"Rehabilitating" VENUS as a Human Destination
by Peter Kokh © Lunar Reclamation Society 1992, 1998, 2000
This Paper is a compilation of articles
previously published in
Moon Miners' Manifesto
A subsequent Similar Proposal (2003) by Geoffrey Landis
We strongly suggest that you read the Articles Below in the Sequence they are given and use the links below to revisit specific sections.

Aerostat "Xities" over Venus (below)

Venus: Balloons & Aerobots

Touring Venus from Above

Visits to Venus enroute to Mars

"Subnubilar" Industries Over Venus

Geomorphing Venus

Venus Geomorphed

High Sky Aircraft for Venus

The "Friday File"

"Aerostat 'Xities' over Venus"

by Peter Kokh

["Xity" - Pronounced KSIH-tees, not EX-ih-tees: Human communities beyond Earth's cradling biosphere, that is communities that must provide their own mini-biosphere.]

[The original article, published in MMM # 60 November 1992, p. 3, addressed this concept as it might apply to Jupiter, Saturn, Titan, Uranus, and Neptune as well, and those parts of the article have been omitted.]


We think of Venus as a forbidding place forever "off limits" to humans. Our "twin planet" has a thick crushing atmosphere and an unsurvivable surface, abysmal lands were the temperatures and pressures far exceed all human capacity to adapt - even within technomiraculous protective cocoons.

Yet there are thinner, higher, more temperate regions in the atmosphere of this "hell planet" where the conditions are relatively benign. Such a planet-girdling pseudo "ecosphere" lacks but one thing to make it an attractive site for human outposts or settlements - "terra firma", solid land at the seemingly benign levels.

But this lack is something we can, with determination, do something about. We only need to expand conservatively on the known concepts of lighter-than-air craft. Several people have been predicting the return of great dirigibles to Earth's own skies. Visionaries have gone further to speculate about aerostat outposts high in Earth's atmospheres - not transportation vehicles but lighter-than-air "platforms", either free-floating or tethered to a surface location. These could serve various purposes: remote sensing, robotic probe teleoperations centers, atmosphere mining operations, air traffic control, and rocket launching space ports above the thickest layers of the atmosphere.

In the oxygen-rich atmosphere of Earth we would need to use helium gas for buoyancy, but as Venus' atmosphere has no significant amount of pure oxygen to cause combustion concerns, using the lighter and more buoyant hydrogen would work better. Of equal or even greater advantage is that the needed hydrogen could be mined from Venus' atmosphere locally.

Aerostats seem doable using the lightweight composite materials and fabrics now available or in the works, many of which could be fabricated in situ by mining the atmosphere itself. Available in Venus' atmosphere are hydrogen, carbon, nitrogen, oxygen, sulfur, and possibly phosphorous and other elements present as methane, ammonia, ethane, propane, phosphine, hydrogen sulfide, carbon monoxide, acetylene, water vapor, and other compounds.

A Demonstrator Aerostat

The feasibility of aerostat outposts over Venus can be tested by dropping into the upper atmosphere a pressurized crew compartment carrying an inflatable gas envelope, the lift gas with which to inflate it, and an underslung Pegasus-like shuttle by which the crew could escape to orbit.

Such a demonstrator aerostat could help define the ideal float altitude, stabilization mechanisms, and thermal management strategies. The crew could experiment with pilot atmosphere mining and processing equipment, with options for deriving energy from the atmosphere, and identifying problems. Surface observations of Venus and atmospheric science would be done on a contingency basis.

The lift numbers are good. The Veneran atmosphere, mostly carbon dioxide CO2, has an even higher average molecular weight, 44, than does our own atmosphere, 29. Further, since carbon dioxide suffocates rather than feeds combustion, it would be quite safe to use hydrogen (molecular weight 2) for buoyancy. The 22-fold lift advantage would mean a given dirigible volume structure in Venus atmosphere could support 3 times as much platform mass as a similar structure in Earth's atmosphere where the helium to air lift factor is 7.24.

Hydrogen, in the form or water vapor, is present in Venus' atmosphere but in nowhere near the same abundance as on Earth. We'd have to process an enormous amount of Air de Venus to get enough for our needs. Helium is unavailable on Venus so ammonia (NH3, molecular weight 17) and methane (CH4, molecular weight 16) are the next lightest gases that could be processed on site. But since they both incorporate hydrogen, the same strictures apply.

There are alternatives. We could either separate out nitrogen, N2, molecular weight 28, or process the CO2 to produce equal amounts of carbon monoxide, molecular weight 26, and oxygen, molecular weight 32. We'd save the oxygen for the internal breathing atmosphere of our aerostat xity, and use the CO for buoyancy, making do with a 1.7:1 lifting ratio for a mere 1/13th the payload or supported platform mass. That is, for an aerostat xity of given design size and mass, our gas bags would have to have 13 times the volume (2.36 x both radius and length) if they are to be filled with CO rather than H2. While discouraging, the prospect of having no lighter buoyancy gas than carbon monoxide would not rule out aerostats for Venus, just raise the engineering threshold. Even with CO, Veneran aerostats, size for size, could support half again as much platform mass as their Jovian equivalents.

OPTIONAL AEROSTAT PLANS (Overhead): A gas filled hull providing buoyancy support of the central platform on which habitats etc. sit, or from which they are suspended, could be in the form of a torus (top left), catamaran (top right), horseshoe (bottom left), pontoon raft (bottom right)

Power and Thermal Management

How would an aero-xity get energy with which to go about its business? Solar Power is not an option beneath the cloud decks of Venus. Nor are elements to use in fission or fusion reactors.

Energy production on Venus will have to be more resourceful. Could lightning be harnessed? What about some analog of OTEC, circulating a working refrigerant liquid between hot lower atmospheric levels and cooler upper ones?

As to thermal management, that should be a simple matter of picking a float altitude with the right temperature. If the outpost has excess heat to radiate, a colder and thinner altitude would provide the needed heat sink. However, radiators at the end of tethers flying above the outpost (i.e. supersats) might do the trick, especially if parking in a higher colder altitude meant being in the clouds, and losing visibility of the planet's surface.

The Structure

Since the chosen flotation level is thermally and barometrically neutral, the 'tight' hulls of habitat structures supported on the central platform are needed less to insulate and pressurize than to contain breathable air in a setting of unbreathable ambient atmosphere. Bladders in the torus or catamaran "pontoons" can moderate buoyancy if it becomes desirable to raise or lower the floatation altitude at some higher or lower level in the atmosphere.

