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It later became the Imperium's center under Muad'Dib's empire. It was the original and for a long time sole source of the Spice Melange, which was vitally important for space travel. Eventually, because of the vision of Pardot Kynes it was terraformed into a green world.
- This article is a stub: It may require more information.
In its earliest known period, many mountain ranges and deep grabens existed in all regions of the planet, thanks to its high geological activity.
During its early existence, Arrakis had formed enough oxigen to allow the evolution of diverse land and marine life, with abundant land-dwelling mammals and reptiles. It's notable that the very large reptiles known from other planets never evolved.
Then an oxygen catastrophe occured. Even after millennia of accumulated data, the cause of that catastrophe remained unknown to the scientists. The most probable theory involves cometary impact or near-miss: Arrakis's atmosphere could be swept away by a comet, followed by evaporation of the oceans (49.7 million years ago). The recycling of water vapor caused a partial rejuvenation of the atmosphere, which just slowed the rate of evaporation process, before it eventually was all lost to space.
Very little land life remained in later-formed wind-deposited sediments. Marine sediments indicate that the only suvivors were several protochordata species of worms (mostly of the burrowing type), several protozoa micro-organisms, varieties of plankton, including the ancestors of the shai-huludata. The extinction of vegetation prevented replenishment of new oxygen.
Gases released from volcanic activity were added to the atmosphere and eventually established a new equilibrium. Depleted by water vapors, the planet could not sustain the remaining oceans and standng water, and they also disappeared.
The dramatic oxygen decrease was followed by a gradual rise. The reappearance of oxygen was puzzling to scientists until W. N. Dragan, C. D. Umbo, and A. H. Hautan discovered that part of the Sandworms' metabolic processes produced oxygen. When the amount was well above minimum requirement, 3 species of small, oxygen-breathing animals had reappeared.
Arrakis had three natural moons, one, lay in Arrakis's ecliptic plane, was destroyed by impact from an on-rushing asteroid/comet; most of the debris impacted the planet's surface but a ring structure was formed around the planet. The ring of dust caused a major reduction in star energy striking the surface. Hence surface temperatures were reduced and an ice age occurred. Many life species perished while others assumed dominance. Perhaps oft-told legends refer to this event, and would place it at about 19,460 BG but geological data suggest that the event occurred at least 184460 BG.
During the extensive desertification, the sand blasting resulted to severe erosion of previous morphology. Most grabens were filled by dust resulting to a mostly flat planet, if not to some elevations because of the planet's intense geologic activity.
The planet was colonized by the Fremen/DE 8500 years ago. Most animal and vegetable life species on Arrakis today are generally believed to have been imported by them.
The famous planetologist Pardot Kynes/DE had a vision to make Arrakis more hospitable to life and cooperated with the Fremen to plant the deserts. The process started very slowly due to political and other reasons, before massive plantings began. This cautionless man-made interference to the natural course of the planet proved to be catastrophic. Both vegetation and sandworm metabolism produced oxygen, however the water needed for vegetation was lethal to sandworms; their death rate was much more higher than the rate of vegetation expansion. Combined with oxygen loss due to chemical reaction caused by the planet's high geological activity, the amount of oxygen dropped dramatically.
The terraforming of Arrakis reduced the eolian erosion, and with little in the way of water erosion, mountains are rising "rapidly" (in a geological time sense) resulting in conditions similar to the earliest phase.
In the next millennia, a survey proved a decrease in the numbers of birds and mammals, subsequently linked to a decrease in oxygen content. Leto II appointed a Planetology Commission tp head a scientific task force. By that time, humans showed signs of oxygen-deficiency distress, the probable cause of several hundred deaths. This was remedied by local manufacture and large scale transport of oxygen from other planets.
Since that time the areas under cultivation and those reserved for desert have been carefully managed. Contemporary plant life is sufficient to maintain a level of 23.58%.
The precise chemical composition of Arrakis is 69.723% silicates, 21.388% metallics, 7.691% sulfides, and 1.198% hydrogen and miscellaneous.
Arrakis has a density of 4.95 g/cm3 and an acceleration due to gravity of 86 cm/sec2. With such a gravitational attraction, the light gases such as hydrogen and helium have all but escaped into space.
