At the Seibertron website:
http://www.seibertron.com/transforme...skyfire/18350/

Dark Skyfire bio
In an era millions of years before the establishment of the Destron faction’s army, he operated in the same organization as Skyfire. Specialized for outer space exploration, his entire body is coated with a substance that protects it against unknown viruses, magnetic storms, and the like. Although he has a strong scientific curiosity, he agonizes over it being at odds with his great combat skills.