"Valentine Heights:" Aero-Xity "on" Venus

We'll attempt to satisfy your growing visual curiosity with some MacPaint 'artistic' renderings to suggest what such constructs might look like. Then we'll discuss why on Earth (or on Venus!) we might someday want to deploy aerostat xities or outposts.

FLOAT LEVEL OF VENUS AEROSTAT XITY: 1) Space and vacuum above the atmosphere; 2) Unbroken cloud level 30=40 miles above the surface; 3) Venus aerostat xity floating just under the cloud deck about 30 miles (150,000 ft.) above the surface in cool CO2 atmosphere at the 1 ATM pressure level with a clear view of the surface. An upper atmosphere meteorology station is borne on tethered balloon above while a lower atmosphere station is trailed by tether below; 4) the super oven-hot super dense lower layers of the atmosphere; 5) Super hot surface of Venus: continents, empty oceanic basin, craters, volcanoes live and dormant, mountain massifs, valleys and trenches.

While on the surface dusky daylight and lightning- punctuated darkness cycle every 118 days, aboard the aero-xity riding 300 kph winds, dawn comes every four days.

"Valentine Heights"

SKETCH OF VENERAN AEROSTAT XITY: Cutaway of a large donut torus or horseshoe float with cellular ballonets and bladders provides buoyancy support for the xity. Hydrogen gas is preferred, but carbon monoxide processed more easily from the atmosphere will do. The torus directly supports the central main spaceframe platform. Standing on the platform are a central residential-agricultural-environmental dome and auxiliary domed vertical cylinder structures. Below is suspended an elevator to a lower meteorology station and two open-air platforms: the one on the left supports teleoperated refining, processing, and manufacturing from atmosphere-sourced chemical feedstocks; the one on the right is a landing & takeoff platform for unpiloted drone aircraft for close near-surface observation and teleoperated surface sampling and mining.

"Cupid's Blind"

This advanced scheme would employ a larger pontoon-raft for support. The "open air' environment would feature terraced interior side slopes under an overall sky blue dome.

Building it

While structurally, there is no reason why such xities could not work, actually building one is quite another problem. Would it be built in space and then lowered with "sufficient gentility" into the atmosphere? Would you instead bring in only a starter structure i.e. a buoyant processing plant, then begin to mine the atmosphere for feedstocks from which to make building materials (e.g. carbon into Kevlar and structural graphite?) out of which to fashion the great remaining bulk of the structure? The atmosphere of Venus offers much less diversity of elements with which to work chemical magic than do the atmospheres of the four gas giant planets or Titan, for example. The architectural, engineering, and construction challenges either way are rather daunting. So the concepts sketched above may prove to be as unrealizable as much of the great "glimpse of the future" cover sketches of issues of Popular Science and Popular Mechanics of half a century ago. Anyway, we have tried to stimulate your imagination.


If all that Veneran "cloud miners" have to work with are C, O, N, H, and S -- carbon, oxygen, nitrogen, hydrogen, and sulfur -- then in addition to agricultural products (importing phosphorus and other micro-nutrients) what serviceable synthetic materials could they produce? And what sorts of things could they make from them? Structural elements from which to expand? Mere low-performance furnishings and craft stuffs? Are exotic nitrogen-based ceramics and Kevlar among the possibilities?

The fewer basic needs can be met by self-manufacture from ambient elements, the more must at first be imported at high cost. Eventually raw materials for manufacturing might be supplemented by ores "tele-dredged" from the torrid surface.


What purposes might a Veneran aero-xity serve? Well, for one sure thing, such a supremely isolated and self-quarantined place might make the ultimate 'Alcatraz'. You wouldn't even need guards. Supplies and fresh inmates could be brought in by tele-piloted craft with no manual overrides. Anyone want out? Just step out the airlock and take a breath of Veneran air, or walk the plank off the main platform and plummet into the incinerating sulfurous hell depths below. Hey, Halloween is coming up!

On a less ghoulish note, such a facility would offer unequaled opportunities to conduct Venus science and exploration: An economic geography of the planet could be pieced together against a far future day when we might somehow be able to transform the pressure-cooker atmosphere into something humans could handle,with unproxied access to the surface.

A down-facing observatory would map the Veneran terrain below using multi-spectral remote sensing techniques. More ambitiously, rugged oven-hardened ceramic-hulled, diamond-wired teleoperated explorers, samplers, and eventually miner vehicles, etc. might be developed to serve as our stand ins on the surface, operated by crews in the aero-xity. These could be stationary surface stations or mobile ones. Prior to this, we could begin to get our feet "hot", probing every lower and lower as the hardiness of our equipment allows, by drone airborne craft teleoperated from "The Heights".

Philosophically, the ultimate rationale behind an aerostat settlement over Venus may simply be our drive to continue brazenly pushing the "human envelope". Born "naked apes", we seem to have a deep-seated characteristic need to keep learning to first survive and then thrive in one seemingly more hostile environment after another. On Earth we've already long left our native tropical home lands and mastered the deserts and swamps, the temperate forests and grasslands, and even the arctic tundra and ice. The ocean deeps too have seen our first timid encampments. All of this courtesy of technology, be it so humble as clothing, hunting and fishing tools, shelter building skills, and thermal management tricks of the trade.

Those who deem unnatural human expansion into the for-a-little-while-yet hostile reaches of space, only show that they do not understand our own history. Had they been in control, we'd still be in the cave or swinging from the vines or timidly darting across the savannas. Our species has no limit on where we might live and pursue our needs except those it sets for itself. And those who would confine our beachheads in space to the inner hulls of artificially gravid zoo-like imitations of old Earth, are hardly more daring than the stay-at-homes. There will always be some of us, however few, that will want to get away from the common haunts of our kind and test new niches, vault new hurdles, face new challenges. Homo est animal incognitum probans.

We will build a "xity" over Venus because Venus is there.

Easier said than done, to be sure. To transform such a vision into reality, we will have to find ways to make economic sense of it all. But before even considering what such a community might trade with the human universe beyond the all-hiding cloud deck, we'll have to demonstrate ways to push local self-sufficiency to the limits with the very limited material feedstocks available locally - and for a long time that will mean "mining" the atmosphere alone, period!

