Soviet Venus missions that never flew

Between the landings of Venera 9 and 10 in 1975 and the break-up of the Soviet Union, the Lavochkin design bureau and its partners drew up more Venus missions than they launched. Two never got past a bureau index and a proposal: 4V-3, a repeat of the soil-sampling landers of Venera 13 and 14 planned for December 1984, and 6V, a Venus craft on the universal UMVL platform pencilled in for 1983, then 1990, 1996 and 2000. Two reached real hardware on the ground: DZhVS, a long-lived seismic station whose 500 °C components were built and tested in research set for 1977 to 1980, and the six-wheeled, wind-powered KhM-VD rover mock-ups that VNIITransmash built in 1984 and 1986. Two more were joint projects with France. Venera-84, called 5V Venera-EOS in Russian sources, was meant to float a large French balloon in the clouds and was reshaped into Vega once Halley's comet came within reach. Vesta, studied by CNES from October 1984 and discussed with the Soviet side into 1986, would have paired Soviet Venus landers with a French asteroid probe. In 2019 NPO Lavochkin engineers took up the rover idea again on paper. None of these flew in the form described here.

The sources disagree on when the bureau's leadership changed. Georgy Babakin, who led the bureau from Venera 4 to Venera 7, died on 3 August 1971. NPO Lavochkin's own history says S. S. Kryukov took over from the end of 1971 and that Vyacheslav Kovtunenko became chief designer in 1977; the same page dates Kovtunenko's rise to general designer to 1986 in one paragraph and 1987 in another. V. G. Perminov, the bureau's leading designer for Mars and Venus spacecraft, tells it differently in the memoir NASA published in 1999: Kryukov, once a deputy of Sergei Korolev, resigned after Minister S. A. Afanasyev cancelled the Mars soil return project in 1978, and only then was Kovtunenko brought in from the Yuzhnoye bureau in Dnepropetrovsk. Perminov writes that Kovtunenko kept the Venus spacecraft Kryukov had started and in 1979 began UMVL, a universal design for Mars, Venus and the Moon. The first-hand account of DZhVS used here, in Novosti Kosmonavtiki in 2001, is signed V. Perminov and N. Morozov, who write as members of the design team.

DZhVS grew out of a gap in the Venera 9 and 10 programme. Perminov and Morozov write that the flight programme of neither lander included seismic activity or the crust, experiments they call of the first importance for understanding the planet, so at the scientists' request the designers looked at doing them on later flights. Their first idea was active sounding: set off a charge some distance from a seismograph and record the waves that come back from deeper layers. On Venus an ordinary charge would have needed heavy insulation to survive the descent and then 10 to 15 minutes at 500 °C while the ringing from the lander's own impact died away, and throwing it far enough through the dense air was hard. So the designers considered sending a nuclear charge on a second descent craft, built from a first-generation station, and detonating it far from the first. The article says this could not be done because international agreements prohibit putting nuclear charges into space. What remained was passive seismology, waiting for venusquakes, and for that the scientists wanted a lander that would work on the surface for at least a month. Venera 9 and 10 had lasted 53 and 65 minutes.

The first approach was to keep ordinary electronics cool for longer. The pressure hull would be a Dewar flask, an inner sphere hung inside an outer one on thin titanium rods working in tension, because the joints had to carry up to 175 tonnes when a 500 kg instrument compartment decelerated at up to 350 g in the atmosphere. Radiant heat still leaked through, so the gap was to be packed with tiny shiny evacuated glass beads, and the inside of the inner sphere lined with lithium nitrate trihydrate, a salt that soaks up heat as it melts. After a long search the design reached five days on the surface. The bureau then brought in NIITP, the thermal processes institute of the Ministry of General Machine Building, and NPO Energiya of the Ministry of Medium Machine Building to reach the 30 days the scientists wanted; both later sent reports listing measures that would make 30 days possible with ordinary equipment.

