On September 23, 1999, NASA lost the $125 million Mars Climate Orbiter after a 286-day interplanetary cruise, undone not by cosmic radiation or mechanical failure, but by an unhandled interface bug. Ground-based software written by Lockheed Martin calculated thruster data in imperial pound-force seconds, while NASA’s navigation systems ingested the metrics expecting standard newton-seconds. This quiet discrepancy accumulated over millions of miles, sending the probe plunging to an altitude of just 57 kilometers into the Martian atmosphere—well below its designed survival threshold. The orbiter was promptly incinerated. For the modern tech ecosystem, the mission remains the quintessential cautionary tale of distributed systems integration. It serves as an indelible reminder that even the most ambitious engineering triumphs can be dismantled at the boundaries, where assumptions go unverified and data contracts are ignored.