(covers information from several alternate timelines)
The "Badlands" was a region of space located in Sector 04-70 of the Alpha Quadrant. A segment of the border between the United Federation of Planets and the Cardassian Union was located in this region.
The Badlands were known for intense plasma storms and gravitational anomalies. Additionally, in the late 2360s, a few ships had disappeared in this region. For these reasons, it was commonly avoided by most interstellar traffic. (DS9: "The Maquis, Part I")
During the Cardassian occupation of Bajor, the Bajoran Resistance frequently used the Badlands as a refuge from Cardassian patrols. Because of the severely limited sensor ranges in the area, the Bajorans used echolocation techniques to navigate and detect other ships. (DS9: "Starship Down")
Because of its strategic location inside the Demilitarized Zone between Cardassian and Federation space, the Badlands became a favorite hiding place and staging area for the Maquis during their insurrection against Cardassian control from 2370 to 2373.
In their first major operations, the Maquis took the kidnapped Gul Dukat to a class M asteroid in the Badlands. (DS9: "The Maquis, Part I") When Thomas Riker and a Maquis cell hijacked the USS Defiant from Deep Space 9 in 2371, they piloted the Defiant to the Badlands to rendezvous with other Maquis attack ships prior to launching an assault on Cardassian space. (DS9: "Defiant")
Around stardate 48300, the Caretaker abducted several starships from the Badlands, including a Maquis raider piloted by Chakotay, and the Federation starship USS Voyager, which had been sent to track Chakotay. (VOY: "Caretaker") The Vetar was also abducted from the Badlands around the same time. (VOY: "The Voyager Conspiracy")
Bajoran trader Razka Karn also hid out in the Badlands when the Tholians were pursuing him for some unscrupulous "business" practices. (DS9: "Indiscretion") Kasidy Yates's freighter route between Bajor and Dreon VII often took her close to the Badlands as well. (DS9: "For the Cause")
When the Cardassian Union was annexed by the Dominion in 2373, (DS9: "By Inferno's Light") the remaining Maquis cells that managed to escape the Jem'Hadar took shelter on Athos IV, an abandoned mining colony on the edge of the Badlands. The Maquis sent a disguised distress signal, coded as a confirmation of the launch of a missile strike against Cardassia Prime, to send word to Michael Eddington that the Maquis remnant had survived. Those few survivors were rescued by Starfleet a short time later. (DS9: "Blaze of Glory")
The Badlands remained a strategic location during the Dominion War from 2373 to 2375. Fleet movements in the region required additional escorts to guard against ambushes from inside the plasma storms. (DS9: "Waltz") In 2375, the IKS Koraga was destroyed by the Jem'Hadar near the edge of the Badlands. (DS9: "Penumbra")
The Badlands were conceived during the development of Star Trek: Voyager – to be precise, at some point amid a stretch of two or three days, from 8 or 9 August to 10 August 1993. On the 10th, Jeri Taylor noted, "We posit 'Badlands,' a turbulent area of space where some ships have been lost (some of them might crop up during the series). But it's a hiding place for our bad guys [meaning the crew of Chakotay's Maquis raider], who think they're invulnerable." In notes Taylor dated 17 August 1993, the Badlands were likened to the Bermuda Triangle. It was stated, in a beat outline for VOY premiere "Caretaker", that ships traversing the Badlands had to "maneuver through holes." (A Vision of the Future - Star Trek: Voyager, pp. 186, 190 & 231) In the first draft script for "Caretaker", the Badlands were described as "a huge flailing plasma storm with electromagnetic flares whipping out dangerously like tentacles."