Atmospheric pressure at the equator is 760 mm, about average for a planet of this diameter and mass.
Along with the local star group, there is an extensive dust cloud that permeates the Canopus near-space. This dust cloud was first detected by the Arrakian astronomer Chelin in 12704 AG. Evidence in 12984 AG correlated ice-age-like periods with the dust cloud opacity: the peculiar velocity of Canopus carried the cloud along with the planetary system through regions of varying cloud opacity. This had the resulting effect of reducing the radiation incidents on Arrakis, thus triggering near ice-age conditions. A similar, but even more severe shift in conditions occurred when Arrakis's third moon was destroyed by an asteroid/comet some 200,000 years ago.
Arrakis revolves about Canopus at a mean distance of 87 million km (significantly closer than most C subclass planets). Planetary rotation is in the B class, meaning that the general air circulation was broken up into eddies (cyclones and anticyclones). The planet's orbit was roughly circular throughout historical times and the axis of rotation was directed almost perpendicular to its ecliptic plane; Because of this there was very slight seasonal change, or no observable seasons other than a very slight advance and retreat of the poles Only the geological record and theoretical calculations tell that conditions during the past were drastically different from those later.
The second (B) and fourth (D) planets (the "Twins") circling Canopus are much larger than Arrakis, having a corresponding radius of only 6127.9621438 km (as of year 14521 AG). The Twins also have highly elliptical orbits lying well outside the ecliptic plane defined by the orbit of Arrakis about Canopus.
As a result of the gravitational pulls of the Twins, Arrakis achieves a highly eccentric orbit, maximum ellipticity 2.1, every 12323 years. The length of the year varies from 295 standard days to 595. By 14521 it is 353 days. When Arrakis is in its most elliptical phase, seasonal changes are extreme. Winters are extremely severe all over the planet.
The Twins also have a profound impact upon Arrakeen geology and tectonics.
Because of the large axial tilt, the polar axis of rotation processes a full revolution every 43,000 years.
The star nearest the north celestial pole is the + 9 magnitude star Yuspen.
Because of the two moons, and the Twins, Arrakis's rotation has major changes. The day averages 22.4 standard hours; theoretical calculations show that under special circumstances the day can be as short as 3.81572 hours and as long as 51.36405 hours. These changes in rotation rate, as well as the effects of the Twins have had profound impact on the geologic evolution of Arrakis.
The shortest days of record occurred from 12310 AG to 12420 AG with 5 nElroodim 12370 AG being the absolute shortest day, 5.28 hours long. The longest day recorded thus far was on 25 nAlraanim 15052 AG and endured 43.2 standard hours.
Arrakis had three natural moons, Krelln, Arvon, and one, which lay in Arrakis's ecliptic plane. That was destroyed by impact from an on-rushing asteroid/comet; most of the debris impacted the planet's surface but a ring structure was formed around the planet.
The two moons Krelln and Arvon cause major changes in Arrakis's rotation about its own axis (the Twins also contribute, but their effects are longterm).
Arrakis has its own magnetic field caused by its fluid core in a mechanism not fully understood. This however is severely contracted by Canopus, which emits an abnormally high flux of charged particles with imbedded magnetic-field segments. As a result, particles impinge directly on atmospheric molecules. No known effect on Arrakis weather has been proven to be a result of this interaction.
Magnetic disturbances make the main field unreliable for navigation. Alternative means for direction finding, such as the paracompass, were developed to overcome this problem.
The sky had an almost uniform dullness due to light scattering by the dust although occasionally, more often in the polar regions, it often appeared bluish. Thin, cirrus clouds occurred seasonally in the polar vicinity.
Its 1000 ± 5 mbar mean surface pressure, mean global wind speed of 20 ± 3 km/h and standard height, and 286 ± 2° absolute planetary mean temperature (annualized), all are compatible with Neta 2C-53B guidelines.
The composition was quite similar to that of other Neta 2C-53B planets except that the amount of ozone was anomalously high and that of water vapor anomalously low. Ozone was concentrated only 2 km above the surface produced by Canopus's strong ultraviolet flux and absorbed much of the flux.
