Dependendo do que você considera um "ataque alfa", é necessário voltar até " Uma verdadeira história " por Lucian de Samosata no século II.
O Rei da Lua e o Rei do Sol estão lutando pelo direito de colonizar Júpiter. O Rei da Lua constrói uma teia gigante no espaço que bloqueia os raios do Sol, tornando o planeta inabitável.
As for us, we were taken off to the sun that day, our hands tied behind our backs with a section of spider-web. The enemy decided not to lay siege to the city, but on their way back they built a wall through the air, so that the rays of the sun should no longer reach the moon. The wall was double, made of cloud, so that a genuine eclipse of the moon took place, and she was completely enshrouded in unbroken night.
Caso contrário, o conceito de destruição planetária (do espaço / com armas nucleares) remonta pelo menos até 1951:
"This discussion is interesting, but futile," put in Eichlan, forestalling a scornful reply. "It is more to the point, I think, to discuss that which must be done; or, rather, who is to do it, since the thing itself admits of only one solution—an atomic bomb of sufficient power to destroy every trace of life upon that accursed planet.
E. "Doc" Smith (1951), Gray Lensman