“The surface of Venus is a place of crushing pressure and hellish temperature. Rise above it, though,
Drifting between these two levels are the ten thousand floating cities of Venus.”
The first paragraph is completely accurate. The second is not, of course, but Landis, who has worked as
A comparison of Earth and Venus, sometimes called "Earth's twin" for its similar size. Image: NASA
Venus's gravity is 90 percent of Earth's, and it's easier to get to than Mars, reachable in just five months as opposed to nine for Mars.
At NASA, the idea of sending humans to Mars and Venus was first proposed in the run-up to Neil Armstrong’s historic moonwalk, during the Apollo program, when the space agency was giddy with exploration and rich in funds. Public support for the space agency was also on its way to heights it would never otherwise reach. It
Landis, who wears a beard beneath a swoop of reddish-brown hair, joined NASA two decades after Apollo, at the end of the Reagan era, and two years after the Challenger disaster rocked humanity's resolve to explore space. After receiving his Ph.D. in physics from Brown University, Landis worked as a postdoctoral researcher at NASA, as a senior scientist at the Ohio Aerospace Institute, and served as a visiting professor of Astronautics at MIT.
At a conference on space exploration in Albuquerque in 2001, Landis delivered a presentation that has since linked his name with a small sect of space scientists who have seriously considered the human exploration and colonization of Venus.
Landis in 2011. Image:
To begin to explore the cloud planet—nicknamed for the thick swaths of carbon dioxide and sulphuric acid that encircle it—Landis proposed a solar-powered airplane that could navigate the atmosphere and even a land-sailer that could survive the planet’s extreme surface climate. He developed the concept in more detail at another conference in 2003, where he claimed that “robotic exploration of Venus could potentially lead to the development of a human mission to explore the clouds of Venus by aircraft,” concluding that “ultimately we could even envision colonization of the Venus atmosphere.”
Landis’ early proposals for exploring the Venusian atmosphere by way of large balloons and solar powered airplanes, as implausible as they may seem, have recently inspired other researchers at NASA to explore the idea. In October, Dale Arney and Chris Jones, a pair of NASA scientists based in Langley, Virginia, completed a study for an idea they call the High Altitude Venus Operational Concept. HAVOC proposes that an initial manned mission orbit Venus for a length of 30 days, before making an attempt at living above the hellish planet. The video that accompanied the report, viewable below, garnered over half a million views on YouTube.
Venus is also easier to get to than Mars. You can travel to Venus in five months whereas Mars takes nine. If you're taking the shortest path, opportunities to travel to Venus come once every 1.6 years, whereas the optimal window for Mars comes every two years.
An image from Landis's 2003 paper
It is precisely this complex, inhospitable environment (and our relative ignorance as to how it came to be this way) that calls for closer exploration of the planet. Venus’s boiling environment and carbon-rich atmosphere offers the solar system’s best example of global warming in the extreme. Scientists theorize that as recently as one billion years ago, Venus used to be much cooler, a hospitable desert planet. But a number of hypothesized events, such as the halt of plate tectonics some 700 million years ago, could have contributed to a massive buildup of carbon in the atmosphere, heating Venus up to hellish temperatures and evaporating the oceans that may have once existed there.
By the late 1970s, NASA climate modeler James Hansen concluded that the CO2 combined with sulfate aerosols in the atmosphere were "responsible for the basic climatic state on Venus." This was instructive for Earth, Hansen wrote, because sulfates and CO2 were increasingly being emitted by human industry, contributing to the buildup from more natural emission sources such as volcanoes. (Hansen’s would be one of the loudest and earliest voices of concern about the effects of atmospheric carbon dioxide on Earth’s climate)
The double vortices at Venus' south pole. Image: ESA
“Certainly Venus is a prime example of a greenhouse effect planet—maybe it’s the future of the Earth, but the far, far future of the Earth,” said Landis. Regardless, "we learn about our planet by learning about other planets, and we learn to live on our planet by living on other planets.”
The exploration of Venus began in earnest in 1961 when the Soviet Union launched Tyazhely Sputnik (otherwise known as Venera 1VA No. 1), a mission to send a fly-by probe to Venus. The rocket exploded before it even left Earth’s atmosphere. In 1962, NASA’s Mariner 2 revealed that heat radiation detected by telescopes was coming not from the planet’s atmosphere but from its hot surface.
In 1966, after several more failed attempts to get its program off the ground (or somewhere near Venus) the Soviets finally succeeded in putting the first man-made object on another planet, when Venera 3 crash landed on Venus. On December 15, 1970, Venera 7 touched down on the planet’s surface relatively intact and became the first probe to transmit data from the Venusian surface. Given the extreme environment, it didn't last very long.
An image of the surface taken by the Soviets' Vanera 13 lander in 1981. It survived 127 minutes.
"The surface environment of Venus is a warning," Carl Sagan wrote. "Something disastrous can happen to a planet rather like our own."