About the same time the designers learned that the Minsk Institute of Radioelectronics had microcircuits that worked at up to 250 °C in instruments lowered into deep boreholes. That pushed them toward a bolder station whose instruments would themselves withstand 500 °C. IKI director Roald Sagdeev liked the idea and put his institute to work on the science programme, and Academician B. Ye. Paton, president of the Ukrainian Academy of Sciences, brought in Ukrainian institutes. In 1976 and 1977 NPO Lavochkin and IKI drew up and approved the Basic principles for an automatic station for long-duration research on the surface of Venus. DZhVS would have two compartments. The upper one, sealed and insulated, held ordinary instruments kept below 50 °C for two hours to measure the weather, soil, radiation and light and to take a panorama. It would then be switched off, and the 500 °C instruments would be switched over to the lower compartment, which carried sensitive seismographs, kept an internal pressure of 0.1 to 0.3 MPa and ran on a radioisotope thermoelectric generator of about 30 W. Data would go to Earth directly and through the orbiter. The article's text rates the lower compartment's equipment for about a year at 500 °C; its drawing of the 30-day station labels the same section 'at least one month'.

Research on elements, materials and equipment was set for 1977 to 1980, to be followed by a design project if the results were good, and they were encouraging. A cable bureau in Mytishchi and the Ukrainian Institute of Materials Science produced heat-resistant wire; Elekon in Kazan made a prototype sealed connector in a titanium body; the Institute of Solid State Physics built a diamond-crystal radiation detector able to work at 500 °C; scientists from the Institute of Physics of the Earth worked on heat-resistant seismic sensors; and VNIIRTI reported that a silicon-germanium radioisotope generator could be made at 3 kg per watt, or 2 kg with a new process from its Sukhumi branch. The Minsk institute supplied prototype chips for a receiver mock-up, which ran for several months in an IKI thermal chamber held at 500 °C. Yet the bureau never reached the step of analysing the results and choosing a variant. Perminov and Morozov blame the workload: the radar mappers that flew as Venera 15 and 16, due to launch in June 1983, and then Vega, due in December 1984. The DZhVS teams were moved to other work and could not be brought back years later, and funding for space projects began to fall at the end of the 1980s. No cancellation decree is cited. Some of the work lived on, the article says: a Mashinoapparat motor for the drill that bored even basalt on Venus, heat-resistant wire later used in aviation, and heat-resistant chips and radiant-heat shielding methods reused in a study for a probe to pass 10 solar radii from the Sun's surface.

4V-3 was the bureau's plan for the 1984 launch window, indexed V-84. V. Karfidov's 2021 catalogue of Soviet probe projects describes it as a probe to continue the study of Venus by repeating the sampling and analysis of soil with a landing in a new region, using a landing module like that of 4V-1M, the series that flew as Venera 13 and 14. Two were proposed for launch in December 1984. The entry closes with one line: the 4V-3 project was not carried out and was replaced by project 5V. No second source for 4V-3 was found for this page, and Karfidov gives no date for the switch.

The authors of the 1986 overview of the Vega balloon experiment in the Soviet journal Pis'ma v Astronomicheskiy Zhurnal, among them Sagdeev, V. M. Linkin, Jacques Blamont and R. Preston of JPL, write that Blamont first proposed balloons for studying the dynamics of the Venus atmosphere as early as 1967. The EOS name was in use by April 1974, when a Soviet-French symposium in Moscow on the EOS-Venera project heard a proposal to follow transmitting balloons with ground radio interferometers, the method Vega would use. Between 1974 and 1980, under a joint programme of the Interkosmos Council of the Soviet Academy of Sciences and the French space agency CNES, a comprehensive balloon station was developed in both countries, sending its measurements to Earth through an orbiter, and the scheme needed a separate carrier for each balloon station and each orbiter. Karfidov names two craft in the family, 5VS and 5VP, but no source read for this page says which role each had. IKI calls the programme 5V Venera-EOS. Igor Marinin, writing on the Russian space news site Pro Kosmos in June 2025, calls it Venera-84 and says the launch of two stations was set for 1984 and officially timed to the 200th anniversary of the Montgolfier brothers' balloon, which is why it was nicknamed Montgolfier to Venus. In his account the Soviet side would supply an orbiter and a lander with a balloon deployment system, and French engineers in Toulouse the balloon and its gondola.

