One of the most interesting aspects of Arrakeen surface morphology is that the mountain chains and grabens run either north-south or east-west (geographic coordinates). This geometry is noted on a number of Neta-2C planets but never as clearly defined as on Arrakis. As will be seen shortly, this geometry is intimately connected with the nature of tectonic processes on the planet.
The small polar caps lie below bled-level. This "polar sink" is uncommon but geological evidence has shown that the ice caps were much more massive in the distant past even existing as such during the early periods of human habitation (Hackelrhued). Periodic episodes of ice advance occurred with massive glaciers and continental glaciation from the north polar cap extending as far south as 62° N latitude while that from the southern cap had furthest advance to 58° S. These massive ice movements from the poles scoured much of the rock in the polar areas, carried it to more temperate climes where the ice melted and deposited its mix of rock flour. The polar sinks were thus created. Since the present ice caps exist in depressions it has been suggested that energy from Canopus be focused with large solar satellite arrays to form polar lakes. The water from these lakes would then be drained through tunnels to provide irrigation to those areas of Arrakis most in need of the water. Ghralic has provided compelling arguments against such a project, concluding that the present climatic balance on the planet would be seriously disturbed with possibly disastrous results.
GEOLOGIC HISTORY, TECTONICS. Arrakis, as a Neta 2C class planet, evolved after formation much as other planets of the classification. The oldest rocks on Arrakis have been dated, isotopically, as being 1.1 eons in age (1 eon = 1 billion standard years). These older rocks have been found only by deep drilling and furthermore have been located only in a few places, existing as small fragments contained in much younger rock. Almost all other planets of the same classification have rock exposed at the surface with ages greater than 2.1 eons. The evidence that geologic processes on Arrakis are much more dynamic in the destruction of ancient rock and the formation of new rock and surface features is thus convincing.
The ancient Terrans held a simplistic view of planetary genesis, still accepted today in most respects. They believed that planets were formed by accretion of smaller fragments, dust, gas and ices remaining about a star after or during stellar formation. As each planet grew, its interior warmed through gravitational contraction with heat released by radioactive decay. The surfaces and interiors of Neta-class (modern terminology) planets soon became molten. After about one eon sufficient cooling occurred to form a solid crust. Convection in the planet's molten interior caused continued breakup of the crust and formation of new crust (must like scum floating on the surface of a bubbling pot of molten fanmetal). As cooling continued the crust thickened to the point where it became stable and a basically permanent feature. This typically occurred about 1.5 eons after formation.
Eventually the interior became only quasi-molten. However, heat generated by radioactive decay continued to cause a slow convection which in turn produced on-going disturbances within the crustal material. These included volcanic eruptions, quakes and movement of portions of the crust with respect to the other portions, such phenomena continuing to the present. The Terrans called these crustal motions "plate tectonics" and, as noted above, ascribed the heat energy from radioactivity to be the driving energy source. From the relatively few scientific records remaining from Terran times it appears that this explanation was universally accepted. However, of the four Neta-class planets in their planetary system only one exhibits plate tectonics behavior.
Today we know exactly what causes plate tectonics, why only some Neta planets exhibit plate tectonics behavior, and hence why Arrakis is more tectonically active than any other Neta planet. Bnaceret has summarized current understanding. Heat from radioactive decay by itself is insufficient to cause crustal (plate) movements. Also, internal heat is not necessary although in all cases internal heating results from action of the mechanism primarily responsible for plate motions.
Two mechanisms are known: convection currents resulting from severe internal heating and external gravitational torques. In some cases both mechanisms play a major role. The former is the sole mechanism for only a few planets, none of which exist in the Terrans' planetary system. The required heating comes in part from radioactive decay but mostly from neutrinos emitted by the host starts). Absorption of neutrinos by the planet produces the heat. Since neutrinos have no mass or charge most will pass through a planet without interaction. Hence, in the absence of large external gravitational torques, the severe internal heating required occurs only when the neutrino flux is very large. Very few stars produce a sufficiently large flux. Suffice it to say that Canopus does not produce a large flux of neutrinos.