Surely one of the activities furthered by such a cloud-hugging settlement would be brainstorming of the possibilities, challenges and strategies for "terraforming" this runaway greenhouse world. Most of what has been written to date, even by well known authors, fits the category of garbage in, garbage out. They all conveniently neglect one or more of the harsh realities which constrain the possible avenues of approach. We've been keeping a "Friday File" [Venus = Norse Fria] on the subject for a future speculative article.


The proper adjective for Venus?

Alert readers will have noticed that NASA/JPL-folk use the term Cytherean as an adjective, e.g. the "Cytherean atmosphere" or surface or whatever. Why? Because the adjectives for names originating in Latin, like Mars, Jupiter, and Venus, are customarily built on the genitive (possessive case form) stem of the word. Thus we have Martian from Martis, Jovian from Jovis. But apparently these prudes, or if prudes they're not then these people scared silly of a misunderstanding public, are afraid to use the genitive of Venus. You see it happens to be Veneris, from which, oh yes, our word Venereal, as in disease.

Now Science Fiction Writers, equally skittish about seeming propriety, have gotten around the problem by using the nominative stem: Venus, Venusian. That seems harmless enough but the linguistic scholars howled foul. Hence the public servants in charge of space science have avoided the matter by using a totally different word from some beat-around-the-bush association. Cytherea was an island near the mythological ocean birthplace of Aphrodite, the Greek love goddess identified with the Venus of the Romans.

For our money, the Russians seam to have come up with the best solution. Use the genitive root, but add simply -an rather than the 'offensively suggestive' -eal, -ean, or -ian. Thus simply "Veneran". The reason it works is because the stress now falls on the first syllable instead of the second. A simple and elegant solution! If any one out there is still so uptight about his/her own sexuality as to be still squeamish about that, so be it. The use of Cytherean is absurdly pathetic. So we've adopted the Russian use which is both linguistically defensible and free enough of other associations.

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Venus: Balloons and Aerobots

by Bruce Moomaw

[The original article was printed with permission in MMM #134 April 2000, p.4]

For [continued exploration of Venus], there has been [quite a bit] of work on exploring with what is called phase-change variable-buoyancy balloons. Let's suppose we have a Venus balloon floating along in the clouds filled with two substances: a simple buoyant gas (helium), and a liquid that boils into gas above a certain temperature, increasing the balloon's buoyancy (plain water). As the balloon sinks to the hotter levels of Venus' atmosphere, the water starts evaporating into steam and the balloon goes back up -- and then, when it rises above the equilibrium level, the water condenses and the balloon goes back down. Moreover, since there's a delay between the time a substance absorbs or dumps enough heat to undergo a phase change and the time it actually completes that change, the balloon keeps perpetually oscillating several kilometers above and below the equilibrium altitude rather than settling down at that altitude -- like one of those bobbing mechanical drinking ducks.

What does that get us? Well, suppose that the balloon has a small water tank fastened to its bottom which the condensing water runs into. When the balloon is on the negative-buoyancy part of its cycle and headed down, you just shut a valve on the tank to trap the water -- and the balloon retains its negative buoyancy and keeps going down, all the way down to the surface of Venus. After an hour or so taking pictures and analyzing the surface, when the instrument gondola is starting to heat up dangerously, you open the valve, the water boils back into steam, and the balloon takes off for Venus' cloud layer again, where the gondola can cool off until Earth decides it's time for the next dive. (On the way down, you can open the valve part way to slow the balloon's descent -- or even stop it to hover in the lower atmosphere instead of going all the way to the surface.)

Neat, eh? And by taking into account the speed and direction of Venus' winds (which are 400 kph in the clouds but drop down to only 4 kph at the surface), you can land fairly near a specific location. (This is complicated by the fact that, while you can slow down the balloon's descent by opening the valve, you can't speed it up again -- so you have to deliberately "undershoot" your target and then slow down the balloon's descent by some extra amount later so it gets blown to the point you want.) Nice surface and aerial photos, weather data and surface composition analyses. The balloon would be made of a remarkable plastic film called "polybenzoxasole", several times tougher than steel, and which holds up beautifully to Venus' savage surface temperatures.

In another LPSC paper, Ronald Greeley details a simpler Venus mission called VEVA that he proposed as a candidate for the latest Discovery mission selection. Two balloons just blow along at a fixed altitude in Venus' clouds, with each one dropping four small multispectral camera-equipped impact probes at appropriate locations. Anyway, both the Venus and the Titan phase-change aerobots are very high on NASA's intermediate-term Solar System wish list (with the giant-planet Montgolfier balloons being lower-priority).

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"Touring Venus from Above"

A Fresh Look at a Forgotten World

by Peter Kokh

[The original article was published in MMM #114 April 1998, p. 8]


Prior to 1960, we basked in our mainstream expectation that underneath Venus' perpetual cloud cover, we would find a very warm oceanic world with scattered islands covered with steamy jungles and forbidding swamps. Writers like C.S. Lewis and Robert Heinlein made Venus a common setting for Solar System interplanetary adventure tales.

Suddenly, crudely, without warning, in the early 60s, Earth-based radar shattered this unsuspected illusion. Venus was dry, self-cleaning-oven-hot, cursed with an unbreathable brimstone-dosed carbon dioxide atmosphere of crushing density.

Overnight, Venus was "off the list." Off the list of places to explore. Off the list of places to tour. Off the list of worlds that might harbor life. Off the list for human colonization. Off the list of human horizons altogether. Venus remained in the heavens, of course, as an astronomical object, as an environmental object lesson, as a deceptively beautiful siren beacon, and as a significant gravity well useful for redirecting and accelerating objects bound for the outer solar system (like the Galileo probe on its way to Jupiter).

This once-upon-a-time paradise world of C.S. Lewis' "Pearlandra" was suddenly the perfect illustration for medieval concepts of the Hell of the Scriptures. As a "purely" scientific curiosity, (don't you believe that for a moment!) Venus remained high on the priority list as a destination for our probes. We "wanted to know" not only what Venus was really like: its topographic features, contours of could-have-been continents and could-have-been ocean basins and mountains and trenches and volcanoes and impact craters. Down deep our aim has always been to "terraform" our lost Sister Planet, at least in our imagination. We would dissipate its excessive atmosphere and radiate out into space all that trapped heat, and refill its oceanic basins drop by drop with comet water.

Still smarting from our loss, we masochistically needed to know how much of a Sister World we could have had, had not something gone terribly awry. Even though Venus is closer to the Sun and gets twice as much solar warmth, that does not explain why it is many times twice as hot on the surface, nor why its atmosphere became so crushingly dense.

