Crewed missions to Venus that never flew

Nobody has ever flown to Venus, yet for more than a decade from 1960 engineers near Moscow and in Huntsville, Houston, Cleveland and Washington drew up ships to take people there. The attraction was the calendar. In the Soviet plan of 1962 a crewed Mars flyby would last about two years and a Venus flyby a little over one. Some American planners came to see Venus as a proving ground for Mars, and on both sides ships were drawn to pass Venus on the way to or from Mars. Nothing on this page flew: what remains is mass estimates, trajectory tables, contractor reports, a few laboratory tests and at least one museum model. Soviet designs come first, then American ones, then the floating habitats of later decades.

Soviet crewed planning for Venus was written into government resolutions before any probe had reached the planet. A joint resolution of the Communist Party Central Committee and the Council of Ministers, No. 715-296 of 23 June 1960, provided for a heavy interplanetary ship for flights to Mars and Venus and for preparing expeditions to the surfaces of the Moon, Mars and Venus. Its contents are known here from the resolution that stopped them. No. 420-174 of 13 May 1961, whose scan Roscosmos has published, revised space plans toward tasks of defence significance. Clause 1(v) orders "the development of the heavy interplanetary ship for flight to Mars and Venus" stopped, and clause 1(d) stops "the work of preparing expeditions to the surface of the Moon, Mars and Venus".

Korolev's OKB-1 went on working all the same. V. Karfidov's 2021 survey of crewed ship projects (headed Kosmonavtika on the copy read here) says the bureau's interplanetary designs of 1959 to 1961 were gathered in the first half of 1962 into a "Plan for the mastery of Mars and Venus": flybys of both planets, then ships that would enter orbit, then landings, every stage launched by the N-1. A 2017 page on the site of a Bauman Moscow State Technical University research centre quotes the tasks in the N-1 draft project that Korolev approved on 16 May 1962, among them "a flyby of Mars and Venus by a crew of two or three and return to Earth" and "expeditions to the surface of Mars and Venus and the choice of a site for a research base". Karfidov is plain about how deep this went: the projects were estimates of mass, with no structural design behind the solutions they assumed.

TMK-V, the Venus flyby ship, was almost a copy of the Mars flyby ship TMK-M, and both grew from the flyby design Gleb Maksimov's sector had drawn in 1959. In Karfidov's figures one N-1 would put 75 t into a parking orbit, and a departure stage burning kerosene or liquid hydrogen would send away a ship of 15 or 19 t, about 12.5 m long and 3 m across, with a 2.5 t return capsule. Draft design was scheduled from July 1962 to December 1964, with two more years for building and testing. The Mars ship would leave early in 1967 and TMK-V would follow that summer. The Bauman page gives Maksimov's TMK as 12 m long, 6 m across and 75 t, leaving for Mars on 8 June 1971. Its 75 t equals Karfidov's figure for everything one N-1 put in orbit, departure stage included, while his 15 to 19 t is the ship alone; the diameters, 6 m against 3 m, and the Mars departure dates, 1971 against early 1967, do not reconcile.

The later stages of the plan leaned on electric propulsion. TMKE-V, a Venus orbiter assembled from two N-1 launches, would have weighed 100 t in Earth orbit, spiralled out under a reactor-powered electric engine, spent up to nine months in Venus orbit, dropped a 1 t landing probe and come home as a 66 t ship, three years in all. Though the harder project, it was proposed to leave before its Mars twin, in the first quarter of 1969, with three crew. STMKE-V went further. Sketched, Karfidov writes, when there were no accurate data on the pressure and temperature at the surface, it would have put three people on Venus for nine months and needed 960 t in Earth orbit, 14 N-1 launches; of the 795 t that would reach Venus orbit, 410 t was the landing and ascent module. Launch was possible no earlier than 1975. Two decisions ended the line. In the summer of 1962 Korolev ruled that the TMK would use liquid-propellant engines, because usable electric engines were not expected soon, and work on the heavy interplanetary ship went on only until 1964, when a government resolution set OKB-1 the task of a lunar expedition.

