Zero-X is a fictional Earth spacecraft that first appeared in two of Gerry and Sylvia Anderson's Supermarionation productions, the film Thunderbirds Are Go (1966) and the television series Captain Scarlet and the Mysterons.

They separate from the main body when the craft is at a sufficiently high altitude and fly back to base; on re-entry, they rendezvous with the spacecraft and dock with it to again act as wings and provide propulsion in the atmosphere.

On reaching Mars, the MEV detaches from the main body, which is left in orbit piloted by a single astronaut, and descends towards the planet's surface.

[1] The first crewed mission to Mars ends in failure after the Zero-X is accidentally sabotaged by The Hood, who has stowed away on the craft to photograph its wing mechanisms.

Although the crew escape, the lifting body control systems on the MEV take damage during the confrontation, causing the Zero-X to malfunction on its return to Earth.

The craft crashes into Craigsville, United States (roughly 20 miles from its launch site, the fictitious Glenn Field Spaceport).

A series featuring the adventures of the crew of the Zero-X appeared in TV Century 21 comic[5][10] and its successors, including Countdown.

The stories follow the "Mark III" Zero-X spacecraft as it explores the other planets of the Solar System before pushing on into interstellar space.

International Rescue attempts to recover the Zero-X escape capsule, believing it to be the key to understanding how Tracy survived and his current situation.

He also regards the brevity of the Martian landing as a plot hole: "After spending, presumably, many years and billions of dollars mounting this expedition to Mars, all they get for their effort is a couple of hours driving around on the surface."

[15] Stephen La Rivière calls Zero-X "the star of Thunderbirds Are Go", praising Meddings' design and acknowledging its commercial nature: "... cynics would suggest that the various detachable segments (wings and nose cone) had less to do with the storyline and more to do with potential toy manufacturing!

He believes that with the attention to detail given to the various stages of the craft's assembly and take-off, these scenes constitute "launch sequence porn", elaborating: "It's a bunch of people effectively saying, 'Action?

'"[18] The Los Angeles Times comments that the launch is presented "with the ritual deliberation of a Greek Orthodox mass",[19] while website Entertainment Focus calls the sequence "meticulous" and "foreshadowing a mechanical ballet which would define [2001].