https://web.archive.org/web/20131111054341/http://www.yuzhnoye.com/index.php?idD=48&id=124&path=News/News_e&lang=en</a> <a href="#fnref:10" class="footnote-back-ref">↩</a></p></li> <li id="fn:11"><p>Bart Hendrickx; Bert Vis (2007). Energiya-Buran: The Soviet Space Shuttle. Springer Science & Business Media. ISBN 978-0-387-73984-7. <a href="978-0-387-73984-7" target="_blank">978-0-387-73984-7</a> <a href="#fnref:11" class="footnote-back-ref">↩</a></p></li> <li id="fn:12"><p>"Ukrainian Zenit rocket makes its return to flight". Spaceflight Now. <a href="http://www.spaceflightnow.com/news/n0706/29zenit/" target="_blank">http://www.spaceflightnow.com/news/n0706/29zenit/</a> <a href="#fnref:12" class="footnote-back-ref">↩</a></p></li> <li id="fn:13"><p>"Land Launch User's Guide Revision B" (PDF). Space International Services. 1 October 2014. Archived from the original (PDF) on 25 June 2016. Retrieved 8 February 2015. <a href="https://web.archive.org/web/20160625025453/http://www.landlaunch.ru/download/llug_eng.pdf" target="_blank">https://web.archive.org/web/20160625025453/http://www.landlaunch.ru/download/llug_eng.pdf</a> <a href="#fnref:13" class="footnote-back-ref">↩</a></p></li> <li id="fn:14"><p>"Sea Launch Receives Zenit-3SL Hardware for Next Launches". Sea Launch. Archived from the original on 2007-09-27. <a href="https://web.archive.org/web/20070927204518/http://www.sea-launch.com/news_releases/nr_070903.html" target="_blank">https://web.archive.org/web/20070927204518/http://www.sea-launch.com/news_releases/nr_070903.html</a> <a href="#fnref:14" class="footnote-back-ref">↩</a></p></li> <li id="fn:15"><p>Sudakov, Dmitry (26 July 2017). "Ukraine kills Antonov aircraft maker". PravdaReport. Archived from the original on 27 November 2020. Retrieved 4 May 2019. <a href="https://web.archive.org/web/20201127225658/https://www.pravdareport.com/business/138261-ukraine_antonov/" target="_blank">https://web.archive.org/web/20201127225658/https://www.pravdareport.com/business/138261-ukraine_antonov/</a> <a href="#fnref:15" class="footnote-back-ref">↩</a></p></li> <li id="fn:16"><p>"Land Launch User's Guide Revision B" (PDF). Space International Services. 1 October 2014. Archived from the original (PDF) on 25 June 2016. Retrieved 8 February 2015. <a href="https://web.archive.org/web/20160625025453/http://www.landlaunch.ru/download/llug_eng.pdf" target="_blank">https://web.archive.org/web/20160625025453/http://www.landlaunch.ru/download/llug_eng.pdf</a> <a href="#fnref:16" class="footnote-back-ref">↩</a></p></li> <li id="fn:17"><p>"Spacecraft Design". Astro Space Center of Lebedev Physical Institute. <a href="http://www.asc.rssi.ru/radioastron/description/design_eng.htm" target="_blank">http://www.asc.rssi.ru/radioastron/description/design_eng.htm</a> <a href="#fnref:17" class="footnote-back-ref">↩</a></p></li> <li id="fn:18"><p>"Angola's first communications satellite lifts off from Kazakhstan". Spaceflightnow. <a href="https://spaceflightnow.com/2017/12/26/angolas-first-communications-satellite-ready-for-launch-tuesday/" target="_blank">https://spaceflightnow.com/2017/12/26/angolas-first-communications-satellite-ready-for-launch-tuesday/</a> <a href="#fnref:18" class="footnote-back-ref">↩</a></p></li> </ol>