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Thursday, October 7, 2021

Foundation series

From Wikipedia, the free encyclopedia
 
The Foundation series
Foundation gnome.jpg
First edition dust-jacket of Foundation


AuthorIsaac Asimov
CountryUnited States
LanguageEnglish
GenreScience fiction
PublisherAstounding Magazine, Gnome Press, Spectra, Doubleday
Published1942–1993
Media typePrint

The Foundation series is a science fiction book series written by American author Isaac Asimov. First published as a series of short stories in 1942–50, and subsequently in three collections in 1951–53, for thirty years the series was a trilogy: Foundation, Foundation and Empire, and Second Foundation. It won the one-time Hugo Award for "Best All-Time Series" in 1966. Asimov began adding new volumes in 1981, with two sequels: Foundation's Edge and Foundation and Earth, and two prequels: Prelude to Foundation and Forward the Foundation. The additions made reference to events in Asimov's Robot and Empire series, indicating that they also were set in the same fictional universe.

The premise of the stories is that, in the waning days of a future Galactic Empire, the mathematician Hari Seldon spends his life developing a theory of psychohistory, a new and effective mathematical sociology. Using statistical laws of mass action, it can predict the future of large populations. Seldon foresees the imminent fall of the Empire, which encompasses the entire Milky Way, and a Dark Age lasting 30,000 years before a second empire arises. Although the inertia of the Empire's fall is too great to stop, Seldon devises a plan by which "the onrushing mass of events must be deflected just a little" to eventually limit this interregnum to just one thousand years. To implement his plan, Seldon creates the Foundations—two groups of scientists and engineers settled at opposite ends of the galaxy—to preserve the spirit of science and civilization, and thus become the cornerstones of the new galactic empire.

One key feature of Seldon's theory, which has proved influential in real-world social science, is the uncertainty principle of sociology: if a population gains knowledge of its predicted behavior, its self-aware collective actions become unpredictable.

Publication history

Original stories

The original trilogy of novels collected a series of eight short stories published in Astounding Magazine between May 1942 and January 1950. According to Asimov, the premise was based on ideas in Edward Gibbon's History of the Decline and Fall of the Roman Empire, and was invented spontaneously on his way to meet with editor John W. Campbell, with whom he developed the concepts of the collapse of the Galactic Empire, the civilization-preserving Foundations, and psychohistory. Asimov wrote these early stories in his West Philadelphia apartment when he worked at the Philadelphia Naval Yard.

Foundation trilogy

The first four stories were collected, along with a new introductory story, and published by Gnome Press in 1951 as Foundation. The later stories were published in pairs by Gnome as Foundation and Empire (1952) and Second Foundation (1953), resulting in the "Foundation Trilogy", as the series is still known.

Later sequels and prequels

In 1981, Asimov was persuaded by his publishers to write a fourth book, which became Foundation's Edge (1982).

Four years later, Asimov followed up with yet another sequel, Foundation and Earth (1986), which was followed by the prequels Prelude to Foundation (1988) and Forward the Foundation (1993), published after his death in 1992. During the two-year lapse between writing the sequels and prequels, Asimov had tied in his Foundation series with his various other series, creating a single unified universe. The basic link is mentioned in Foundation's Edge: an obscure myth about a first wave of space settlements with robots and then a second without. The idea is the one developed in Robots of Dawn, which, in addition to showing the way that the second wave of settlements was to be allowed, illustrates the benefits and shortcomings of the first wave of settlements and their so-called C/Fe (carbon/iron, signifying humans and robots together) culture. In this same book, the word psychohistory is used to describe the nascent idea of Seldon's work. Some of the drawbacks to this style of colonization, also called Spacer culture, are also exemplified by the events described all the way back in 1957's The Naked Sun.

The link between the Robot and Foundation universes was tightened by letting the robot R. Daneel Olivaw - originally introduced in The Caves of Steel - live on for tens of thousands of years and play a major role behind the scenes in both the Galactic Empire in its heyday and in the rise of the two Foundations to take its place.

Asimov's Foundation series novels

Note: This plot outline for the seven novels follows the series' in-universe chronology, which is not the order of publication. After many years as a trilogy comprising Foundation, Foundation and Empire, and Second Foundation, the series was expanded by two prequels and two sequels.

Prelude to Foundation (1988)

Prelude to Foundation opens on the planet Trantor, the empire's capital planet, the day after Hari Seldon has given a speech at a mathematics conference. Several parties become aware of the content of his speech (that using mathematical formulas, it may be possible to predict the future course of human history). Seldon is hounded by the Emperor and various employed thugs who are working surreptitiously, which forces him into exile. Over the course of the book, Seldon and Dors Venabili, a female companion and professor of history, are taken from location to location by Chetter Hummin who, under the guise of a reporter, introduces them to various Trantorian walks of life in his attempts to keep Seldon hidden from the Emperor. Throughout their adventures all over Trantor, Seldon continuously denies that psychohistory is a realistic science. Even if feasible, it may take several decades to develop. Hummin, however, is convinced that Seldon knows something, so he continuously presses him to work out a starting point to develop psychohistory. Eventually, after much traveling and introductions to various, diverse cultures on Trantor, Seldon realizes that using the entire known galaxy as a starting point is too overwhelming; he then decides to use Trantor as a model to work out the science, with a goal of later using the applied knowledge on the rest of the galaxy.

Forward the Foundation (1993)

Eight years after the events of Prelude, Seldon has worked out the science of psychohistory and has applied it on a galactic scale. His notability and fame increase and he is eventually promoted to First Minister to the Emperor. As the book progresses, Seldon loses those closest to him, including his wife, Dors Venabili, as his own health deteriorates into old age. Having worked his entire adult life to understand psychohistory, Seldon instructs his granddaughter, Wanda, to set up the Second Foundation.

Foundation (1951)

Called forth to stand trial on Trantor for allegations of treason (for foreshadowing the decline of the Galactic Empire), Seldon explains that his science of psychohistory foresees many alternatives, all of which result in the Galactic Empire eventually falling. If humanity follows its current path, the Empire will fall and 30,000 years of turmoil will overcome humanity before a second Empire arises. However, an alternative path allows for the intervening years to be only one thousand, if Seldon is allowed to collect the most intelligent minds and create a compendium of all human knowledge, entitled Encyclopedia Galactica. The board is still wary but allows Seldon to assemble whomever he needs, provided he and the "Encyclopedists" be exiled to a remote planet, Terminus. Seldon agrees to these terms – and also secretly establishes a second Foundation of which almost nothing is known, which he says is at the "opposite end" of the galaxy.

After fifty years on Terminus, and with Seldon now dead, the inhabitants find themselves in a crisis. With four powerful planets surrounding their own, the Encyclopedists have no defenses but their own intelligence. At the same time, a vault left by Seldon is due to automatically open. The vault reveals a pre-recorded hologram of Seldon, who informs the Encyclopedists that their entire reason for being on Terminus is a fraud, insofar as Seldon did not actually care whether or not an encyclopedia was created, only that the population was placed on Terminus and the events needed by his calculations were set in motion. In reality, the recording discloses, Terminus was set up to reduce the Dark Ages from 30,000 years to just one millennium, based on following his calculations. It will develop by facing intermittent and extreme "crises" – known as "Seldon Crises" – which the laws governing psychohistory show will inevitably be overcome, simply because human nature will cause events to fall in particular ways which lead to the intended goal. The recording reveals that the present events are the first such crisis, reminds them that a second foundation was also formed at the "opposite end" of the galaxy, and then falls silent.

The Mayor of Terminus City, Salvor Hardin, proposes to play the planets against each other. His plan is a success; the Foundation remains untouched, and he becomes the effective ruler. Meanwhile, the minds of the Foundation continue to develop newer and greater technologies which are smaller and more powerful than the Empire's equivalents. Using its scientific advantage, Terminus develops trade routes with nearby planets, eventually taking them over when its technology becomes a much-needed commodity. The interplanetary traders effectively become the new diplomats to other planets. One such trader, Hober Mallow, becomes powerful enough to challenge and win the office of Mayor and, by cutting off supplies to a nearby region, also succeeds in adding more planets to the Foundation's control.

Foundation and Empire (1952)

An ambitious general of the current Emperor of the Galaxy perceives the Foundation as a growing threat and orders an attack on it, using the Empire's still-mighty fleet of war vessels. The Emperor, initially supportive, becomes suspicious of his general's long-term motive for the attack, and recalls the fleet despite being close to victory. In spite of its undoubted inferiority in purely military terms, the Foundation emerges as the victor and the Empire itself is defeated. Seldon's hologram reappears in the vault on Terminus, and explains to the Foundation that this opening of the vault follows a conflict whose result was inevitable whatever might have been done – a weak Imperial navy could not have attacked them, while a strong navy would have shown itself by its successes to be a direct threat to the Emperor himself and been recalled.

