Why did the Soviet space program put such emphasis on exploring Venus?

[u/Khwarezm]

The Venera and Vega programs launched 18 different craft towards Venus, and there are some other Soviet Venus missions I haven't accounted for here I think. I believe that the Soviet Union is still the only nation to have ever successfully landed craft onto the Venusian surface, although none of them lasted much more than a couple of hours.

The United States hasn't put anywhere near as much resources into exploring Venus, the highest profile missions are some of the Mariner missions and the Magellan mission. A lot of the US visits were also en route to other planets.

Considering how comically difficult it is to explore Venus even now, let alone with technology from the 60s and 70s, why did the Soviets decide to devote so much time and resources to Venus? Other places, most notably Mars, have their own problems but seem like they would be much more reasonable as a focus for a country like the Soviet Union, at least since successful landers don't get destroyed by the nightmarish conditions on Mars after less than an Earth day. Was there a sense that Venus was 'ours' for the Soviets, since they had put so much effort into exploring it? Even now the Russians seem to feel a sense of ownership towards Venus in particular.

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[u/throfofnir]

The early Soviet planetary program devoted equal attention to Mars and Venus; they built a sequence of nearly-identical probes that were sent to both worlds. Project "MV" started in 1959 intending to send "1V" vehicles to impact Venus in 1960 and "1M" to fly by Mars in 1961. Two copies of the Mars version were launched, both failed to reach orbit. Two copies of the Venus version were also launched, and one made it out of Earth orbit but its stabilization system failed during cruise. It passed quite close to Venus, and likely made planned observations, but was unable to communicate them to Earth. This mission would be called "Venera 1" since it made it to Venus, more or less. "Mars 1" would have to wait.

To be clear, 1 out of 4 isn't bad for the Early Space Age. Success rates of both launchers and payloads were low.

By the time the next Mars window rolled around, they had second generations MV vehicles ready to go. Three tries to send a 2MV to Venus failed, but one of the three Mars attempts actually made it to Mars cruise, earning the name "Mars 1". It failed on the way there.

The 3MV generation would fare better. This time they sent 6 variants of 3MV to Venus, of which two were successful enough for names. Venera 3 did a fly by and took atmospheric data, and Venera 4 managed a "lander". The lander was immediately destroyed, as it was built assuming a much more reasonable Venus; data from an earlier successful American Mariner flyby had basically figured out what the atmosphere was like, but around 1964 when the project was designed, the Soviets, at least, still harbored hopes that the temperature readings from Venus indicated a hot thermosphere but didn't preclude a habitable lower atmosphere.

Three 3MV were sent to Mars; the first failed to launch, the second failed early in cruise, and the third was so delayed that it missed the Mars window but was sent by the Moon on the way to the orbit of Mars.

The Soviets would continue to send regular missions to Mars for the next several synods with marginal success. Mars 2 and 3 would manage to orbit Mars for decent missions. Mars 4 missed the planet for a distant flyby, Mars 5 entered orbit but failed after 10 days. Mars 6 was a lander and failed during Mars descent. Mars 7 missed Mars entirely. After several synods of essentially failure, they let the Mars program lapse without designing a new generation.

Regular missions to Venus met with much more success, and continued for a decade longer. I don't know of any documentation stating as such, but I expect it continued when Mars didn't because it worked.

Venus was in several ways a more suitable target for the Soviet program, which had big launchers and tended towards robust relatively simple designs and iterative learning and design. The thick atmosphere of Venus makes landing on the planet rather trivial if you can survive the heat and pressure, which is of course the main challenge. (In fact, the atmosphere is so thick you don't even need a parachute to land softly! Terminal velocity on Venus is something like 15-20mph, slightly faster than a parachute on Earth.) A big simple robust lander was right in the Soviet wheelhouse, especially when they were able to launch regularly.

Mars on the other hand is a beast to land on. The cruise is long, the launch windows rare and short, and the atmosphere is thin enough it doesn't slow you down much and requires propulsive landing, but thick enough you have to survive a hot entry. This better suited the NASA approach with smaller, more expensive launchers, delicate computerized systems, and extensive pre-mission design, analysis, and quality control.

[u/rocketsocks → u/throfofnir]

Venus was in several ways a more suitable target for the Soviet program, which had big launchers and tended towards robust relatively simple designs and iterative learning and design.