Before Kynes' transformation, major gaseous constituents were nitrogen (74.32%), oxygen (23.58%), and argon (1.01%). The most important trace gases were water vapor (less than 0.5%), carbon dioxide (0.035%), and ozone (0.52%). On planets as technically active as Arrakis, atmospheric oxygen is rapidly depleted by chemical combination with rock.
Considerable dust was present in the atmosphere at all times. The atmospheric dust content was within the bounds of the Neta 2C-53B classification.
Marta Ptahtercicah (AG 9527) investigated the mechanisms of water vapor transport in terms of the minimum amount required to sustain any life and the correctness was confirmed using Arrakis as the test case. A slight amount of water vapor transported between the poles during the seasonal exchange.
The climate over most of the planet was hot and dry. Sub-freezing temperatures occurred only at the poles. Nights were generally and relatively cool. When Arrakis is in its most elliptical phase, seasonal changes are extreme. Winters are extremely severe all over the planet.<re name=geom/>
An almost constant temperature difference (annual mean) of 27o C existed between the equator and the poles, resulting to atmospheric flow between equator and poles. The cooler and denser air from the poles flowed along the surface, and was warmed quickly by surface radiation. In the northern hemisphere this flow was deflected westward, in the southern hemisphere eastward (Coriolis effect, planetary designation 3).
All weather phenomena in inhabited regions were associated with dust storms.
Dust clouds (and the generating storms) were naturally the dominant feature of Arrakis's weather. Dust was injected into the atmosphere as slender pillars by small vortex systems common to the desert portions of all Neta-class planets. They are caused daily by severe heating of the ground surface with cooler temperatures above and light wind. The hot air rose and pulled down the cooler air. The presence of a light wind was critical to the process since it was needed for the vortex to form. These whirls do not present a hazard to humans. These phenomena ancient lore recognized as the spirits of ancestors.
On most habitable planets storms are preceded by a large, readily noticeable decrease in wind speed. Arrakian storms were preceded by an extremely small decrease in integrated wind speed which was calculated with the use of weather poles.
L.L. Nefad (9156 AG) simplistically proposed that the Coriolis storms (q.v.) were but a manifestation of the accumulation of multiple vortices associated with the turning of the wind vector by planetary rotation; Joon F. Hohshas (11301 AG) provided a better basis of understanding.
The dust whirls and storms generated considerable dust charging through friction making electrical phenomena an integral part of the environment: Lightning discharges occurred frequently within the clouds and occasionally bolts struck the surface. It was also a minor contributor to total atmospheric ozone.
Tiny grains (about sand sized) remained mostly in the lower levels of the Coriolis storms which caused severe erosion that in theory would erode all protrusions of the planet (if the planet were not so geologically active; see #Geology) consisting it totally flat.
When the storms decay, much of the dust settled back onto the surface. Water vapor absorbed on the grains was carried downward also (a phenomenon locally called El-Sayal). Ionization by ultraviolet rays gradually released the water back to the atmosphere and return was complete within a few days.
Apart from the surface erosion from storms and the presence of dune fields noted above, other surface phenomena affected by weather, were the dust chasms (or tidal dust basins), areas of sand with quicksand-like behavior and the drum sands, a sound-emitting sand.
Arrakis evolved after formation much as other planets of the Neta 2C classification. The oldest rocks on Arrakis have been dated, isotopically, as being 1.1 eons old (1 eon = 1 billion standard years) and have been found only by deep drilling and only in a few places, existing as small fragments contained in much younger rock. Almost all other Neta 2C planets 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.
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.
One of the most interesting aspects of Arrakeen surface morphology is that the mountain chains and grabens (deep valleys) 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. These trends are a result of the particular geometry of the Menaris-Extaris-Arrakis system and stress-field orientation so produced (see #Plate Tectonics).
In the earliest known phase of the planet's history, many mountain ranges and deep grabens existed in all regions of the planet.
During the middle phase, extensive desertification had occurred with the earlier mountains severely eroded, primarily by sand blasting, and the surface was mostly flat. Most grabens were filled with dust and called tidal dust basins or dust chasms by the natives. Only its intense geologic activity (Arrakis is the most active of all Neta planets) ensured the existence of any elevation, as the rapid erosion was balanced by the high rate of formation: isolated garres and ridges, a few volcanic peaks, and of course, the dune fields.
