Science fiction is a strange beast. If you believed everything you read, it could either be the most inventive literary genre ever, or a worthless pool of mindless trash. In fact, it's both, depending on the author (occasionally, with true genius, simultaneously). SF sinks to its deepest depths - and achieves some of its greatest moments - on the TV, in the cinema, and on your computer screen. In the first of three articles, we delve into science fiction on the box. Thanks to videos, satellite and cable, many of the older shows are around again. If you like SF, take a trip down memory lane - if you thought it wasn't for you, sample one or two of my recommendations: you may be surprised.

For television, science fiction has been an excuse to scare - the boundaries between SF and horror are weaker here than anywhere else. In this brief tour I can only touch on some personal favourites and recognised milestones - there are plenty more. I have intentionally left out animations, partly because I can't stand them and also because the proliferation of near-SF childrens' programmes makes it a topic in its own right. There's probably too heavy a bias towards UK subjects - but that's life. Rather than show a small selection of pictures from the series, there are links to sites dripping with them.

Early TV drama was given a mysterious, misty quality by the limited technology, ideal for the darker recesses of SF. On the other hand, much of the production was live, which didn't leave much room for special effects and trickery. That didn't seem to matter in the 1954 broadcast of George Orwell's 1984 (a mere six years after the book was written). Seen today, the production is mild and the images fuzzy, but at the time Peter Cushing's despair as Winston Smith and the shocking negativity of the story was enough for questions to be asked in the British Parliament about the suitability of the programme. Despite, or perhaps because of this, the second performance four days later had a significantly bigger audience.

More typical of TV SF was Nigel Kneale's Quatermass , shown the previous year. This six part series was to spawn three sequels, and told of the dangers of space travel, when an early astronaut returns contaminated, turning into a huge destructive vegetable. There are reminders of the film The Thing that had hit the movie screens in 1951. Here too a space vegetable was on the rampage, though in this case it was more like a mobile carrot than the 100 foot high root vegetable that troubled Quatermass. The monster was finally electrocuted in Westminster Abbey by the eponymous hero of the piece, Professor Bernard Quatermass. If the script seems to creak, the special effects are hilarious - yet at the time Quatermass made a big impact, persuading TV makers that science fiction could sell in the same way that Star Wars would encourage a whole flood of space movies.

By comparison, the early efforts of the US studios were considerably more solid in appearance, if less scary. A good example would be The Adventures of Superman . Compared with recent excursions onto the screen, these were decidedly hammy, but for 1952 (the show ran to six seasons in all), the special effects were a little more convincing. As stories these were not in the same class as the UK series, lying somewhere between a western and a police saga.Inevitably, bearing in mind the comic book origins, the baddies were particularly two dimensional. Sadly, George Reeves, the actor who was Superman for so many viewers, became so typecast that he couldn't get work after the series finished, finally shooting himself.

The 60s brought a dramatic change in TV science fiction. Perhaps it's because this was my own childhood period, but there seems something rather special about it. This was a time when children throughout the UK delighted in being frightened from behind the couch, watching scary programs through the cracks - why and when the practice died out, I'm not sure: perhaps it was the end of innocence for humanity.

The original seasons of The Twilight Zone ushered in the new era. This was crisper story telling; an adventurous series of one-off episodes that ranged from pure fantasy to hard SF, from pathos to humour. In comparison with other early productions, Twilight Zone remains watchable and often intelligent, even if the acting sometimes leaves a little to be desired. Rod Serling's format was recreated in the 80s, but the result didn't even come up to pale shadow standards. In fact, another early series probably best picked up the Twilight Zone baton - The Outer Limits . Again a set of single stories was presented with strong scripts and reasonably high quality production values that resulted in a programme that can be watched to this day without wincing.

SF had not disappeared this side of the Atlantic. The BBC launched a new title in 1963 that was to appear on our screens (with gaps) over the next 33 years - Doctor Who . This was the definitive "behind the couch" programme, aimed at a family audience, and with a remit to both educate and scare. Looking back at the early productions, the acting could sometimes be as wooden as the props, but there was something exciting and mysterious about the show that still comes across. One of the big plusses in Dr Who's favour was the wide-open format. The ability to travel anywhere in time and space gave the writers the whole span of history and SF to roam.