Landis traces his own pursuit of Venus to a paper published
To start, Sagan advocated bombing the upper Venusian atmosphere with genetically modified blue-green algae. The idea was to reduce the carbon-dioxide-saturated atmosphere to a level conducive to supporting terrestrial life. According to Sagan, the algae (specifically harvested from the Nostocacae family) have been known to survive immersion in liquid nitrogen and in hot springs whose temperatures sometimes exceed 80 Celsius, making them ideal candidates for weathering the extreme atmospheric conditions found on Venus. These algae are also known to be capable of photosynthesizing "evolving molecular oxygen," suggesting that they would be able to perform the crucial task of dissociating carbon dioxide into oxygen and elemental carbon, significantly lowering the planetary temperature and allowing for photosynthesis in green plants.
Sagan's lofty geoengineering proposal didn’t make it very far. “It was a wonderful, radical notion for 1961, but they were only just beginning to understand Venus,” said Landis. [Sagan] didn’t quite understand how thick the atmosphere of Venus really was. He was one of the first to understand that Venus had a very thick carbon dioxide atmosphere,” but they didn’t quite understand that it was 92 times denser than the Earth’s atmosphere. You just can’t convert that much carbon dioxide into oxygen.”
Three decades later Sagan himself declared the idea “fatally flawed.” But he still thought Venus bore important lessons for Earth. In his 1980 book Cosmos, Sagan mused on the “goldilocks” quality of Earth by pointing to the effects that carbon dioxide had had on Venus's climate:
Like Venus, the Earth also has about 90 atmospheres of carbon dioxide; but it resides in the crust as limestone and other carbonates, not in the atmosphere. If the Earth were moved only a little closer to the Sun, the temperature would increase slightly. This would drive some of the CO2 out of the surface rocks, generating a stronger greenhouse effect, which would in turn incrementally heat the surface further. A hotter surface would vaporize still more carbonates into CO2, and there would be the possibility of a runaway greenhouse effect to very high temperatures. This is just what we think happened in the early history of Venus, because of Venus' proximity to the Sun. The surface environment of Venus is a warning: something disastrous can happen to a planet rather like our own.
The Terraforming Options
As outlandish as Sagan's plans for "microbiological planetary engineering" may seem, a number of other proposals have surfaced in the five decades since, calling for a complete reverse of the planet's greenhouse effect. In his 1981 book New Earths, James Oberg proposed making Venus habitable by removing 98 percent of its atmospheric mass by displacing 10 quintillion tons of CO2 into outer space. According to his calculations, if such a project were designed to take place over a time span of 100 years, this would involve the removal of roughly 300,000 tons of gas per second. By comparison, the Amazon moves roughly 10,000 tons of water per second.
A conceptual image of a terraformed Venus. Image: Daein Ballard/Wikimedia Commons
In more expansive visions, pumping Venus full of sulfur dioxide or hydrogen—or
surrounding it in Sun shields— could terraform its climate into submission .
In 2010, the Nobel prize-winning atmospheric chemist Paul Crutzen proposed releasing massive amounts of sulfur dioxide high in the Venusian atmosphere, which he argued would lower surface temperatures and slow the runaway greenhouse effect by re-creating conditions similar to a massive volcanic eruption on Earth. The idea echoed his now famous proposal for Earth: pumping gas into the atmosphere to stave off the effects of global warming—a kind of plan B for the climate that helped propel the geoengineering craze.
In the early 1990s, a scientist named Paul Birch proposed
The Cloud Options
In Landis’s more down-to-Earth vision, humanity’s place on Venus will not be on the planet's surface but instead dozens of miles up in the planet’s thick cloud cover.
"A hundred and fifty million square kilometers of clouds, a billion cubic kilometers of clouds. In the ocean of clouds the floating cities of Venus are not limited, like terrestrial cities, to two dimensions only, but can float up and down at the whim of the city masters, higher into the bright cold sunlight, downward to the edges of the hot murky depths… The barque sailed over cloud-cathedrals and over cloud-mountains, edges recomplicated with cauliflower fractals. We sailed past lairs filled with cloud-monsters a kilometer tall, with arched necks of cloud stretching forward, threatening and blustering with cloud-teeth, cloud-muscled bodies with clawed feet of flickering lightning."
At 50 kilometers up, Venus is remarkably Earth-like, excluding the need for any serious terraforming projects. The atmospheric pressure is a comfortable one bar, the gravity about 90 percent that of Earth's, and temperatures fall within a hospitable range of 0-50 degrees Celsius."
In the HAVOC proposal, 129-meter-long blimps would be deployed after entering Venus's atmosphere and later form the basis for larger floating habitats. Image: NASA
Although Landis' plans predate the Langley proposal by over a decade, he sees the two not so much as competing propositions but as two different concepts toward the same aim: placing humans on Venus. "Their work is a little more focused on the initial phases of exploration," said Landis. "We're definitely thinking along similar directions, but I can't claim credit for their work. They've done a lot of work on filling in the details for the initial concepts for early missions.”