One of the first visual ideas for the Badlands involved a fiery effect. "There were always supposed to be these whirling fires inside the Badlands," explained Gary Hutzel. However, these elements didn't make it to the screen when the region made its first appearance, in "Caretaker". (Star Trek: Deep Space Nine Companion (p. 457))
Since Visual Effects Producer Dan Curry designed the "Caretaker" sequences which were set in the region to involve panning camera moves, the use of nitrogen smoke elements filmed on a soundstage to achieve the look of the Badlands for their initial appearance was deemed too difficult. As a result, a mixture of high-tech and low-tech methods were employed instead, with a computer-generated 3D environment created by Amblin Imaging. "The plasma storm was a combination of CGI and high-speed photography of liquid nitrogen over black velvet," explained Curry. "The CGI vortexes were not working for us as well as we hoped, so we went back in and took liquid nitrogen and mixed it with the CGI elements to give it back some of the organic qualities we were looking for." The elements were painstakingly composited and finessed by editor Don Greenberg at Digital Magic. (Cinefantastique, Vol. 27, No. 4/5, pp. 57-58) Ultimately, the resultant appearance of the Badlands wasn't entirely satisfactory, though. "No one really liked them," noted Gary Hutzel. (Star Trek: Deep Space Nine Companion (p. 420))
When the Badlands began appearing on Star Trek: Deep Space Nine, the visual effects artists didn't know they would be asked to depict the area as frequently as they were. "We didn't think we would be coming so often," Gary Hutzel explained. (Dreamwatch, issue 37, p. 34)
For the reappearance of the Badlands in DS9: "For the Uniform", the DS9 visual effects team depicted the Badlands with a new look. "They'd been reworked a couple times," remembered Gary Hutzel, "but when it fell upon me to do the Badlands for this episode I decided to throw out everything that had been done and start over." The redesign of the roiling plasma fields involved several steps. First, Hutzel's group of VFX artists layed out a twenty-foot-square piece of black velvet on the floor of Image G. They then climbed up into catwalks at the facility, which were eighteen feet above ground, and pails of liquid nitrogen were poured from the high catwalks down on the velvet. "It splattered real good," commented Hutzel, grinning. "We needed that much force to get the violence of the effect." As the liquid nitrogen landed on the velvet, it was filmed at 120 frames per second. (Star Trek: Deep Space Nine Companion (p. 420))
When it came time to create visuals of the Badlands for DS9: "Blaze of Glory", Gary Hutzel decided that the effects footage previously used to represent the area could be improved on. He created the swirling clouds and the suddenly appearing plasma tornadoes, bringing two opposing natural elements together for these effects. (Dreamwatch, issue 37, p. 33)
The plasma tornadoes in "Blaze of Glory" were influenced by demands from the DS9 producers. "The producers began asking, 'Where's our pillars of fire?'" Gary Hutzel relayed. For the effect, Hutzel called on the help of Gary Monak and requested that he create the illusion. Beginning to do so, Monak crafted a box that, at its bottom, had a powerful fan which could create a vortex. He stated, "The boxes were over eight feet tall and we made a couple different kinds to experiment with." Monak also claimed that the "most effective" box, the one that was selected for the effect, was rectangular. (Star Trek: Deep Space Nine Companion (p. 457)) According to Dreamwatch (issue 37, p. 33), however, the box which was used for the effect measured four feet square. The box was made from drywall, painted black, and coated with fireproof material on three sides, with heat-proof glass on the fourth. (Star Trek: Deep Space Nine Companion (p. 457); Dreamwatch, issue 37, p. 33) Noted Monak, "We left one side of the [box] [...] off and filmed through that opening." (Star Trek: Deep Space Nine Companion (p. 457)) To achieve different effects, the team not only left a side of the box open but also subsequently capped the box and a vent was placed on top. Air was sucked in through another vent on the opposite side of the box, which caused the air inside to spiral. (Dreamwatch, issue 37, pp. 33 & 34) "Once we shot some nitrogen in there and got it rotating in a counter-clockwise direction," Monak continued, "we injected fire with a propane burner. The heat made the flame rise so we got this finger of fire going. The hotter we made it, the higher the flame would rise in the box." (Star Trek: Deep Space Nine Companion (p. 457)) Hutzel and his team filmed the blazing propane