The terraforming of Arrakis reduced the eolian erosion, and with little in the way of water erosion, mountains are rising "rapidly" (in a geological time sense) resulting in conditions similar to the earliest phase. The dramatic changes that have occurred since then were detailed by A. G. Xenach in 15029 AG.
Mountains were isolated with a few beink volcanic peaks (such as Mt. Idaho, Mt. Kynes, and Observatory Mt.). Several ranges had peaks exceeding 7,400 meters in elevation. Mt. Idaho had been the highest peak. Its summit was 9,524 meters above the bled, compared to only 7,393 meters 7000 years earlier. 
There are numerous grabens, the greatest of which were formed by dynamic development rather than running water. The greatest is Grose Valen, with maximum depth of 1.2 km, maximum width of 2.8 km and a length of about 730 km.
The chasms expand and contract rapidly and can be crossed only by very long and expensive bridges, which are quickly destroyed. Hence most travel is by air.
Filling of the chasms later resulted primarily from landslides and rockfalls. Many of these had reopened through geological processes, and many more have formed.
Bodies of waterEdit
Few permanent rivers or bodies of standing water are present on Arrakis and drainage systems are poorly developed even after Leto II's ecological transformation. Flash floods occur occasionally in mountainous areas, but all in all Arrakis is still quite water poor.
Water ice is present in the polar caps, as is the case with all Neta-2C planets, but the total amount is small compared to that of other planets of the group.
Garres are plentiful, and are easily distinguished by their flat tops. They are the oldest exposed areas on the planet, being remains of ancient plateaus formed by widespread lava flow very early in the planet's evolution when water was plentiful and water erosion dominant. Ancient water courses are still visible on their tops and their sides.
According to Zhuurazh Hackelrhued the ice caps were much more massive in the distant past even existing as such during the early periods of human habitation. 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 areas, carried it to more temperate climes where the ice melted and deposited its mix of rock flour. The uncommon "polar sinks" were thus created, and the polar caps lie below bled-level.
Since the resulting 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.
The exceptional geologic activity on Arrakis are caused by external gravitational torques from the unusual closeness and large size of the Twins. Quakes are common and the amount of volcanic activity is on the high side, but not extreme. The planetary mean of crust portion displacement (with respect to other crustal segments) is 30 cm per year.
New mountains are formed and old ones destroyed at a geologically rapid rate. Grabens open, oscillate, and close at equally rapid rates. Over one 2,000 year period, the Tramblisch Range rose 3,125 meters.
The crust and upper layers of Arrakis are composed almost entirely of silicates; the middle and lower layers are primarily silicates, with significant amounts of metals and sulfides; the core is primarily metallic with a small amount of sulfides.
The crust of Arrakis is rather thin, averaging only 10 kilometers in thickness. The source of volcanic activity is an incipiently molten region immediately below.
The remainder of the planet is basically solid except for a small, fluid central core which produces a relatively weak magnetic field. Even after many thousands of years of study the exact mechanism by which the magnetic field is produced was not fully understood.
Arrakis is the only planet in the system to harbor organic life forms. Life on Arrakis has been subject to harsh conditions during its history.
References and notesEdit
- ↑ 1.0 1.1 1.2 1.3 1.4 1.5 1.6 1.7 1.8 Geology - morphology
- ↑ 2.0 2.1 2.2 2.3 2.4 Oxygen saga
- ↑ 3.0 3.1 3.2 3.3 3.4 3.5 3.6 3.7 3.8 Geology - geometric aspects
- ↑ Arrakeen conservatory
- ↑ 5.0 5.1 5.2 5.3 5.4 Geology - Tectonics
- ↑ Arrakis, planetary system
- ↑ 7.0 7.1 7.2 7.3 7.4 7.5 7.6 Arrakis, atmosphere - weather phenomena
- ↑ 8.0 8.1 8.2 Arrakis, Atmosphere - Climate
- ↑ 9.0 9.1 9.2 9.3 9.4 Arrakis, Atmosphere - Composition
- ↑ Arrakis, atmosphere - physical characteristics
- ↑ 11.0 11.1 Arrakis - Weather prediction
- ↑ Arrakis, atmosphere - surface effects