Practically, while as "dispassionate, uninvolved" scientists we still wanted to know more, we all personally resigned ourselves to Venus being off the list as a target for future manned exploration, future outposts and farther future settlements, and, of course, as a future tourist destination.

If we but clean up our radar screens of emotional noise, Voilą!
Venus reappears!
A planet that can support manned scientific outposts, and an exotic tourist stop.

Okay, we have had 35 years to pout. It is time to grow up and take another look. We did it for China, and Russia. We are doing it for Cuba. Why not Venus too? And what do you know? Suspend our wounded spirits and Voilą! Venus reappears, both on the screens of human expeditions and outposts, and on the screens of tourist destinations. Yes, despite the fact that it remains a "hell hole"!

In MMM # 60 NOV '92, pp. 3-6 "PUSHING THE ENVELOPE: Aerostat Xities 'afloat' in the atmospheres of Venus, Jupiter, Saturn, Titan, Uranus, & Neptune" [an edited version of which is included just above], we pointed out some advantageous facts lost in the static of woe-is-us reports about Venus. The thick and visually impenetrable cloud deck over Venus is very high up over the surface compared to clouds on Earth - indeed about 30-40 miles up (150-200,000 feet. Just below this cloud deck it is

(1) clear, affording panoramic views of the surface free of any obstructing clouds
(2) not so dense, in fact, about as thick as our own atmosphere at sea level
(3) not so hot, well within temperature ranges we find comfortable on Earth.

NOTES: "Aerostat" means a buoyant structure such as a balloon, blimp, or dirigible, capable of staying airborne indefinitely so long as its relative buoyancy is maintained. On Venus, sufficient buoyancy can be provided by either hydrogen, helium, or less efficiently, by carbon monoxide.

"Xity": a communal habitat beyond Earth's life-sustaining envelope that must provide and maintain its own biosphere.

NOTE: Venus and Titan are the most favorable worlds for aerostat-supported activities. It would be very difficult to sustain buoyancy in the low average molecular weight atmospheres of gas giant planets: Jupiter, Saturn, Uranus, Neptune.

So where does this leave us? Obviously, we should be as busy planning a floating science outpost over Venus as we are planning science outposts on Mars' surface. From such an outpost, with a variety of instruments, we could study the Veneran surface below from relative proximity, with both visual and other instruments. Tethered probes could sample lower atmospheric levels and those higher up. And, if we could devise thermally hardened instruments that would survive for days or longer on the surface, we could teleoperate them from our aerial perch. Even teleoperated rovers are not beyond the realm of the possible, using greaseless magnetic bearings, etc.

But we promised to talk about tourism! While surface excursions remain as far-fetched as they have been for the past 35 years, tourists could descend by ship through the upper atmosphere to rendezvous and dock with a floating hotel just below the cloud decks, staying long enough to get the feeling of Venus topography - or as long as it takes before the return-to-Earth window opens.

The plan sketched in the first article above, or any of many conceivable alternative architectures could serve just as well as a tourist resort complex. OR, a science outpost could could have facilities to host "a handful of tourists" coming to visit and be nosy from time to time. This makes sense, at least initially. Indeed, the few early tourists could prove very useful to the scientists stationed there, in a work-study type of vacation, contributing badly needed visiting expertise fully accredited by universities on Earth. They could also relieve the regular staff in food-production and other distractions from their scientific tasks. As such these tourists would in fact "help pioneer" any next steps toward major expansion of this beachhead presence on the once Forbidden Planet.

Ticket Co$t - The Bottom Line

How expensive would it be to make such a tourist excursion to Venus? Less, it turns out, than a comparable visit to Mars!! - Consider:

* Using Economical Hohmann Transfer Trajectories

(1)* Slightly less Delta V and Fuel Expenditure is needed to go from Earth to Venus and back (5.47 kps), than from Earth to Mars and back (5.54 kps).

(2)* Shorter in-Transit Times Earth <=> Venus (5 months) than Earth <=> Mars, (8.5 months avg) thus less exposure to the radiation hazards of space.

(3)* Shorter at-Planet Stays Waiting for the Earth-return launch window to reopen, typically 11 months on Venus versus 18 months on Mars.

(4)* Shorter Interval Between Launch Windows in either direction, 19+ months for Earth <=> Venus vs. 25+ months for Earth <=> Mars.

Gravity and Weight in Veneran Aerostat Tourist Facilities

Earth 100% 110 lbs 150 lbs 200 lbs

Venus 91% 91 lbs 136 lbs 182 lbs

From a gravity point of view, visitors to Veneran aerostat stations would feel quite at home.

Our Prediction for all this? Sooner than you think! By mid-21st century or sooner. The following article sheds further light on the possibilities

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"Visits to Venus En Route to Mars"

by Peter Kokh

[The original article was published in MMM #115 May 1998, p. 3]

STANDARD MARS TOURIST ITINERARY -Spend 8 or 9 months en route to Mars. Tour till you've seen enough then hibernate for the rest of your 18 month stay until the return launch window opens. Send 8 or 9 months in space. Total time away from Earth two and a half to three years.

STANDARD VENUS TOURIST ITINERARY - Spend 5 or 6 months on route to Mars. Spend 11 months on an aerostat, looking at Venus' surface features through telescopes, and work for the science crew there until the eleven month wait for your 5 or 6 month return trip to Earth. Total round trip time two years.

That's the deal using minimum fuel expenditure Hohmann transfer paths to Mars and Venus. And the windows open only every 25 months or so for Mars, and every 19 months or so for forbidden Venus.

BEHOLD THE TWO FOR LESS THAN ONE DEAL -But if you had to get to Mars in between, there is a way using the so-called "conjunction class" trajectory to Mars, first swinging in toward Venus for a gravitational boost. It takes about a year in space to get to Mars by way of this detour. You'll get there just two months before it is time to return home the ordinary way. Leave from Earth a couple of weeks sooner if willing to pop for the fuel to break into Venus orbit, and then launch out again three weeks earlier, and you get nice length stays at both worlds and still get home in under two years, less time than it takes to visit one. A deal which should prove very popular!





