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For every nature-park world we will probably find dozens that didn't quite make it. We do not yet know whether life arises wherever there is liquid water to be had — we may begin to find out on Mars and Europa. But if a planet has oceans but no life it is a candidate for terraforming, and only the ecopoetic or gardening stage is required — no need to sling comets from the outer system to provide water, or hoover up 90 bars of CO2 out of the atmosphere.
Worlds with limited 'primitive' life may even allow a sort of biological nonaggression pact, the native forms going quietly on in their own local ecosystems.
There are still ethical questions we're precluding or at least greatly altering their evolutionary prospects , but not like the ethics of sterilizing a rich, living world. In Lois McMaster Bujold's Vorkosigan books , the world Barrayar seems to have been a particularly bad choice in real estate. Humans are allergic to practically every plant on the planet, and terraform by slash-and-burn agriculture and bulk dumping of fertilizer. It's one of the few SF settings I've seen that touch on the biochemical issues of colonization.
If your planning horizon is short enough Say, because you're transplanting undesirables to a new world the prospect of a planetary triple toe loop probably doesn't bother you. On the other hand, any culture that practices terraforming obviously does think in the long term and I think the idea of transporting prisoners to other worlds is unlikely even with FTL. Why dump the prisoners on Ceti Alpha V when it's cheaper to dump them on Antarctica? Using Earth as a baseline, the prime real estate would probably be any world that has not yet hit it's equivalent of the Devonian era.
So long as complex life is confined largely to the seas, terraforming the land is remarkably straightforward. It's a lot of hard work, but it's not hard work that fights back and evolves to destroy your work. And the presence of marine ecosystems means you don't have to terraform the oceans Or only have to introduce species like salmon, eels, or tortoises, that return nutrients to the land from the ocean.
I did some calculations for terraforming ocean volumes comparable to the Earth's, and was quickly reminded that humans are just a thin biofilm confined to a narrow portion of the habitable world. Completely lifeless worlds are your next best bet. But you should probably check out the local neighborhood and find out why the place is lifeless In his novel Nemesis Isaac Asimov included a fictional life-signs scanner that worked by detecting complex repetitive electromagnetic events.
Something like that wouldn't spot anything without a rudimentary nervous system, but it was an interesting idea. Throw in spectrographic analysis, telescopic studies, and automated surveys, and any colonists should have a good idea of what they're getting into even if they are the first humans to set foot on the planet. I find this to be a highly questionable assertion.
Without even going into far afield things like amino acid chirality, most earth-born bacteria and virii do a poor job jumping across species. It can't recall the last time I caught a cold from a tree. But beyond that I think you vastly underestimate the sheer hostility of the environment that is the human body. While you may be right about our response being an allergic reaction, our bodies aren't the only factor.
Those foreign bacteria will be trying to compete with the fauna you already carry around with you. Fauna that has been selected for ruthless survival in that environment over uncountable generations.
Think like this — a gang wants to move into the city to do their business. You are talking about how they would do against the cops, but completely ignoring the fact that Don Corleone is going to have some very pointed ideas about them moving in on his territory. I never have learned the co-ordinates of Sanctuary, nor the name or catalogue number of the star it orbits — because what you don't know, you can't spill; the location is ultra-top-secret, known only to ships' captains, piloting officers, and such.
So I don't want to know. With the possibility that Luna Base might be taken and Terra herself occupied, the Federation kept as much of its beef as possible at Sanctuary, so that a disaster back home would not necessarily mean capitulation. Literally retarded, like a kid who takes ten years to learn to wave bye-bye and never does manage to master patty-cake. It is a planet as near like Earth as two planets can be, same age according to the planetologists and its star is the same age as the Sun and the same type, so say the astrophysicists.
It has plenty of flora and fauna, the same atmosphere as Earth, near enough, and much the same weather; it even has a good-sized moon and Earth's exceptional tides. With all these advantages it barely got away from the starting gate. You see, it's short on mutations; it does not enjoy Earth's high level of natural radiation. Its typical and most highly developed plant life is a very primitive giant fern; its top animal life is a proto-insect which hasn't even developed colonies.
I am not speaking of transplanted Terran flora and fauna — our stuff moves in and brushes the native stuff aside. With its evolutionary progress held down almost to zero by lack of radiation and a consequent most unhealthily low mutation rate, native life forms on Sanctuary just haven't had a decent chance to evolve and aren't fit to compete.
Their gene patterns remain fixed for a relatively long time; they aren't adaptable — like being forced to play the same bridge hand over and over again, for eons, with no hope of getting a better one. As long as they just competed with each other, this didn't matter too much — morons among morons, so to speak. But when types that had evolved on a planet enjoying high radiation and fierce competition were introduced, the native stuff was outclassed.
Now all the above is perfectly obvious from high school biology. Not transients like me, but the colonists who live there, many of whom were born there, and whose descendants will live there, even into the umpteenth generation — what about those descendants? It doesn't do a person any harm not to be radiated; in fact it's a bit safer — leukemia and some types of cancer are almost unknown there.
Besides that, the economic situation is at present all in their favor; when they plant a field of Terran wheat, they don't even have to clear out the weeds. Terran wheat displaces anything native. But the descendants of those colonists won't evolve. This chap told me that they could improve a little through mutation from other causes, from new blood added by immigration, and from natural selection among the gene patterns they already own — but that is all very minor compared with the evolutionary rate on Terra and on any usual planet.
