Monday, April 4, 2011

Worlds for Man - Part 2 - Venus

"Worlds For Man - Part 2 - Venus"

(c) 2007, 2011 by Jordan S. Bassior

Venus is in many ways a disappointment. The cllosest separate planet to the Earth, with almost the size and mass of the Earth, with the gravity to retain a thick atmosphere, Venus should be a prime choice for colonization. But the planet's proximity to the Sun and lack of a moon, coupled with a denser crust and resultant feebler tectonic action, have caused her to suffer a runaway greenhouse effect (the atmosphere is mainly composed of carbon dioxide) that has resulted in surface temperatures averaging over 400 degrees Celsius -- hotter than Mercury, and owing to atmospheric convection experienced globally rather than merely on the dayside.  To put more simply, Venus is everywhere, at every latitude, even in the shade or underground, at temperatures sufficient to melt lead (1).

With such high temperatures, and a surface pressure of 90 atmospheres coupled with clouds of sulfuric acid vapor, Venus is an extraordinarily hostile environment. Even robot probes can only endure a matter of hours on the Venusian surface, and vehicles capable of protecting organic life forms from such conditions would have be extraordinarily well-armored and thus bulky. Any permanent habitations would require powerful heat pumps to maintain survivable conditions within for prolonged periods (vehicles could operate for shorter periods using heat sinks) (2). Thus, the colonization of the Venusian surface would be very expensive, dangerous (3) and difficult.

Near-Term,  there is fortunately another option. 50 km above the Venusian surface, the pressure and temperatures are Earth-like (1 atmosphere and 0-50 degrees Celsius). In addition, at this altitude solar energy is abundant -- 1.9 times per square meter the amount available on Earth. Consequently, the early colonization of Venus might involve the construction of blimp or dirigible-like floating stations ("aerostat habitats," in Geoffrey Landis' terms), in which the provision of life support would not be unusually difficult. From these stations, human crews could supervise robots and conduct excursions onto the surface. The stations might float freely, blown by the winds around the planet every 100 hours or less; or they might be tethered to the ground (4).

One thing that would ease their design is that ordinary Earth air (a 21:79 oxygen-nitrogen mix) is a lifting gas under Venusian atmospheric conditions -- consequently, the aerostats' gas bags could be used as combination air reservoirs and large common areas (5). Thus, life in such a hab might not be unduly claustrophic; provided that the total load was not increased too much the gas bags could be formed as parkland, complete with soil, plants, and water lakes whose aqueous contents could double as droppable ballast (6).

Ground stations might also exist, but would be used as bases for surface operations rather than long-term habs. The ground stations would be mostly robot-manned, and most actual scouting work would probably be done by fleets tele-operable semi-independent robot robers, with humans remaining within the safety of the thick-walled ground habs rather than risking their lives in bulky, probably mecha-like Venus Suits (7). Conditions within the ground stations would certainly be spartan and claustrophobic, especially during this early phase of colonization.

Venus offers some useful resources. The planet is probably metal rich, though not as much so as the Earth (8), and certainly contains volatiles, especially carbon, oxygen and nitrogen. Unlike most terrestrial worlds, it lacks ice, but with the available solar energy and hydrogen-containing minerals, enough water could be obtained for colonial purposes. Venus also has a moderate gravity which would be better for health purposes than the lower gravities obtaining on the other terrestrials. Unfortunately, none of these advantages are particularly dramatic (Venus is outcompeted by Mercury as a source of minerals and by Earth and Mars as a source of volatiles) and hence Venusian colonization will probably be a slow process (9).

Middle-term colonization will see this slow process yield significant growth. The aerostat habs will have grown into genuine "floating cities" (again using Landis' terms); on the surface, the ground stations will have time to grow into immense warrens.

Load will be a major problem in the floating cities: every effort will be made to build things out of light but strong substances, such as the nanoformed carbon-filament polymers which will be then be spinnable kilometers long (10). Here will live many humans and organic artificials, in a sort of floating fairyland.

Refrigeration will be the major problem on the ground: where ever possible labor will be done by inorganic artificals, so that as little space as possible needs to be conditioned to Earth norms. Thus the surface will be the realm of robots -- specifically, ones designed to survive Venusian temperatures and pressures.