A century later, an unknown outsider called the Mule has begun taking over planets at a rapid pace. The Foundation comes to realize, too late, that the Mule is unforeseen in Seldon's plan, and that the plan cannot have predicted any certainty of defeating him. Toran and Bayta Darell, accompanied by Ebling Mis – the Foundations's greatest psychologist – and a court jester named Magnifico familiar with the Mule, set out to Trantor to find the Second Foundation, hoping to bring an end to the Mule's reign. Mis studies furiously in the Great Library of Trantor to decipher the Second Foundation's location in order to visit it and seek their help. He is successful and also deduces that the Mule's success stems from his being a mutant who is able to change the emotions of others, a power he used to first instill fear in the inhabitants of his conquered planets, then to make his enemies devoutly loyal to him. Mis is murdered by Bayta Darell before he can reveal the location, she having realised that Magnifico is in fact the Mule and has been using his gifts to drive Mis forward in his research, so that he can learn the location himself and subjugate the Second Foundation. Dismayed at having made a mistake which allowed Bayta to see through his disguise, the Mule leaves Trantor to rule over his conquered planets while continuing his search.

Second Foundation (1953)

As the Mule comes closer to finding it, the mysterious Second Foundation comes briefly out of hiding to face the threat directly. It consists of the descendants of Seldon's psychohistorians. While the first Foundation has developed the physical sciences, the Second Foundation has been developing Seldon's mathematics and the Seldon Plan, along with their own use of mental sciences. The Second Foundation ultimately wears down the Mule, who returns to rule over his kingdom peacefully for the rest of his life, without any further thought of conquering the Second Foundation.

However, as a result, the first Foundation has learned something of the Second Foundation beyond the simple fact that it exists, and has some understanding of its role. This means their behavior will now be chosen in light of that knowledge, and not based on uninformed natural human behavior, which means their behavior will no longer be the natural responses required by the mathematics of the Seldon Plan. This places the Plan itself at great risk. In addition, the first Foundation starts to resentfully consider the other as a rival, and a small group secretly begins to develop equipment for detecting and blocking mental influence in order to detect members of the Second Foundation. After many attempts to infer the Second Foundation's whereabouts from the few clues available, the Foundation is led to believe the Second Foundation is located on Terminus (the "opposite end of the galaxy" for a galaxy with a circular shape). The Foundation uncovers and destroys a group of fifty members of the Second Foundation and is left believing they have destroyed the Second Foundation. No longer concerned with the perceived threat, their behavior as a society will tend towards those anticipated by the Plan.

In fact the group of fifty were volunteers on Terminus whose role was to be captured and give the impression that they composed the whole of the Second Foundation, so that the Seldon Plan would be able to continue unimpeded. The Second Foundation itself, however, is finally revealed to be located on the former Imperial Homeworld of Trantor. The clue "at Star's End" was not a physical clue, but was instead based on an old saying, "All roads lead to Trantor, and that is where all stars end." Seldon, being a social scientist and not a physical one, placed the two Foundations at "opposite ends" of the galaxy, but in a sociological rather than physical sense. The first Foundation was located on the Periphery of the galaxy, where the Empire's influence was minimal; the Second Foundation was on Trantor, where, even in its dying days, the Empire's power and culture were strongest.

Foundation's Edge (1982)

Believing the Second Foundation still exists (despite the common belief that it has been extinguished), young politician Golan Trevize is sent into exile by the current Mayor of the Foundation, Harla Branno, to uncover the Second Foundation; Trevize is accompanied by a scholar named Janov Pelorat. The reason for their belief is that, despite the unforeseeable impact of the Mule, the Seldon Plan still appears to be proceeding in accordance with the statements of Seldon's hologram, suggesting that the Second Foundation still exists and is secretly intervening to bring the plan back on course. After a few conversations with Pelorat, Trevize comes to believe that a mythical planet called Earth may hold the secret to the location. No such planet exists in any database, yet several myths and legends all refer to it, and it is Trevize's belief that the planet is deliberately being kept hidden. Unknown to Trevize and Pelorat, Branno is tracking their ship so that, in the event they find the Second Foundation, the first Foundation can take military or other action.

Meanwhile, Stor Gendibal, a prominent member of the Second Foundation, discovers a simple local on Trantor who has had a very subtle alteration made to her mind, far more delicate than anything the Second Foundation can do. He concludes that a greater force of Mentalics must be active in the Galaxy. Following the events on Terminus, Gendibal endeavors to follow Trevize, reasoning that by doing so, he may find out who has altered the mind of the Trantor native.

Using the few scraps of reliable information within the various myths, Trevize and Pelorat discover a planet called Gaia which is inhabited solely by Mentalics, to such an extent that every organism and inanimate object on the planet shares a common mind. Both Branno and Gendibal, who have separately followed Trevize, also reach Gaia at the same time. Gaia reveals that it has engineered this situation because it wishes to do what is best for humanity but cannot be sure what is best. Trevize's purpose, faced with the leaders of both the First and Second Foundations and Gaia itself, is to be trusted to make the best decision among the three main alternatives for the future of the human race: the First Foundation's path, based on mastery of the physical world and its traditional political organization (i.e., Empire); the Second Foundation's path, based on mentalics and probable rule by an elite using mind control; or Gaia's path of absorption of the entire Galaxy into one shared, harmonious living entity in which all beings, and the galaxy itself, would be a part.

After Trevize makes his decision for Gaia's path, the intellect of Gaia adjusts both Branno's and Gendibal's minds so that each believes he or she has succeeded in a significant task. (Branno believes she has successfully negotiated a treaty tying Sayshell to the Foundation, and Gendibal – now leader of the Second Foundation – believes that the Second Foundation is victorious and should continue as normal.) Trevize remains, but is uncertain as to why he is "sure" that Gaia is the correct outcome for the future.

Foundation and Earth (1986)

Still uncertain about his decision, Trevize continues on with the search for Earth along with Pelorat and a local of Gaia, advanced in Mentalics, known as Blissenobiarella (usually referred to simply as Bliss). Eventually, Trevize finds three sets of coordinates which are very old. Adjusting them for time, he realizes that his ship's computer does not list any planet in the vicinity of the coordinates. When he physically visits the locations, he rediscovers the forgotten Spacer worlds of Aurora, Solaria, and finally Melpomenia. After searching and facing different dilemmas on each planet, Trevize still has not discovered any answers.

Aurora and Melpomenia are long deserted, but Solaria contains a small population which is extremely advanced in the field of Mentalics. When the lives of the group are threatened, Bliss uses her abilities (and the shared intellect of Gaia) to destroy the Solarian who is about to kill them. This leaves behind a small child who will be put to death if left alone, so Bliss makes the decision to keep the child as they quickly escape the planet.

Eventually, Trevize discovers Earth, but it, again, contains no satisfactory answers for him (it is also long-since deserted). However, it dawns on Trevize that the answer may not be on Earth, but on Earth's satellite – the Moon. Upon approaching the planet, they are drawn inside the Moon's core, where they meet a robot named R. Daneel Olivaw.

Olivaw explains that he has been instrumental in guiding human history for thousands of years, having provided the impetus for Seldon to create psychohistory and also the creation of Gaia, but is now close to the end of his ability to maintain himself and will shortly cease to function. Despite replacing his positronic brain (which contains 20,000 years of memories), he is going to die shortly. He explains that no further robotic brain can be devised to replace his current one, or which will let him continue assisting for the benefit of humanity. However, some additional time can be won to ensure the long term benefit of humanity by merging R. Daneel Olivaw's mind with the organic intellect of a human – in this case, the intellect of the child that the group rescued on Solaria.

Once again, Trevize is put in the position of deciding if having Olivaw meld with the child's superior intellect would be in the best interests of the galaxy. The decision is left ambiguous (though likely a "yes") as it is implied that the melding of the minds may be to the child's benefit, but that she may have sinister intentions.

Development and themes

The early stories were inspired by Edward Gibbon's The History of the Decline and Fall of the Roman Empire. The plot of the series focuses on the growth and reach of the Foundation, against a backdrop of the "decline and fall of the Galactic Empire." The themes of Asimov's stories were also influenced by the political tendency in SF fandom, associated with the Futurians, known as Michelism.

The focus of the books is the trends through which a civilization might progress, specifically seeking to analyze their progress, using history as a precedent. Although many science fiction novels such as Nineteen Eighty-Four or Fahrenheit 451 do this, their focus is upon how current trends in society might come to fruition and they act as a moral allegory of the modern world. The Foundation series, on the other hand, looks at the trends in a wider scope, dealing with societal evolution and adaptation rather than the human and cultural qualities at one point in time. In this he followed the model of Thucydides' work The History of the Peloponnesian War, as he once acknowledged.

Furthermore, the concept of psychohistory, which gives the events in the story a sense of rational fatalism, leaves little room for moralization. Hari Seldon himself hopes that his Plan will "reduce 30,000 years of Dark Ages and barbarism to a single millennium," a goal of exceptional moral gravity. Yet events within it are often treated as inevitable and necessary, rather than deviations from the greater good. For example, the Foundation slides gradually into oligarchy and dictatorship prior to the appearance of the galactic conqueror, known as the Mule, who was able to succeed through the random chance of a telepathic mutation. But, for the most part, the book treats the purpose of Seldon's plan as unquestionable, and that slide as being necessary in it, rather than mulling over whether the slide is, on the whole, positive or negative.