The Venus flyby came back in 1966 at TsNIIMash, formerly NII-88, the lead research institute of the Soviet rocket industry. M. D. Evtifyev, in a manuscript on the institute's Mars projects published by buran.ru, writes that in early June 1966 a group there was told to study OKB-1's TMK and draft its own ship for six people, this time for a flyby of two planets. The code name was Mavr, which Evtifyev reads as Mars and Venus at once; Karfidov reads it as MArs and VeneRa and gives the other reading in a footnote. The ship would leave in 1975 on an Earth, Mars, Venus, Earth path lasting 480 to 600 days, the pass of Venus shortening the flight home. Two spherical Venus probes, a lander and an orbiter, would ride beside a Mars probe with a 6 m heat shield. The crew would live in a block 6 m across with six cabins, a laboratory, a radiation shelter and a 14 m² greenhouse lit by a 30 m² solar concentrator that doubled as a radio telescope dish. The designers rejected spin gravity and, after consulting the Institute of Biomedical Problems, carried exercise equipment including a centrifuge.

The sources do not agree on Mavr's mass. Evtifyev gives the initial mass as 105,680 kg, yet the components in his own list, from the 71,500 kg living block to 37,250 kg of propellant, add up to about 150.7 t, and Karfidov gives 151 t from the same figures. Encyclopedia Astronautica describes a different Mavr altogether: a 1963 OKB-1 variation on Maksimov's TMK, 75 t on a single N-1 with three crew, passing Venus on the way back from Mars. TsNIIMash director Yu. A. Mozzhorin approved the report on the theme, design studies of crewed interplanetary complexes for an expedition with a flyby of Mars and Venus, on 12 July 1968. When the fourth and last N-1 failed on 23 November 1972, Evtifyev writes, the hopes for Mavr and the later Mars programme Aelita were buried with it.

Chelomei's OKB-52 had its own Venus craft, without a crew. Its kosmoplan family of modular winged probes was authorised by resolution No. 714-295 of 23 June 1960, and the Bauman page counts two kosmoplan variants for flights to Mars and Venus under the theme K. The 1961 resolution treated it much as it treated Korolev's ship. Clause 1(g) stops the automatic uncrewed kosmoplan for flights to Mars and Venus with return to Earth and landing at a set airfield, while a later point keeps the lunar kosmoplan K going only as far as a draft project due in 1963. Anton Pervushin writes that OKB-52 did issue a draft project in 1963 for an uncrewed kosmoplan K for flights to the Moon, Mars and Venus. The resolution had limited that draft to the Moon; whether Mars and Venus came back into it is not settled by the sources.

The earliest American study covered here was a Mars study that included Venus. In May 1962 the Future Projects Office at NASA's Marshall Space Flight Center awarded General Dynamics, Lockheed and the Aeronutronic Division of Ford study contracts worth $250,000 each under the name EMPIRE, for Early Manned Planetary-Interplanetary Roundtrip Expeditions. Aeronutronic drew flybys passing both Mars and Venus, comparing a trajectory the Italian engineer Gaetano Crocco had presented in 1956 with a symmetric one. Its final report of 21 December 1962 chose the symmetric path, leaving Earth between 16 July and 19 August 1970: the ship would pass Venus 97 to 102 days out, at 4,890 to 7,520 miles, pass Mars at the midpoint and be home after 611 to 631 days. It was a 188-ton ship with a NERVA nuclear engine, six crew in two spinning living modules and a lifting-body for reentry, and David Portree reports its cost estimate as $12.6 billion.

Apollo hardware replaced the nuclear ships in 1965. A Marshall team under Harry Ruppe, reporting in NASA TM X-53205 of 5 February 1965, put a modified Apollo Command and Service Module inside a hangar on a flyby ship for three. Its Venus example would leave Earth orbit in August 1978, pass low over the day side of Venus on 11 December 1978 and return on 16 August 1979. The team also ran a mission worth analysis and found that dropping crewed Venus flybys from a space programme would cost just 2% of its total worth, because it is not possible to land on Venus. North American Aviation, briefing its study in June 1965, went the other way and made Venus phase one: a crewed flyby leaving Earth orbit on 30 October 1973 for 415 days, launched directly by one three-stage Saturn V, at a cost of $2,301,700,000.