Gravitational torques are the dominant mechanism for most planets exhibiting plate tectonics behavior. Requirements are (1) adjacent planet(s) with mass considerably larger than the planet in question and/or one or more moons with mass of an appreciable fraction of the host planet, and (2) orbits of the adjacent planet(s) and/or the moon(s) which lie appreciably outside the ecliptic plane of the planet, and are preferably eccentric. The resulting gravitational torques generate large stresses which in turn cause crustal movement with associated tectonic phenomena. The planet is heated internally by friction, but this heating is secondary to the entire process.
Arrakis, as noted earlier, has larger planets on each side, Menaris and Extaris, both of which have highly elliptical orbits with orbital planes lying well outside that of Arrakis. Plate tectonics on Arrakis is thus caused by gravitational torques. The unusual closeness and large size of Menaris and Extaris cause Arrakis to exhibit exceptional geologic activity. Quakes are common and the amount of volcanic activity is on the high side, but certainly not extreme. Portions of the crust are displaced with respect to other crustal segments by the astounding amount of 30 centimeters per year (planetary mean). New mountains are formed and old ones destroyed at a geologically rapid rate. Over one 2,000 year period, the Tramblisch Range rose 3,125 meters. Grabens open, oscillate, and close at equally rapid rates. The north-south and east-west trends of all mountain ranges and grabens is a result of the particular geometry of the Menaris-Extaris-Arrakis system and stress-field orientation so produced.
Arrakis is a favorite planet for planetary geologists because one can literally see geologic processes in action with only a short time of observation. Mapping, however, is a problem and the planet is a civil engineer's nightmare.
INTERIOR. The crust of Arrakis is rather thin, averaging only 10 kilometers in thickness. An incipiently molten region, the source region for volcanic activity lies immediately below. The remainder of the planet is basically solid except for a small, fluid central core. Arrakis has a relatively weak magnetic field which is produced in the core. It is of interest to note that even after many thousands of years of study the exact mechanism by which the magnetic field is produced is still not fully understood.
It has been known for some time that the chemical composition of a planet depends upon its distance from the main star and that same planets consist primarily of silicates, some primarily of hydrogen (quasi-stars), some primarily of sulfides, while some are mostly metallic. The Neta class is defined specifically as comprising those planets with a composition of 60 ± 10% silicates (by mass), 30 ± 10% metals, 10 ± 5% sulfides and less than 5% hydrogen. The crust and upper layers of Arrakis are composed almost entirely of silicates, the middle and lower layers are primarily silicates, but with significant amounts of metals and sulfides, while the core is primarily metallic with a small amount of sulfides. The precise chemical composition of Arrakis is 69.723% silicates, 21.388% metallics, 7.691% sulfides, and 1.198% hydrogen and miscellaneous.
J.R.
Further references: ARRAKIS, ATMOSPHERE OF BEFORE THE ATREIDES; Th. Zed Ghralic, "The Geology of Arrakis: Present Views," Geological Record 90: 748-73; H.K.; Praeshan, Arrakeen Archeology (Topaz: Carolus UP); Z.G. Kynes, "S
urface Mature Summary of Arrakis," Bulletin of Planetology NS 901: 39-49; A.G. Xenach, "Comparison of Rakeen Datums, 10000-15000," Geological Record 79: 35-40; Zhuurazh Hackelrhued, "The 'Polar Sink' Phenomenon of Arrakis," Geological Record 85: 573.-95; P.R. Bnaceret, The Mechanisms of Plate Tectonics, Science Occasional Papers (Loomar: RIT Press).
ARRAKIS, Oxygen Saga
All known "intelligent" forms of life require oxygen, and the atmospheres of all habitable planets contain at least 19% oxygen. The history of oxygen on Arrakis is unique, including one proved oxygen-depletion catastrophe and one near-catastrophe, the latter occurring in historical times, making Arrakis worth special note.
The major source of atmospheric oxygen is plant photosynthesis. If life evolves on a planet at all, rudimentary plant life is first seen in the fossil record about one-and-a-half to two billion years after planet formation. Two billion years or so pass before the required 19% oxygen is reached. By this time advanced plant life forms are widespread. Fossil remains of lycopsids and sphenopsids are especially common. Arrakis followed this sequence, its atmospheric oxygen content reaching 19% about 900 million years ago.