To the Langley scientists, Landis’s idea was an inspirational precursor.
Landis' initial proposal for Venusian sky cities was much broader in scope than the HAVOC mission, involving the construction of massive aerostat habitats floating 30 miles above the surface of the planet. These would serve as 'forward operating bases' for surface missions and relay stations for interplanetary travel. In essence, these cities would exist in massive floating envelopes of breathable air, a mixture of oxygen and nitrogen which would act as a lifting gas in Venus' carbon dioxide atmosphere.
Linked blimps would form floating habitats under the HAVOC proposal. Image: NASA
"You’d really have to do this for the long term exploration of space. This is where the future is. We’re moving out into the solar system.” —Dale Arney
"Well of course anything humans do has some risk," he said. "But you'd want to make your cities quite robust. Obviously, the larger a balloon is the more time you have to deal with a leak. If you have a tiny balloon, a child's balloon, it pops instantly. You'd want a giant balloon with multiple different chambers in it [for these floating cities]. It'd be huge compared to any balloon we've ever had on earth. It would absolutely dwarf the Hindenburg."
The exploratory ships proposed for the HAVOC mission would be 130 meters in length, the equivalent of two Boeing 747s placed end to end, which is still only roughly half the length of the Hindenburg. Landis’s vision calls for habitats orders of magnitude larger. The aerostat habitats he imagines would be comprised of multiple balloons, each up to a kilometer in diameter, capable of supporting tens of thousands of people.
"The city was a dome, or rather, a dozen glistening domes melted haphazardly together, each one faceted with a million panels of glass. The domes were huge, the smallest nearly a kilometer across, and as the barque glided across the sky the facets caught the sunlight and sparkled with reflected light. Below the domes, a slender pencil of rough black stretched down toward the cloudbase like taffy, delicate as spun glass, terminating in an absurdly tiny bulb of rock that seemed far too small to counterbalance the domes."
'Beautiful, you think, yes? Like the wonderful jellyfishes of your blue planet’s oceans. Can you believe that half a million people live there?'”
Despite the warm public reception for the HAVOC proposal and his own buoyant optimism, Landis acknowledges the chances of a manned mission to Venus in the near future are remote. Funding for U.S. moon missions petered out by 1973; NASA’s overall budget shrunk from a peak of $5.9 billion in 1966 to a low of $3.2 billion in 1974. As a percentage of federal spending, it continues to shrink: in 1966, NASA made up 4.4 percent of all federal spending. Now it's around 0.5 percent.
"As with all missions, money and politics are the real problems. I think we could do it, technically, although there's a lot of detailed engineering work that needs to be done. It's getting the political buy-in that is tough," said Landis. "My belief is, we need to go out and colonize the solar system but politically we can't do anything without a consensus on our direction."
Why, if Venus is so promising, does the Red Planet steal all the attention? In an ironic twist, this may have to do with the rovers Landis has already helped land there. "I think [Venus] tends to be ignored possibly because the images we're getting from Mars are so spectacular," he said. The best way to build the political and economic support needed for manned missions to Venus is simply sending more robots there to begin with.
From a 1970s Soviet proposal for colonizing Venus's clouds. Image via Technica Molodezhi
The HAVOC team, meanwhile, has effectively disbanded.
“Currently Chris and I don’t have any imminent plans to do any work in this specific area, but there certainly are plenty of opportunities to explore for robotic missions and things like that,” said Arney. “A rigorous robotic campaign is needed, similar to what we’ve been doing with Mars for the last couple of decades. So really that would have to start picking up. Science proposals for Venus missions will have to get in the works.”
So far, the HAVOC team hasn't received any sort of feedback from the current administration or from members of Congress regarding their study. “I can’t really speak to the politics and how all of that is going to change, but right now Congress and the President are pretty focused on the asteroid redirect and Mars missions."
A rover that could survive the intense heat of Venus would be cooled by a Stirling Cooler with electronics at 200 °C and external radiator at 500 °C. Image: Geoffrey Landis and Kenneth Mellott from NASA's Glenn Research Center
In spite of the immediate bearing on our scientific understanding of climate change, Arney admits there isn’t much short-term economic (or military) incentive to send a manned mission to the planet.
Yet scant economic incentive isn't the same as no economic incentive. While Venus might not be a goldmine, there are fiscally compelling reasons to give colonizing the planet serious consideration, especially in the long term.
“Economically I’m not sure what kind of market there would be in the near term for those [atmospheric] resources," he added, "but if you think in the long term where humans are a multi-planet species, readily available atmospheric resources would be useful."
Notwithstanding a future market for nitrogen, Arney thinks that private companies, firms like SpaceX and Boeing, also have a role to play in developing the technology for future NASA missions to Venus.