To begin with, stories alternated between the "educational" historical sagas and trips into the future introducing a string of alien monsters, beginning with the unforgettable Daleks. The historical episodes disappeared in later seasons, as for a while did the future when the third doctor, the late lamented Jon Pertwee, was consigned to current day Earth (it didn't really matter - the monsters came to him, as England suffered more extra-terrestrial invasions in a few years than ever before or since). Here was another strength of the programme - generally a series lasted as long as the actor playing the principle character. By allowing regeneration, a string of actors could bring their own, individual interpretation, never more individual than with the fourth Doctor, Tom Baker, who brought much more humour to the part. The Baker period saw more horror elements in the show, causing much wailing from the self-appointed watchdogs of TV standards.

With increasing years, Dr Who became quite technically sophisticated, but it could never match US special effects and eventually became a victim of the BBC's difficulties with how to classify it. Extremely popular video releases and a one-off TV movie this year keep the show alive - but who knows what the future will hold (allegedly).

Only three years later, another show premiered. If the concept was less sophisticated - a Western in space - the delivery was much more polished than Dr Who: colour from the beginning and using sets and special effects that were in a different league. Star Trek's original episodes do look dated now, but they're much more watchable than early Dr Who. Although the original show was terminated after three seasons, it never went away, as repeat showings carried it through until it made the breakthrough to the big screen and then back to the TV for the various follow-ons.

The concept of boldly going (in itself a landmark split infinitive) where no man (or no-one as it became in the more politically correct Next Generation) had gone before left plenty of room for different types of adventure, and though the all-in-one episode had less opportunity for plot development than Dr Who's stories, which in the early days could span as many as 10 episodes, the large continuing cast encouraged characters to blossom.

Where Star Trek differed from many early SF shows was in showing a positive picture of the future. Okay, it may have been a future too narrowly extrapolated from present day USA (with a spot of 19th century naval tradition thrown in), but it was the sort of future you wanted to be in, not the hell of 1984.

There's one peculiar breed of TV science fiction that's worth a mention - puppet shows. Although I'm not covering animation, these were a strange, halfway house. In those early days, because special effects were so difficult, the thought of making a scaled-down production with model actors must have seemed quite attractive. Whatever the reason, we were happy to watch a set of big-headed puppets whose acting skills were inherently wooden. The Andersons , responsible for most of the shows, had some early attempts, but the genre really came into being in 1963 with Roberta Leigh's Space Patrol and the Gerry and Sylvia Anderson's Fireball XL5 .

Space Patrol had a strange, fey feel to it, more a child of the flying saucer than the rocket science that fuelled most of the Andersons' work, but both series were essentially cops in space. The Anderson line continued with a string of successes including Thunderbirds and Captain Scarlet, before moving into live action productions such as UFO and Space Precinct, though many would say that it's only with this latest series that the acting changed much.

From the earliest days, written Science fiction has had a strong vein of humour. This has rarely emerged in the movies (with exceptions like the best-forgotten Morons from Outer Space) and is relatively uncommon on the small screen. When it has got there, however, there have been some surprising successes - none more so than Mork and Mindy. A spin-off of the popular Happy Days, Mork and Mindy was essentially a showcase for the talents of Robin Williams, without which it would be long forgotten. It could be relentlessly mawkish, and downright silly, but Williams' drive and hysteria carried it along into the history books.

The Hitchhiker's Guide to the Galaxy was also a sort of spin-off. Originally a superb radio series from the hand of Douglas Adams, it became a best-selling set of books and then this never quite satisfactory TV outing. That's a bit unfair though - at its best it was excellent, but it never managed to be quite as funny as the other versions. Still, the (not computer generated) computer graphics are entrancing and many of the elements that make this a unique foray into SF humour remain hilarious.

The long service award has to go to Red Dwarf . Beginning with the unpromising premise of the last man alive stuck on a huge mining ship, the result has been an explosion of ideas and jokes that has gone from strength to strength in later seasons. The interplay between the four principal characters - said human, an evolved cat, a hologram of the world's most irritating person and a desperate-to-please android is simply brilliant, with gags flooding in at every level from the subtle to the blatant. There was an attempt at a US version, but it proved that the raw edges, inevitably rubbed off when crossing the Atlantic, were the lifeblood of Red Dwarf.