Sources disagree on the balloon's size and mass. Marinin gives the whole floating station about 220 kg, made up of a Teflon envelope 10 m across and a gondola of science equipment of about 50 kg, expected to work for five Earth days, with its data stored on the orbiter's tape recorder for relay to Earth. A 2020 tribute to Blamont by Pierre-François Mouriaux and Philippe Varnoteaux for the Société astronomique de France describes the French EOS balloon as 9 m in diameter with a gondola of 220 kg. The two may be measuring different things, the whole station in one case and the gondola in the other, or different stages of the design; neither says. Marinin also dates the start of work on Venera-84 to the early 1980s, which does not fit the 1974 to 1980 development in the 1986 balloon paper; Thérèse Encrenaz of the Paris Observatory, writing in 2026, places the project under study at the end of the 1970s.

Halley's comet ended the plan. IKI's history of Vega says development of the V-85 5VK station began under a party and government decree of 8 May 1980, and that ballistic analysis then showed the carrier could be sent past Halley after the Venus flyby. Largely on Sagdeev's initiative the comet was added, and in IKI's words the preceding project was in effect wound up. Encrenaz dates the proposal to the Franco-Soviet meetings in Ajaccio in September 1980, where it was suggested that the Venera-84 orbiter drop the lander and balloon into the atmosphere and then head for the comet. Karfidov says the compromise was found in 1981: work on 5VS stopped, 5VP was reworked to widen the Halley studies, and the balloon station was made smaller and lighter and would send its data straight to Earth with no relay. The 1986 balloon paper credits that step to Sagdeev and Linkin: a low-power transmitter heard directly by sensitive stations on Earth, which would also track the balloon by very long baseline interferometry. The technical assignment for the new complex, 8K82K-5VK, was drawn up and approved by its developers between May and September 1981 and finally approved by Minister Afanasyev on 24 February 1982, according to the Russian State Archive of Scientific and Technical Documentation (RGANTD), which holds it.

French and Russian accounts tell the end of the French balloon differently. Karfidov says the French side declined to develop a lightened balloon station and Marinin that it declined to build one for Vega, so the task fell to Soviet engineers, and the Vega balloons that flew in June 1985, 3.4 m across, were designed and built in the Soviet Union. The Blamont tribute puts it the other way round: in the end the Soviets preferred to replace the French EOS balloon with two smaller ones. A French popular history on Clubic says the mass budget forced a choice between Halley and the big balloon. France stayed in the experiment in other roles. The 1986 paper lists Blamont as co-leader, with Linkin, of the balloon's meteorological and nephelometer experiments, and at the Interkosmos Council's request CNES organised and coordinated the international radio telescope network that tracked the balloons alongside a Soviet one, with Blamont and Preston as its scientific leaders. No source read for this page says how far the French balloon hardware got before the change.

6V, first designated 183V, was the bureau's next Venus design. Karfidov lists what it was to do: photograph the surface during the last 10 km of descent, deploy a series of balloons for different altitudes, run an active and a passive seismic experiment, and study Venus from orbit. It was to be built like 1F, the craft that flew to Mars as Phobos, with a spherical descent craft in place of the science compartment. The 1978 programme set two launches for 1983. The space research programme for 1986 to 2000 that NPO Lavochkin drew up in 1984 moved two launches to 1990, followed by paired launches of modified 6V-1 and 6V-2 craft in 1996 and 2000. Karfidov's verdict is that work on 6V did not get beyond technical proposals. Perminov's memoir does not mention 6V, but it describes the slow progress of the UMVL platform behind 1F: begun in 1979, it produced the Phobos craft only about ten years later.

