Formed in England in 1969, UFO began as a hard rocking outfit with plenty of emphasis on space-rock and riff-heavy boogie. Their first two albums bore a passing resemblance to early Deep Purple with a healthy dose of the space-metal of Hawkwind mixed in. These early albums found great success in Japan, France and Germany, but met with general indifference in their native country and the United States. A third live album, which was released exclusively in Japan, showed the band to be an engaging act onstage, but did little toward increasing their exposure. In June of 1973, all this took a turn for the better, when teenager Michael Schenker of the German metal band Scorpions permanently joined the group on guitar. Although Schenker spoke not a word of English, his guitar playing sensibilities communicated plenty with the core band members and it was during this time that UFO's music really began to jell.
The first two albums to feature Schenker on guitar—Phenomenon and Force It—represented a change in sound for UFO. Although a bit of their space-rock sound remained on these albums, this was clearly a transitional period. UFO were forging ahead into new territory, creating original music that in retrospect, can now be seen as a bridge between hard rock and early heavy metal. With Schenker on board, the group picked up a harder-edged, guitar-driven sound, and the tracks have a raw immediacy that the more sterilized album versions lack. Cited as a primary influence by the likes of Kirk Hammett of Metallica, Steve Harris of Iron Maiden, and Dave Mustaine of Megadeth, this era of UFO was certainly a precursor to the 1980s heavy metal scene.
UFO disbanded in 1988 but reformed only four years later. The new incarnation does not feature Schenker, who originally quit the band in 1978. They continue to tour and release albums.