The books also wrestle with the idea of individualism. Hari Seldon's plan is often treated as an inevitable mechanism of society, a vast mindless mob mentality of quadrillions of humans across the galaxy. Many in the series struggle against it, only to fail. However, the plan itself is reliant upon the cunning of individuals such as Salvor Hardin and Hober Mallow to make wise decisions that capitalize on the trends. On the other hand, the Mule, a single individual with mental powers, topples the Foundation and nearly destroys the Seldon plan with his special, unforeseen abilities. To repair the damage the Mule inflicts, the Second Foundation deploys a plan which turns upon individual reactions. Psychohistory is based on group trends and cannot predict with sufficient accuracy the effects of extraordinary, unforeseeable individuals, and as originally presented, the Second Foundation's purpose was to counter this flaw. Later novels would identify the Plan's uncertainties that remained at Seldon's death as the primary reason for the existence of the Second Foundation, which (unlike the First) had retained the capacity to research and further develop psychohistory.

Asimov tried to end the series with Second Foundation. However, because of the predicted thousand years until the rise of the next Empire (of which only a few hundred had elapsed), the series lacked a sense of closure. For decades, fans pressured him to write a sequel. In 1982, after a 30-year hiatus, Asimov gave in and wrote what was at the time a fourth volume: Foundation's Edge. This was followed shortly thereafter by Foundation and Earth. This novel, which takes place some 500 years after Seldon, ties up all the loose ends and ties all his Robot, Empire, and Foundation novels into a single story. He also opens a brand new line of thought in the last dozen pages regarding Galaxia, a galaxy inhabited by a single collective mind. This concept was never explored further. According to his widow Janet Asimov (in her biography of Isaac, It's Been a Good Life), he had no idea how to continue after Foundation and Earth, so he started writing the prequels.

Asimov's imprecise future history

Asimov (right) was inspired by the Future History stories of Heinlein (left), but self-consciously wrote that his was "not the beautiful job that Heinlein did, but was actually made up 'ad hoc'".

In the spring of 1955, Asimov published a future history of humanity in the pages of Thrilling Wonder Stories magazine based upon his thought processes concerning the Foundation universe at that point in his life. According to the publication, "the scheme was not originally worked out as a consistent pattern and only includes about one-quarter of his total writings". Because of this, the dating in the foundation series is approximate and inconsistent.

Asimov estimates that his Foundation series takes place nearly 50,000 years into the future, with Hari Seldon born in 47,000 CE. Around this time, the future emperor Cleon I is born in the imperial capital Trantor, 78 years before the Foundation Era (FE) and the events of the original Foundation trilogy. After Cleon inherits the crown, the mathematician Hari Seldon comes to Trantor from Helicon to deliver his theory of psychohistory that predicts the fall of the empire, which triggers the events of Prelude to Foundation. Forward the Foundation picks up the story a few years later, with the emperor being assassinated and Seldon retiring from politics.

At the start of the Foundation Era, the events of the original Foundation novel (first published in Astounding Science Fiction as a series of short stories) take place, and the in-universe Foundation Era truly begins. According to Asimov, he intended this to take place around the year 47000 CE, with the Empire in decay as it battles the rising Foundation, who emerges as the dominant power a few centuries later. Thus begins the events of the Foundation and Empire, which include the unpredicted rise of the Mule, who defeats the Foundation thanks to his mutant abilities. The events of Second Foundation chronicle the titular Second Foundation's search and defeat of the Mule, and their conflict with the remnants of the original Foundation, averting the Dark Age. Asimov estimates that the Mule rises and falls somewhere around 47300 CE.

Foundation's Edge takes place 500 years after the establishment of the Foundation, outside of the original trilogy of novels. Foundation and Earth follows immediately after, with humanity choosing and justifying a third path distinct from the opposing visions of the two Foundations. According to Asimov, the Second Galactic Empire is established 48000 CE, 1000 years after the events of the first novel.

Asimov himself commented that his fiction's internal history was "actually made up ad hoc. My cross-references in the novels are thrown in as they occur to me and did not come from a systemized history. ... If some reader checks my stories carefully and finds that my dating is internally inconsistent, I can only say I'm not surprised."

Cultural impact

Impact in nonfiction

In Learned Optimism, psychologist Martin Seligman identifies the Foundation series as one of the most important influences in his professional life, because of the possibility of predictive sociology based on psychological principles. He also lays claim to the first successful prediction of a major historical (sociological) event, in the 1988 US elections, and he specifically attributes this to a psychological principle.

In his 1996 book To Renew America, U. S. House Speaker Newt Gingrich wrote that he was influenced by reading the Foundation trilogy in high school.

Paul Krugman, winner of the 2008 Nobel Memorial Prize in Economic Sciences, credits the Foundation series with turning his mind to economics, as the closest existing science to psychohistory.

The businessman and entrepreneur Elon Musk counts the series among the inspirations for his career. When Musk's Tesla Roadster was launched into space on the maiden flight of the Falcon Heavy rocket in February 2018, amongst other items it carried a 5D optical data storage copy of the Foundation series.

Stating that it "offers a useful summary of some of the dynamics of far-flung imperial Rome", Carl Sagan in 1978 listed the Foundation series as an example of how science fiction "can convey bits and pieces, hints and phrases, of knowledge unknown or inaccessible to the reader". In the nonfiction PBS series Cosmos: A Personal Voyage, Sagan referred to an Encyclopedia Galactica in the episodes "Encyclopaedia Galactica" and "Who Speaks for Earth".

Awards

In 1966, the Foundation trilogy beat several other science fiction and fantasy series to receive a special Hugo Award for "Best All-Time Series". The runners-up for the award were the Barsoom series by Edgar Rice Burroughs, the Future History series by Robert A. Heinlein, the Lensman series by Edward E. Smith and The Lord of the Rings by J. R. R. Tolkien. The Foundation series was the only series so honored until the establishment of the "Best Series" category in 2017. Asimov himself wrote that he assumed the one-time award had been created to honor The Lord of the Rings, and he was amazed when his work won.

The series has won three other Hugo Awards. Foundation's Edge won Best Novel in 1983, and was a bestseller for almost a year. Retrospective Hugo Awards were given in 1996 and 2018 for, respectively, "The Mule" (the major part of Foundation and Empire) for Best Novel (1946) and "Foundation" (the first story written for the series, and second chapter of the first novel) for Best Short Story (1943).

Impact in fiction and entertainment

Science fiction parodies, such as Douglas Adams' The Hitchhiker's Guide to the Galaxy and Harry Harrison's Bill, the Galactic Hero, often display clear Foundation influences. For instance, "The Guide" of the former is a spoof of the Encyclopedia Galactica, and the series actually mentions the encyclopedia by name, remarking that it is rather "dry", and consequently sells fewer copies than the guide; the latter also features the ultra-urbanized Imperial planet Helior, often parodying the logistics such a planet-city would require, but that Asimov's novel downplays when describing Trantor.

The 1957 short story Marius, which set off Poul Anderson's early future history, the Psychotechnic League, clearly shows the influence of Asimov's Foundation—though moved from the far future of a collapsing Galactic Empire to a near future of a late 20th Century Earth struggling to recover from the devastation of a nuclear Third World War. In this situation, the Finnish Professor Valti starts the science of Psychodynamics, which makes it possible to mathematically predict the future, and The Psychotechnic Institute makes use of Valti's formulas to subtly "guide" and manipulate the emerging world government. The similarity to Seldon and the Foundation is obvious, nor did Anderson try to hide it.

Frank Herbert also wrote Dune as a counterpoint to Foundation. Tim O'Reilly in his monograph on Herbert wrote that "Dune is clearly a commentary on the Foundation trilogy. Herbert has taken a look at the same imaginative situation that provoked Asimov's classic—the decay of a galactic empire—and restated it in a way that draws on different assumptions and suggests radically different conclusions. The twist he has introduced into Dune is that the Mule, not the Foundation, is his hero."

In 1995, Donald Kingsbury wrote "Historical Crisis", which he later expanded into a novel, Psychohistorical Crisis. It takes place about 2,000 years after Foundation, after the founding of the Second Galactic Empire. It is set in the same fictional universe as the Foundation series, in considerable detail, but with virtually all Foundation-specific names either changed (e.g., Kalgan becomes Lakgan), or avoided (psychohistory is created by an unnamed, but often-referenced Founder). The novel explores the ideas of psychohistory in a number of new directions, inspired by more recent developments in mathematics and computer science, as well as by new ideas in science fiction itself.

In 1998, the novel Spectre (part of the Shatnerverse series) by William Shatner and Judith and Garfield Reeves-Stevens states that the Mirror Universe divergent path has been studied by the Seldon Psychohistory Institute.

The oboe-like holophonor in Matt Groening's animated television series Futurama is based directly upon the "Visi-Sonor" which Magnifico plays in Foundation and Empire. The "Visi-Sonor" is also mirrored in an episode of Special Unit 2, where a child's television character plays an instrument that induces mind control over children.

During the 2006–2007 Marvel Comics Civil War crossover storyline, in Fantastic Four #542 Mister Fantastic revealed his own attempt to develop psychohistory, saying he was inspired after reading the Foundation series.

According to lead singer Ian Gillan, the hard rock band Deep Purple's song The Mule is based on the Foundation character: "Yes, The Mule was inspired by Asimov. It's been a while but I'm sure you've made the right connection... Asimov was required reading in the 60's."