"Subnubilar Industries Over Venus"

Economic Opportunities on Venus to begin with
Atmosphere Mining 30 miles above its Torrid Surface

[* sub NU bi lar: <below the cloud deck>]

by Peter Kokh

[The original article was published in MMM #114 April 1998, p. 10]

ATMOSPHERE RESOURCES -An "opportunist" is only as good as s/he is capable of seeing every first-blush-drawback as an advantage worth leveraging. Venus' atmosphere, the only easily accessible local resource depository, is mostly (97%) Carbon Dioxide, CO2. That represents 70.5% Oxygen by weight and 26.5% Carbon. Less abundant elements represent some definite industrial-economic worth as well as disproportionately large greenhouse responsibility.









25% (water vapor)






15% (cloud stuffs)*

* CO carbon monoxide, HCl hydrogen chloride, HF hydrogen fluoride, H2S hydrogen disulfide, COS carbonyl sulfide, and SO2 sulfur dioxide.

FUEL - Carbon dioxide can be reacted with available water vapor to produce methane CH4 and oxygen O2 to burn in rocket aircraft plying between the various aerostats, and in station-keeping/attitude thrusters, and to fuel various internal combustion engines.

POWER - Aero-factories can tap solar energy filtering through the cloud deck to provide primary electrical power for industry, appliances and lighting. They may need to keep pace with the terminator so as to be always in daylight to maintain a constant solar power flux or use methane-oxygen generators at night.

CARBON - Oxygen is needed for aerostat-living space atmospheres, along with Nitrogen, which is the 3rd most abundant element present. But as an industrial keystone, the sheer abundance of carbon in Venus' atmosphere makes it king. Carbon along with hydrogen, oxygen, and nitrogen is a principal ingredient of living tissues. But here we are concerned with industrial significance. With the development in recent decades of Kevlar, a carbon-carbon composite, carbon emerges as a structural material of great strength and low weight, from which many things can be made, things formerly made out of metals, ceramics, woods, and plastics. It will be a challenge of heroic significance to chemical engineers to find chemical pathways from carbon dioxide to Kevlar fiber that can be implemented on an industrial scale.

The goal is modular building components out of which an original aerostat with modules made on Earth can be duplicated with local Kevlar equivalents. Interior furnishings can also be of Kevlar. The original aerostat can then be cannibalized for strategic metals. These are absent in Venus' atmosphere. Whether processes developed for use on Venus can be operated efficiently enough to produce competitive exports for other off-Earth products is to be seen. Graphite is also made of carbon, as is diamond, buckminsterfullerene and other less familiar materials.

SULFUR - Sulfuric acid H2SO4, sulfur dioxide SO2, carbonyl sulfide COS. and hydrogen disulfide H2S are far more significant both industrially, and as part of any future terraforming equation than their abundance in the atmosphere might lead one to think. We'll save the second part of that assertion for the next article. On Earth quite a few very serviceable products have been made of sulfur from building blocks to water-impervious hard shells from hot-sulfur-impregnated fabrics. Why not analogous products from hot-sulfur impregnated Kevlar meshes and gauze. These might be less expensive than all-Kevlar products e.g. for making the shells of hydrogen gas buoyancy tanks that make aerostats possible. Worth exploring.

ORGANICS & SYNTHETICS - Carbon, hydrogen, oxygen, nitrogen! From these we can grow food, and fibers for clothes, bedding, and upholstery; make countless handy plastic products; even pharmaceuticals. Man does not live by structural materials alone!

GOING DOWN FOR THE NITTY GRITTY - Need, iron, aluminum, silicon, other nonvolatile elements? We can't advance further towards diversifying our brash sky-bound Veneran startup industries until we can access material on the ever so hostile, charring-hot surface. Scoops at the end of drag line tethers lowered thirty miles to the surface then hauled up with their booty, would be one way. A line loop anchored to the surface establishing a bucket conveyor would be another, binding the aerostat factory overhead to a particular site. Chute dropped, helium balloon-returned scoops might be simpler and a more logical choice to start off, especially if only trial amounts of surface materials are required. Methane and oxygen fueled sample rocket returns run up against the high temperature problem. We mentioned metals, but an earlier prize goal might be the simple raw silicates which would yield raw glass stuffs and ceramic stuffs.

Aerostat-produced products of glass, fiberglass, glass composites, ceramics, fiberglass ceramics, and sulfur/fiberglass composites would enormously diversify a startup industry whose prime products were graphite and Kevlar, and sulfur composites.

Venus has major industrial potential!

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"Geomorphing Venus"

How to make Venus an "M class" Planet

by Peter Kokh

[The original article was published in MMM #114 April 1998, p. 11]

In previous articles, we have seen how the supposed fire & brimstone hellhole of Venus can not only become, in its subnubilar reaches, 30 miles or so above the surface, a venue for scientists and even hardy tourists, but how it can develop industrially from such aerostat perches to potentially support someday sooner than anyone imagines, a respectable population of committed Venerans. As full and as satisfying as life might become for these "Sky Folk" (remember when writers used to dismiss imaginary Venerans as fog-eaters, swamp rats, and such?) their dream must assuredly be to someday descend to a cooled surface and colonize its twin "continents" and many "islands", and to sail across rewatered oceanic basins. "Terraforming" will fuel their culture.

How will it happen? All the schemes we've read about to date seem to be cases of GIGO, "garbage in, garbage out". It is useless to theorize if starting assumptions are wrong or only half the truth. Seeding Venus' upper atmosphere with blue-green algae and hoping for "the big rain" is pretty Quixotic. There is not enough water vapor left on Venus to make such a scheme work.

TOOL ONE - The challenge seems truly daunting. All that heat buildup in a runaway greenhouse. That unimaginably thick carbon dioxide atmosphere. Ninety times too dense, an unbreathable composition. Not enough water. An task impossible? The facts themselves point the way and we can find it if we respect the facts. They are not a crushing set of disadvantages, but a rather happy set of leveraging points. The first tool we need is attitude, the right attitude.

LEVERAGING OUR PRESENCE - We'll have to be on site in numbers, engaged in significant economic activity in the pattern sketched in the preceding article. How we do industry there in the heights can be tweaked in our favor. Making maximum withdrawal from the atmosphere of hydrogen and sulfur in their several compounds will eat away at the source of 45% of the greenhouse effect. That is significant. Water vapor would be collected in aerial reservoirs to support extensive agricultural operations. This vapor is 25% of the problem. Cloudstuffs and sulfur contribute another 20%. Further, remove the cloudstuffs, clarify the atmosphere from top to bottom, and you open the oven door, allowing substantial hear-radiation to space. Encouraged by the potential good side effects of our industriousness, to what does the rest of the problem reduce? "Too much CO2, too little H2O."