Do they stay frozen at their present level while the rest of the human race moves on past them, until they are living fossils, as out of place as a pithecanthropus in a spaceship? Or will they worry about the fate of their descendants and dose themselves regularly with X-rays or maybe set off lots of dirty-type nuclear explosions each year to build up a fallout reservoir in their atmosphere?
Accepting, of course, the immediate dangers of radiation to themselves in order to provide a proper genetic heritage of mutation for the benefit of their descendants. This bloke predicted that they would not do anything. He claims that the human race is too individualistic, too self-centered, to worry that much about future generations. He says that the genetic impoverishment of distant generations through lack of radiation is something most people are simply incapable of worrying about.
And of course it is a far-distant threat; evolution works so slowly, even on Terra, that the development of a new species is a matter of many, many thousands of years. If one is dealing with near-future colonization of the non-shirtsleeve planets of the solar system using weak chemical rockets, the difficulties are overwhelming.
It is vastly easier to colonize hypothetical human-habitable garden worlds around other stars using handwaving faster than light starships because the author said so. The sad fact of the matter is that it is about a thousand times cheaper to colonize Antarctica than it is to colonize Mars. Antarctica has plentiful water and breathable air, Mars does not.
In comparison to Mars, Antarctica is a garden spot. Yet there is no Antarctican land-rush. One would suspect that there is no Martian land-rush either, except among a few who find the concept to be romantic. I'll believe in people settling Mars at about the same time I see people setting the Gobi Desert.
The Gobi Desert is about a thousand times as hospitable as Mars and five hundred times cheaper and easier to reach. Nobody ever writes "Gobi Desert Opera" because, well, it's just kind of plonkingly obvious that there's no good reason to go there and live.
It's ugly, it's inhospitable and there's no way to make it pay. Mars is just the same, really. We just romanticize it because it's so hard to reach. On the other hand, there might really be some way to make living in the Gobi Desert pay.
And if that were the case, and you really had communities making a nice cheerful go of daily life on arid, freezing, barren rock and sand, then a cultural transfer to Mars might make a certain sense.
If there were a society with enough technical power to terraform Mars, they would certainly do it. On the other hand. So by the time they got there and started rebuilding the Martian atmosphere wholesale, they wouldn't look or act a whole lot like Hollywood extras.
Any resemblance to — ah — real persons and places is quite coincidental. After some years it finds that this is costing a lot more than it expected, and has given no tangible returns for the money spent. Two factions then arise on the mother world. One, the conservative group, wants to close the project down — to cut its losses and get out.
But this sort of argument is no use with the taxpayers, and the conservatives are beginning to get the upper hand. I should have explained at the beginning that planet B has been attracting the finest brains of A, which is another reason why A is getting annoyed. Still, the plan is put forward — and is promptly turned down by A. There is a protracted tug-of-war behind the scenes, but the home planet is adamant.
They can force the issue out into the open, and appeal to the public on world A. The other choice is to carry on with the plan without informing Earth — I mean, planet A — and this is what they finally decided to do.
He had a team of first-class scientists behind him, and they backed him up. So the plan went ahead; but no one knows yet if it will be successful. As a general rule colonists like places with breathable atmospheres, so they don't immediately die upon stepping out of the transport spacecraft. Unfortunately, if there are no starships, the only naturally occurring place like that in the solar system is Terra.
Everywhere else is a non-shirtsleeve environment, the colonists will have to build and maintain a large pressurized volume to live in. This might be a purpose-build operation that is part of a grand plan to colonize the place.
Or it might be unplanned, usually by some organization establishing some kind of base ; then as other bases and boomtowns spring up nearby, the entire establishment morphs into a colony. Functionally a colony on an airless world is a space habitat that is sited on the ground instead of floating in orbit.
Structurally they will be different. A ground based colony will have access to lots of local resources that a space colony will have to import. Because radiation from galactic cosmic rays GCR and solar proton storms is not healthy for children and other living things.
It heinously expensive to ship radiation shielding to a space habitat under construction, but planet-based naturally-occurring lava tubes are practically free. Planets with no atmospheres will need to build underground for radiation protection.
On Terra people suffer about 0. Or pile lots of Martian dirt on top of the buildings. Titan got lucky, it actually has a denser atmosphere than Terra.
Old illustrations of lunar colonies liked to depict them under transparent domes, because the artist did not know about the radiation hazard. Since all the living spaces have to be pressurized and otherwise equipped with life support, they will be limited and the colony will feel cramped. Cubicles will be minuscule, and the connecting corridors will be narrow. Much the same as any underground building or rabbit burrow.
Privacy will be very hard to come by. Terraforming is using planetary engineering to make a planet's environment more like a prime vacation spot, or a least one where an unprotected human being won't instantly die.
It generally takes hundreds to thousands of years for the process to be complete. It also requires access to incredibly large amounts of advanced technology, planetary-sized stocks of raw materials, and an energy budget comparable to all of Terra combined.