Adaptations

Radio

An eight-part radio adaptation of the original trilogy, with sound design by the BBC Radiophonic Workshop, was broadcast on BBC Radio 4 in 1973—one of the first BBC radio drama serials to be made in stereo. A BBC 7 rerun commenced in July 2003.

Adapted by Patrick Tull (episodes 1 to 4) and Mike Stott (episodes 5 to 8), the dramatisation was directed by David Cain and starred William Eedle as Hari Seldon, with Geoffrey Beevers as Gaal Dornick, Lee Montague as Salvor Hardin, Julian Glover as Hober Mallow, Dinsdale Landen as Bel Riose, Maurice Denham as Ebling Mis and Prunella Scales as Lady Callia.

Film

By 1998, New Line Cinema had spent $1.5 million developing a film version of the Foundation Trilogy. The failure to develop a new franchise was partly a reason the studio signed on to produce The Lord of the Rings film trilogy.

On July 29, 2008, New Line Cinema co-founders Bob Shaye and Michael Lynne were reported to have been signed on to produce an adaptation of the trilogy by their company Unique Pictures for Warner Brothers. However, Columbia Pictures (Sony) successfully bid for the screen rights on January 15, 2009, and then contracted Roland Emmerich to direct and produce. Michael Wimer was named as co-producer. Two years later, the studio hired Dante Harper to adapt the books. This project failed to materialize and HBO acquired the rights when they became available in 2014.

Television

In November 2014, TheWrap reported that Jonathan Nolan was writing and producing a TV series based on the Foundation Trilogy for HBO. Nolan confirmed his involvement at a Paley Center event on April 13, 2015.

In June 2017, Deadline reported that Skydance Media would produce a TV series. In August 2018 it was announced that Apple TV+ had commissioned a 10 episode straight-to-series order. However, on April 18, 2019, Josh Friedman left the project as co-writer and co-showrunner. This was apparently planned, with either Friedman or screenwriter David Goyer leaving and the other staying. On June 22, 2020, Apple CEO Tim Cook announced the series would be released in 2021. On 13 March 2020, Apple suspended all active filming on their shows due to the COVID-19 outbreak; filming resumed on October 6, 2020.

The series is filmed at Troy Studios, Limerick, Ireland and the budget was expected to be approximately $50 million. The first two episodes premiered on September 24, 2021. Metacritic gave the first season a weighted average score of 63 out of 100 based on 22 reviews, indicating "generally favorable reviews".

Books within the greater Foundation series

Merging with other series

The series is set in the same universe as Asimov's first published novel, Pebble in the Sky, although Foundation takes place about 10,000 years later. Pebble in the Sky became the basis for the Empire series. Then, at some unknown date (prior to writing Foundation's Edge) Asimov decided to merge the Foundation/Empire series with his Robot series. Thus, all three series are set in the same universe, giving them a combined length of 18 novels, and a total of about 1,500,000 words (see the List of books below). The merge also created a time-span of the series of around 20,000 years.

The stand-alone story Nemesis is also in the same continuity; being referenced in Forward the Foundation, where Hari Seldon refers to a twenty-thousand-year-old story of "a young woman that could communicate with an entire planet that circled a sun named Nemesis." Commentators noted that Nemesis contains barely disguised references to the Spacers and their calendar system, the Galactic Empire and even to Hari Seldon which seem to have been deliberately placed for the purpose of later integration into the Foundation universe.

Asimov's "Author's Note" in Prelude to Foundation

The foreword to Prelude to Foundation contains the chronological ordering of Asimov's science fiction books. Asimov stated that the books of his Robot, Empire, and Foundation series "offer a kind of history of the future, which is, perhaps, not completely consistent, since I did not plan consistency to begin with." Asimov also noted that the books in his list "were not written in the order in which (perhaps) they should be read". In the Author's Note, Asimov noted that there is room for a book between Robots and Empire and The Currents of Space, and that he could follow Foundation and Earth with additional volumes.

Forward the Foundation, Nemesis, and The Positronic Man do not appear in Asimov's list, as they were not yet published at the time, and the order of the Empire novels in Asimov's list is not entirely consistent with other lists. For example, the 1983 Ballantine Books printing of The Robots of Dawn lists the Empire novels as: The Stars, Like Dust, The Currents of Space, and Pebble in the Sky. Given that The Currents of Space includes Trantor and that The Stars, Like Dust does not, these two books possibly were accidentally reversed in Asimov's list.

Asimov's standalone novels set in the Foundation universe

While not mentioned in the "Author's Note" of Prelude to Foundation, the novels The End of Eternity (1955), Nemesis (1989), and The Positronic Man (1992) are related to the greater Foundation series.

The End of Eternity is vaguely referenced in Foundation's Edge, where a character mentions the Eternals, whose "task it was to choose a reality that would be most suitable to Humanity". (The End of Eternity also refers to a "Galactic Empire" within its story.) Asimov himself did not mention The End of Eternity in the series listing from Prelude to Foundation. As for Nemesis, it was written after Prelude to Foundation, but in the author's note Asimov explicitly states that the book is not part of the Foundation or Empire series, but that some day he might tie it to the others.

In Forward the Foundation, Hari Seldon refers to a 20-thousand-year-old story of "a young woman that could communicate with an entire planet that circled a sun named Nemesis", a reference to Nemesis. In Nemesis, the main colony is one of the Fifty Settlements, a collection of orbital colonies that form a state. The Fifty Settlements possibly were the basis for the fifty Spacer worlds in the Robot stories. The implication at the end of Nemesis that the inhabitants of the off-Earth colonies are splitting off from Earthbound humans could also be connected to a similar implication about the Spacers in Mark W. Tiedemann's Robot books. According to Alasdair Wilkins, in a discussion posted on Gizmodo, "Asimov absolutely loves weird, elliptical structures. All three of his non-robot/Foundation science fiction novels — The End of Eternity, The Gods Themselves, and Nemesis — leaned heavily on non-chronological narratives, and he does it with gusto in The Gods Themselves."

In The Robots of Dawn, Dr. Han Fastolfe briefly summarizes the story from The Positronic Man (1992) or "The Bicentennial Man" (1976) in a conversation with Elijah Baley.

Asimov's novels set in the greater Robot/Empire/Foundation universe

The following novels are listed in chronological order by narrative:

  1. I, Robot (1950) - a fixup novel composed of 9 short stories about robots, set in the 21st century on Earth
  2. The Positronic Man (1992) - a standalone robot novel, co-written with Robert Silverberg, based on Asimov's 1976 novelette "The Bicentennial Man", set from the 22nd to 24th centuries
  3. Nemesis (1989) - a standalone novel, set in the 23rd century in a star system about 2 light years from Earth, when interstellar travel was new
  4. The Caves of Steel (1954) - first Robot Series/R. Daneel Olivaw novel, set in the 35th century on Earth
  5. The Naked Sun (1957) - second Robot Series/R. Daneel Olivaw novel, set in the 35th century on the Spacer planet Solaria
  6. The Robots of Dawn (1983) - third Robot Series/R. Daneel Olivaw novel, set in the 35th century on the Spacer planet Aurora
  7. Robots and Empire (1985) - fourth Robot Series/R. Daneel Olivaw novel, set in the 37th century on Earth, Solaria, Aurora, and Baleyworld
  8. The Stars, Like Dust (1951) - first Empire Series novel, set thousands of years in the future before the founding of a Galactic Empire
  9. The Currents of Space (1952) - second Empire Series novel, set thousands of years in the future during Trantor's unification of the galaxy into a Galactic Empire
  10. Pebble in the Sky (1950) - third Empire Series novel, primarily set thousands of years in the future on Earth, when the galaxy is unified into a Galactic Empire
  11. Prelude to Foundation (1988) - first Foundation Series novel
  12. Forward the Foundation (1993) - second Foundation Series novel
  13. Foundation (1951) - third Foundation Series novel
  14. Foundation and Empire (1952) - fourth Foundation Series novel
  15. Second Foundation (1953) - fifth Foundation Series novel
  16. Foundation's Edge (1982) - sixth Foundation Series novel
  17. Foundation and Earth (1986) - seventh Foundation Series novel
  18. The End of Eternity (1955) - a standalone novel, about Eternity, an organization "outside time" which aims to improve human happiness by altering history

Other authors contributing to the expanded series

Asimov's novels covered only 500 of the expected 1,000 years it would take for the Foundation to become a galactic empire. The novels written after Asimov did not continue the timeline but rather sought to fill in gaps in the earlier stories. The Foundation universe was once again revisited in 1989's Foundation's Friends, a collection of short stories written by many prominent science fiction authors of that time. Orson Scott Card's "The Originist" clarifies the founding of the Second Foundation shortly after Seldon's death; Harry Turtledove's "Trantor Falls" tells of the efforts by the Second Foundation to survive during the sacking of Trantor, the imperial capital and Second Foundation's home; and George Zebrowski's "Foundation's Conscience" is about the efforts of a historian to document Seldon's work following the rise of the Second Galactic Empire.

Also, shortly before his death in 1992, Asimov approved an outline for three novels by Roger MacBride Allen, known as the Caliban trilogy, set between Robots and Empire and the Empire series. The Caliban trilogy describes the terraforming of the Spacer world Inferno, a planet where an ecological crisis forces the Spacers to abandon many long-cherished parts of their culture. Allen's novels echo the uncertainties that Asimov's later books express about the Three Laws of Robotics, and in particular the way a thoroughly roboticized culture can degrade human initiative.

