The Helius was a transport ship designed to carry human colonists to Mars to set up a colony on the planet. While transporting a group of families, the ship was caught in a proton storm, resulting in all systems going offline. The ship missed Mars and was headed towards an asteroid belt when Thunderbird 3 arrived with the aid of Captain Lee Taylor. During the rescue the ship lost its landing pods after nearly colliding with a large asteroid which also damaged it's oxygen supply. Unable to return to Earth, the ship had to make a forced landing on Mars.
- An identical ship can be seen in the later episode Long Haul.