Arrakis followed the normal evolutionary sequence for the next 850 million years. By this time a great diversity of marine and land life had evolved. Land-dwelling mammals and reptiles were abundant. However, the fossil record makes it clear that the very large reptiles found on some planets even today never evolved.
The oxygen catastrophe on Arrakis occurred about 49.7 million years ago. Only a few sedimentary rocks are found less than 49.7 million years old, and their formation ceased about 48.5 million years ago. Since sedimentary rocks almost invariably require the presence of standing water in order to form the evidence shows that the oceans largely disappeared 49.7 million years ago. The small, remnant oceans and all traces of standing water disappeared within the next million years.
A nearly complete extinction of life occurred concurrently. Very few remains of land life have been found in wind-deposited sediments formed since; most animal and vegetable life species on Arrakis today are generally believed to have been imported by the Fremen during their original colonization of the planet. Sediments show an almost complete lack of oxygen, an amount certainly far below that required for intelligent life. This dramatic oxygen decrease was followed by a gradual rise. By the time the Fremen arrived some eighty-five hundred years ago, the oxygen amount was well above minimum requirement, and three species of small, oxygen-breathing animals had reappeared.
The fossil record in the marine sediments deposited after the event indicates that the only survivors were several species of worms, mostly of the burrowing type, phylum protochordata, and several microorganisms of the protozoa phylum together with some varieties of plankton. Of these, only class shaihuludata, phylum protochordata, survived to recent times. The fascinating story of the evolution of this worm from a small marine creature to the water-aversive Shai-Hulud (sandworm) of present-day Arrakis is given by Satorinia. As a bottom-burrowing organism, the worm was able to survive the initial cataclysmic event. It was thus given time to adapt to the gradual evaporation of what remained of the original oceans. The worm's predators had undergone mass extinction. In addition, lack of competition for food provided conditions which helped the adaptation. By the time desertification was complete, Shai-Hulud had become perfectly adapted to an arid environment. Scientists generally believe that sandworms could evolve once again into marine-dwelling creatures, given a few million years of gradual change in environment. But the worm cannot withstand sudden contact with water today any more than it could have withstood sudden contact with air 49.7 million years ago. For many centuries it was believed that Shai-Hulud was responsible for the desertification of Arrakis. However, many scientists now believe that sandworms are the product, not the cause.
It is strange that even today, with all the scientific data that have been accumulated, we still do not know what caused this catastrophe. However, the cometary hypothesis is the most probable answer. This theory involves cometary impact or near-miss. The comet sweeps away the bulk of Arrakis's atmosphere; the oceans gradually evaporate, but at a rapidly slowing rate as water vapor causes a partial rejuvenation of the atmosphere. However, water vapor is continually lost to space. Volcanic activity adds gases to the atmosphere and eventually over a million years or so a new equilibrium is established. Meanwhile, the oxygen has been lost and cannot be replenished because the vegetation has been killed, as have almost all living species. The planet, severely depleted in water vapor, can no longer sustain the residual ocean mass.
Arrakis would probably not be suitable for man today if it were not for sandworms. After recognition that an oxygen catastrophe had occurred on the planet, scientists were puzzled as to where the present oxygen came from. Dragan et al. solved the problem when they discovered that as part of its metabolic processes Shai-Hulud produces oxygen. If this fact had been known earlier, the recent near-catastrophe in oxygen deprivation could have been avoided.
Man produced this near-catastrophe by interfering with the natural course of events. Specifically, about five millennia ago, the famous planetologist Pardot Kynes started to plant the deserts of Arrakis, thereby transforming the planet into a site much more hospitable to life. The process was very slow in getting started, for political and other reasons, and it was not until about 4,000 standard years ago that massive plantings began. In hindsight, the caution that should have been taken is evident. Vegetation requires water, but water kills sandworms. Both vegetation and sandworms produce oxygen; Atmospheric oxygen is rapidly depleted by chemical combination with rock on a planet, as tectonically active as Arrakis. Hence, unless the rates at which vegetated areas are expanded and worms are killed are carefully controlled, the amount of oxygen can dip below the minimum required. This dire event almost happened.