After Asimov's death and at the request of Janet Asimov and the Asimov estate's representative, Ralph Vicinanza approached Gregory Benford and asked him to write another Foundation story. He eventually agreed, and with Vicinanza and after speaking "to several authors about [the] project", formed a plan for a trilogy with "two hard SF writers broadly influenced by Asimov and of unchallenged technical ability: Greg Bear and David Brin." Foundation's Fear (1997) takes place chronologically between part one and part two of Asimov's second prequel novel, Forward the Foundation; Foundation and Chaos (1998) is set at the same time as the first chapter of Foundation, filling in background; Foundation's Triumph (1999) covers ground following the recording of the holographic messages to the Foundation, and ties together a number of loose ends. These books are now claimed by some to collectively be a "Second Foundation trilogy", although they are inserts into pre-existing prequels and some of the earlier Foundation storylines and not generally recognized as a new Trilogy.

In an epilogue to Foundation's Triumph, Brin noted he could imagine himself or a different author writing another sequel to add to Foundation's Triumph, feeling that Hari Seldon's story was not yet necessarily finished. He later published a possible start of such a book on his website.

More recently, the Asimov estate authorized publication of another trilogy of robot mysteries by Mark W. Tiedemann. These novels, which take place several years before Asimov's Robots and Empire, are Mirage (2000), Chimera (2001), and Aurora (2002). These were followed by yet another robot mystery, Alexander C. Irvine's Have Robot, Will Travel (2004), set five years after the Tiedemann trilogy.

In 2001, Donald Kingsbury published the novel Psychohistorical Crisis, set in the Foundation universe after the start of the Second Empire.

Novels by various authors (Isaac Asimov's Robot City, Robots and Aliens and Robots in Time series) are loosely connected to the Robot series, but contain many inconsistencies with Asimov's books, and are not generally considered part of the Foundation series.

In November 2009, the Isaac Asimov estate announced the publication of a prequel to I, Robot under the working title Robots and Chaos, the first volume in a prequel trilogy featuring Susan Calvin by fantasy author Mickey Zucker Reichert. The first book was published in November 2011 under the title I, Robot: To Protect, followed by I, Robot: To Obey in 2013 and I, Robot: To Preserve in 2016.

Wednesday, October 6, 2021

Atmosphere of Venus

Atmosphere of Venus
Venus
Cloud structure in Venus's atmosphere in 1979,
revealed by ultraviolet observations from Pioneer Venus Orbiter
General information
Height250 km (160 mi)
Average surface pressure93 bar (1,350 psi)
Mass4.8 × 1020 kg
Composition
Carbon dioxide96.5 %
Nitrogen3.5 %
Sulfur dioxide150 ppm
Argon70 ppm
Water vapor20 ppm
Carbon monoxide17 ppm
Helium12 ppm
Neon7 ppm
Hydrogen chloride0.1–0.6 ppm
Hydrogen fluoride0.001–0.005 ppm

The atmosphere of Venus is the layer of gases surrounding Venus. It is composed primarily of carbon dioxide and is much denser and hotter than that of Earth. The temperature at the surface is 740 K (467 °C, 872 °F), and the pressure is 93 bar (1,350 psi), roughly the pressure found 900 m (3,000 ft) underwater on Earth. The Venusian atmosphere supports opaque clouds of sulfuric acid, making optical Earth-based and orbital observation of the surface impossible. Information about the topography has been obtained exclusively by radar imaging. Aside from carbon dioxide, the other main component is nitrogen. Other chemical compounds are present only in trace amounts.

Aside from the very surface layers, the atmosphere is in a state of vigorous circulation. The upper layer of troposphere exhibits a phenomenon of super-rotation, in which the atmosphere circles the planet in just four Earth days, much faster than the planet's sidereal day of 243 days. The winds supporting super-rotation blow at a speed of 100 m/s (≈360 km/h or 220 mph) or more. Winds move at up to 60 times the speed of the planet's rotation, while Earth's fastest winds are only 10% to 20% rotation speed. On the other hand, the wind speed becomes increasingly slower as the elevation from the surface decreases, with the breeze barely reaching the speed of 10 km/h (2.8 m/s) on the surface. Near the poles are anticyclonic structures called polar vortices. Each vortex is double-eyed and shows a characteristic S-shaped pattern of clouds. Above there is an intermediate layer of mesosphere which separates the troposphere from the thermosphere. The thermosphere is also characterized by strong circulation, but very different in its nature—the gases heated and partially ionized by sunlight in the sunlit hemisphere migrate to the dark hemisphere where they recombine and downwell.

Unlike Earth, Venus lacks a magnetic field. Its ionosphere separates the atmosphere from outer space and the solar wind. This ionized layer excludes the solar magnetic field, giving Venus a distinct magnetic environment. This is considered Venus's induced magnetosphere. Lighter gases, including water vapour, are continuously blown away by the solar wind through the induced magnetotail. It is speculated that the atmosphere of Venus up to around 4 billion years ago was more like that of the Earth with liquid water on the surface. A runaway greenhouse effect may have been caused by the evaporation of the surface water and subsequent rise of the levels of other greenhouse gases.

Despite the harsh conditions on the surface, the atmospheric pressure and temperature at about 50 km to 65 km above the surface of the planet is nearly the same as that of the Earth, making its upper atmosphere the most Earth-like area in the Solar System, even more so than the surface of Mars. Due to the similarity in pressure and temperature and the fact that breathable air (21% oxygen, 78% nitrogen) is a lifting gas on Venus in the same way that helium is a lifting gas on Earth, the upper atmosphere has been proposed as a location for both exploration and colonization.

History

Mikhail Lomonosov was the first person to hypothesize the existence of an atmosphere on Venus, based on his observation of the transit of Venus of 1761 in a small observatory near his house in Saint Petersburg, Russia.

Structure and composition

Composition

Composition of the atmosphere of Venus. The chart on the right is an expanded view of the trace elements that all together do not even make up a tenth of a percent.

The atmosphere of Venus is composed of 96.5% carbon dioxide, 3.5% nitrogen, and traces of other gases, most notably sulfur dioxide. The amount of nitrogen in the atmosphere is relatively small compared to the amount of carbon dioxide, but because the atmosphere is so much thicker than that on Earth, its total nitrogen content is roughly four times higher than Earth's, even though on Earth nitrogen makes up about 78% of the atmosphere.

The atmosphere contains a range of compounds in small quantities, including some based on hydrogen, such as hydrogen chloride (HCl) and hydrogen fluoride (HF). There is carbon monoxide, water vapour and atomic oxygen as well. Hydrogen is in relatively short supply in the Venusian atmosphere. A large amount of the planet's hydrogen is theorised to have been lost to space, with the remainder being mostly bound up in sulfuric acid (H2SO4). The loss of significant amounts of hydrogen is proven by a very high D–H ratio measured in the Venusian atmosphere. The ratio is about 0.015–0.025, which is 100–150 times higher than the terrestrial value of 1.6×10−4. According to some measurements, in the upper atmosphere of Venus D/H ratio is 1.5 higher than in the bulk atmosphere.

Phosphine

In 2020 there was considerable discussion regarding whether phosphine (PH3) might be present in trace amounts Venus' atmosphere. This would be noteworthy as phosphine is a potential biomarker indicating the presence of life. This was prompted by an announcement in September 2020, that this species had been detected in trace amounts. No known abiotic source present on Venus could produce phosphine in the quantities detected. On review an interpolation error was discovered that resulting in multiple spurious spectroscopic lines, including the spectral feature of phosphine. Re-analysis of data with the fixed algorithm either do not result in the detection of the phosphine or detected it with much lower concentration of 1 ppb.

The announcement promoted re-analysis of Pioneer Venus data which found part of chlorine and all of hydrogen sulfide spectral features are instead phosphine-related, meaning lower than thought concentration of chlorine and non-detection of hydrogen sulfide. Another re-analysis of archived infrared spectral measurements by the NASA Infrared Telescope Facility in 2015 did not reveal any phosphine in Venusian atmosphere, placing an upper limit for phosphine concentration at 5 ppb—a quarter of the spectroscopic value reported in September.

Troposphere

Comparison of Atmosphere Compositions – Venus, Mars, Earth (past and present).

The atmosphere is divided into a number of sections depending on altitude. The densest part of the atmosphere, the troposphere, begins at the surface and extends upwards to 65 km. At the furnace-like surface the winds are slow, but at the top of the troposphere the temperature and pressure reaches Earth-like levels and clouds pick up speed to 100 m/s (360 km/h).

1761 drawing by Mikhail Lomonosov in his work on the discovery of atmosphere of Venus

The atmospheric pressure at the surface of Venus is about 92 times that of the Earth, similar to the pressure found 900 m (3,000 ft) below the surface of the ocean. The atmosphere has a mass of 4.8×1020 kg, about 93 times the mass of the Earth's total atmosphere. The density of the air at the surface is 67 kg/m3, which is 6.5% that of liquid water on Earth. The pressure found on Venus's surface is high enough that the carbon dioxide is technically no longer a gas, but a supercritical fluid. This supercritical carbon dioxide forms a kind of sea that covers the entire surface of Venus. This sea of supercritical carbon dioxide transfers heat very efficiently, buffering the temperature changes between night and day (which last 56 terrestrial days).