on Paramount Stage 16, shooting over seven thousand feet of film during one afternoon. The footage was photographed at 250 frames per second. (Dreamwatch, issue 37, p. 33) Once the fiery pillar was filmed, it was an easy task for Hutzel to combine that element with the other Badlands footage he'd already created. (Star Trek: Deep Space Nine Companion (p. 457)) The film was delivered to film-transferrers CIS Hollywood, where it was treated electronically to optimise the highlights, transferred to a digital disc one hundred inches at a time, then shifted onto tape for more post-production work to be done. (Dreamwatch, issue 37, p. 34) The resultant flame effect made its debut in "Blaze of Glory". (Star Trek: Deep Space Nine Companion (p. 457))
The cloud layer of the Badlands was once more created with liquid nitrogen. A day was allocated for the filming of the substance, canisters of which were delivered to Image G, treated with great care by all the visual effects artists there, which included Gary Hutzel. To produce the violent cloud swirls required for the Badlands, the liquid nitrogen was again spilled from a gallery above the Image G stage. The stage surface was firstly pre-chilled with a small amount of nitrogen, poured gently over. On the ground level, Hutzel next talked two assistants, who were in his supervision, through the precise maneuvers he wanted: beginning at the back of the gallery, and letting three shots go, then moving to the front and retreating towards the rear, pouring as they went. Concluding his instructions to the pair of assistants, Hutzel reminded them, "Make sure you're not too close to each other." The two men then ascended to the gallery to practice and, following a couple of dry runs to ensure everyone was synchronized, Hutzel called for action. The two crew members did exactly as he had guided them to do and, as they made their way back to the rear of the gallery, Hutzel ordered the camera to roll, beginning to film the nitrogen. Cameraman Paul Maples, shielding his face from the substance as best he could, captured the shots of the liquid nitrogen while small areas of heat on the stage surface attracted it. Little whirlpools formed, though the majority of the substance billowed out harmlessly into the atmosphere. After filming some footage with light falling on the stage from one side, Hutzel took another series of shots with the light directly behind. The liquid nitrogen footage was additionally treated at CIS Hollywood, enabling its use as an element of "Blaze of Glory" in post-production. (Dreamwatch, issue 37, p. 34)
Although new footage of the Badlands was created for "Blaze of Glory", Gary Hutzel opted to standardize the Badlands from then on, using stock footage. This plan was what caused him to shoot a couple different variations of the liquid nitrogen footage, with the light from various sources. As a result, any subsequent installment that included multiple shots of the Badlands could show different views of the area, rather than constantly having to reuse the same effects footage. Hutzel's decision to capture stock footage of the Badlands was due to how often the area was reappearing on Star Trek: Deep Space Nine. "Now we have generic stuff to use," he concluded. (Dreamwatch, issue 37, p. 34)
From a scientific perspective, using the name "Badlands" for a certain region of space was somewhat realistic. Andre Bormanis stated, "I don't know if that term has ever been used specifically with respect to some astronomical phenomenon, but one could imagine regions of space that would be extremely inhospitable to Human exploration. We see things like this in images that come from telescopes, like the Hubble, all the time, regions of space where you have fierce stellar winds [for instance] [....] So, there are some really extraordinary regions in space that one would be a little bit reckless or foolhardy to fly a spaceship through, even something that has the kind of shielding and engine technology that we've proposed on Star Trek. And again, it's easy to imagine that, someday when there's interstellar travel and they're navigating some of these regions of space, that they might call some particular nebula complex or some place where there are these fierce stellar winds a 'Badlands' kind of a region." (Real Science with Andre Bormanis, VOY Season 1 DVD special feature)
There were some early concerns, first voiced by Eric A. Stillwell, that the Badlands were too similar to the later-invented Briar Patch. At the end of the first outline for the Star Trek film that became Star Trek: Insurrection (in which the Briar Patch was introduced), Michael Piller included a note that informed Rick Berman of this issue. (Fade In: The Making of Star Trek Insurrection)