By Mark Savage
Entertainment reporter, BBC News
When Star Trek: Enterprise came to an end in 2005, many fans were left wondering where they would get their regular fix of the science fiction series.
For many, the answer lay on the internet - where fans have taken on the task of continuing the show in dozens of different productions.
The most prominent of these "fan films" is Star Trek: Hidden Frontier, which has so far produced 46 episodes over seven seasons.
Filmed entirely by volunteers, it draws on characters and events from the official series - but has gained notoriety for its controversial storylines.
The programme is set in the Briar Patch, a chaotic area of space introduced in the ninth Star Trek movie, Insurrection, and has a cast of almost 50 actors - all working for free.
Hidden Frontier was created by Rob Caves, who also acts as cameraman, boom operator, scriptwriter, animator and editor on the show.
"It started back in 2000," he recalls. "I was at film school at Loyola Marymount University in Los Angeles and I met some other Star Trek fans that wanted to start up a project.
"We had a Star Trek club in the area that wanted to help out and we got some actors from that.
All of the backgrounds are created on computer after filming
"Los Angeles is very well known for actors wanting to get their break, so we also got a lot of people who would work for free."
With cast and crew assembled, the team began the process of filming their first episodes.
But a limited budget meant they could not afford the expensive sets and locations of a real television series.
The solution was to shoot everything against a green screen in a garage, with the backgrounds added later using computer graphics.
Actress Risha Denney, who plays Capt Elizabeth Shelby on the show, remembers the early shoots as being "a lot smaller, a lot more cramped and a lot more difficult" than they are today.
"Even though we've got more technical - with longer shoots, more language and more props - it's got a lot easier because we know each other and we're set in out ways now."
The team's growing confidence has also allowed them to tackle controversial issues in the programme.
Most notably, they introduced an openly gay character, Lt Corey Aster, in the second season of the programme.
Hidden Frontier portrayed the first gay kiss in Star Trek history
Played by JT Tepnapa, who is also one of the show's co-producers, Lt Aster was the first Star Trek character to have a gay kiss on screen.
"We decided pretty early on that, because we were doing a show that didn't have any direct studio connections, we'd try and do things that Star Trek hadn't done," says Caves.
"One of our actors had clinical depression and so there was a story written about that.
"We told stories that had gay characters, or you had commentary on 9/11."
The episode discussing the repercussions of September 11 2001 featured a Star Trek security council implementing new anti-terror laws.
"That was kind of a way to talk about some of the things that I guess we are concerned with in our day and age - about how to protect us from terrorism without losing freedom," says Caves.
"The science fiction setting is perfect for telling stories without hitting people over the head with them."
It takes between four and six weeks to make one episode of Hidden Frontier, and new programmes are released on the show's website as soon as they are finished.
Risha Denney plays Capt Elizabeth Shelby on the show
Around 50,000 episodes are downloaded for free every month, and more than 2,000 people regularly contribute to the website's forum pages.
Risha Denney says she has even been recognised for her role in the programme.
"I've not had anyone walk up to me," she says, "but some people realise after 20 to 30 minutes of conversation that they've seen me on internet".
Denney says the series has also acted as a calling-card for Hollywood.
"Some of more well-liked characters ended up leaving because they got parts elsewhere."
"And if I was still pursuing acting actively it would help me a lot."
Caves says the programme has helped him make contacts in the film industry, and he has met several producers "to discuss projects to do when Hidden Frontier is over".
There are about 50 actors in the cast of Hidden Frontier
However, he says he has no plans to abandon the series just yet.
"Hollywood is very much set up so you'll be working for a while then you won't be working, so it's good practice to be doing something regularly."
Indeed, Caves would encourage other people to make their own tribute films.
"Everything you need to do on a fan film now you can do on a home computer," he says.
"It's not break-the-bank kind of expensive, but if you're going to start up a fan film you do need a few thousand dollars to get started.
"But for fans of the show it's an incredible thing to be able to play in the sandbox."