The large amount of CO2 in the atmosphere together with water vapour and sulfur dioxide create a strong greenhouse effect, trapping solar energy and raising the surface temperature to around 740 K (467 °C), hotter than any other planet in the Solar System, even that of Mercury despite being located farther out from the Sun and receiving only 25% of the solar energy (per unit area) Mercury does. The average temperature on the surface is above the melting points of lead (600 K, 327 °C), tin (505 K, 232 °C), and zinc (693 K, 420 °C). The thick troposphere also makes the difference in temperature between the day and night side small, even though the slow retrograde rotation of the planet causes a single solar day to last 116.5 Earth days. The surface of Venus spends 58.3 days in darkness before the sun rises again behind the clouds.

Atmosphere 
Venusatmosphere.svg
Height
(km)
Temp.
(°C)
Atmospheric
pressure
(atm)
0 462 92.10
5 424 66.65
10 385 47.39
15 348 33.04
20 306 22.52
25 264 14.93
30 222 9.851
35 180 5.917
40 143 3.501
45 110 1.979
50 75 1.066
55 27 0.5314
60 −10 0.2357
65 −30 0.09765
70 −43 0.03690
80 −76 0.004760
90 −104 0.0003736
100 −112 0.00002660

The troposphere on Venus contains 99% of the atmosphere by mass. Ninety percent of the atmosphere of Venus is within 28 km of the surface; by comparison, 90% of the atmosphere of Earth is within 10 km of the surface. At a height of 50 km the atmospheric pressure is approximately equal to that at the surface of Earth. On the night side of Venus clouds can still be found at 80 km above the surface.

The altitude of the troposphere most similar to Earth is near the tropopause—the boundary between troposphere and mesosphere. It is located slightly above 50 km. According to measurements by the Magellan and Venus Express probes, the altitude from 52.5 to 54 km has a temperature between 293 K (20 °C) and 310 K (37 °C), and the altitude at 49.5 km above the surface is where the pressure becomes the same as Earth at sea level. As manned ships sent to Venus would be able to compensate for differences in temperature to a certain extent, anywhere from about 50 to 54 km or so above the surface would be the easiest altitude in which to base an exploration or colony, where the temperature would be in the crucial "liquid water" range of 273 K (0 °C) to 323 K (50 °C) and the air pressure the same as habitable regions of Earth. As CO2 is heavier than air, the colony's air (nitrogen and oxygen) could keep the structure floating at that altitude like a dirigible.

Circulation

The circulation in Venus's troposphere follows the so-called cyclostrophic flow. Its windspeeds are roughly determined by the balance of the pressure gradient and centrifugal forces in almost purely zonal flow. In contrast, the circulation in the Earth's atmosphere is governed by the geostrophic balance. Venus's windspeeds can be directly measured only in the upper troposphere (tropopause), between 60–70 km, altitude, which corresponds to the upper cloud deck. The cloud motion is usually observed in the ultraviolet part of the spectrum, where the contrast between clouds is the highest. The linear wind speeds at this level are about 100 ± 10 m/s at lower than 50° latitude. They are retrograde in the sense that they blow in the direction of the retrograde rotation of the planet. The winds quickly decrease towards the higher latitudes, eventually reaching zero at the poles. Such strong cloud-top winds cause a phenomenon known as the super-rotation of the atmosphere. In other words, these high-speed winds circle the whole planet faster than the planet itself rotates. The super-rotation on Venus is differential, which means that the equatorial troposphere super-rotates more slowly than the troposphere at the midlatitudes. The winds also have a strong vertical gradient. They decline deep in the troposphere with the rate of 3 m/s per km. The winds near the surface of Venus are much slower than that on Earth. They actually move at only a few kilometres per hour (generally less than 2 m/s and with an average of 0.3 to 1.0 m/s), but due to the high density of the atmosphere at the surface, this is still enough to transport dust and small stones across the surface, much like a slow-moving current of water.

Meridional (north-south) component of the atmospheric circulation in the atmosphere of Venus. Note that the meridional circulation is much lower than the zonal circulation, which transports heat between the day and night sides of the planet

All winds on Venus are ultimately driven by convection. Hot air rises in the equatorial zone, where solar heating is concentrated and flows to the poles. Such an almost-planetwide overturning of the troposphere is called Hadley circulation. However, the meridional air motions are much slower than zonal winds. The poleward limit of the planet-wide Hadley cell on Venus is near ±60° latitudes. Here air starts to descend and returns to the equator below the clouds. This interpretation is supported by the distribution of the carbon monoxide, which is also concentrated in the vicinity of ±60° latitudes. Poleward of the Hadley cell a different pattern of circulation is observed. In the latitude range 60°–70° cold polar collars exist. They are characterized by temperatures about 30–40 K lower than in the upper troposphere at nearby latitudes. The lower temperature is probably caused by the upwelling of the air in them and by the resulting adiabatic cooling. Such an interpretation is supported by the denser and higher clouds in the collars. The clouds lie at 70–72 km altitude in the collars—about 5 km higher than at the poles and low latitudes. A connection may exist between the cold collars and high-speed midlatitude jets in which winds blow as fast as 140 m/s. Such jets are a natural consequence of the Hadley-type circulation and should exist on Venus between 55–60° latitude.

Odd structures known as polar vortices lie within the cold polar collars. They are giant hurricane-like storms four times larger than their terrestrial analogs. Each vortex has two "eyes"—the centres of rotation, which are connected by distinct S-shaped cloud structures. Such double eyed structures are also called polar dipoles. Vortices rotate with the period of about 3 days in the direction of general super-rotation of the atmosphere. The linear wind speeds are 35–50 m/s near their outer edges and zero at the poles. The temperature at the cloud-tops in each polar vortex is much higher than in the nearby polar collars, reaching 250 K (−23 °C). The conventional interpretation of the polar vortices is that they are anticyclones with downwelling in the centre and upwelling in the cold polar collars. This type of circulation resembles a winter polar anticyclonic vortex on Earth, especially the one found over Antarctica. The observations in the various infrared atmospheric windows indicate that the anticyclonic circulation observed near the poles penetrates as deep as to 50 km altitude, i.e. to the base of the clouds. The polar upper troposphere and mesosphere are extremely dynamic; large bright clouds may appear and disappear over the space of a few hours. One such event was observed by Venus Express between 9 and 13 January 2007, when the south polar region became brighter by 30%. This event was probably caused by an injection of sulfur dioxide into the mesosphere, which then condensed, forming a bright haze. The two eyes in the vortices have yet to be explained.

False colour near-infrared (2.3 μm) image of the deep atmosphere of Venus obtained by Galileo. The dark spots are clouds silhouetted against the very hot lower atmosphere emitting thermal infrared radiation.

The first vortex on Venus was discovered at the north pole by the Pioneer Venus mission in 1978. A discovery of the second large 'double-eyed' vortex at the south pole of Venus was made in the summer of 2006 by Venus Express, which came with no surprise.

Images from the Akatsuki orbiter revealed something similar to jet stream winds in the low and middle cloud region, which extends from 45 to 60 kilometers in altitude. The wind speed maximized near the equator. In September 2017 JAXA scientists named this phenomenon 'Venusian equatorial jet'.

Upper atmosphere and ionosphere

The mesosphere of Venus extends from 65 km to 120 km in height, and the thermosphere begins at approximately 120 km, eventually reaching the upper limit of the atmosphere (exosphere) at about 220 to 350 km. The exosphere begins when the atmosphere becomes so thin that the average number of collisions per air molecule is less than one.

The mesosphere of Venus can be divided into two layers: the lower one between 62–73 km and the upper one between 73–95 km. In the first layer the temperature is nearly constant at 230 K (−43 °C). This layer coincides with the upper cloud deck. In the second layer, the temperature starts to decrease again, reaching about 165 K (−108 °C) at the altitude of 95 km, where mesopause begins. It is the coldest part of the Venusian dayside atmosphere. In the dayside mesopause, which serves as a boundary between the mesosphere and thermosphere and is located between 95–120 km, temperature increases to a constant—about 300–400 K (27–127 °C)—value prevalent in the thermosphere. In contrast, the nightside Venusian thermosphere is the coldest place on Venus with temperature as low as 100 K (−173 °C). It is even called a cryosphere.

The circulation patterns in the upper mesosphere and thermosphere of Venus are completely different from those in the lower atmosphere. At altitudes 90–150 km the Venusian air moves from the dayside to nightside of the planet, with upwelling over sunlit hemisphere and downwelling over dark hemisphere. The downwelling over the nightside causes adiabatic heating of the air, which forms a warm layer in the nightside mesosphere at the altitudes 90–120 km. The temperature of this layer—230 K (−43 °C)—is far higher than the typical temperature found in the nightside thermosphere—100 K (−173 °C). The air circulated from the dayside also carries oxygen atoms, which after recombination form excited molecules of oxygen in the long-lived singlet state (1Δg), which then relax and emit infrared radiation at the wavelength 1.27 μm. This radiation from the altitude range 90–100 km is often observed from the ground and spacecraft. The nightside upper mesosphere and thermosphere of Venus is also the source of non-local thermodynamic equilibrium emissions of CO2 and nitric oxide molecules, which are responsible for the low temperature of the nightside thermosphere.