Fogg wrote the definitive book on the topic , sadly out of print. His web page has lots of terraforming information. Terraforming a world inhabited by sentient beings is considered to be attempted genocide , or at the least to be very rude. Extreme moralists go to the point of only allowing terraforming on planets that are totally lifeless. Examples include Sir Arthur C. And while the majority of these range in size from tiny rocks to planetesimals, there are also a handful of bodies that contain a significant percentage of the mass of the entire Asteroid Belt.
Of these, the dwarf planet Ceres is the largest, constituting of about a third of the mass of the belt and being the sixth-largest body in the inner Solar System by mass and volume. In addition to its size, Ceres is the only body in the Asteroid Belt that has achieved hydrostatic equilibrium — a state where an object becomes rounded by the force of its own gravity.
For this reason, the idea of colonizing Ceres someday has some appeal, as well as terraforming. Ceres also has the distinction of being the only dwarf planet located within the orbit of Neptune. This is especially interesting considering the fact that in terms of size and composition, Ceres is quite similar to several Trans-Neptunian Objects TNOs — such as Pluto , Eris , Haumea , Makemake , and several other TNOs that are considered to be potential candidates for dwarf planets status.
With this mass, Ceres comprises approximately a third of the estimated total mass of the Asteroid Belt between 2. The next largest objects are Vesta , Pallas and Hygiea, which have mean diameters of more than km and masses of 2. The mass of Ceres is large enough to give it a nearly spherical shape, which makes it unique amongst objects and minor planets in the Asteroid Belt. Ceres follows a slightly inclined and moderately eccentric orbit, ranging from 2.
It has an orbital period of 1, Earth days 4. Based on its size and density 2. If true, it is possible that this ocean could harbor microbial extraterrestrial life, similar to what has been proposed about Mars , Titan , Europa and Enceladus.
It has further been hypothesized that ejecta from Ceres could have sent microbes to Earth in the past. Other possible surface constituents include iron-rich clay minerals cronstedtite and carbonate minerals dolomite and siderite , which are common minerals in carbonaceous chondrite meteorites. Assuming the presence of sufficient antifreeze such as ammonia , the water ice would become unstable at this temperature.
Therefore, it is possible that Ceres may have a tenuous atmosphere caused by outgassing from water ice on the surface. However, it was not until early that several localized mid-latitude sources of water vapor were detected on Ceres. Possible mechanisms for the vapor release include sublimation from exposed surface ice as with comets , cryovolcanic eruptions resulting from internal heat, and subsurface pressurization.
The limited amount of data thus far suggests that the vaporization is more likely caused by sublimation from exposure to the Sun. As with the moons of Jupiter and Saturn , terraforming Ceres would first require that the surface temperature be raised in order to sublimate its icy outer layer.
This could be done by using orbital mirrors to focus sunlight onto the surface, by detonating thermonuclear devices on the surface, or colliding small asteroids harvested from the Main Belt onto the surface.
The orbital mirrors would once again come into play here, where they would be used to trigger photolysis and transform the water vapor into hydrogen and oxygen gas. While the hydrogen gas would be lost to space, the oxygen would remain closer to the surface.
Ammonia could also be harvested locally, since Ceres is believed to have plentiful deposits of ammonia-rich clay soils. The end result would be an ocean world with seas that are km in depth. Within this shell, Ceres temperature could be increased, UV lights would convert water vapor to oxygen gas, ammonia could be converted to nitrogen, and other elements could be added as needed.
Using water harvested from the surface, this land could be irrigated, oxygen gas could be processed, and nitrogen could be pumped in to act as a buffer gas.
The benefits of colonizing and para terraforming Ceres are numerous. For instance, it would take comparatively less energy to sublimate the surface than with the moons of Jupiter or Saturn. Also, Ceres appears from all accounts to be rich in resources, which include water ices and ammonia, and has a surface that is equivalent in total land area to Argentina.
This level of energy is high enough that solar-power facilities could run on its surface. And being the largest body in the asteroid belt, Ceres could become the main base and transport hub for future asteroid mining infrastructure, allowing mineral resources to be transported to Mars, the Moon, and Earth. Its small escape velocity, combined with large amounts of water ice, means that it also could process rocket fuel, water and oxygen gas on site for ships going through and beyond the Asteroid Belt.
Despite the benefits of a colonized or transformed Ceres, there are also numerous challenges that would need to be addressed first. As always, they can be broken down into the following categories — Distance, Resources and Infrastructure, Hazards and Sustainability. For starters, Ceres and Earth are on average approximately ,, km apart, which is 1.
Hence, any crewed mission to Ceres — which would involve the transport of both colonists, construction materials, and robotic workers — would take a considerable amount of time and involve a large expenditure in fuel. To put it in perspective, missions to Mars have taken anywhere from to over days, depending on how much fuel was expended. Since Ceres is roughly twice that distance, we can safely say that it would take a minimum of a year for a spacecraft to get there.
However, since these spacecraft would likely be several orders of magnitude heavier than anything previously flown to Mars — i.
And while NASA currently has plans on the table to build laser-sail spacecraft that could make it Mars in three days times , these plans are not practical as far as colonization or terraforming are concerned. And while certainly feasible, no such drive systems exist at this time. These could be harvested from the Asteroid Belt, but the process would be time-consuming, expensive, and require a large fleet of haulers and robotic miners.