Like the movies, TV science fiction was highly influenced by Star Wars. Initially the response was simple copying, like the tedious Battlestar Galactica , but soon the TV was running shows with effects that would not look out of place on the big screen.

Pride of place has to go to the Star Trek family . With a total of three spin-off series to date, Star Trek has been followed by The Next Generation , Deep Space Nine and Voyager . Of these, the first is arguably the most successful, maintaining the free-roaming nature of the original and the widest range of storylines. DS9's confinement to a space station has proved restricting, though it allowed for more soap opera style development of character. Voyager too is constrained by the underlying need to get home from their original disaster, and is generally regarded as having the weakest scripts of the Star Trek world.

Star Trek is not alone, though. Babylon 5 takes on a similar theme to DS9, but improves upon it. Equally, Lois and Clark (aka The New Adventures of Superman) does a good job of dragging the Superman myth into the 90s. How much its success is down to the witty storylines and how much to giving the part of Lois Lane to Terri Hatcher , probably the most pictured woman on the web, is open to debate. The fact remains it has proved to be one of those shows that manages to appeal to a full family audience, back to the attraction of the early Doctor Who.

In a very different vein, mention must also go to the superb X-Files . By combining two attractive elements - paranormal research and anti-government conspiracy theories - with a pair of strong lead players, X-Files became a near-instant success. Constantly walking the tightrope between SF and horror - some of the science is decidedly shaky - X-Files succeeds by keeping up a constant tension. It's perhaps no coincidence that Sculley is reminiscent of the Jodie Foster character in Silence of The Lambs, because the X-Files employs a very similar approach of constantly twanging the guts - and it works.

A surprising quantity of written science fiction is sophisticated, aimed very much at an adult audience. At the movies and on the TV, the target is rarely anything more than the average teenager. At least films could venture into the steamier side of SF and discover sex in space, but the box in the corner of the sitting room was generally not allowed this option.

Of the series already mentioned, X-Files is probably the most sophisticated, but there have been other worthy contenders over the years. Often these have been based on 'real science fiction' - existing books and short stories. Probably the most extravagant attempt was the three TV movies that made up the Martian Chronicles.

Once upon a time, movie posters carried headlines like "the book they said could never be filmed" - if there truly is such a book, it is probably Ray Bradbury's Martian Chronicles. This is a complex, allegorical fantasy - Bradbury never intended it to be real - a series of mystical short stories involving Mars. To film three of these stories was a noble endeavour, but one that was almost inevitably doomed to failure. It would be hard to say who was more confused, the actors or the audience.

For me, the best of the lot was a little-publicised BBC series called Out of the Unknown. It looks dated now, but still packs a punch in four seasons from the late 60s and early 70s. Many of the totally unconnected, one-off episodes are based on excellent SF short stories - the one that particularly sticks in my mind is The Little Black Bag, based on a Cyril Kornbluth story of a future medical kit that is accidentally brought back to the present and is used not to save lives, but for cosmetic surgery. But there were many more beauties, all performed on a relatively low budget but with the gritty edge of a play.

A final plaudit should go to a pair of dramas that appeared in the 80s BBC "straight" series, Play for Today. The Flip Side of Dominick Hide and its sequel featured a time traveller from an aseptic future, let loose in our world. It's a funny and uplifting play, with an appeal that's centred around Dominick's bewilderment at the unfamiliar, raucous aspects of 20th century life. I'm not sure why it worked so well - but it did.

TV science fiction is currently riding high, with more high budget series than ever - an indicator of the popularity is the way that the UK listings magazine Radio Times has dedicated a page to the subject. At its best, TV science fiction has a subtlety that the big screen could never emulate. But the movies have one huge advantage. Seeing the Star Wars destroyer fly overhead on the TV is faintly interesting. Seeing it on a huge movie screen with enough power in the speakers to shake the building is awesome. In the next part of this series I'll be looking at SF in the cinema.