NASA wants to send humans to Venus – here's why that's a brilliant idea

October 16, 2018 by Gareth Dorrian And Ian Whittaker, The Conversation
Credit: NASA

Popular science fiction of the early 20th century depicted Venus as some kind of wonderland of pleasantly warm temperatures, forests, swamps and even dinosaurs. In 1950, the Hayden Planetarium at the American Natural History Museum were soliciting reservations for the first space tourism mission, well before the modern era of Blue Origins, SpaceX and Virgin Galactic. All you had to do was supply your address and tick the box for your preferred destination, which included Venus.

Today, Venus is unlikely to be a dream destination for aspiring space tourists. As revealed by numerous missions in the last few decades, rather than being a paradise, the planet is a hellish world of infernal temperatures, a corrosive toxic and crushing pressures at the surface. Despite this, NASA is currently working on a conceptual manned to Venus, named the High Altitude Venus Operational Concept – (HAVOC).

But how is such a mission even possible? Temperatures on the planet's surface (about 460°C) are in fact hotter than Mercury, even though Venus is roughly double the distance from the sun. This is higher than the melting point of many metals including bismuth and lead, which may even fall as "snow" onto the higher mountain peaks. The surface is a barren rocky landscape consisting of vast plains of basaltic rock dotted with volcanic features, and several continent-scale mountainous regions.

It is also geologically young, having undergone catastrophic resurfacing events. Such extreme events are caused by the build up of heat below the surface, eventually causing it to melt, release heat and re-solidify. Certainly a scary prospect for any visitors.

Hovering in the atmosphere

Luckily, the idea behind NASA's new mission is not to land people on the inhospitable surface, but to use the dense atmosphere as a base for exploration. No actual date for a HAVOC type mission has been publicly announced yet. This mission is a long term plan and will rely on small test missions to be successful first. Such a mission is actually possible, right now, with current technology. The plan is to use airships which can stay aloft in the upper atmosphere for extended periods of time.

NASA wants to send humans to Venus – here's why that's a brilliant idea
Venus was once an Earth twin. Credit: NASA / JPL

As surprising as it may seem, the upper atmosphere of Venus is the most Earth-like location in the solar system. Between altitudes of 50km and 60km, the pressure and temperature can be compared to regions of the Earth's lower atmosphere. The atmospheric pressure in the Venusian atmosphere at 55km is about half that of the pressure at sea level on Earth. In fact you would be fine without a pressure suit, as this is roughly equivalent to the air pressure you would encounter at the summit of Mount Kilimanjaro. Nor would you need to insulate yourself as the temperature here ranges between 20°C and 30°C.

The atmosphere above this altitude is also dense enough to protect astronauts from ionising radiation from space. The closer proximity of the sun provides an even greater abundance of available solar radiation than on Earth, which can be used to generate power (approximately 1.4 times greater).

The conceptual airship would float around the planet, being blown by the wind. It could, usefully, be filled with a breathable gas mixture such as oxygen and nitrogen, providing buoyancy. This is possible because breathable air is less dense than the Venusian atmosphere and, as result, would be a lifting gas.

The Venusian atmosphere is comprised of 97% carbon dioxide, about 3% nitrogen and trace amounts of other gases. It famously contains a sprinkling of sulphuric acid which forms dense clouds and is a major contributor to its visible brightness when viewed from Earth. In fact the planet reflects some 75% of the light that falls onto it from the sun. This highly reflective cloud layer exists between 45km and 65km, with a haze of sulphuric acid droplets underneath down to about 30km. As such, an airship design would need to be resistant to the corrosive effect of this acid.

Luckily we already have the technology required to overcome the problem of acidity. Several commercially available materials, including teflon and a number of plastics, have a high acidic resistance and could be used for the outer envelope of the airship. Considering all these factors, conceivably you could go for a walk on a platform outside the airship, carrying only your air supply and wearing a chemical hazard suit.

Venus as seen by Magellan. Credit: NASA
Life on Venus?

The surface of Venus has been mapped from orbit by radar on the US Magellan mission. However, only a few locations on the surface have ever been visited, by the series of Venera missions of Soviet probes in the late 1970s. These probes returned the first – and so far only – images of the Venusian surface. Certainly surface conditions seem utterly inhospitable to any kind of life.