There would also need to be a string of bases between Earth and the Asteroid Belt in order to refuel and resupply these missions — i. In terms of hazards, Ceres is not known to have a magnetic field, and would therefore not be shielded from cosmic rays or other forms of radiation. This would necessitate that any colonies on the surface either have significant radiation shielding, or that an orbital shield be put in place to deflect a significant amount of the radiation the planet receives.
This latter idea further illustrates the problem of resource expenditure. The extensive system of craters on Ceres attests to the fact that impactors would be a problem, requiring that they be monitored and redirected away from the planet. The surface gravity on Ceres is also quite low, being roughly 2. This would raise the issue of the long-term effects of near-weightlessness on the human body, which like exposure to zero-g environments would most likely involve loss of muscle mass, bone density, and damage to vital organs.
In terms of sustainability, terraforming Ceres presents a major problem. Under the circumstances, it seems like it would make more sense to colonize or paraterraform Ceres than to subject it to full terraforming. However, any such venture would have to wait upon the creation of a Lunar base, a settlement on Mars, and the development of more advanced propulsion technology.
It was also require the creation of a fleet of deep-space ships and an army of construction and mining robots. However, if and when such a colony were created, the resources of the Asteroid Belt would be at our disposal. Humanity would effectively enter an age of post-scarcity, and would be in a position to mount missions deeper into the Solar System which could include colonizing the Jovian and Cronian systems, and maybe even the Trans-Neptunian region.
Genesis, third planet of the star system 59 Virgo, can be found Although it's expected to have a shorter life-span than Earth's sun, it still has several billion years to go. No large moon like Earth's orbits Genesis, but it possesses an asteroid-like belt of more than moonlets orbiting between ten and twenty thousand kilometers from its surface.
Most of these satellites have an irregular shape and tumble slowly in their orbits. From the planet's surface, the naked eye can plainly see more than of them forming a beautiful night time display. The largest measures about twenty-eight kilometers long, but it lies so far out that it appears only slightly larger than a star when viewed from the ground. Composition of the moonlets varies from nearly pure iron to siliceous rock. No one knows if the moons ever formed part of one larger moon, or if they are the captured remnants of a prehistoric meteor shower.
The moon belt exerts negligible tidal forces on the oceans, since the moons are distributed evenly around the planet. Principal tidal action is due to the pull of the sun, 59 Virgo. Genesis is barely larger than Earth, with a diameter less than one percent greater and a gravitational attraction at the surface only one percent higher.
Land covers 21 percent of its surface. The bulk of it is divided into four continents: Harvestland, Virginis, Barrenland, and Maiden Spring. Three continents have less area than Earth's average continent, but one, Harvestland, has more surface than Earth's Eurasian land mass.
The continents take a more closed form than continents on Earth and are separated by larger ex- panses of open ocean. Genesis orbits 59 Virgo once every days in nearly circular orbit. Its day clocks iust over 12 hours, the shortest among the present colonies. Its short day lessens extreme daily temperature variations, however. The planet's atmospheric pressure at mean sea level gauges just 55 percent of Earth's, but since the atmosphere contains 31 percent oxygen, Humans can breath it.
The lower atmospheric density reduces the heat transferred from the poles to the equator by atmospheric convection, causing somewhat greater temperature variations with latitude than Earth's.
Lower density also reduces the effective wind pressure, so even though wind velocities average somewhat higher than Earth's, their destructive and wave-generating forces are lower. Genesis is believed to be much younger than the Earth, perhaps by as much as 1. The planet appears to contain more residual heat than Earth and exhibits much greater volcanic activity.
Flying over the surface, one rarely loses sight of active volcanoes. Except for its blue sky and white clouds, the natural surface of Genesis looks more like Earth's moon or Mars than a habitable planet. Not one tree or one blade of grass breaks the monotonous expanse of cold grey rock, stony rubble and sand.
No native animals, not even the smallest insect-like creatures, scurry across the empty waste. There is no food, no soil, no single living thing! If ancient space travellers had landed on Earth half a billion years ago, they would have viewed a similar scene.
Life on all habitable planets began in the sea. Genesis is such a world in its earliest stage of development; so its only life exists in the oceans. Because life evolves from the simple to the complex, most life on this young planet seems elementary when compared with the other colony worlds. Sea life consists mainly of microorganisms. These tiny monocellular species fill all the functions in the life cycle from tiny one-celled photosynthetic plants, resembling Earth's diatoms, to tiny bacteria-like creatures that consume the dead remains of plants and animals.
Larger plants take the forms of simple seaweed while still other small plants containing only a few thousand cells float freely in the water. Animals range in structure from tiny multicellular free-floaters and larger free-floaters resembling iellyfish to numerous species of tiny animals with external skeletons.
The latter creatures look like the trilobites which dominated Earth's seas in the Cambrian period, million years ago. Earth's phylum of arthropods, which today includes lobsters, insects, and spiders, traces its ancestry to the trilobites. All animals on Genesis exhibit extremely simple behavior patterns; they have few instincts apart from the desire to eat and avoid being eaten.
Complex adaptations like the spider's web, the hermit crab's borrowed shell, and the symbiosis between ants and aphids have not even begun to emerge. The discovery of Genesis by Captain Ben Alan and the crew of the Aurora in adtc, did not bring universal jubilation on Earth. No statement illustrates the anguish this planet caused the pioneering movement than the following passage from Ben Alan's personal log. The beautiful, blue sphere below us possessed breathable atmosphere, warm temperatures, no radiological hazards, and no evidence of intelligent life.
