Zond 5

Out of the first four circumlunar missions launched by the Soviet Union there was one partial success, Zond 4, and three failures.[5] 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 shut down the Proton rocket's second stage. The escape rocket fired and pulled the descent module to safety.[6][7] 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.[8]

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.[9]

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.[10] 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.[10] The food deprivation was a part of pathomorphological and histochemical experiments.[11] 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.[11][12] The purpose of sending a variety of terrestrial lifeforms was to test the effect of cosmic radiation on them.[13] However, the test subjects were not analogous to humans, because the choice of life forms were all extremophiles with a substantially higher radioresistance.[14][15][16] The Russian Academy of Sciences stated that a mannequin equipped with radiation sensors occupied the pilot's seat.[1]

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.[9][17] Zond 5 also contained proton detectors.[18] 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.[19]

1969 USSR stamp of Zond 5

High-quality photographs of the Earth, the first photos of their kind,[28] were taken at a distance of 90,000 kilometres (56,000 mi).[1] British astronomer Bernard Lovell, considered to be 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.[29]

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.[30]

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.[31] 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.[13] The authors concluded that the changes in the flight tortoises were primarily due to starvation, with the space travel having little effect.[32] 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.[33][34]

The Zond 5 caused a scare in the United States when on 19 September 1968, the voices of cosmonauts Valery Bykovsky, Vitaly Sevastyanov and Pavel Popovich were transmitted from the spacecraft and intercepted by Jodrell Bank Observatory and the CIA.[35][36] The cosmonauts were apparently reading out telemetry data and computer readings, and even discussing making an attempt to land. At the height of the Cold War, there was a real concern that the Soviets might actually beat NASA to the Moon. Apollo 17 astronaut Eugene Cernan remarked that the incident had "shocked the hell out of us."[37]

Popovich would later recall: "When we realized we would never make it to the moon, we decided to engage in a little bit of hooliganism. We asked our engineers to link the on-the-probe receiver to the transmitter with a jumper wire. Moon flight missions were then controlled from a command centre in Yevpatoria, in the Crimea. When the probe was on its path round the Moon, I was at the center. So I took the mic and said: "The flight is proceeding according to normal; we’re approaching the surface..." Seconds later my report – as if from outer space – was received on Earth, including [by] the Americans. The U.S. space advisor Frank Borman got a phone call from President Nixon [actually Johnson], who asked: 'Why is Popovich reporting from the moon?' My joke caused real turmoil. In about a month's time. Frank came to the USSR, and I was instructed to meet him at the airport. Hardly had he walked out of his plane when he shook his fist at me and said: 'Hey, you, space hooligan!'"[38]

The Zond 5 return capsule is on display at the RKK Energiya museum, located in Moscow Oblast, Russia.[39]

• Animals in space
• Fe, Fi, Fo, Fum, and Phooey, five mice who orbited the Moon 75 times in December 1972, while traveling on NASA's Apollo 17 mission
• Korabl-Sputnik 5, another Soviet mission some mistakenly thought was crewed.

• 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) [2000]. The Soviet Space Race with Apollo. Gainesville, Florida: University Press of Florida. ISBN 978-0-8130-2628-2.

• Zond 5 image of Earth