December 19

On December 19, 1972, the Apollo 17 spacecraft carrying Eugene Cernan, Ronald Evans, and Harrison Schmitt made a successful splashdown in the Pacific Ocean, concluding NASA's final manned lunar landing mission. Launched on December 7, this mission included extensive geological surveys, deploying the lunar rover, and collecting 110 kilograms of lunar samples. Harrison Schmitt became the first professional geologist to walk on the Moon, providing unique scientific insights. Commander Gene Cernan’s final footprint remains the last human mark on the lunar surface to date. The crew conducted three moonwalks, capturing panoramic photographs of lunar terrain. Apollo 17's achievements celebrated the end of an era in space exploration and expanded our understanding of lunar geology. The mission’s success cemented the legacy of the Apollo program in human spaceflight history.

On December 19, 1999, Space Shuttle Discovery launched on mission STS-103, marking the third servicing mission to the Hubble Space Telescope. The crew of seven astronauts ascended to low Earth orbit to repair and upgrade Hubble's critical systems after gyroscope failures threatened its functionality. During three spacewalks, astronauts replaced all six gyroscopes, installed a new onboard computer, and fitted an upgraded Fine Guidance Sensor to improve targeting precision. These upgrades restored Hubble's pointing accuracy and extended its operational lifespan. The mission also included performance assessments of Discovery's systems, reaffirming the shuttle fleet's reliability. Discovery's successful return delivered the enhanced telescope safely back to Earth orbit. Hubble resumed its mission of capturing dazzling cosmic images, furthering our understanding of the universe.

On December 19, 2013, the European Space Agency launched Gaia, a space observatory mission designed to map billions of stars in the Milky Way. The spacecraft lifted off aboard a Soyuz rocket from the Guiana Space Centre in Kourou, French Guiana. Gaia's mission is to measure the positions, distances, and motions of stars with unprecedented precision. Over its planned five-year operational period, the observatory aimed to generate the most accurate 3D catalogue of our galaxy. Scientists anticipated that Gaia's data would revolutionize our understanding of stellar evolution, galactic dynamics, and dark matter distribution. The mission represented a major collaboration among European and international scientific institutions. Early data releases from Gaia quickly became a cornerstone resource for astronomers worldwide.