Vesta, a contraction of Venera and asteroids in Karfidov's reading, was discussed in 1985 and 1986 as a Soviet-French mission of two launches, each carrying a Soviet 5V-type Venera probe and a French Vesta probe. The Soviet craft would drop landers, and possibly balloons, to image the surface during descent, look for volcanic activity and study the circulation and clouds; the French craft would swing past Venus toward an asteroid or a comet. The CNES Phase 0 report of 1985, which NASA published in English in 1986, fills in the plan: about 5 tonnes on each Proton in December 1992 or January 1993, two identical launches a few days apart, a descent module entering the atmosphere at 11.6 km/s in mid-1993 with a planetary probe, a floating probe and a landing probe, a landing at Aphrodite, and a Soviet bus going on past an Apollo-Amor asteroid such as Anteros. The presidents of CNES and Intercosmos approved a joint report recommending Phase A in September 1985; the mission analysis assumed a mid-1991 launch, and the report notes that a decision to postpone was made during the study.

Venus dropped out in 1987, when, Karfidov writes, the project was re-aimed at Mars because Soviet Mars probes were being worked out at the time. The Mars version kept the pairing, with two Proton launches in 1994, and was then split into separate French launches in September and December 1994. As the M1, M2 and M3 Mars programme built up, Vesta was not worked out in more detail.

Leningrad's VNIITransmash, the institute behind the Lunokhod chassis and the PrOP-V penetrometer that measured Venus soil, did the rover work. Its own chronology of space work, as archived in 2018, has two Venus rover entries: in 1984, a six-wheeled running mock-up, KhM-VD, for long-duration work on Venus using the energy of wind flows; and in 1986, a running mock-up KhM-VD2 with one turning wind turbine to recharge the battery, the main energy source for its motor-wheels. Both were test vehicles for use on Earth. The Roscosmos television studio lists a 14-minute film of KhM-VD-2 trials in its Venera collection. Where and when the trials ran is less settled. The Spanish space writer Daniel Marín describes two 160 kg six-wheeled prototypes, which he calls VM-KhD, tested between 1984 and 1987 on the Kamchatka peninsula alongside Mars rover models, with solid lubricants rated to 600 to 800 °C and no radioisotope generator, which he says was ruled out as too heavy. KamchatkaMedia, a regional news agency, wrote in April 2026 that a 1986 expedition to the Tolbachik and Shiveluch volcanoes studied wind fields for a wind-powered Venus rover, and it dates the Mars and Venus rover trials there to 1986 to 1989. None of the Russian sources read for this page gives the 160 kg mass, the lubricants or the name VM-KhD.

The idea came back in February 2019. Speaking at the Korolev Readings, an unnamed representative of NPO Lavochkin quoted by TASS on 1 February described a rover that would move across Venus the way Curiosity moves across Mars and work at 500 °C. With its entry, descent and landing systems it would weigh 872 kg, or 1,059 kg with margin, and it would need high-temperature batteries, motors, drives and electronics. It would travel inside a descent craft, drive autonomously and communicate through an orbiter or a lander. The speaker said no formal research work (NIR) was under way and the study was being done on an initiative basis, that the next step would be a technical proposal, that he hoped the rover would enter the federal space programme after 2025, and that it would not be part of Venera-D.

On 26 September 2026 the Russian Venus mission in development was Venera-D. IKI director Anatoly Petrukovich said, according to TASS as relayed by Lenta.ru on 14 September 2026, that its draft design should run from 2026 to 2028; the same report recalls that in April 2026 Sergei Chernyshev, a vice-president of the Russian Academy of Sciences, described it as an orbiter and a lander planned for launch in 2036. The report mentions no rover. Later lander, rover and balloon ideas are collected under Venus proposals and Venus concepts.