As the landing craft began its descent, we stared intently at the main screen which amplified the view below. We broke beneath a layer of clouds and glimpsed our first clear view of the grey landscape. We came down in a desert! Thinking that surely it couldn't go on forever, we pressed forward, travelling at kilometers per hour, meters above the surface.
Four hours later upon reaching the seacoast, hydrocarbon scanners had not revealed the slightest chemical traces of life. Even Earth's most barren wastes would not have produced such readings.
We continued parallel to the shore for fourteen hours more, circumnavigating the entire continent without sensing a living thing on the land. Yet carbon readings in the sea revealed some life there and proved our sensors were functioning. We took microspopic samples from many places, but even stagnant pools of water in the rocks didn't reveal a single living cell. The next day and for fourteen days after, I dispatched landing parties to the surface.
At last the awful reality dawned on us. This planet is a desert. True, some elementary life exists in the sea which probably accounts for the oxygen atmosphere, but how could Humankind survive on those dreadful rock plains below?
Aurora remained on Genesis for four months, studying what native life there was. When it returned to Earth, Alan's report classified Genesis uninhabitable, but he appended the following comment to his recommendation. The planet contains the fundamental conditions necessary to support our form of life. When our technology advances enough to allow us to transport much larger payloads across the interstellar space, then we will be able to bring enough equipment and enough supporting life forms from our mother planet to permit life as we know it to thrive there.
He went on to exercise his preogative as captain and named the planet, an unprecedented custom for a world considered uninhabitable. For 20 years no planetologist challenged Alan's conclusion. The problems of colonizing his barren planet seemed insurmountable. Humans need more than food too. Few would voluntarily agree to spend their lives in a desolate wasteland. Grass, trees, and other living animals may not seem like necessities of life, but early in the history of space travel, scientists learned how important they could be.
After more than two years on the first permanent Martian base, the total bleakness of that planet's landscape began to have serious psychological effects upon the trained and experienced travellers that staffed them. No large and inexperienced group of pioneers could have coped with Genesis indefinitely. Yet even before the discovery of Genesis, events were under way that eventually made its colonization possible. Contact with the Ardotians in adtc created a tremendous increase in the level of both Human and Ardot knowledge.
Within a few years, the formulation of the Comprehensive Unified Field Theory led to the development of highly efficient matter-antimatter reactors.
These reactors allowed people to transport far greater cargoes across interstellar space at a fraction of the cost. Both Humans and Ardotians soon became interested in Ben Alan's barren planet again. They reasoned that Genesis provided a rare opportunity for an advanced civilization to create a biologically perfect world, a world without disease, pests, vermin, even weeds!
All the Ardotians asked in return for their contribution were detailed reports about the progress of the experiment. Techniques for creating living soil from barren rock had to be developed.
The proper mix of desirable Earth species had to be selected, and safeguards to insure that Genesis would not become contaminated by pests and diseases from Earth had to be refined.
Finally, a large-scale evacuation plan had to be drawn up, should the entire proiect fail catastrophically.
No detail escaped scrutiny. As a final check, Ardotian computers analyzed the entire plan, independently assessed its probable outcome and made several important recommendations. Planners chose the southernmost tip of Harvestland for the first settlement, which pioneers named Malthus.
Situated at the edge of the southern tropic zone, the climate is warm and the ocean is protected from violent storms. The colony organization followed the lines of a socialist de mocracy, similar in concept to the highly successful kibbutz used in the 20th century redevelopment of Israel. The first pioneers brought food for five years, although the starship made the round trip to Earth annually, bringing still more food, equipment and new colonists. Pioneers lived in temporary housing constructed from parts of the ship that brought them, early precursors to the residential spires of today's pioneering vessels.
At the same time, the pioneers began to develop aquaculture of both native and imported species to hedge against possible failure of the primary food supply. The first pioneers had no resources for manufacturing or processing industrial goods. Most of them were biologists or farming technicians, with a smattering of the mechanics, programmers, and comtechs needed to keep their equipment functioning.
Life's foothold on the planet was assured as food production became self-sustaining at the end of the fourth year. After that the slow process of building basic industries began, first with the importation of mineral recovery equipment, followed by critical manufacturing processes.
Development of Genesis has proceeded steadily, if more slowly than on worlds more bountifully endowed by nature. Today, 92 years later, it boasts a modern, industrial society with many of the luxuries and conveniences of Earth.
After six months, soil preparation crews an equipment began to work. Giant combination soil preparation machines, larger than any previous built, performed the task.
In one operation, these mechanical monsters broke rock into coarse chunks using laser drills, then ground fine with ultrasonic grinders and mixed it with nutrients and mulch from giant hoppers they dragged behind them. Earth's natural soil is very fine-grained, but organic mulch within it inhibits its natural tendency to compact and congeal into a solid mass.
On Genesis, soil technicians must add a synthetic mulch prepared from seaweed. Since the mass of the synthetic humus cannot equal the mass of natural humus, special chemical treatments must augment it. The addition of fixed nitrogen and other necessary plant minerals follows the mulch, and the soil is chemically balanced.
The addition of bacteria and worms of appropriate species complete the formation of synthetic soil. While the prep grass grew we began sprouting seedling trees in the mature soil of the developed area not far from my home.
