This song, along with Under the Bridge, are the best songs the Chili Peppers have ever done.
I don't think the reference to space is Bowie-related at all. By saying it was fabricated in a "Hollywood basement," the reference is clearly to various conspiracy-buff theories that the moon walk never happened on the moon, but was filmed in Hollywood to dupe the public.
I think the reference to Kurt Cobain is due to the fact that the perils of fame, wealth and stardom hastened his demise. Cobain was clearly unhappy being what he had become, and he destroyed himself in the desperation to get away from the image he felt he had to uphold and the pressures of success. By asking Cobain if he can "hear the spheres singing songs off Station to Station," perhaps Keidis is wondering out loud whether Cobain might have escaped his lowest point if he just didn't give in to it and take his life. Bowie's life was in disarray around the time of Station to Station, yet somehow he survived it--he used his music to expell all the pain, anger, insecurity, and pain that Cobain ended with suicide. As Brian Eno once told Bowie, "music is where you can crash your plane and walk away from it." So Bowie used his art to express his dispair--to experiment, and whether the experiment worked or failed, he could walk away from it to experiment another day. Cobain was not placated by channeling his pain into his art, and thus walked away from life itself.
But then when Keidis closes the verse about Cobain and Station to Station with "And Alderanís not far away, itís Californication," he seems to be expressing a very glass-is-half-empty view. In the end, even if artists deal with their pain through their art, the "doomed planet" is still not far away. But this time the doomed planet is Earth. It's going to Hell in a handbasket--and taking all of its people (artists included) with it.