Example of a Zond circumlunar spacecraft
|Names||Soyuz 7K-L1 s/n 9|
|Mission type||Lunar flyby|
|Mission duration||6 days, 18 hours, 24 minutes|
|Launch mass||5,375 kilograms (11,850 lb)|
|Start of mission|
|Launch date||14 September 1968, 21:42UTC|
|Launch site||Baikonur 81|
|End of mission|
|Recovered by||Soviet vessels Borovichy and Vasiliy Golovin|
|Landing date||21 September 196816:08 UT|
|Semi-major axis||6,613 kilometres (4,109 mi)|
|Perigee altitude||202 kilometres (126 mi)|
|Apogee altitude||282 kilometres (175 mi)|
|Epoch||13 September 1968|
|Flyby of Moon|
|Closest approach||18 September 1968|
|Distance||1,950 km (1,210 mi)|
Zond 5 (Russian: Зонд 5), one of the spacecraft of the Soviet Zond program, became the second spaceship to travel to and circle the Moon in September 1968, and was the first to return safely to Earth. Zond 5 carried the first terrestrial organisms to return safely to Earth after flying around the Moon. These travelers included two tortoises, fruit fly eggs, and plants. The tortoises underwent biological changes during the flight, but it was concluded that the changes were primarily due to starvation, and little affected by space travel.
The Zond spacecraft was a version of the Soyuz 7K-L1 crewed lunar-flyby spacecraft. It was launched by a Proton-K carrier rocket with a Block D upper-stage to conduct scientific studies during its lunar flyby.
Out of the first four circumlunar missions launched by the Soviet Union there was one partial success, Zond 4, and three failures. After Zond 4's mission in March 1968, a follow-up, Zond 1968A, was launched on 23 April. The launch failed when an erroneous abort command shutdown the Proton rocket's second stage. The escape rocket fired and pulled the descent module to safety. In July, Zond 1968B was being prepared for launch when the Block D second-stage rocket exploded on the launchpad, killing three people, but leaving the Proton first-stage booster rocket and the spacecraft itself with only minor damage.
The Zond 5 mission was originally planned to fly cosmonauts around the Moon, but the failures of Zond 1968A and Zond 1968B led the Soviets to send an uncrewed mission instead, from fear of the negative propaganda of an unsuccessful crewed flight.
Two Russian tortoises (Agrionemys horsfieldii) were included in the biological payload, weighing 0.34–0.4 kilograms (0.75–0.88 lb) each pre-flight. Soviet scientists chose tortoises since they were easy to tightly secure. There were also two tortoises used as control specimens and four more in a vivarium. Twelve days before launch, the two space-bound tortoises were secured in the vehicle and deprived of food and water; the control tortoises were similarly deprived. The food deprivation was a part of pathomorphological and histochemical experiments. The biological payload also included fruit fly eggs, cells of wheat, barley, pea, pine, carrots and tomatoes, specimens of the wildflower species Tradescantia paludosa, three strains of the single-celled green algae Chlorella, and one strain of lysogenic bacteria. The purpose of sending a variety of terrestrial lifeforms was to test the effect of cosmic radiation on them. The Russian Academy of Sciences stated that a mannequin equipped with radiation sensors occupied the pilot's seat.
Kazan Optical and Mechanical Plant had developed the AFA-BA/40 imager, which was installed on the spacecraft, giving it the ability to image the Earth. Zond 5 also contained proton detectors. Zond 5 could transmit some of its data back to ground stations, although data stored onboard and collected after return to Earth has less noise.
Launch and trajectory
Zond 5 launched on 14 September at 9:42.10 UTC, from Site 81 at the Baikonur Cosmodrome. The thrust of the third-stage rocket was terminated at 160 kilometres (99 mi), which was the start of a 251-second coast. Block D, the upper-stage rocket, ignited and burned for 108 seconds, placing the spacecraft into a parking orbit of 191 by 219 kilometres (119 mi × 136 mi). Fifty-six minutes into the parking orbit the Block D fired a final time for the trans-lunar injection. After this maneuver, the launch was announced to the world. Mission Control discovered issues with Zond 5's attitude and traced the issue to a contaminated star tracker. Heat caused some of the interior coating to outgas, which delayed an attitude correction on the way to the Moon. The maneuver was performed 325,000 kilometres (202,000 mi) from Earth using the Sun and the Earth as reference points.