Bellcomm's Manned Venus Flyby is dated 1 February 1967. Feldman, Ferrara, Havenstein, Volonte and Whipple wrote it for NASA Manned Space Flight to guide the technical goals of the Apollo Applications Program. Three astronauts would leave on one standard Saturn V in a Command and Service Module similar in some respects to Apollo's, with an Environmental Support Module in the adapter where the lunar module rode and the spent S-IVB stage used as living space and as the frame for solar cells. Total injected weight was 106,775 lb. The reference mission would leave Earth on 31 October 1973, reach Venus after 123 days on 3 March 1974, pass 3,340 nautical miles above it and return on 1 December 1974. Four probes of about 500 lb each would be released about 24 hours before closest approach. The authors wrote that it was clearly not their intent to recommend that NASA undertake a Venus flyby in 1973 or at any time, only to show one was feasible and so guide the choice of long-duration systems.

Houston had its own plan the same month. Jack Funk and James Taylor of the Manned Spacecraft Center proposed, in MSC Internal Note 67-FM-25 of 13 February 1967, three single-launch Apollo Venus flybys as the final goal of the Apollo Applications Program, with launch periods opening on 4 April 1972, 14 November 1973 and 7 June 1975. In the 1972 example the crew would launch on 2 April, leave a 48-hour Earth orbit for Venus on 5 April, pass the day side on 23 August and reenter on 30 March 1973, 359 days after launch. Portree writes that Houston preferred a Venus flyby followed by a Venus orbiter to the Mars flybys then under study, because both would be shorter and need less propulsion.

A crewed Venus orbiter was worked out at NASA's Lewis Research Center in Cleveland. Edward A. Willis Jr.'s TM X-52311 of 1967 studied stopover missions for departures from 1975 to 1986 and found that an elongated parking orbit, 1.1 by 20.9 Venus radii, kept the mass down. For 1980, the hardest year, a 565-day trip with 40 days at Venus would need 1,412,000 lb in Earth orbit with Apollo-level chemical propulsion (Figure 6; the summary rounds it to about 1.5 million, the conclusions to 1.4 million), and the easiest Mars orbiting mission would be 70% heavier. A manned landing on Venus, Willis wrote, was not then under consideration, and in difficulty and timing the Venus orbiting mission had a place ahead of the Mars orbiting and landing missions. His introduction still allowed that scientific opinion did not reject life on Venus or suitable sites for a manned landing.

Some American plans passed Venus twice. NASA's Planetary Joint Action Group, reporting in October 1966, described a triple flyby past Venus, Mars and Venus again. At Bellcomm in September 1967 Bankovskis and Vanderveen found an opportunity leaving Earth orbit on 26 May 1981, passing Venus on 28 December 1981 and 1 March 1983 with Mars between, home after 790 days; a month later Vanderveen found another leaving on 28 November 1978, 800 days long, with Venus passes on 11 May 1979 and 29 January 1980. D. Cassidy, C. Davis and M. Skeer worked out what such ships would drop, in a Bellcomm report of 30 November 1967. At the first Venus pass of a 1977 triple flyby the crew would release 15 probes weighing 27,200 lb: six drop sondes, four meteorological balloons, two landers built to survive, two camera probes that would plunge to the surface and an 8,000 lb orbiter to map the planet by radar in about 120 days. For the third Venus pass of the sequence, on a 1978 Venus and Mars flyby, they added large balloons to filter the air for aerosol life, and they expected that crews might one day explore the atmosphere in propeller-driven cruising vehicles.

