THIS DAY IN SPACE

Apollo 13 Oxygen Tank Explodes
On April 13, 1970, during the Apollo 13 mission en route to the Moon, an explosion in one of the spacecraft's oxygen tanks crippled the Service Module and changed the mission's objective from lunar landing to emergency survival. Astronaut Jack Swigert famously reported, 'Houston, we’ve had a problem,' which has since become a cultural reference point. The explosion caused a loss of oxygen, water, and electrical power, forcing the crew to shut down the Command Module and move into the Lunar Module, which was intended for just two astronauts for two days. The team had to jury-rig systems for carbon dioxide removal and rely on precise burns to return to Earth safely. Ground control at NASA, along with the astronauts' ingenuity, orchestrated one of the most dramatic space rescues in history. The event highlighted the unpredictable dangers of space travel and the incredible resilience of those involved, making April 13 one of the most significant days in NASA’s timeline.

Transit 1B Navigation Satellite Launch
April 13, 1960, saw the launch of Transit 1B, a pioneering satellite in what would become the U.S. Navy’s satellite-based navigation system. Transit was the first operational satellite navigation system, a precursor to today’s GPS. Transit 1B’s successful launch was crucial in demonstrating the feasibility of using satellite Doppler shifts for positioning. The system was originally intended for Polaris submarine navigation but was later expanded for civilian use. Transit satellites would allow users on Earth to determine their position within a few hundred meters — a revolutionary concept at the time. It remained in service until the mid-1990s when it was superseded by GPS. The success of the Transit system laid the groundwork for global satellite navigation technology. April 13 thus marks a foundational step toward the precise navigation systems we rely on daily, from smartphones to aircraft.