The Venus Express probe has shown through stellar occultation that the atmospheric haze extends much further up on the night side than the day side. On the day side the cloud deck has a thickness of 20 km and extends up to about 65 km, whereas on the night side the cloud deck in the form of a thick haze reaches up to 90 km in altitude—well into mesosphere, continuing even further to 105 km as a more transparent haze. In 2011, the spacecraft discovered that Venus has a thin ozone layer at an altitude of 100 km.

Venus has an extended ionosphere located at altitudes 120–300 km. The ionosphere almost coincides with the thermosphere. The high levels of the ionization are maintained only over the dayside of the planet. Over the nightside the concentration of the electrons is almost zero. The ionosphere of Venus consists of three layers: v1 between 120 and 130 km, v2 between 140 and 160 km and v3 between 200 and 250 km. There may be an additional layer near 180 km. The maximum electron volume density (number of electrons in a unit of volume) of 3×1011 m−3 is reached in the v2 layer near the subsolar point. The upper boundary of the ionosphere (the ionopause) is located at altitudes 220–375 km and separates the plasma of the planetary origin from that of the induced magnetosphere. The main ionic species in the v1 and v2 layers is O2+ ion, whereas the v3 layer consists of O+ ions. The ionospheric plasma is observed to be in motion; solar photoionization on the dayside and ion recombination on the nightside are the processes mainly responsible for accelerating the plasma to the observed velocities. The plasma flow appears to be sufficient to maintain the nightside ionosphere at or near the observed median level of ion densities.

Induced magnetosphere

Venus interacts with the solar wind. Components of the induced magnetosphere are shown.

Venus is known not to have a magnetic field. The reason for its absence is not at all clear, but it may be related to a reduced intensity of convection in the Venusian mantle. Venus only has an induced magnetosphere formed by the Sun's magnetic field carried by the solar wind. This process can be understood as the field lines wrapping around an obstacle—Venus in this case. The induced magnetosphere of Venus has a bow shock, magnetosheath, magnetopause and magnetotail with the current sheet.

At the subsolar point the bow shock stands 1900 km (0.3 Rv, where Rv is the radius of Venus) above the surface of Venus. This distance was measured in 2007 near the solar activity minimum. Near the solar activity maximum it can be several times further from the planet. The magnetopause is located at the altitude of 300 km. The upper boundary of the ionosphere (ionopause) is near 250 km. Between the magnetopause and ionopause there exists a magnetic barrier—a local enhancement of the magnetic field, which prevents the solar plasma from penetrating deeper into the Venusian atmosphere, at least near solar activity minimum. The magnetic field in the barrier reaches up to 40 nT. The magnetotail continues up to ten radii from the planet. It is the most active part of the Venusian magnetosphere. There are reconnection events and particle acceleration in the tail. The energies of electrons and ions in the magnetotail are around 100 eV and 1000 eV respectively.

Due to the lack of the intrinsic magnetic field on Venus, the solar wind penetrates relatively deep into the planetary exosphere and causes substantial atmosphere loss. The loss happens mainly via the magnetotail. Currently the main ion types being lost are O+, H+ and He+. The ratio of hydrogen to oxygen losses is around 2 (i.e. almost stoichiometric) indicating the ongoing loss of water.

Clouds

Venusian clouds are thick and are composed mainly (75–96%) of sulfuric acid droplets. These clouds obscure the surface of Venus from optical imaging, and reflect about 75% of the sunlight that falls on them. The geometric albedo, a common measure of reflectivity, is the highest of any planet in the Solar System. This high reflectivity potentially enables any probe exploring the cloud tops sufficient solar energy such that solar cells can be fitted anywhere on the craft. The density of the clouds is highly variable with the densest layer at about 48.5 km, reaching 0.1 g/m3 similar to the lower range of cumulonimbus storm clouds on Earth.

The cloud cover is such that typical surface light levels are similar to a partly cloudy day on Earth, around 5000–10000 lux. The equivalent visibility is about three kilometers, but this will likely vary with the wind conditions. Little to no solar energy could conceivably be collected by solar panels on a surface probe. In fact, due to the thick, highly reflective cloud cover, the total solar energy received by the surface of the planet is less than that of the Earth, despite its proximity to the Sun.

Photograph taken by the unmanned Galileo space probe en route to Jupiter in 1990 during a Venus flyby. Smaller-scale cloud features have been emphasized and a bluish hue has been applied to show that it was taken through a violet filter.

Sulfuric acid is produced in the upper atmosphere by the Sun's photochemical action on carbon dioxide, sulfur dioxide, and water vapour. Ultraviolet photons of wavelengths less than 169 nm can photodissociate carbon dioxide into carbon monoxide and monatomic oxygen. Monatomic oxygen is highly reactive; when it reacts with sulfur dioxide, a trace component of the Venusian atmosphere, the result is sulfur trioxide, which can combine with water vapour, another trace component of Venus's atmosphere, to yield sulfuric acid.

CO2CO + O
SO2 + OSO3
2SO3 + 4H2O → 2H2SO4·H2O

Surface level humidity is less than 0.1%. Venus's sulfuric acid rain never reaches the ground, but is evaporated by the heat before reaching the surface in a phenomenon known as virga. It is theorized that early volcanic activity released sulfur into the atmosphere and the high temperatures prevented it from being trapped into solid compounds on the surface as it was on the Earth. Besides sulfuric acid, cloud droplets can contain a wide array of sulfate salts, raising pH of droplet to 1.0 in one of scenarios explaining the sulfur dioxide measurements.

In 2009 a prominent bright spot in the atmosphere was noted by an amateur astronomer and photographed by Venus Express. Its cause is currently unknown, with surface volcanism advanced as a possible explanation.

Lightning

The clouds of Venus may be capable of producing lightning, but the debate is ongoing, with volcanic lightning and sprites also under discussion. The Soviet Venera 9 and 10 orbiters obtained ambiguous optical and electromagnetic evidence of lightning. The European Space Agency's Venus Express in 2007 detected whistler waves which could be attributed to lightning. Their intermittent appearance indicates a pattern associated with weather activity. According to the whistler observations, the lightning rate is at least half of that on Earth, but this is incompatible with data from the JAXA Akatsuki spacecraft which indicate a very low flash rate.

The mechanism generating lightning on Venus, if present, remains unknown. Whilst the sulfuric acid cloud droplets can become charged, the atmosphere may be too electrically conductive for the charge to be sustained, preventing lightning.

Throughout the 1980s, it was thought that the cause of the night-side glow ("ashen glow") on Venus was lightning.

Possibility of life

Due to the harsh conditions on the surface, little of the planet has been explored; in addition to the fact that life as currently understood may not necessarily be the same in other parts of the universe, the extent of the tenacity of life on Earth itself has not yet been shown. Creatures known as extremophiles exist on Earth, preferring extreme habitats. Thermophiles and hyperthermophiles thrive at temperatures reaching above the boiling point of water, acidophiles thrive at a pH level of 3 or below, polyextremophiles can survive a varied number of extreme conditions, and many other types of extremophiles exist on Earth.

The surface temperature of Venus (over 450 °C) is far beyond the extremophile range, which extends only tens of degrees beyond 100 °C. However, the lower temperature of the cloud tops means that life could plausibly exist there, the same way that bacteria have been found living and reproducing in clouds on Earth. Any such bacteria living in the cloud tops, however, would have to be hyper-acidophilic, due to the concentrated sulfuric acid environment. Microbes in the thick, cloudy atmosphere could be protected from solar radiation by the sulfur compounds in the air.

The Venusian atmosphere has been found to be sufficiently out of equilibrium as to require further investigation. Analysis of data from the Venera, Pioneer, and Magellan missions has found hydrogen sulfide (later disputed) and sulfur dioxide (SO2) together in the upper atmosphere, as well as carbonyl sulfide (OCS). The first two gases react with each other, implying that something must produce them. Carbonyl sulfide is difficult to produce inorganically, but it is present in the Venusian atmosphere. However, the planet's volcanism could explain the presence of carbonyl sulfide. In addition, one of the early Venera probes detected large amounts of toxic chlorine just below the Venusian cloud deck.

It has been proposed that microbes at this level could be soaking up ultraviolet light from the Sun as a source of energy, which could be a possible explanation for the "unknown UV absorber" seen as dark patches on UV images of the planet. The existence of this "unknown UV absorber" prompted Carl Sagan to publish an article in 1963 proposing the hypothesis of microorganisms in the upper atmosphere as the agent absorbing the UV light. In 2012, the abundance and vertical distribution of these unknown ultraviolet absorbers in the Venusian atmosphere have been investigated from analysis of Venus Monitoring Camera images, but their composition is still unknown. In 2016, disulfur dioxide was identified as a possible candidate for causing the so far unknown UV absorption of the Venusian atmosphere. The dark patches of "unknown UV absorbers" are prominent enough to influence the weather on Venus. In 2021, it was suggested the color of "unknown UV absorber" match that of "red oil" - a known substance comprising a mixed organic carbon compounds dissolved in concentrated sulfuric acid.