Little of it outlived 1967. Portree ties the end to politics more than to Venus: the Apollo 1 fire of 27 January 1967 damaged NASA's standing with Congress, and in August 1967 Congress cut all funds for crewed planetary mission planning from NASA's fiscal 1968 budget and slashed the Apollo Applications Program, which shrank into Skylab. Karfidov gives another reason for the Apollo-based projects: they were not approved because preference went to automatic probes. Science was closing in at the same time. Mariner 2 had measured, by Portree's account, at least 800 °F over the whole planet in December 1962, and on 18 October 1967 Venera 4 descended into the atmosphere; the next day Mariner 5 flew past, its radio occultation pointing to a surface pressure 75 to 100 times Earth's. Bellcomm's probe report was being finished as those results came in. Crewed planning revived in 1969 and 1970 inside NASA's much larger post-Apollo plan, Portree notes, and that plan had no place for a step as small as an Apollo flyby.

One Venus station study of the same year carried no crew at all. Martin Marietta's Buoyant Venus Station feasibility study, a six-volume final report of July 1967 under NASA contract NAS1-6607, examined an inflatable station released from a Venus orbiter, floating in the cooler upper atmosphere and dropping sondes toward the surface, in versions of 200, 2,000 and 5,000 lb. The report opens by saying that future NASA planetary exploration may require an unmanned capsule to probe the Venusian atmosphere. Balloons eventually reached Venus with the Vega balloons of June 1985.

Floating became the way people could still imagine living at Venus. In September 1971, according to a blog that reproduces the cover, the Soviet youth magazine Tekhnika Molodezhi printed flying islands of Venus proposed by the engineer and science fiction writer Sergei Zhitomirsky: platforms carrying soil, gardens and houses under a film envelope, with living quarters inside the platform and propellers underneath. A 2022 article in Nauchnaya Rossiya places his airships at 50 to 60 km, with a shell of thin corrugated metal and ammonia or water turned to vapour by the heat as the working fluid. Geoffrey Landis of NASA Glenn set out the case in a paper for a conference in Albuquerque in February 2003. At about 50 km, he wrote, Venus is the most Earthlike environment in the solar system other than Earth, and because breathable air is a lifting gas in carbon dioxide, lifting about half a kilogram per cubic metre, a habitat's whole envelope could be living space. He proposed exploring from aerostats first and, in the long term, cities built to float at about 50 km.

HAVOC, the High Altitude Venus Operational Concept, turned that into a campaign. Dale Arney and Chris Jones of NASA Langley's Space Mission Analysis Branch presented it at AIAA SPACE 2015 in Pasadena (31 August to 2 September 2015) in five phases from robotic exploration to a permanent human presence. A 31 m robotic airship would go first. The crewed airship would be 129 m long, carrying two astronauts for 30 days at 50 km, where the study gives gravity of 8.73 m/s². The round trip would take 440 days, 110 out, 30 at Venus and 300 home, with 348.5 t in low Earth orbit. The two proposals give different temperatures for almost the same level: Landis puts 0 to 50 °C where the pressure is one bar, slightly above 50 km, while HAVOC gives 75 °C and 1.05 atmospheres at 50 km. A companion paper found FEP Teflon kept 90% of its transmittance after 30 days in concentrated sulfuric acid. The proofs-of-concept paper calls HAVOC an internal NASA study.

Crewed Venus plans of the 2020s are Mars plans. A white paper for the 2023 to 2032 planetary science decadal survey by Noam Izenberg, Ralph McNutt and colleagues, posted on 8 June 2020, notes that some crewed Mars trajectories pass Venus and argues that astronauts on such a flyby could steer probes in real time. A NASA Langley and Marshall team designed a deep space habitat for such a flyby for a conference in November 2020, and a 2022 JPL concept for a crewed Mars orbital mission in 2033 would come home through a Venus flyby after about 30 days in high Mars orbit, 1.6 years in all. Karfidov notes that NASA's 1969 Mars expedition plan also returned past Venus, releasing two 900 kg probes there. Neither document featured on NASA's Moon to Mars architecture page, the 2025 Architecture Update and the April 2026 Moon Base users guide, mentioned Venus when checked on 26 September 2026. Robotic cloud missions are under Venus Life Finder.