The Demystification of Venus

On this day in 1970, the Soviet lander Venera 7 achieved the first soft-landing on another planet, after a bumpy journey through the Venusian nightside atmosphere. For 23 minutes, the spacecraft described its surroundings, confirming what orbiters and flyby missions from both the USA and the USSR had feared: The planet that had been venerated as a paragon of celestial beauty for millennia was actually a nightmarish parody of all the hopes placed on it.

By the time the Venera and Mariner programs began exploring Venus, it had become burdened by thousands of years of high expectations. From being a symbol of fertility in ancient mythology to more modern characterizations of the planet as a tropical world, spurred by observations of its thick cloud cover, Venus had long been thought of as being hospitable to life.

Venera 7 quickly showed that not to be the case. With surface pressures 92 times those of Earth, temperatures of 887 degrees Fahrenheit, and a suffocatingly toxic atmosphere, Venus is a hellscape beyond human imagining. It takes the planet 243 Earth days to rotate once, and it does so clockwise, unlike any other planet in the solar system. This means that a Venusian day is longer than a Venusian year, and the Sun rises in the west and sets in the east. It is a thoroughly weird and disconcerting place.

Indeed, it's a testament to the Soviets' sophisticated planetary landers that Venera 7 was even able to withstand Venus's harsh conditions for almost half an hour. The Soviets subsequent probes were equally impressive—Venera 13, for example, spent 127 minutes transmitting data back to Earth, even managing to capture a picture of the tortured surface.

But as the challenges of traversing Venus became ever more clear during the 1970s, the focus of interplanetary exploration naturally shifted to Mars. The Red Planet may be inhospitably cold and in dire need of a magnetosphere, but at least it isn't a scalding, pressure-cooked acid bath that rotates backwards.

There is a brutal irony to the discovery that Venus is aggressively inhospitable: Its punishing cloud cover happens to also be the secret of its striking radiance. About 70 percent of the Sun's light is reflected off Venus's atmosphere, making it the brightest object in the skies after the Sun and the Moon. It is so striking that the planet has long been referred to as the morning/evening star, having been elevated to stellar status in spite of its planetary trappings.

Ancient peoples across the world were captivated by this luminous world, and imbued it with enormous cultural significance. It was so important to Mayan civilization that wars and sacrifices were scheduled to coincide with its motions. The planet was also commonly associated with goddesses of beauty, fertility, and love, which is why it ended up with the name Venus.

As the planet transitioned from a mythological entity into a scientific target, theories about its paradisiacal beauty accelerated. Much like the canal-like features of Mars, observations of Venus's heavy cloud cover inspired tales of a lush, romanticized planet, inspiring writers like Edgar Rice Burroughs, Ray Bradbury, and C.S. Lewis to portray it as a habitable—even heavenly—world.

In his PhD thesis, a young Carl Sagan would argue against this presumptuous characterization of the planet, suggesting instead that it was hot, dry, lifeless, and smothered by greenhouse gases.

In Cosmos: A Personal Journey, he lampooned the optimism about Venus at the time. "The absence of anything you could see on Venus led some scientists and others to deduce that the surface was a swamp," he said in the Cosmos episode "Heaven and Hell."

Sagan breaks it down. Credit: YouTube/Cosmos.

"If there's a swamp, there's ferns, If there's ferns, maybe there's even dinosaurs," he continued. "Observation: you couldn't see a thing. Conclusion: dinosaurs."

No wonder the hellscape revealed by the first flybys and landers was such a letdown. How great would it be to have a neighboring planet stuck in the Cretaceous, overrun with alien dinosaurs? But as Sagan also said, "better by far to embrace the hard truth than a reassuring fable."

The fantasies of countless past generations were tied up in Venus's habitability, and they could not have been more wrong—though as Amy Shira Teitel wrote two weeks back, Venus's upper atmosphere could potentially support colonies in the far future.

A portion of Venus's western Eistla Region reconstructed using radar data. Image: ​NASA/Wikimedia Commons

But ultimately, the real Venus may be more useful to future generations as a nightmare than as a daydream. For starters, it is the ultimate example of a runaway greenhouse gas effect in action.

Human activity on Earth is causing increased temperatures, atmospheric carbon dioxide levels, and ocean acidification. It's not like our planet is going to morph into a Venusian inferno next year, but the trend is both obvious and ominous. If human-driven climate change continues unchecked, we are going to look really stupid, given that there is such a pertinent demonstration of these disastrous tipping points one planet over.

Along those lines, the disjunct between the mythic version of Venus and its true scientific nature is a great example of the human tendency to idealize the universe to our own detriment. As our increasingly ambitious space missions have shown, it's pretty rough out there. Venus is not only a warning of what our own planet could become, it's a reminder that Earth is an incredible anomaly in the universe.

So while Venera 7 dispelled the Venusian heaven of our ancestors forty-four years ago, it replaced that myth with a clearer understanding of how uniquely paradisiacal our own planet is—and how fragile. Or, to put it in Cosmos terms: Observation: Venus is almost laughably inhospitable. Conclusion: let's not wreck Earth.