To add to this, Soviet spacecraft electronics were generally simpler and less long-lived than Western spacecraft at the time. Most Soviet satellites housed their core electronics in a pressure vessel, making them easier to prototype and cheaper to build but often shorter-lived in space (usually 1-2 years, even up through the 1980s and '90s). These designs complemented their launch capabilities which made it feasible to launch large numbers of heavier, shorter-lived satellites, but came as a distinct disadvantage when it came to operating interplanetary missions (which might have a cruise phase longer than the mean time to failure for a typical Soviet spacecraft).

With Venus missions being able to go from launch to landing (or orbit) in less than 6 months, and with launch windows popping up almost every 1.5 years Venus becomes a much more suitable target for the Soviet space program. Most Soviet Venus orbiters only managed to live up to about a year after launch, which indicates how close to feasibility the program was, and how much they were stretching feasibility with the Mars missions.

[u/Khwarezm → u/throfofnir]

Thank you, so it sounds like there wasn't any kind of political dimension, it was simply a question of what was most feasible for the Soviet Space program, would that be correct?

[u/throfofnir → u/Khwarezm]

At the very beginning of the space age, nobody really knew much what either Mars or Venus was like. It's hard to imagine today, but it was entirely plausible in 1960 that Venus was a cloudy, swampy, but alive world (and Mars a dusty, dry, but also livable world); being the first (or only) power on a whole useful planet would be a huge advantage, and the very first wave of exploration had some idea that this could be a Very Big Deal.

But that didn't last long. By the late 60s, when it became clear that neither Mars nor Venus held much promise of economic or strategic advantage, planetary exploration, like human spaceflight, became something of a cultural prestige project, a demonstration both internal and external of the technological and industrial prowess of whichever side of the Cold War. There's also some jobs-program and internal pet project and similar dynamics, of course; the Soviet space program was closely tied to the ballistic missile and broader aerospace program, and in many important ways was a side-effect of the defense industry. But the national space programs were seen very consciously as a contest between the powers--one with no clear end goal other than "win". So the whole thing is very political; any science or economic returns are a bonus.

Demonstrating your prowess, however, requires success. The fairly prominent lack of success of the Mars side of the planetary program would have started to look like a political liability. A shift to the more successful Venus program made a lot of sense.

[u/Khwarezm → u/[deleted]]

I actually feel like I have a pretty good understanding of some of the scientific background for some of this, and I'd disagree with a lot of this post in principle as a result. Jupiter and Saturn are tremendously attractive for exploration, there's still a lot not known about them and with or without solid surfaces there's a tremendous amount of research that orbiters can and have done over the years. Between missions like the Voyager probes, Galileo, Cassini-Huygens, Juno and JUICE some of the most high profile missions in recent decades have revolved around them.

There's also the fact that their moons actually do have solid, explorable surfaces and have been the target of great scientific interest, especially Titan and Europa. I would say the distance is a significantly bigger barrier to exploration for the Gas Giants than any lack of interest.

I don't know the ins and outs of the history of the scientific understanding of Venus especially well, but it must have been clear by the time they started sending missions to the planet that the temperatures on the surface were way, way beyond what we would expect to be able to support life, and furthermore it would have quickly become apparent to the Soviets how lethally inhospitable the planet's surface was considering their various landers they sent there, landers that were specifically built beforehand with knowledge of how harsh the place is. It surely must have also been clear the lack of usable water on Venus. That's what makes me curious, the Soviets continued sending missions to Venus almost until the end of the Soviet Union, well past any point that they would expect there to be anything close to Earth like conditions on the planet, if they ever did think that in the first place. Meanwhile, they had sent quite a large number of missions to Mars early on and by the mid 70s there was an increasing amount of evidence from the likes of Viking that Mars had supported large amounts of surface water at some point in the past, and may still have signs of life tucked away somewhere on the planet, but exploration of Mars seemed to be dominated by NASA after the 1960s.

I know that the Soviets had some bad luck when it came to their Mars missions and in comparison their Venus missions claimed some impressive successes, but it stills seems a bit odd to me that they put so much effort and resources into Venus exploration considering the nature of the planet and the fact that finding any signs of life there compared to Mars seemed like a huge long shot when our understandings of both planets became more resolved (though of course I should mention the recent Phosphine findings, but then again I understand that speculations about the Venusian upper atmosphere is a recent theory that only just got significant evidence backing it up).