Since no natural barriers existed to blunt the ferocious gales that blew off the south Genesean Ocean, protecting the young trees from wind damage became our most pressing problem. Solid shelter of any kind would have been prohibitively expensive, but fortunately a wind-breaking field had been developed a few years earlier.
The field employed a special configuration of the g-field to slow inrushing air to a standstill in the space of two decimeters. Unfortunately, the field would kill anyone who accidently walked through it, so its perimeter had to be guarded by sensors, coupled to visual, sound, and telepathic alarms to warn stray children or absent-minded scientists who might not heed posted warnings.
After two years huge transplanting machines began to move the seedlings from the nursery beds to the forest site. The machines passed over the seedling beds, picking up the young trees together with their roots and a clump of soil, then travelled out to the newly plowed forest and deposited the seedlings in holes dug by the machine itself.
Each machine carried about seedlings and planted at the rate of two per minute. The machines planted the trees in a predesigned pattern that allowed for optimum tree growth and insured that mature trees would someday provide natural shelter for future seedlings, thus avoiding the need to raise the young trees in a sheltered nursery.
A major conflict arose among the forest planning staff over the pattern in which the trees would be planted. Some wanted to plant the trees in regular rows resembling a European garden, while others wanted an irregular, pseudo-random pattern that would resemble a natural forest. The forest, now quite mature, is one of my favorite vacation spots on Genesis. It gives me great satisfaction to walk among the towering trees and feel that I helped place them there.
Colonists are going to want to grow local food they can eat, the native plants and animals can be unsuitable as food in so very many ways. Since plants and animals depend upon a circle of life, terraformers will have to transplant a minimal but viable Terran ecosystem that is self-sustaining.
And try to avoid importing anything that is a threat to said ecosystem, such as potato blight. And of course also import useful things that are not food, such as Bamboo. There are some science fiction novels where aliens invade not by full-blown terraforming but simply by introducing alien hyper-invasive species to alienoform the Terran ecosystem the functional equivalent of introducing xenomorph -bunnyrabbits to Australia.
High's No Truce With Terra. The spray of compressed air pushed out thick-bodied probes biovats studded with antennae and lmobs. Then the timers counted through and small wasplike rocket engines screamed, only for seconds but enough to break the balance that poised the probes so delicately between gravity and outward spiraling force. The probes now yielded to gravity and fell Earthward on a long slanting descent.
A panel opened in the lead probe and a thick package ejected. Seconds later another, and then another and another and still more. Each probe clicked and shuddered and hissed and released panels and springs, and the thick packages fell blunt-nosed into atmosphere. The heat dissipated rapidly, never reaching the precious payload behind the shield. Finally the speed fell to something sensible, friction was far behind, and more relays clicked in each probe. The first probe began to tumble.
Small tubes extended and a thin spray whipped away by centrifugal force from each tube. For two hundred miles the probe tumbled, ever lower, ever slower, still spraying its cargo of superseeds, genetically altered seeds for grass, wheat, alfalfa, corn, hay, all manner of plants, all mutated for swift growth under the most hostile of environments.
All along the flight path of Pegasus the larger probes fell away and spat flame and fell, the thick packages ejected and began their entry into the high atmosphere of Earth. The Tumblers kept spraying across an area of Earth fifty-nine degrees north and south of the equator. Much of their payload would fall into the sea. Just as much would fall to ground in a gentling rain of life.
Beneath the Floaters, the ablation heatshields fell away to lighten the load. Springs snapped out stiffly, blowing away door panels, ejecting long ribbons of nylon. Parachutes slowed down descent, valves opened, and helium gushed from containers into flyweight plastic. Eggs, billions of eggs of spiders, honeybees, beetles, butterflies, earthworms rained gently to the largely barren land below. The Tumblers and Floaters separated. Not yet the Floaters.
They would drift for days and then for weeks, releasing their spore at timed intervals until, at last, the helium would seep through the balloon plastic and lift would decay.
Those still aloft, having escaped storms and lightning and cold, would then descend silently, also to be absorbed by earth or water and disappear: Marc Seavers knew thaf after their swooping curve about the Earth when they came back into direct observation of what remained of Hestia on the moon, no sign would be visible of the biovats that had left Pegasus.
Of course the campus lacked the black tumble of half-burned trees, snags, uprooted trunks. Ecological succession is the process of change in the species structure of an ecological community over time. The time scale can be decades for example, after a wildfire , or even millions of years after a mass extinction.
The community begins with relatively few pioneering plants and animals and develops through increasing complexity until it becomes stable or self-perpetuating as a climax community. A consequence of living is the sometimes subtle and sometimes overt alteration of one's own environment.
It is a phenomenon or process by which an ecological community undergoes more or less orderly and predictable changes following a disturbance or the initial colonization of a new habitat. Succession may be initiated either by formation of new, unoccupied habitat, such as from a lava flow or a severe landslide , or by some form of disturbance of a community, such as from a fire , severe windthrow , or logging.
Succession that begins in new habitats, uninfluenced by pre-existing communities is called primary succession , whereas succession that follows disruption of a pre-existing community is called secondary succession. Primary succession is one of two types of biological and ecological succession of plant life, occurring in an environment in which new substrate devoid of vegetation and other organisms usually lacking soil, such as a lava flow or area left from retreated glacier , is deposited.
