Vegatron is a radioactive ore found on Planet Vega. The Vegan Empire uses it for construction of their weapons including the Saucer Beasts, with the radiation being used as its power source. However, the mining and overuse of Vegatron caused the planet to become unstable, causing the Empire to seek out new worlds to conquer. Eventually, the radiation caused a disaster resulting in the planet's destruction.
In terms of defense, alloys of Vegatron are much stronger than steel and are resistant to conventional Earth weaponry. Weaponry from the Vegatron blades and the radiation the Vegatron gives off is highly hazardous to environments. When against forces such as the Space Alloy Gren constructed Grendizer, the armor is less effective but weapons can still damage the giant robot on a minor level. Vegatron radiation also reacts very badly with proton radiation, causing dangerous reactions that could kill a person.