On 18 September, the spacecraft flew around the Moon, although it did not orbit it. The closest distance was 1,950 kilometres (1,210 mi). On the way back from the Moon, another star tracker failed. The spacecraft also erroneously switched off the guided reentry system. The Soviet government had deployed eight ships to the Indian Ocean prior to the launch, as a precaution in case the spacecraft could not reach Soviet territory; only three of them had rescue helicopters on board.
Reentry and recovery
On 21 September, the reentry capsule entered the Earth's atmosphere. The primary landing zone was in Kazakhstan, but instead Zond 5 splashed down in the Indian Ocean and was recovered by the Soviet vessels Borovichy and Vasiliy Golovin. It landed at -32°38' longitude and 65°33' latitude, 105 kilometres (65 mi) from the nearest Soviet naval ship. The landing occurred at night, which impaired recovery efforts.
Zond 5 became the first spacecraft to circle the Moon and return to Earth. The entire journey took 6 days, 18 hours and 24 minutes. Although the ballistic reentry would probably have been lethal for human occupants, it did not appear to affect the biological specimens, which were alive when the descent module was opened four days after landing. USS McMorris shadowed the Soviet recovery ships, collecting intelligence, but left shortly after the spacecraft was brought on board the Soviet ship.
Results and future plans
High-quality photographs of the Earth, the first photos of their kind, were taken at a distance of 90,000 kilometres (56,000 mi). British astronomer Bernard Lovell, considered Britain's top space expert, said that the Zond 5 mission showed that the Soviets were ahead in the Space Race. The British Interplanetary Society believed that the USSR would be able to send cosmonauts around the Moon within a matter of months.
In October 1968, sources in the U.S. claimed the mission was not as successful as the Soviets advertised. The mission had been intended to fly closer to the Moon, and its actual distance did not allow for useful lunar photography. They also said that the angle at which the spacecraft reentered the atmosphere was too steep for a cosmonaut to have survived. The sources indicated that the spacecraft landed in the Indian Ocean when the planned location was in Soviet territory, which was a factor in the recovery taking ten hours.
The official Soviet news agency, TASS, announced in November 1968 that the flight had carried living animals. The tortoises were dissected on 11 October after fasting for 39 days. The flying tortoises, identified as No. 22 and No. 37, had lost 10% of their body weight during the trip, but showed no loss of appetite. The control tortoises lost 5% of their weight. Comparison of analyses of blood from the space-travelling tortoises and the control specimens revealed no differences. Another analysis showed the flying tortoises had elevated iron and glycogen levels in their liver and that the flight also affected the internal structures of their spleens. The authors concluded that the changes in the flight tortoises were primarily due to starvation, with the space travel having little effect. In November 1968, it was announced that the spacecraft was planned as a precursor to a crewed lunar spacecraft. The Soviets made this announcement a month before the planned Apollo 8 flight, in an attempt to show they were close to being able to carry out a crewed trip to the Moon.
- "Zond 5". NASA Space Science Data Coordinated Archive. Retrieved 28 February 2019.
- Siddiqi 2018, p. 80.
- Betz, Eric (18 September 2018). "The First Earthlings Around the Moon Were Two Soviet Tortoises". Discover. Retrieved 14 July 2019.
- Siddiqi 2003, p. 653.
- "Tentatively Identified Missions and Launch Failures". NASA Space Science Data Coordinated Archive. Retrieved 9 March 2019.
- Zak, Anatoly (14 July 2018). "L1 No. 7L: A circumlunar mission attempt". Russian Space Web. Retrieved 8 July 2019.
