It's grim down south. Suicidally so on the remote escarpment of lunar terrain where the Dungeness nuclear reactor hums its menacing mantra out across beaches in a lonely corner of Britain.

But who is that emerging from the colourless void of bleakness? Two humanoid life forms strangely oblivious to high-speed horizontal rain transformed into icy splinters by a skin-splitting wind chill factor. This ain't no party, this ain't no disco, and extra-terrestrial electro duo Orbital certainly aren't fooling around.

Clambering back into their transport module which cleverly assumes the innocent form of an unmarked minibus - we glide past row upon row of gaily-painted shed-like dwellings strikingly similar to David Bowie's bonkers spaceship in The Man Who Fell To Earth. Derek Jarman lives in one of these, which might explain why all his films are so strange. Hundreds of these misshapen igloos huddle around the hulking power station, but not a living soul stirs. Illogical, Captain.

It was a great idea on the drawing board. Spend a day cataloguing the motorway junctions of exotic Kent with two of its grooviest sons. Scoot down the M25 (which gave Orbital their fantastic name) visit their home studio in their native Sevenoaks, motor down to Dungeness with a nine-hour remix of Kraftwerk's 'Autobahn' tumbling ironically from the stereo . . .

So far so mental. But plans to photograph these twin peaks of sci-fi Techno inside the vast and alarmingly shoddy-looking power station - a conceptual link with their blistering collection of remixes entitled 'Mutations' -are instantly blocked by The Man, who demands written permission secured two weeks in advance. Your name's not down, you're not coming in.

Junior Orby Paul Hartnoll - 23, with fractionally the longer hair of the duo - must content himself testing his new mini-recorder inside the Dungeness propaganda. . . erm, information centre, sampling Geiger-counter clicks and reassuring voiceovers by Michael 'Screen Test ' Rodd insisting a Chernobyl-style meltdown could absolutely never in a million years happen here because of something called a "Positive Void Coefficient". Which makes everyone feel a lot safer.

Outside the heavy, Auschwitz-style perimeter fence, Paul records mechanised belches from a robot-manned lighthouse while older brother Phil - 27, and the most amiable skinhead you could ever meet - expresses deep unease about standing in the belly of the beast. Ground Control to major discomfort.

Phil was a skinhead proper in his youth "for about six months" before realising his Anti-Nazi tattoo and love of Trojan reggae was earning him few friends amongst the crop-topped Cro-Magnon's of Sevenoaks. These days, he sighs, his bristled bonce is more a response to creeping baldness. Hartnoll and Hartnoll, it swiftly transpires, are top geezers.

Orbital are so far off the map they virtually collapse in on themselves and form a black hole where Planet Pop used to be. They are musical cousins of Slartibartfast from The Hitch-Hiker's Guide To The Galaxy, the geezer who customised crinkly coastlines in comfortable isolation for years before fickle fashion showered him with awards, fair-weather friends and critical hysteria... then promptly consigned him to obscurity once more.

Well, not quite. Phil and Paul nonchalantly accept they are no longer hot news to the self-appointed arbiters of dancefloor style - the sort of toxic slime any sane person would cross entire solar systems to avoid, after all - but Orbital were bleeping and blooping long before Acid went Techno and will still be tweaking and twiddling when rave culture opportunists start claiming that, hey, there's always been a Peruvian pan-pipe element to their music.

Paul recalls "making music before the term House was around. We were listening to New Order and Divine, a lot of Hi-NRG, Cabaret Voltaire, Kraftwerk . . . we were just lucky, the sort of thing we were doing became popular". He allies himself more with disco oddballs like Midi Rain and J Saul Kane - "The people that, if this scene all finished, it's not going to mean anything to them anyway" - than any blatantly commercial hands-in-the-air merchants.

Phil admits premature success often destroys bands, and Orbital's memorably static appearance on Top Of The Pops when their 'Chime' single hit Number 17 was more down to discomfort than any avant-garde anti-fame statement.

"I like modern dance music, but there's a lot of rubbish out there. I never think in terms of being a rave act, my thoughts are one day to start getting into film soundtracks," shrugs Paul.

Which makes perfect sense. Phil describes Orbital 's unique brand of ambient Techno as "journey music" and 'Mutations' certainly covers several thousand square miles of moody moonscape. Especially since it has been "dimensionally enhanced" by a mysterious black box borrowed from London radio station Kiss FM, which blasts its widescreen proportions far beyond the flat, tinny Dungeness of most dance musk production.

Paul grew up reading science fiction and cites Star Trek: The Next Generation as a major influence on Orbital's planet of sound. while Phil mumbles something about "the mystery of space". Hmmmm. Behind their knowing image and deadpan humour, perhaps the pair really are men who fell to Earth? Why is their Sevenoaks studio plastered with corn-circle paraphernalia? Is it really just spooky coincidence that they (almost) share a surname with the first Doctor Who?

" I get a bit paranoid sometimes," confesses Phil, drawing baffled looks from the citizens of sleepy Romney. "I might look like I've come from another planet, but I'm probably quite normal . . . "

Hanging out in Australia over New Year. where they played to 4,000 Techno-mental Aussie ravers, the brothers planned to make a video documentary about the mountain hippy communes of Nimbin, only to have their tapes burnt in strong-arm eviction moves by fascist police and local rednecks. "One of the policemen said 'You lot should be shot like the f---ing Abbos'! " spits a disgusted Paul.

But the mellow atmosphere in Sydney persuaded him Britain's rave scene has reached the upper ceiling of its Positive Void Coefficient. "We decided we're not going to do any more dodgy old raves, full of people who don't know what they're hanging around for, they've paid 15 quid to get in and it's just musically banal."

Nowadays the duo are highly selective about live shows, but fleet-footed readers may have caught them at 2000AD's 15th birthday bash at London's Camden Palace last week. If you missed out, you can see them giving peace a dance at the North London CND rave on March 21.

Orbital - they come in peace to save our ailing planet from screaming nuclear death and crap pop music. And for a handful of your paltry Earth pounds, anyone can share the lavishly detailed explorations of inner space offered by their manically mutating sound. Watch the skies ....