Star Trek: Deep Space Nine is now twenty years old. The first episode aired on 3 January 1993, whilst The Next Generation was still on the air, and it was for 176 episodes over seven seasons, ending in May 1999.
Deep Space Nine was originally dismissed as the unwanted stepchild of the Star Trek franchise. After a brief eruption of press surrounding its start, it was soon overshadowed by the end of The Next Generation, the release of the first Next Generation movie (Generations) and the arrival of Star Trek: Voyager. However, in the years since DS9's conclusion, it has been critically reappraised and is now often widely cited as the best of the six Star Trek television series.
Deep Space Nine was the result of a conversation in 1991 between Brandon Tartikoff (the then-head of Paramount Television) and The Next Generation producer-showrunners Michael Pillar and Rick Berman, whilst TNG was in its fourth season. With TNG expected to end after six years (it ultimately ended after seven), Paramount was keen to expand the franchise and keep the name going through a new show that would initially air alongside TNG and then take over from it afterwards. Tartikoff himself suggested that if both the original series and TNG were, in Gene Roddenberry's Western analogy, "Wagon Train to the stars," then the new show could be "The Rifleman in space." Rather than being based around space travel and exploration - an area TNG was already handling well - the new show would be set in one location and would deal with the characters exploring issues in greater depth.
Pillar and Berman developed the premise even further. They initially discussed a planetside starbase but realised the costs of location filming for every episode would soon become ruinous. They instead settled on a space station as the main setting. They also decided to use a non-Federation station, feeling this would force the characters to solve problems through ingenuity rather than the superior technology of Starfleet. They also decided to explore some of the races and situations established in TNG rather than relying on old Star Trek stand-bys like the Klingons and Romulans. In particular, the Ferengi and Cardassians of TNG were to be explored in much greater depth than on TNG and a new culture, the Bajorans, was introduced as well (with enough forewarning that their backstory could be established on TNG a year before DS9 aired).
Despite initial plans to not involve space exploration as a major theme, the writers changed their minds and established that a stable wormhole was located in the Bajoran system, linking Federation territory to the Gamma Quadrant on the far side of the Galaxy. This allowed them to explore unknown space or have new aliens arriving on DS9 whilst still retaining a static setting.
For their cast of characters, the producers cast Avery Brooks as Commander Sisko, a survivor of the Battle of Wolf 359 on TNG. Arguably the most professional military commander of the various Star Trek characters, Brooks played Sisko as reserved in command but also a man of deeply-held convictions, a strong family man and also a man with a dry sense of humour. In particular, Sisko was much more of a rule-bender than Picard ever was, feeling the ends often justified the means (most devastatingly in the sixth season episode In the Pale Moonlight, which may just feature the most amoral act ever performed by a main character in Star Trek's history). Backing him up was a considerably more dysfunctional crew than any seen before or since in Star Trek: Nana Visitor as terrorist-turned-solider Kira Nerys; Siddig El Fadil as the arrogant-genius Dr. Bashir; Rene Auberjonois as the shapechanging security chief Odo; Terry Farrell as Lt. Dax (a 28-year-old woman with the memories of a 300-year-old slug living in her abdomen); Cirroc Lofton as Sisko's son Jake; and Armin Shimerman as the station's resident Ferengi barkeep Quark. In addition, Colm Meaney's character of Chief Miles O'Brien was transferred over from TNG (and promoted to the main cast).
It would be fair to say that, like its forebear, DS9 took a while to find its feet. Early episodes focused on the Bajoran political-religious situation and tended to over-emphasise TNG characters and situations (the Duras sisters, Lwaxana Troi, Q and Vash all appeared in DS9's first season). The results were episodes that were often very well-made - and certainly DS9's first season wipes the floor with TNG's first two seasons - but tended to be a little too safe, too neat and too traditional. A notable exception was the episode Duet, a morally complex story which packed genuine emotional power. The second season saw the show adopt more of its own identity, relaxing on the Bajoran stuff (after the opening trilogy) and instead hinting at an enigmatic new threat on the horizon called 'the Dominion'. In the second season finale, the Dominion was revealed to be an anti-Federation, an alliance of several powerful races in the Gamma Quadrant that viewed the Federation as a distinct threat.
DS9 took a big step forwards in the third season. Writer Ira Steven Behr was promoted to showrunner following Michael Pillar's departure and immediately began steering the show away from technobabble solutions to episodes in favour of more human drama. Rules banning holodeck malfunction episodes were put in place. Another important addition was the arrival of Ronald D. Moore from TNG writing team and the addition of a starship permanently stationed at DS9, the Defiant. The third season focused on the cold war between the Federation and the Dominion, with the threat represented by the Dominion becoming pressing. This culminated in the two-part storyline Improbable Cause/The Die is Cast, in which the Dominion destroyed a large portion of the Romulan and Cardassian fleets, vowing that the Federation and Klingons would be next.