FIRST BLUSH - The agenda would seem to be twofold,

(1) blast the bulk of that crushing atmosphere into space
(2) bring in a zillion cometfuls of water-ice.

REASSESSMENT - On second look, that oppressively thick carbon dioxide atmosphere is not surprising. It represents about the same amount of CO2 absorbed into Earth's crustal rocks as carbonates. Indeed, if their were to be a runaway greenhouse here, all that potential carbon dioxide what be baked out of the rocks and released, "Veneraforming" the Earth. To consider is the apparent loss to space of 99% of Venus' one time reservoir of water. Now there seems no magic button to push to make the events roll back in reverse. The water is largely gone, and without it as a catalyst, the carbon dioxide can't be reabsorbed into the surface rocks. We could bring in a zillion comets, a major undertaking. The clouds would soon thicken a hundred fold with water vapor. If somehow we could cool the place and just let it rain ...

BACK TO THE INDUSTRIAL TOOLS WE WILL HAVE BUILT UP - We will have mastered the chemical engineering challenges to wholesale extraction of carbon from the carbon dioxide. Why stop with producing Kevlar products for domestic aerostat civilization consumption. Can we extract hundreds, even thousands of times as much carbon as we'll need for these needs and somehow shoot it into space to the realm of the Venus-Sun Lagrangian point 1. Either as a thick carbon dust cloud or as some sort of Kevlar parasol, this carbon is available for blocking the Sun, and to thwart its heat maintenance engine. Meanwhile we will have been working on the source of the other 45 percent of the runaway greenhouse effect.

HYDROGEN PIPELINE - The atmosphere becomes less CO2, more molecular oxygen O2 . Now for every nine zillion tons of cometary water ice we would have brought in, we need to find a way to bring in only one zillion tons of hydrogen. Combine it with the waiting hydrogen, the dissipating greenhouse effect, and Voilą, the big rain begins. If we were to bring in enough hydrogen to mate with all the oxygen freed by extracting all that carbon, we'd get an honest to goodness ocean many hundreds of feet in average depth - many times the volume of water Venus once had. We'd end up with a Nitrogen Oxygen atmosphere of similar ratios to Earth but about two and a half times the density. Anyway, it is beginning to look like a plan.

WE ARE THE ANSWER - An initial aerostat city uses made-on-Venus materials to duplicate itself. Two become four become eight become sixteen become thirty two and now we see the parable in the film 2010 in which the monoliths multiplied in Jupiter's atmosphere exponentially. Slow and insignificant at first, there is an inexorable crescendo as the Sun is blocked, the atmosphere changes in composition and cools and then dissolves in an incoming flood of hydrogen into the Big Rain. There are problems! But this makes much more sense than any previous plan. Best of all the human presence grows apace, not waiting for the process to be completed.

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"Venus Geomorphed"

Fast Forward X-Hundred Years.
What could we expect from our Project?

by Peter Kokh

[The original article was published in MMM #115 May 1998, p. 5]


I. The New Atmosphere

Venus' new atmosphere would be a carefully selected residual of its old one.
How closely can we get it to resemble Earth's? Our familiar mix is:

76.084 % Nitrogen 0.934 % Argon
20.946 % Oxygen 0.031 % Carbon Dioxide
"up to" 1.0 % Water Vapor

The game plan is to end up with a breathable mix of nitrogen, argon, and oxygen, with just enough carbon dioxide to make a biosphere work, no more. Currently, Venus has about 3,000 times more carbon dioxide in its atmosphere than does Earth. This C02 is fair game. The tactic we've floated is to disassociate the gas into carbon and oxygen, O2, and use the carbon to produce Kevlar and graphite products and, in some fashion, to use the excess to create a giant parasol at the Venus-Sun Lagrange 1 point to intercept continued solar heating for as long as necessary.

The residual 60.5 ATMs of oxygen would be reacted with imported hydrogen to make water vapor which would eventually rain out as temperatures fell. Just enough oxygen would be preserved to create a breathable mix with the Nitrogen and Argon in Venus' present atmosphere. That is perhaps 2 to 3 times as much N2 and Ar as we have. An elegant way of reducing these gasses has not occurred to us.

The upshot is an atmosphere that will still be noticeably heavier than what we are used to, and with a much greater capacity to absorb water vapor than has our own atmosphere. This water vapor will have a greenhouse effect, but one that probably cannot be avoided. Compensating, the planet should be just as overcast as it is presently, with water vapor clouds. A seasonal (see immediately below) pattern of winds, fogs, and thunderstorms should develop.

And, oh yes, the niche of friendly pressures and temperatures enjoyed by the interim aerostat-based subnubilar Veneran civilization (last issue) will have dissipated. That's a substantial trade off to be anguished over, as it will be irreversible.

II. Where Day and Night are Seasons

Venus' year is 224 days long, covering 1.6° of its orbit each day. It rotates on its axis once every 243 days, turning 1.48° per day. If it rotated in the same counterclockwise direction as it orbits the Sun, as does Earth, its rotation would lag behind its revolution so slightly that it'd take 360/(1.60-1.48) = 2,960 days or 8.1 years for just one day-night cycle!!

Fortunately, the direction of rotation is just the opposite so that the daily 1.60° and 1.48° increments are added instead of subtracted, the smaller from the greater. 360 / (1.60+1.48) = 116.78 days or 58.39 days (c. 2 months) of daylight, alternating with 58.39 days of darkness. This "sunth" is not quite four times as long as the dayspan/nightspan "sunth" cycle on the Moon (29.53 Earth days long).

The upshot is that there are two day/night cycles per Veneran Orbit Year. Actually, not quite. Two Veneran "Sunths" are 233.57 days long, about 9 days longer than one Veneran "Versary". There are 25 pairs of Sunths (50) in a 26 Versary period.

Keep in mind that as Venus axial tilt to the plane of its orbit around the Sun is only about 2°, there is no "seasonal pattern" tied to the Veneran Versary or Orbital Year. It is the "Sunth" with its hotter 8 week long dayspans and cooler 8 week long nightspans that produces the true "Seasons" on Venus. We predict that Venerans will count their year-like periods as three sunth-sets ("trisols"?) of 3 x 116.78 = 350.35 Earth dates long. Their sunth would come out to an even 112 dates of 16 weeks if they marked dates as 25 hrs. 1.5 min. long. Or they could keep the Earth minute, hour, day, and week, but mark their own sunths and "trisols".