The is a different story however. Certain kinds of extremophile organisms already exist on Earth which could withstand the conditions in the atmosphere at the altitude at which HAVOC would fly. Species such as Acidianus infernus can be found in highly acidic volcanic lakes in Iceland and Italy. Airborne microbes have also been found to exist in Earth's clouds. None of this proves that life exists in the Venusian atmosphere, but it is a possibility that could be investigated by a mission like HAVOC.

The current climatic conditions and composition of the atmosphere are the result of a runaway greenhouse effect (an extreme greenhouse effect that cannot be reversed), which transformed the planet from a hospitable Earth-like "twin" world in its early history. While we do not currently expect Earth to undergo a similarly extreme scenario, it does demonstrate that dramatic changes to a planetary climate can happen when certain physical conditions arise.

By testing our current climate models using the extremes seen on Venus we can more accurately determine how various climate forcing effects can lead to dramatic changes. Venus therefore provides us with a means to test the extremes of our current climate modelling, with all the inherent implications for the ecological health of our own planet.

We still know relatively little about Venus, despite it being our nearest planetary neighbour. Ultimately, learning how two very similar planets can have such different pasts will help us understand the evolution of the solar system and perhaps even that of other star systems.

Explore further: Mystery of rare volcanoes on Venus

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18 comments

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Mark Thomas
4 / 5 (4) Oct 16, 2018
conceivably you could go for a walk on a platform outside the airship, carrying only your air supply and wearing a chemical hazard suit.


Maybe so, but there would be serious forward and backward biological contamination issues to consider before taking that walk. Before we risk that, we need to understand if microbes are already living there, how they survive and their relationship (if any) to life on Earth.

https://en.wikipe...mination

https://en.wikipe...of_Venus
cantdrive85
1 / 5 (7) Oct 16, 2018
Popular science fiction of the early 20th century depicted Venus as some kind of wonderland of pleasantly warm temperatures, forests, swamps and even dinosaurs.

Lest we forget Velikovsky predicted a hot Venus, in the 700 degree range. The top "scientists" of the time predicted a hot day in Phoenix.
barakn
4.6 / 5 (10) Oct 16, 2018
A broken clock is correct twice a day.
Mark Thomas
4.6 / 5 (10) Oct 16, 2018
Immanuel Velikovsky was a fraud that argued "a few thousand years ago, Venus collided repeatedly with the Earth and Mars, altering the course of history and causing many notable events that are chronicled in the Bible and in legends of ancient peoples."

https://www.nytim...mos.html

cantdrive85
1 / 5 (7) Oct 16, 2018
So that would explain how GR is correct sometimes too then, but is the clock broken or the observer?
jonesdave
3.8 / 5 (10) Oct 16, 2018
So that would explain how GR is correct sometimes too then, but is the clock broken or the observer?


GR has always been shown to be correct by every experiment designed to test it. Velikovsky was a world class moron. And he got the mechanism wrong. Wildt got it right, prior to Velikovsky.
cantdrive85
2.1 / 5 (7) Oct 16, 2018
Wildt was off by over 600 degrees, Velikovsky only missed it by 100 degrees or so.
Ojorf
3.7 / 5 (9) Oct 16, 2018
So that would explain how GR is correct sometimes too then, but is the clock broken or the observer?

No, it explains that you and Velikovcky have much in common.
jonesdave
3.8 / 5 (10) Oct 16, 2018
Wildt was off by over 600 degrees, Velikovsky only missed it by 100 degrees or so.


It doesn't matter. Velikovsky's guess was nothing to do with science, and he got the mechanism wrong. Wildt got it right. I doubt we knew the full extent of the atmospheric pressure of Venus at the time Wildt did his work. Had we known, then he would have been a lot closer, I daresay. And Wildt's correct mechanism doesn't violate the laws of physics. The moron Velikovsky's does, and can therefore be discounted.
cantdrive85
2 / 5 (8) Oct 16, 2018
Wildt guess was based on the pseudoscientific greenhouse nonsense, and the max temps possible missed it by hundreds of degrees with zero possibilities to reconcile discrepancies. And Velikovsky's mechanism doesn't violate any laws of physics contrary to your hand wavy exclamations.
jonesdave
3.7 / 5 (9) Oct 16, 2018
Wildt guess was based on the pseudoscientific greenhouse nonsense, and the max temps possible missed it by hundreds of degrees with zero possibilities to reconcile discrepancies. And Velikovsky's mechanism doesn't violate any laws of physics contrary to your hand wavy exclamations.