In other words, it is the gradual growth of an ecosystem over a longer period. In contrast, secondary succession occurs on substrate that previously supported vegetation before an ecological disturbance from smaller things like floods, hurricanes, tornadoes, and fires which destroyed the plant life. In primary succession pioneer species like lichen , algae and fungi as well as other abiotic factors like wind and water start to "normalize" the habitat.
Primary succession begins on rock formations, such as volcanoes or mountains, or in a place with no organisms or soil. This creates conditions nearer optimum for vascular plant growth; pedogenesis or the formation of soil is the most momentous process. These pioneer plants are then dominated and often replaced by plants better adapted to less harsh conditions, these plants include vascular plants like grasses and some shrubs that are able to live in thin soils that are often mineral based.
For example, spores of lichen or fungus, being the pioneer species, are spread onto a land of rocks. Then, the rocks are broken down into smaller pieces and organic matter gradually accumulates, favouring the growth of larger plants like grasses , ferns and herbs. These plants further improve the habitat and help the adaptation of larger vascular plants like shrubs, or even medium- or mountainous-sized trees.
More beasts are then attracted to the place and finally a climax community is reached. A good example of primary succession takes place after a volcano has erupted. The lava flows into the ocean and hardens into new land. The resulting barren land is first colonized by pioneer plants which pave the way for later, less hardy plants, such as hardwood trees , by facilitating pedogenesis , especially through the biotic acceleration of weathering and the addition of organic debris to the surface regolith.
An example of primary succession is the island of Surtsey , which is an island formed in after a volcanic eruption from beneath the sea. Surtsey is off the South coast of Iceland and is being monitored to observe primary succession in progress. The soil depths increase due to decomposition of plant matter and there is a gradual increase of species diversity in the ecosystem. The labels I-VII represent the unalike stages of primary succession.
Secondary succession is when an ecosystem is diminished to a smaller population of species and it is doing its darnedest to expand. You see this in a forest burnt to the ground by a forest fire.
In rocketpunk this would be done in an interstellar colony on an alien planet, trying to remove the alien ecosystem locally and replacing it with a Terran ecosystem that can be used to do things like, you know, grow food to eat.
Secondary succession is one of the two types of ecological succession of plant life. As opposed to the first, primary succession , secondary succession is a process started by an event e. Simply put, secondary succession is the ecological succession that occurs after the initial succession has been disrupted and some plants and animals still exist. It is usually faster than primary succession as:.
Many mechanisms can trigger succession of the second including facilitation such as trophic interaction, initial composition, and competition-colonization trade-offs. The factors that control the increase in abundance of a species during succession may be determined mainly by seed production and dispersal, micro climate; landscape structure habitat patch size and distance to outside seed sources ; Bulk density, pH, soil texture sand and clay.
Imperata grasslands are caused by human activities such as logging, forest clearing for shifting cultivation, agriculture and grazing, and also by frequent fires. The latter is a frequent result of human interference. However, when not maintained by frequent fires and human disturbances, they regenerate naturally and speedily to secondary young forest. The time of succession in Imperata grassland for example in Samboja Lestari area , Imperata cylindrica has the highest coverage but it becomes less dominant from the fourth year onwards.
While Imperata decreases, the percentage of shrubs and young trees clearly increases with time. In the burned plots, Melastoma malabathricum, Eupatorium inulaefolium, Ficus sp.
Soil properties change during secondary succession in Imperata grassland area. Soil carbon stocks also increase upon secondary succession from Imperata grassland to secondary forest.
For more details on this topic, see Fire ecology. Generation of carbonates from burnt plant material following fire disturbance causes an initial increase in soil pH that can affect the rate of secondary succession, as well as what types of organisms will be able to thrive. Soil composition prior to fire disturbance also influences secondary succession, both in rate and type of dominant species growth.
For example, high sand concentration was found to increase the chances of primary Pteridium over Imperata growth in Imperata grassland. The byproducts of combustion have been shown to affect secondary succession by soil microorganisms. For example, certain fungal species such as Trichoderma polysporum and Penicillium janthinellum have a significantly decreased success rate in spore germination within fire-affected areas, reducing their ability to recolonize. Vegetation structure is affected by fire.
In some types of ecosystems this creates a process of renewal. Following a fire, early successional species disperse and establish first. This is then followed by late successional species. Species that are fire intolerant are those that are more flammable and are desolated by fire.
More tolerant species are able to survive or disperse in the event of fire. The occurrence of fire leads to the establishment of deadwood and snags in forests. This creates habitat and resources for a variety of species. Fire can act as a seed dispersing stimulant. Many species require fire events to reproduce, disperse, and establish. For example, the knobcone pine "Pinus attenuata" has closed cones that open for dispersal when exposed to heat caused by forest fires.
This particular conifer grows in clusters because of this limited method of seed dispersal. A tough fire resistant outer bark and lack of low branches help the knobcone pine survive fire with minimal damage.
So we will count upon a native flora which, undoubtedly, will appear very strange to us. Of course, as you know, we are taking across with us our own seeds and our own spores. We take so much for granted, don't we? You do not realize what has been supplied you by nature on this world of ours—until you come to count up what you must take along with you, if you hope to survive. Keppler says that of some twenty thousand nectar insects, this one species pollinates more than all the rest put together.