The first recognition that something was amiss occurred in 12820. A wildlife survey, completed that year, showed a dramatic decrease in the numbers of birds and mammals, and the general health of several species was poor. Concurrently, scientific studies showed that the atmospheric oxygen content had dropped from 20.12% to 19.68%. As a result, Lord Leto appointed a Planetology Commission to head a scientific task force.
Eight years were required to produce the final report. In the meantime oxygen content had dropped to 19.23%, dangerously close to the critical level. Humans were exhibiting signs of oxygen-deficiency distress and several hundred deaths have been attributed to this problem. If local manufacture and large scale transport of oxygen for human consumption had not been started, the death toll would have been much higher.
Since that time the areas under cultivation and those reserved for desert have been carefully managed. The atmospheric oxygen content reached a minimum of 19.07% in 12840 and started to rise perceptably by 12845. Today the oxygen is controlled at 23.58%, and present plant life is sufficient to maintain this level.
J.R.
Further references: SANDWORMS; Arna Satorinia, Adversity to Supremacy: The Evolution of Shaihuludata (Loomar: RTT Press); W.N. Dragan, C.D. Umbo, and A.H. Hautan, "Oxygen as Waste Product in Shaihuludata," Science (Loomar) 70: 442-453.
ASSASSIN'S HANDBOOK
Originally a third-millennium compilation of information on poisons to aid professional assassins, The Assassin's Handbook was expanded in the fifth millennium (5345-5348) by a committee appointed by Emperor Kelal Djordjevich to discuss the theory and practice of legalized murder under the rules of the Great Convention and the conditions defined by the Guild Peace. The expanded Handbook resulting from the committee's deliberations was widely circulated and read during the Old (pre-Atreides) Imperium, for it was held in high regard by mercenaries and master assassins employed by the emperor and the Great Houses. Also used by several training schools for professional assassins, the Handbook fell into some official disrepute during the reign of Paul Muad'Dib and the Regency of his sister Alia, although its principles continued to be employed. During the long
reign of Emperor Leto Atreides, the Handbook was officially held to be as contemptible as the profession of assassin; and Emperor Leto's Imperial guard, the warrior females or "Fish Speakers" were ordered to confiscate copies of the Handbook whenever they found it, although privately they were instructed to master its principles. As a result of this suppression, far fewer copies of the Handbook survive than might be desired. A few may be found in museums on Giedi Prime and Grumman, while the remainder appear to be located in private collections.
The authorship of the original version of the handbook is a matter for controversy, but a consensus seems to assign it to Keshas Zhorzh, a third millennium assassin employed by House Moritani. Zhorzh was suspected of several murders of prominent aristocrats, especially members of House Ginaz, House Atreides, and House Herzog. Oddly, Zhorzh himself succumbed to chaumurky, probably administered by an Imperial servant, in 3756. On Zhorzh's life, see The Practice of Death by Zhautii Kuuraveer.
The expanded version of The Assassin's Handbook is attributed by most authorities to the committee of nine appointed by the Protector Kelal Djordjevich; it was later ratified by the Landsraad (5359), by which time several of the authors, themselves mentats and master assassins employed by the Great Houses, had become victims of the vicissitudes of their profession. One of the committee, however, deserves special note: the Imperial representative, Count Otho Fenring, himself known to have been an able assassin — indeed, some have argued, one of the supreme artists of his profession. Count Fenring's influence on the final draft of the The Assassin's Handbook appears to have been considerable, especially when the text is compared to his monograph on The Fine Art of Professional Homicide, the passages concerning methods of circumventing the rules of kanly without detection. In the early millennia after the Butlerian Jihad, assassination flourished, but assassination in general was often crude and impulsive, lacking in the finer artistry and subtlety which the master assassins of the old Imperium attained. The accomplishments of these highly skilled professionals must be in large part attributed not only to years of careful refinement of their art, but to the tutelage of such repositories of cunning as The Assassin's Handbook.
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