a vertical rocket-powered ascent in the "classical" manner. In more recent years Virgin Galactic have re-established the concept, providing the first private commercial suborbital spaceflights in a similarly launched vehicle. The Zero-X contrasts in this way with Thunderbird 3, which, though nominally more advanced (hinted at because of its secrecy), is still a vertical-ascent rocket. Zero-X has a total delta velocity of 40 miles per second, a standard acceleration of 1 g, a maximum acceleration of 10 g, and an emergency acceleration of 15 g. It is built by New World Aircraft Corporation, the same company that builds Skyship One. Appearances Thunderbirds Are Go The first crewed mission to Mars ended in failure after the Zero-X spacecraft was accidentally sabotaged by the Hood, who had stowed aboard the craft to photograph its wing mechanisms. The crew managed to escape and two years later a second Zero-X craft successfully reached Mars. However, soon after touching down on the surface, the MEV fired upon a Martian "rock snake" in the belief that it was a lifeless rock formation, provoking retaliation by fire-shooting rock snakes, resulting in the first open combat between humans and extraterrestrials. While the astronauts managed to escape, the lifting body control systems on board the MEV sustained damage during the confrontation, causing the Zero-X to crash upon its return to Earth, landing in Craigsville, United States (roughly 20 miles from its launch site, the fictitious Glenn Field Spaceport). The crew survived, having been saved at the last moment by International Rescue. In both missions, the Zero-X carried a crew of three with two scientists: Paul Travers (captain of the mission) - Travers was modelled on Sean Connery, who was starring as James Bond at the time Thunderbirds Are Go was made. Greg Martin (space captain) Brad Newman (navigator) Dr Tony Grant (astrophysicist) Dr Ray Pierce (astronomer) Captain Scarlet Re-commissioned by the Spectrum Organisation, the Zero-X returned to Mars in 2068 in search of the source of alien signals detected from Earth.(But only the MEV comes into the picture, not the entire Zero-X) The crew's hostile actions led to a "war of nerves" with the Mysterons in Captain Scarlet and the Mysterons. After tracing the signals to an alien city complex, the mission commander, Spectrum officer Captain Black, gave the order to fire upon the facility after mistaking imaging devices for weapons and fearing they were about to be attacked.