Wrong, idiot. We didn't know the extent of Venus' CO2 budget at that time. And Velikovsky's mechanism most certainly violates the laws of physics. No way whatsoever could it have been shot out of Jupiter. No way could it have performed the orbits that the cretin ascribed to it. No way could it then settle into the most circularised orbit in the solar system in that time. Among many other impossibilities. He was a moron. End of story.
Spacebaby2001
4.2 / 5 (5) Oct 16, 2018
...pseudoscientific greenhouse nonsense...


Grandpa? Is that you??
barakn
4 / 5 (4) Oct 16, 2018
The atmospheric pressure in the Venusian atmosphere at 55km is about half that of the pressure at sea level on Earth. In fact you would be fine without a pressure suit, as this is roughly equivalent to the air pressure you would encounter at the summit of Mount Kilimanjaro.
At the moment, almost all spacecraft provide air at roughly 1 atm pressure. It's standardized so that when spacecraft are mated, there isn't rapid pressurization in one and rapid depressurization in another. So our astronaut will need to breathe pure oxygen while spending a long time in a slowly depressurizing pressure chamber to avoid decompression sickness before being able to exit. https://www.faa.g.../dcs.pdf
jonesdave
3.3 / 5 (7) Oct 16, 2018
.....pseudoscientific greenhouse nonsense,....


Lol. Pseudoscience despite us having measured the atmospheric content, and the pressure. And we know how much radiation it receives. Etc, etc. And we know it is an 'old' planet, given its topography, which it couldn't support if it were recently molten. Anybody that believes Velikovsky's nonsense is, by definition, scientifically illiterate.
fishnuke
4 / 5 (4) Oct 16, 2018
Interesting article on Venus, but exactly zero reasons presented to send people there. Unmanned probes and balloons for sure, explore away. But what, specifically, would require an astronaut? Walk around an expensive balloon, gazing down at clouds, getting sunburn?

The fact that there's a region of atmosphere near STP is neat, but not compelling. There is nothing there. You'd be more useless than hanging around in LEO. This is as bad and wasteful an idea as the Lunar Gateway (LOP-G). Get on with colonizing moon and Mars, and mining asteroids. Places with resources.

Only thing to be done with Venus is planet bomb it with icy Kuiper belt objects, to terraform it. Love to do the same to Mars. Plenty of water and nitrogen out there. But I'm currently living in a country that thinks going back to burning coal is a good idea... So not holding my breath for the launch of the colonization armadas any time soon.
Da Schneib
5 / 5 (1) Oct 16, 2018
They sure ain't goin' to the surface. But a lot more data can be gathered from the upper atmosphere than we have now. It's likely to be disappointing, though. I wouldn't spend the money now. Better to wait a century or so.
danR
4.2 / 5 (5) Oct 16, 2018
There's a physical oversight here that needs to be addressed.

The transition between Venusian LEO (LVO?) and floating bulky airships (and the tanks of gas to inflate them [or the bulky machinery to extract N2] ) is going to involve at some point a high-temperature, maximum aerodynamic buffeting and drag, regime. Certainly drogues and parachutes will account for some of the transition, but time is of the essence: those ships do have to get inflated during a parachute transition which will be measured in a few minutes at best. The best retro-firing system couldn't support that tonnage.

Perhaps you would need a high-efficiency, long-wing airframe to buy time, but at some point of several minutes-long, the bulky, flopping, ungainly drag-parasitic airship is going to render aerodynamic lift futile.

I can only suggest using hyper-robust materials and just letting the chutes and craft overshoot to ~3 atmospheres, and then lift to operating elevation later hours later.
V4Vendicar
1 / 5 (3) Oct 16, 2018
Pure stupidity

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