By this time, the work of terraforming may have begun. The main problems are the heat, and the lack of water. The heat could be reduced by orbiting sunshields (which could double as solar power stations) (11), as proposed by Robert Zubrin. Water (on the scale needed to terraform a moderate-sized terrestrial planet) would be a more difficult problem: iceteroid bombardment would take a very long time to deliver enough to make a difference.

Paul Birch has suggested crashing one of Saturn's small ice moons onto Venus to deliver a lot of water at once: of course, if colonization has already begun, this would be a very dangerous technique. Perhaps an ice moon could be pushed into Venus orbit, behind a sunshield, and then the moon sliced up and dropped onto Venus in smaller, more manageable pieces?

Landis has pointed out that the floating cities could also serve as sunshields and atmosphere converters. While a single floating city would not be able to achieve much in this regard, as they spread (especially if linked by large areas of artifical floating "wilderness") a lot of floating cities could perform considerable terraforming over time.

Because of the division of Venus into two main environments -- the soaring sky-world and the sweltering surface -- there is an obvious social conflict likely to develop. Especially where terraforming issues are concerned, the interests of the organic sapients in the cloud-cities and the inorganic sapients in the surface-habs may not be compatible. Skydwelling humans, cosmopolitan in outlook, might take for granted that Venus would be improved by becoming more Earthlike; but robots already optimized to Venusian surface conditions may see no need to introduce corrosive free oxygen and salt water into their world.


In the end, Venus is likely to be terraformed, if only because by doing so the Venusians would be joining a community of Earth-like worlds in the Inner System, including Earth, Luna, Mars and Mercury. This process may or may not involve a war between Sky and Surface, or some degree of accommodation to the needs of the surface-dwellers (12).

Venus will become Earth-like, but it will not be Earth. Two great continents will stand amidst shallow salty seas, but these continents lack the rugged mountains and these oceans the abyssal depths of the Earth's, because of the much simpler Venusian geological history (which involved complete crustal recycling every several hundred millions years rather than Earth's tectonic dance of eruption, merging and subduction) (13). The air will be breathable, but also thicker -- the process of carbon-sequestration will reduce its density but not down to that of the Earth, and a thicker atmosphere will be beneficial as protection from solar radiation, especially given the weaker magnetic field.

Venusian populations, fauna and flora will be more slender than those of Earth, both because of the lower gravity and because ectomorphy is adaptive to hot environments. With thick air and low gravity, flight will be easier. Humans won't be able to fly with simple strap-on wings, but the minimum practical airplane or glider will be much smaller and more manageable than is the case on Earth (14). It is possible that a Venusian subrace may emerge which is engineered for flight with hollow bones and improved respiration -- shades of Olaf Stapledon! This flying culture might develop from the old floating cities, and use them as homes (15).

Likewise, in the extensive shallow seas, there might develop a marine sapient culture. This might be based around cetaceans, and it might also include marine-modified humans like the "selkies" of Earth (see Part 3), who might also participate in Venusian colonization.

A terraformed Venus might resemble the Venus of the old pulps in several ways. With shallow seas and low-lying lands, there would be much marine life and wide marshes. Extensive forests and jungles would be an obvious ecological component stablizing the terraforming and keeping carbon dioxide sequestered. If there was political disunity, possibly stemming from the terraforming disputes, there might be all sorts of exotic adventures and intrigue. With the ruins of earlier colonization stages and failed projects littering the landscape, it might even be a place that an Eric John Stark or a Northwest Smith might find not wholly unfamiliar. Heck, at least one zoology enthusiast might create a safari park stocked with dinosaurs, and some might later escape and go feral ...

Venus would have a rich future, possibly with as much change and history and brilliant culture as has the Earth.

(1) - The Venusian crust has had more than enough time to equalize itself to atmospheric temperatures.  Unlike Earthly caverns, Venusian ones won't have cooled during the night and retained the lower temperatures, because the Venusian night isn't that much cooler than the Venusian day.  Furthermore, since Venus is still geologically active, temperature probably increases with depth as one descends, just as is the case on Earth below a certain level.  This factor, coupled with the lack of plate tectonics, is one big reason why the Venusian crust melts every several hundred million years, renewing its own surface.

(2) - This would necessitate nuclear reactors as the only practical means of powering the air conditioning.  Fortunately, Venus is probably almost as rich in radioactives as is the Earth, since it is still geologically active and hence probably has a uranium-thorium core just like our own planet.