The honey bee would take care of practically of this work, as his range is tremendous. There are a few plants—Keppler tells me—such as red clover, which he cannot work on; but his cousin the bumblebee, with his longer proboscis, could attend to them.
So, first and foremost among living things, we bring bees. Such an insect will be vitally necessary to keep the greenery from choking our new earth; and the one best suited for this job is, paradoxically enough, one of mankind's oldest scourges, the grasshopper.
He is an omnivorous feeder and would keep the greenery in check— after he got his start. Our first problem may be that he will not multiply fast enough; and then that he multiply too fast. So to keep him in check, and also the butterfly and the moth, we will take parasitic flies. Here on earth, with a balanced and bewilderingly intricate economy already established, a tremendously longer list would be vital to provide the proper checks and balances; but starting anew, on Bronson Beta, we can begin, at least, with the few insects we have chosen.
Unquestionably, differentiation and evolution will swiftly set in, and they will find new forms. Otherwise vegetation would fall down, never disintegrate, and pile up till everything was choked. A vial the size of your thumb holds several billion spores of assorted fungi— in case the spores of the fungi of Bronson Beta have not survived. They are absolutely essential.
Our space is so limited, and there is most tremendous competition. Birds offer a somewhat simpler problem; but possibly you have heard some of the arguments over them.
I confess I argued for warblers—yellow warblers. I like them; I have always liked them; and meadow larks. A dense atmosphere — almost entirely nitrogen. And no oxygen — fortunately. But in the decades before the Exodus, many things happened to change our outlook on the Universe.
Some argued that even virulent pathogens and disease vectors should not be exterminated, but should be preserved under strict safeguards. It had long been agreed that we should not attempt any settlement on a planet with intelligent life-forms; the human race had a bad enough record on its home world.
Fortunately — or unfortunately! Suppose we found a planet on which animal life had just begun. Should we stand aside and let evolution take its course on the chance that megayears hence intelligence might arise? But Death focuses the mind on the things that really matter: Was it possible to develop legal and moral codes applicable to all intelligent creatures, and not merely to the bipedal, air-breathing mammals who had briefly dominated Planet Earth?
It made him quite unpopular with those who argued that since H. Someone coined the effective slogan: It may be centuries before we get reports from all the seedships that went out. And if some remain silent — well, the slime moulds may have won…. Many thought that they were too idealistic, and there was certainly no way in which they could ever be enforced.
But they were an expression of intent — a final gesture of goodwill towards a Universe which might never be able to appreciate it. The element is far too reactive to occur in the free state unless it is continually replenished by plants — or their equivalent.
And even if animal life only rarely leads to intelligence, no other plausible route to it has ever been theorized. As you will see by the map, more than fifty per cent of the surface is ice-covered, to an estimated average depth of three kilometres.
All the oxygen we shall ever need! It will burn off the ice and simultaneously crack the steam into oxygen and hydrogen. The hydrogen will quickly leak away into space; we may help it with tuned lasers, if necessary. Magellan, which has spent its entire existence in space, will finally descend to the surface of a planet. Less than a month later, it dropped to 1,, and would not see similar levels again for five years.
In mid, the subprime mortgage crisis spread to the wider U. The resulting situation became acute in September , ushering in a period of unusual market volatility , encompassing record point swings in both directions and reaching the highest levels since The index reached a nearly year low, closing at The entire drop from high in Oct to low in Mar was On April 29, , the index closed at On March 28, , it closed above the closing high from This would be the first of three point milestones in On February 17, , the index first closed above 2,, closing at 2, On February 25, it reached 2, At the end of , the index closed at 2, A period of over a year with no new record highs ended on July 11, closing at 2, This is similar to the Dow Jones Industrial Average , but different from others such as the Russell , which are strictly rule-based.
When considering the eligibility of a new addition, the committee assesses the company's merit using eight primary criteria: For example, in order to be added to the index, a company must satisfy the following liquidity-based size requirements: The index includes non-U. These versions differ in how dividends are accounted for. The price return version does not account for dividends; it only captures the changes in the prices of the index components. The total return version reflects the effects of dividend reinvestment.
Finally, the net total return version reflects the effects of dividend reinvestment after the deduction of withholding tax. The index has traditionally been capitalization-weighted ; that is, movements in the prices of stocks with higher market capitalizations the share price times the number of shares outstanding had a greater impact on the value of the index than do companies with smaller market caps. The transition to float-adjusted capitalization-weighting was made in two steps, the first on March 18, and the second on September 16, Additionally, to remain indicative of the U.
To prevent the value of the Index from changing merely as a result of corporate financial actions, all such actions affecting the market value of the Index require a divisor adjustment.
There is a large range of different corporate actions that can require the divisor to be adjusted. These are listed in the table below: However, the Divisor's value is approximately 8. The divisor is adjusted in the case of stock issuance, spin-offs or similar structural changes, to ensure that such events do not in themselves alter the numerical value of the Index.
The index value is updated every 15 seconds during trading sessions and is disseminated by Reuters America, Inc. In contrast with the median return or the mean return, the CAGR is the measurement of the actual return achieved over the number of years being studied. The current total rate of return including dividends CAGR through is The rate of return without dividends, or just on the index itself through is 8.
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