- "He's still at it, poor fellow. Seems to be under some delusion that he's in charge of the rescue."
— Allington Bridge Controller
A severe electrical storm weakens the Allington Suspension Bridge, causing it to collapse when the Martian Space Probe convoy tries to cross it - sending the massive rocket itself, and its crew of two technicians, crashing down into the river below. Worse - the rocket's impact with the riverbed triggers the automatic onboard launch countdown, which cannot be stopped! International Rescue - summoned by an unexpected source - answers the call and must get those men out, before the now-rogue rocket launches itself - to certain annihilation...
- Main article: Day Of Disaster/Storyline
- Main article: Day of Disaster/Transcript
International Rescue Equipment Used
Non-International Rescue Equipment Used
- Thunderbird 4 makes its second appearance of the series, in this episode.
This episode was released on a 8mm home movie, produced by "Arrow films" (1965)
- Weirdly, during the time lapse when the Martian Space Probe is trapped underwater for 12 hours, daylight doesn't turn into night.
- French: Le pont
- German: Zwölf Stunden Angst
- Spanish: Día desastroso
- Italian: Attesa per il lancio del razzo sonda
- Dutch: Operatie marsraket (TV 1966); Een rampzalige dag (TV 1991); Dag des onheils (VHS, DVD)
- Japanese: 火星ロケットの危機