III. Shortening the days/night cycle

IF we were ever to tamper with that cycle, by impacting comets at the equator and in the equatorial plane, at an angle of roughly 45° to "aim tangentially at" the subsurface point along which Venus' mean angular moment of rotation lies, it would be far more effective to go with the flow and try to speed up the "retrograde" rotation, than to first slow it to a dead stop, then induce rotation in the "right" direction.

AIMING water-ice comets for max. rotation speed up

If we decided we wanted more water than to be had by reacting hydrogen with oxygen liberated from the carbon dioxide in the atmosphere, and we wanted it bad enough, we'd have to get it from comets or from dismantled ice-moons (Saturn's Hyperion is already half dismantled from past impacts.) We could guide the comet ice chunks in their incoming trajectory to best speed up Venus rotation. We'd add this "extra" water before reacting imported hydrogen with atmospheric oxygen, i.e. while the surface was still dry.

Shortening the Veneran sunth would be an uphill battle. To cut it in half down to 58.4 days ( 4 weeks each of daylight and darkness), it would be necessary to speed up the period of rotation more than three times, from 243 days to less than 79.

IV. A Tale of Two (Veneran) Cities

There may be a very good reason to leave well enough alone. Venus' dayspan/nightspan cycle is slow enough that we are really dealing with a 2 month long daylight season and a 2 month long darkness season with substantial temperature swings. Now it is fantasy to expect that a terraformed Venus will have moderate temperatures. We'll be lucky to have them on the underside of boiling. If we succeed in forming an ocean, it will be steam-room hot. There are people who find such an environment "renewing", at least for an hour or two. I'm not one of them, preferring dry sauna heat instead. Extreme heat coupled with extreme humidity would be disabling, if not immediately fatal. So what can we do?

Can we find a surface beachhead or two of more moderate temperatures on our rehabbed Venus? Nightspan at higher elevations seems the best bet. Fortunately the highest spot on the planet, Maxwell Montes (pinning the 0° longitude) is paired at 180° by another high spot. When one passes into dawn, the other passes into nightfall. We could establish a pair of outposts from the very outset, and migrate from one to the other leaving each sunrise for sunset. Such a lifestyle is not so different from that of "snowbirds", people who migrate annually from the snow-belt down to Florida or Arizona. On Venus there'd be three migration cycles in the space of one Earth year.

So we suggest these two settlement areas:

Maxwell Montes in eastern Ishtar Terra 0° longitude, 65° N &emdash; "Maxwell Center"

Tip of the "Scorpion's Tail" in eastern Aphrodite Terra at 180° longitude 18° N &emdash; "Scorpio Center"

[Venus: two "continents" tower over rolling lowlands.
As Sun rises in the West, migrations are to the East.]


V. Oceans & Continents

Venus' new oceans and seas will be less deep than Earth's, there being no deep abyssal basins on Venus. Further, the amount of water producible by reacting imported hydrogen (1/9th the mass of comet ice needed in other schemes) with oxygen liberated from atmospheric carbon dioxide (MMM # 114 MAR, "Geomorphing Venus") is enough to produce a layer an average 800 meters or 0.8 km (2,700 ft.) deep. That's less than a third as much water as Earth boasts, but still a respectable amount and we could look for depths of 4,000 feet as common.*

*[BOE (back-of-envelope calc.): 90 atms/0.91 G x 0.73 (% oxygen in atmospheric CO2) x 1.125 (with hydrogen added) x 15 lbs/inch2 x 144 sq. in /sq. ft x / 64 lbs of water/cubic foot = a column of water 2,731 ft. high or c. 800 meters, i.e. if most Venus' atmospheric oxygen was hydrogenated.]

As a result, the new seas will be subject to significant evaporation during dayspan, and heavy precipitation and refilling during nightspan. If it were not for this natural seasonal redistribution of the waters, we might choose to preferentially deep-fill select basins closest to the two suggested population hubs. But evaporated water will refill by rain any available basins, on cue from seasonal wind and rain cloud circulation patterns. Some seas will be "ephemeral" not lasting the whole of dayspan before becoming dried mud flats. Others will shrink noticeably in surface area as each day season progresses. Others, with steeper shores, will lose volume but not much apparent area. These will be the first targets for seeding with heat-tolerant living species.

Deep water forms of marine life in deeper basins may fare better than shallow water and surface water forms which have to cope with higher temperatures and considerably greater temperature variation. Other species will time their reproductive rhythms, even their feeding (and fasting?) patterns to the long dayspan/nightspan seasons.

On Earth, it is the Ocean, covering 3/4 of the Earth's surface, that is the great thermal flywheel which rules the whether on a global basis. It would be a challenge to give Venus an ocean as extensive in area, even though, there being only two comparatively small continental elevations, and no deep abyssal basins, it would take a much lesser volume of water to cover a greater expanse of surface on Venus than does Earth's multi-lobed global ocean.

To improve drainage and reduce the number of unconnected "landlocked" basins, an equivalent of our Army Corps of Engineers could channel thru basin sills and natural dams and dig canals to interconnect the various bodies of water and globalize the possibilities for marine navigation.

Biospherewise, jobs 1 and 2 are:

(1) Seed the oceans with hot-water-loving microbial cultures, plankton, and nekton: the bottom of any future food chain.

(2) Fix the soil with rain-hardy erosion-resisting algal mats. etc., and with microbes to produce good, fertile soil, and to reduce soil temperatures.

VI. A Question of Goals

Whether the two settlement sites proposed above, or any other Veneran surface outposts ever become full-fledged human settlement communities or just science stations involved in the great terra-forming and biosphere genesis project is another question. Even if we were to succeed in cooling the planet, cannibalizing its present ponderous atmosphere for sunshade materials and for the oxygen portion of a reconstituted shallow ocean, and then successfully seed the latter along with the raw now rain-washed rock-strewn lands, it may well take centuries for the infant biosphere to find its new equilibriums. There may be false starts and global setbacks. Until the new Veneran biosphere settles down and proves itself stable, it may not be a sufficiently friendly place for a pioneering commitment.

Even with major changes in its atmosphere, significant heat reduction, and reformation of a significant ocean, as long as Venus remains as close to the Sun as it is, we might have to rest content with concreating a world where we can watch to see what happens. Indeed, Venerans will not see Terraforming as an episode that introduces them to a new future, but as their future for all foreseeable time to come. The process of making Venus a friendly place for Earth-derived life will be a very open-ended one. Indeed, it will give Venerans a sense of collective vocation and purpose that seems to be utterly lacking in most, if not all Earth cultures of our time. To turn Venus into an enormous biological and biospheric laboratory will be a tremendous feat, even if we never do settle the surface in numbers.