Furthermore, given the extreme deadliness of the Venusian heat, each base would probably require multiple reactors and backup air conditioning systems for safety purposes.  Most Solar worlds will kill you slowly on a life support failure:  Venus would kill you relatively quickly.  One backup system that would help would be to maintain a "cold room" containing ice or liquid nitrogen, which could be used as a heat sink should the air conditioning temporarily fail.

(3) - Any significant breach in a compartment would be instantly fatal to the occupants:  90 atmospheres of 400 degree Centigrade carbon dioxide liberally laced with sulfuric acid would pulp, bake and dissolve the unfortunates therein, leaving only thready black goo in roughly humanoid shape.  Some large bones and the teeth might survive for a while.  One would be wise to design habs and large vehicles with multiple hulls and sealable compartments to limit the consequences of such a penetration:  given the extreme atmospheric pressure, however, this solution would be more than minimally expensive, meaning that some would be tempted to cut corners, resulting in the occasional disaster.

(4) - An airhab might be designed to do both:  it might be an airship which docked for long periods at a time to provide services to ground habs, much like crane-ships and drill-ships do in the seas and harbors of our Earth.  Docking would not necessarily require descending to the surface:  with the carbon- and silicon-fiber cabling already under development, the airhab could remain at a cooler and lower-pressure altitude, communicating by cable-car with the groundhab.  The cable-car could mate with an airlock at the groundhab, so that the passengers could travel from airhab to groundhab in a shirtsleeves environment.

(5) - This is a somewhat counter-intuitive design, because Earthly airships (which use hydrogen or helium as lifting gas) keep their passenger gondolas or decks below their lifting gas bags, so that gas leaks will have no effect on equipment or personnel.  However, on Venus, breathing and lifting gas can be the same, so the design works just fine.

(6) - Safety gratings could ensure that the airhab didn't jettison livestock or (worse) passengers while ensuring an emergency ballast drop.

(7) - The main problem in spacesuit design is combining protection with flexibility. In the Venusian environment, any sizable suit breach would be instantly fatal, and even a pinhole puncture would cause severe injury to the wearer. Consequently, the best design for a Venus suit is a spherical or ellipsoid, heavily armored life support capsule, with the head turret, arms and legs being remotely operated from within that capsule: rather like the "Fat Man" deep-sea diving suits from Tom Swift, Jr.

(8) - Venus is smaller, less dense, and (unlike most terrestrial worlds) hotter and under greater pressure than the Earth, which complicates mining operations.

(9) - I see Venus as the location of hardship stations, and possibly even penal colonies.  Escape from a Venusian penal colony would be considerably more difficult than from a Lunar or Martian one:  even technically-competent prisoners with access to the machine shops would have trouble cobbling together a Venus Suit.

(10) - Carbon-filament nanofibers would probably be destroyed by the conditions pertaining on the Venusian surface, but then the aerohabs aren't meant to descend to the surface, and probably couldn't survive such a descent even if they were made of more refractory materials.

(11) - As has been pointed out already in reference to terraforming Mercury.

(12) - The air-dwellers would have better access to space and hence the commercial advantage, but their large low-density cities would be terribly vulnerable to nuclear weapons; the surface-dwellers would have ready access to all sorts of metals and would be living in habs equivalent to massively-strong bomb shelters, but would have difficulty reaching space against the opposition of the air-dwellers.  It would be an interesting conflict for wargaming purposes.

Of course, it would be better for both sides if they didn't fight, as each would have things the other would need, and hence good grounds for mutually-beneficial trade.  However, because they would probably be culturally-divergent, this might not be enough to keep them from engaging in open warfare.

(13) - It might be a good idea for the terraformers to deliberately open some volcanic rifts, even though this would add to their gas sequestration problems, if only to relieve the internal heat and pressure and hence postpone the Big Melt.  Not that the Melt would be likely to happen any time soon, but I would imagine that some pretty big faulting and rifting occurs naturally on Venus from time to time well before the Melt -- better to have this occur at times and places of the terraformers' choosing, rather than right under a city!

(14) - We've already developed man-portable single-user jetwing vehicles:  these would work even more efficiently on Venus than they do on Earth.  Jet-powered aircycles might become a common mode of personal transportation up among the airhabs.

(15) - Once Venus was fully terraformed, there would be no particular need of the old-fashioned airhabs, but traditions die hard, and hence the culture might continue, finding new economic occupations.

1 comment:

  1. Gee, why am I reminded of Daughter-of-the-Sea from Phoenix Exultant?