- Zak, Anatoly. "Mission L1 No. 8L: A deadly accident". Russian Space Web. Retrieved 9 March 2019.
- Zak, Anatoly. "Zond 5". Russian Space Web. Retrieved 9 March 2019.
- Gaidamakin et al. 1969, p. 2.
- Siddiqi 2003, p. 654.
- Madigral, Alexis C. (27 December 2012). "Who Was First in the Race to the Moon? The Tortoise". Atlantic. Retrieved 9 March 2019.
- Bausman, John (15 November 1968). "Turtles, Flies Circle the Moon". The Journal News. White Plains, New York. Associated Press. p. 24 – via Newspapers.com.
- "Earth-Cloud Photography". NASA Space Science Data Coordinated Archive. Retrieved 28 February 2019.
- "Proton Detectors". NASA Space Science Data Coordinated Archive. Retrieved 28 February 2019.
- "Space Recordings Returned by Zond 5". The New York Times. 24 September 1968. p. 41.
- Siddiqi 2003, p. 655.
- Siddiqi 2003, pp. 655–656.
- Cassutt 2007, p. 320.
- Oleg Pavlenko (Олег Павленко), Из истории Морского космического флота. К 35-летию полета корабля «Зонд-5» (From the history of the Sea Space Fleet. On the 35th anniversary of the Zond 5 mission) ‹See Tfd›(in Russian) (includes photos of the reentry capsule recovery)
- "Zond 5, Landing Point, Miss Distance". NASA. Archived from the original on 27 September 2011.
- Siddiqi 2003, p. 656.
- Siddiqi 2018, pp. 79–80.
- Day, Dwayne A. (9 February 2009). "Chasing the Zond". The Space Review. Retrieved 9 March 2019.
- "ENERGIA's driving force". ENERGIA. Retrieved 9 March 2019.
- "Russ Lead in Race to the Moon Top British Space Expert Says". Arizona Republic. Phoenix, Arizona. Associated Press. 23 September 1968. p. 6 – via Newspapers.com.
- Bloom, Mark (1 October 1968). "Flight of Russian Moonship Called Blow to its Program". Daily News. New York, New York. p. 5 – via Newspapers.com.
- Gaidamakin et al. 1969, p. 1.
- Gaidamakin et al. 1969, p. 3.
- "Soviets Recover Spacecraft After Flight Around Moon Opens Way for a Manned Shot". The Morning Call. Allentown, Pennsylvania. New York Times News Service. 23 September 1968. p. 3 – via Newspapers.com.
- "Soviets Reveal Moonflight Probes Foretell Real Trip". Clarion-Ledger. Jackson, Mississippi. Associated Press. 25 November 1968. p. 34 – via Newspapers.com.
- "Russia: Location of Russian Manned Spacecraft". Astronautix. Retrieved 19 August 2018.
- Cassutt, Michael (2007). Red Moon. Tom Doherty Associates. ISBN 978-1-4299-7172-0.
- Gaidamakin, N. A.; Parfenov, G. P.; Petrukhin, V. G.; Antipov, V. V.; Saksonov, P. P.; Smirvona, A. V. (1969). Zug, George R.; Peters, James A. (eds.). Патоморфологические и гистохимические изменения в органах черепах на борту космического корабля «Зонд-5» [Patho-Morphological and Histochemical Changes in the Organs of Turtles on Board the "Zond-5" Probe] (PDF). 18th IAF Conference (in Russian). Translated by Friedman, Morris D. La Plata, Argentina.
- Siddiqi, Asif A. (2018). Beyond Earth: A Chronicle of Deep Space Exploration, 1958–2016 (PDF). Washington, D.C.: NASA History Program Office. p. 80. ISBN 9781626830424. LCCN 2017059404. SP-2018-4041.
- Siddiqi, Asif A. (2003) . The Soviet Space Race with Apollo. Gainesville, Florida: University Press of Florida. ISBN 978-0-8130-2628-2.
- Zond 5 image of Earth