VII. But what if we don't?

Our Veneran descendants may choose to keep their dearly won aerial civilization and to remain a cloud-top civilization like that teasingly illustrated in "The Empire Strikes Back", Part II of the Star Wars Trilogy. They might grow to cherish this "good life".

The terraforming strategy we've outlined may pay much greater respect to the given facts than any of the garbage-in-garbage-out schemes in circulation. But even with a philosophy of "going with the grain of nature', it would be a gargantuan "cathedral-building" task absorbing the energies of many generations. Further, our radical departure proposal has yet to benefit from peer review. There may be show-stoppers. It may be impractical to make any kind of sunshade in space from liberated carbon, even 1.24 x 1019 tons of it. The 89% mass savings of importing just hydrogen instead of water ice may be mooted by the technical and engineering difficulties uncovered.

Let's first brainstorm every unexplored option, One thing we've got for sure is lots of time.

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"High Sky Aircraft for Venus"

by Peter Kokh

[The original article was published in MMM #115 May 1998, p. 4]

by Peter Kokh


If we are going to have any number of science station and industrial aerostat hamlets in "the high skies" over Venus, we'll need reliable, easily upkept, worry-free, locally co-manufactured means of transporting people and cargo in between. That's a mouthful of design constraints. Can we deliver?

With the surface off limits to casual ventures, aerial transit is it. And none of our Veneran aircraft will be "landing" or "taking off". They will be "arriving" and "departing" - from midair docking gates.

Craft suited for such purposes may have very limited ability to cope with the greater pressures and heat levels of successively lower layers of the atmosphere. It would seem essential to design into them passive fail-safe buoyancy systems to prevent such misadventures.


Methanox (methane/oxygen) is a serviceable fuel combination for both reciprocating prop engines and for rockets. Most importantly, both fuel and oxidizer can be processed on Venus from the atmosphere where its exhaust will return it in the form of the original ingredients.

As landing is not an option in distress situations, some form of back-up power for electric taxi props would be prudent. Another option, however, is to have the entire upper surface of the craft serve as a rectenna for guide-beam slaved Solar Power Satellite microwave transmissions. Such systems, it'd seem, would be pioneered on Earth long before we'll need them on Venus, and by then be a stock item.

Where sprint-rescue speeds are not needed, propeller-driven craft promise the greatest fuel efficiency with adequate speeds as well as superior low speed performance for dock approaches and departures. Aircraft can safely fly at the 1 ATM aerostat level but need climbing ability to reach thinner air for more efficient cruising.

While fuel tanks should be ample for long range and extended cruising and bad weather and other emergency situations, again because landing is not an option, Veneran aircraft should have midair refueling capability. Midair docking capacity for exchanges of crew, passengers, and cargo would be an invaluable advantage, brining enormous flexibility.

To avoid construction of aerial runways that offering surface friction to assist braking and deceleration and provide a platform for acceleration to lift speeds, aircraft should either be buoyant or have some sort of Harrier or other type VTOL or hovering capacity. This would help in midair docking.


Lightweight Kevlar components, manufactured in Veneran high sky facilities, will provide greater strength and lessen the weight to be managed in maintaining lift, buoyancy, and hovering ability. Small complex subassemblies (navigation avionics, other electronics, control & communication systems, airtight docking ports, etc.) can be imported from Earth to mate with Venus-made fuselages, wings, fuel tanks, cabin interiors, and other items designed for ease of on site manufacture and assembly.

A whole family of Veneran aircraft will be needed: small crew transports, smaller and larger passenger craft, craft dedicated for cargo, fast sprint rescue and response craft. Maintaining a "family' resemblance along with the maximum percentage of interchangeable parts will be of compelling benefit.


Obviously, the dirigible is one viable option along with other possible lighter-than-air architectures (there is now a renaissance in interest along with increased exploration of new design options). But full-time partial buoyancy and buoyancy-on-demand with fail-safe, dead man deployment systems will also work while allowing more airstreamed designs and faster cruising speeds.

Hydrogen-filled bags that passively inflate whenever certain impeding conditions degrade will make the High Skies safe for all Venerans to fly. These conditions include minimum speed, maximum desirable or tolerable air density and/or temperatures, as well as certain internal conditions (loss of fuel, power, active crew).

To more efficiently negotiate different altitude ranges as well as variable speeds. wing and/or lift surface designs that allow the loading to be varied are a downrange design consideration.


On Earth, we have built oceanic submersibles that have withstood over 1,000 ATMs of external hull pressure. So it is temperature, not pressure, that looms as the most challenging hurdle facing would be surface exploration craft, including VTOL aircraft and wheeled gondola cabins lowered and lifted by collapse and store balloons. As an interim measure, mid-altitude aircraft could lower retrievable instrumented science/communications packages on tethers.


How serviceable line-of-sight radio communications will be, is unknown. With less of a magnetosphere, solar or cosmic noise could be a big problem on Venus. Satellites could offer GPS navigation assist as well as communications relay. But so could heat and pressure-hardened surface relay stations.

On this as on other challenges above, the old adage applies. "Where there is a will, (and no defeatist attitude!) there's a way."

"High Skies!"

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"The Friday File" - Venus Reclamation R&D Agenda

by Peter Kokh

[The original article was published in MMM #115 May 1998, p. 7]

Calling all "Friends of Fria". Want to contribute by helping brainstorm, engineer and design aerostats, Veneran aircraft, surface probes & rovers, atmosphere mining, tourist opportunities, or terraforming scenarios? Email the writer your homeworked ideas or mail them to: "Friday File" c/o MMM, 1630 N. 32nd Street, Milwaukee WI 53208.

There are a lot of challenges to overcome in rehabilitating Venus. But the biggest of all is not out there, not in or at Venus or Venus' orbit, but in getting rid of our own mental blocks to "imagineering.

A Starter List of Priority R&D Agenda Items


Aerostat "Xities" over Venus

Venus: Balloons & Aerobots

Touring Venus from Above

Visits to Venus enroute to Mars

"Subnubilar" Industries Over Venus

Geomorphing Venus

Venus Geomorphed

High Sky Aircraft for Venus

The "Friday File" (just above)