In September 2020, research studies led by Cardiff University using the James Clerk Maxwell and ALMA radio telescopes noted the detection of phosphine in Venus's atmosphere that was not linked to any known abiotic method of production present, or possible under Venusian conditions. It is extremely hard to make, and the chemistry in the Venusian clouds should destroy the molecules before they could accumulate to the observed amounts. The phosphine was detected at heights of at least 48 km above the surface of Venus, and was detected primarily at mid-latitudes with none detected at the poles of Venus. Scientists note that the detection itself could be further verified beyond the use of multiple telescopes detecting the same signal, as the phosphine fingerprint described in the study could theoretically be a false signal introduced by the telescopes or by data processing. The detection was later suggested to be a false positive or true signal with much over-estimated amplitude, compatible with 1ppb concentration of phosphine. The re-analysis of ALMA dataset in April 2021 have recovered the 20ppb phosphine signal, with signal-to-noise ratio of 5.4, and by August 2021 it was confirmed the suspected contamination by sulfur dioxide was contributing only 10% to the tentative signal in phosphine spectral line band.

Evolution

Through studies of the present cloud structure and geology of the surface, combined with the fact that the luminosity of the Sun has increased by 25% since around 3.8 billion years ago, it is thought that the early environment of Venus was more like that of Earth with liquid water on the surface. At some point in the evolution of Venus, a runaway greenhouse effect occurred, leading to the current greenhouse-dominated atmosphere. The timing of this transition away from Earthlike is not known, but is estimated to have occurred around 4 billion years ago. The runaway greenhouse effect may have been caused by the evaporation of the surface water and the rise of the levels of greenhouse gases that followed. Venus's atmosphere has therefore received a great deal of attention from those studying climate change on Earth.

There are no geologic forms on the planet to suggest the presence of water over the past billion years. However, there is no reason to suppose that Venus was an exception to the processes that formed Earth and gave it its water during its early history, possibly from the original rocks that formed the planet or later on from comets. The common view among research scientists is that water would have existed for about 600 million years on the surface before evaporating, though some such as David Grinspoon believe that up to 2 billion years could also be plausible. This longer timescale for the persistence of oceans is also supported by General Circulation Model simulations incorporating the thermal effects of clouds on an evolving Venusian hydrosphere.

The early Earth during the Hadean eon is believed by most scientists to have had a Venus-like atmosphere, with roughly 100 bar of CO2 and a surface temperature of 230 °C, and possibly even sulfuric acid clouds, until about 4.0 billion years ago, by which time plate tectonics were in full force and together with the early water oceans, removed the CO2 and sulfur from the atmosphere. Early Venus would thus most likely have had water oceans like the Earth, but any plate tectonics would have ended when Venus lost its oceans. Its surface is estimated to be about 500 million years old, so it would not be expected to show evidence of plate tectonics.

Observations and measurement from Earth

Venus transits the face of the Sun on June 8, 2004, providing valuable information on the upper atmosphere through spectroscopic measurements from Earth

In 1761, Russian polymath Mikhail Lomonosov observed an arc of light surrounding the part of Venus off the Sun's disc at the beginning of the egress phase of the transit and concluded that Venus has an atmosphere. In 1940, Rupert Wildt calculated that the amount of CO2 in the Venusian atmosphere would raise surface temperature above the boiling point for water. This was confirmed when Mariner 2 made radiometer measurements of the temperature in 1962. In 1967, Venera 4 confirmed that the atmosphere consisted primarily of carbon dioxide.

The upper atmosphere of Venus can be measured from Earth when the planet crosses the sun in a rare event known as a solar transit. The last solar transit of Venus occurred in 2012. Using quantitative astronomical spectroscopy, scientists were able to analyze sunlight that passed through the planet's atmosphere to reveal chemicals within it. As the technique to analyse light to discover information about a planet's atmosphere only first showed results in 2001, this was the first opportunity to gain conclusive results in this way on the atmosphere of Venus since observation of solar transits began. This solar transit was a rare opportunity considering the lack of information on the atmosphere between 65 and 85 km. The solar transit in 2004 enabled astronomers to gather a large amount of data useful not only in determining the composition of the upper atmosphere of Venus, but also in refining techniques used in searching for extrasolar planets. The atmosphere of mostly CO2, absorbs near-infrared radiation, making it easy to observe. During the 2004 transit, the absorption in the atmosphere as a function of wavelength revealed the properties of the gases at that altitude. The Doppler shift of the gases also enabled wind patterns to be measured.

A solar transit of Venus is an extremely rare event, and the last solar transit of the planet before 2004 was in 1882. The most recent solar transit was in 2012; the next one will not occur until 2117.

Space missions

Recent and current spaceprobes

This image shows Venus in ultraviolet, seen by the Akatsuki mission.

The Venus Express spacecraft formerly in orbit around the planet probed deeper into the atmosphere using infrared imaging spectroscopy in the 1–5 µm spectral range.

The JAXA probe Akatsuki (Venus Climate Orbiter), launched in May 2010, is studying the planet for a period of two years, including the structure and activity of the atmosphere, but it failed to enter Venus orbit in December 2010. A second attempt to achieve orbit succeeded 7 December 2015. Designed specifically to study the planet's climate, Akatsuki is the first meteorology satellite to orbit Venus (the first for a planet other than Earth). One of its five cameras known as the "IR2" will be able to probe the atmosphere of the planet underneath its thick clouds, in addition to its movement and distribution of trace components. With a highly eccentric orbit (periapsis altitude of 400 km and apoapsis of 310,000 km), it will be able to take close-up photographs of the planet, and should also confirm the presence of both active volcanoes as well as lightning.

Venus In-Situ Explorer proposed by NASA's New Frontiers program

Proposed missions

The Venus In-Situ Explorer, proposed by NASA's New Frontiers program is a proposed probe which would aid in understanding the processes on the planet that led to climate change, as well as paving the way towards a later sample return mission.

A craft called the Venus Mobile Explorer has been proposed by the Venus Exploration Analysis Group (VEXAG) to study the composition and isotopic measurements of the surface and the atmosphere, for about 90 days. The mission has not been selected for launch.

After missions discovered the reality of the harsh nature of the planet's surface, attention shifted towards other targets such as Mars. There have been a number of proposed missions afterward, however, and many of these involve the little-known upper atmosphere. The Soviet Vega program in 1985 dropped two balloons into the atmosphere, but these were battery-powered and lasted for only about two Earth days each before running out of power. Since then, there has been no exploration of the upper atmosphere. In 2002, the NASA contractor Global Aerospace proposed a balloon that would be capable of staying in the upper atmosphere for hundreds of Earth days as opposed to two.

A solar flyer has also been proposed by Geoffrey A. Landis in place of a balloon, and the idea has been featured from time to time since the early 2000s. Venus has a high albedo, and reflects most of the sunlight that shines on it making the surface quite dark, the upper atmosphere at 60 km has an upward solar intensity of 90%, meaning that solar panels on both the top and the bottom of a craft could be used with nearly equal efficiency. In addition to this, the slightly lower gravity, high air pressure and slow rotation allowing for perpetual solar power make this part of the planet ideal for exploration. The proposed flyer would operate best at an altitude where sunlight, air pressure, and wind speed would enable it to remain in the air perpetually, with slight dips down to lower altitudes for a few hours at a time before returning to higher altitudes. As sulfuric acid in the clouds at this height is not a threat for a properly shielded craft, this so-called "solar flyer" would be able to measure the area in between 45 km and 60 km indefinitely, for however long it takes for mechanical error or unforeseen problems to cause it to fail. Landis also proposed that rovers similar to Spirit and Opportunity could possibly explore the surface, with the difference being that Venus surface rovers would be "dumb" rovers controlled by radio signals from computers located in the flyer above, only requiring parts such as motors and transistors to withstand the surface conditions, but not weaker parts involved in microelectronics that could not be made resistant to the heat, pressure and acidic conditions.

Russian space science plans include the launch of the Venera-D (Venus-D) probe in 2029. The main scientific goals of the Venera-D mission are investigation of the structure and chemical composition of the atmosphere and investigation of the upper atmosphere, ionosphere, electrical activity, magnetosphere, and escape rate. It has been proposed to fly together with Venera-D an inflatable aircraft designed by Northrop Grumman, called Venus Atmospheric Maneuverable Platform (VAMP).

The High Altitude Venus Operational Concept (HAVOC) is a NASA concept for a manned exploration of Venus. Rather than traditional landings, it would send crews into the upper atmosphere, using dirigibles. Other proposals from the late 2010s include VERITAS, Venus Origins Explorer, VISAGE, and VICI. In June 2018, NASA also awarded a contract to Black Swift Technologies for a concept study of a Venus glider that would exploit wind shear for lift and speed.

Artist's concept of the planned DAVINCI+ probe's descent stages through Venus' atomosphere

In June 2021, NASA selected the DAVINCI+ mission to send an atmospheric probe to Venus in the late 2020s. DAVINCI+ will measure the composition of Venus’ atmosphere to understand how it formed and evolved, as well as determine whether the planet ever had an ocean. The mission consists of a descent sphere that will plunge through the planet’s thick atmosphere, making measurements of noble gases and other elements to understand Venus’ climate change. This will be the first U.S.-led mission to Venus’ atmosphere since 1978.

 

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