For Season 4, the DS9 production crew was ordered to shake up the show in some fashion. A new title sequence was adopted, Sisko was promoted to full captain (in the Season 3 finale) and Michael Dorn was brought on board to reprise his TNG character of Worf. The writers decided to follow up on the Dominion threat in the previous season by having the Dominion orchestrate a split between the Federation and Klingons, leading to a state of near-war between the two sides for most of the season. Whilst successful and highly popular with the fans, the writers did feel this took them off where they were planning to go. In Season 5 they arranged a rapprochement between the two sides just in time for the outbreak of full scale war against the Dominion at the end of the season. This war lasted until the final episode of the series.
Whilst the Dominion War, and the years of cold war leading up to it, are often considered to be DS9's primary storyline, the show's actual main plot centred on the fact that Sisko was 'the Emissary', a Bajoran religious figure with a connection to their gods, the Prophets. In fact, the Prophets turned out to be ultra-advanced aliens living in the wormhole, but who still considered Sisko to be bound to them. Sisko's arc over the seven seasons would see him initially rejecting but later embracing his role as the Prophet. Similarly, Sisko's Cardassian opposite, Gul Dukat (Marc Alaimo), would transform over the course of the series from an antagonistic villain to a semi-ally to ultimately Sisko's nemesis, and serving as his equivalent amongst the Pah-Wraiths, a group of 'evil' Prophets. This story arc, though sometimes risking cheese, was well-handled by the writers and actors and gave the show a dramatic spine which began in the pilot and concluded satisfactorily in the final episode of the series, giving the series a coherent, overall storyline and direction that none of the other Star Trek series possessed. Given that this arc was unplanned and was handled by many different writers over the course of seven seasons, the fact it ended up being as cohesive and solid as it did is impressive.
After DS9 ended the cast and crew went on to other things. Most notably, a lot of them regrouped four years later for the 'new' (or I suppose we should be saying now, 'newer') Battlestar Galactica. Ronald D. Moore was the main showrunner and brought on board DS9 writers David Weddle, Bradley Thompson, Michael Taylor and Jane Espenson (Ira Steven Behr was busy on The 4400). Like DS9, the new BSG was darker and more cynical than its parent series, more willing to challenge audience assumptions, kill off characters and feature long-running storylines. Ultimately, however, BSG's story arc collapsed under a morass of unanswered questions and incoherent storytelling. This indicated that DS9 had been lucky to get away with telling a long-running, multi-year arc with almost no forward planning (and DS9's arc had never been quite as intricate as the storyline BSG set up anyway).
Deep Space Nine should be applauded for many things, including the most reliably consistent standard of storytelling, directing and acting across the various Star Trek series. It had very, very few unwatchably awful episodes and several that must rank amongst the very best episodes that Star Trek as a whole has ever produced: In the Pale Moonlight, Trials and Tribble-ations, The Visitor, In Purgatory's Shadow/By Inferno's Light, Call to Arms and Far Beyond the Stars. By Star Trek standards, the show was relatively gritty and hard-hitting. Relatively major characters died (though only one amongst the regular cast), major Star Trek planets were devastated and most of the final two seasons were dedicated to a gruelling war which exposed the idealism of the Federation as being worth fighting for, but also perhaps somewhat naive in the face of some threats (though the revelation of the existence of the Defiant-class warships and Section 31 showed that the Federation wasn't perhaps quite as toothless as had been thought).
The show generally maintained an optimistic outlook, however, and did not descend into outright bleakness, despite coming closer than any other Trek show (particularly in the amazingly depressing Siege of AR-558). On the flipside the show did comedy better than any of the other shows and in the Odo-Quark relationship had perhaps the most intriguing and well-developed character relationship in the history of the franchise. It also featured the most complex and layered recurring Star Trek character ever, with Andrew Robinson's portrayal of Garak being nothing short of genius. DS9 was also unusual in having a regular, recurring cast of villains including Marc Alaimo's Dukat, Casey Biggs' Damar, Salome Jens's female changeling and, most memorably, Jeffrey Combs's Weyoun. Weyoun may be Star Trek's most amiably entertaining villain, a diplomat with the spiel of a smooth used-car salesman backed up by the most ferocious fighting force in the Galaxy. His ability to ponder the aesthetic value of a painting whilst simultaneously discussing the execution of terrorist suspects was both amusing and chilling.
Deep Space Nine is available in full on DVD right now. A Blu-Ray release, with the show fully remastered in HD, is planned for when the re-relase of TNG is completed. Based on the timescale for that, I expect DS9 will start appearing in that format in late 2015.