"Turtles from Outer Space" makes it sound like that half-ased Muppets movie from about 10 years ago, where Muppets/Disney tried to pull off that Gonzo was really an alien, and that his race really WAS from outer space.
In the *0's Turtles, and the 2000's Turtles, most fans either forget or overlook that the thing or creating factor of the Turtles was an outside source, which was from outer space/another dimension.
In the 80's Turtles, Shredder got the mutagen from krang, who originated from Dimension X. In the 2000's Turtles, the mutagen was a by-product created by the Utrom, a race of highly intelligent, slug-like creatures, who were transporting a psychotically evil member of their species, who became Shredder.
So, there's always been an outside or alien influence on the Turtles. It was mostly relegated to exposition, though, for most of the series.