THIS DAY IN SPACE

Three Mile Island Nuclear Accident
On March 28, 1979, the most serious accident in U.S. commercial nuclear power plant history occurred at the Three Mile Island plant in Pennsylvania. Although not directly a space event, the disaster had profound effects on public perception of large-scale scientific and engineering projects, including space exploration. A partial meltdown of reactor number 2 resulted from a combination of equipment failures, design problems, and human error. While no deaths or injuries occurred, the incident led to the release of small amounts of radioactive gases. The intense media coverage and public concern triggered massive changes in nuclear regulation and had ripple effects in adjacent fields, including aerospace. NASA and other agencies came under pressure to justify their safety protocols for space missions involving radioactive materials, such as RTGs (Radioisotope Thermoelectric Generators) used in deep-space probes. The Three Mile Island incident became a turning point in public scrutiny of high-stakes technology, influencing safety culture even in extraterrestrial ventures.

New Horizons Crosses Mars Orbit
On March 28, 2006, NASA's New Horizons spacecraft crossed the orbit of Mars on its way to Pluto, continuing its historic journey through the solar system. Launched in January 2006, New Horizons was moving at an extraordinary speed of over 36,000 mph, making it one of the fastest spacecraft ever launched. Crossing Mars' orbit just two months after launch was a testament to both the powerful Atlas V rocket and the mission's gravity-assist trajectory planning. Though it did not interact with Mars, the milestone was symbolic, placing New Horizons well into the inner solar system and emphasizing the scale and velocity of interplanetary travel. The spacecraft’s primary mission was a flyby of Pluto and its moons in 2015, after which it continued into the Kuiper Belt. Onboard instruments were already beginning to test and calibrate as it crossed Mars’ path. The event served as a confidence boost to mission planners and a captivating update to the public tracking the spacecraft’s epic voyage into the unknown.