Photo credit: www.esa.int
Commemorating a Decade Since Philae’s Historic Comet Landing
On November 12, 2014, the European Space Agency’s (ESA) Rosetta mission celebrated a significant milestone by achieving the first successful landing on a comet. After a decade of travel and covering more than 500 million kilometers, the lander Philae touched down on Comet 67P/Churyumov-Gerasimenko. As we mark the tenth anniversary of this groundbreaking event, we reflect on the remarkable accomplishments of Philae during its time at the comet.
The Quest for a Landing Site
Rosetta reached its destination on August 6, 2014, initiating the critical task of selecting a safe and scientifically promising landing site for Philae. The team analyzed images of potential sites, focusing on a location that would ensure both stability and scientific utility. After careful evaluation, Agilkia, a relatively smooth section on one of the comet’s lobes, was chosen as the landing spot.
However, the night before Philae’s descent, the team discovered a technical issue: the lander’s descent system, intended to cushion its touchdown, was inoperable. This complication meant Philae would depend solely on harpoons and ice screws to secure itself upon landing. Despite this, the mission continued, and Philae began its seven-hour journey to the comet’s surface. During this descent, the lander began to gather data and capture breathtaking images of the comet’s landscape.
Touchdown and Immediate Discoveries
Philae’s landing on Agilkia was precise, and the sensors in its feet detected the vibrations from the touchdown—marking the first recorded contact between a man-made object and a comet. Unfortunately, the harpoons failed to deploy, leading Philae to bounce off the surface multiple times. This unique situation turned out to be advantageous, as the lander collected data at various locations, providing unprecedented insights into the comet’s surface characteristics.
During its bounces, Philae observed significant differences in texture and density. At its first contact point, the soil felt soft, but just moments later, it encountered a much firmer surface. After colliding with a cliff, Philae’s instruments allowed for the first in situ measurement of the comet’s icy-dust composition, revealing a surprisingly fluffy interior with substantial porosity.
Following its final hop, Philae settled in a region known as Abydos, where it captured the first image of a man-made object resting on a 4.6 billion-year-old cosmic relic. This location remained obscured for nearly two years after the mission.
Scientific Endeavors on the Comet’s Surface
While at Abydos, Philae employed its MUPUS hammer to assess the soft layers of the comet’s surface. This experiment involved a thermal sensor that monitored temperature fluctuations—an unprecedented achievement that synchronized with the comet’s day-night cycle. MUPUS also facilitated the first detailed study of seismic activity on a celestial body since Apollo 17 on the Moon, marking another significant milestone in space exploration.
The CONSERT experiment further demonstrated the lander’s capabilities by sending radio waves through the comet, revealing an intriguing structure composed of loosely packed dust and ice.
Philae’s Legacy in Space Research
During its 64 hours operational on the comet, Philae successfully completed approximately 80% of its planned scientific activities before entering a hibernation phase. Meanwhile, Rosetta maintained communication with the comet, yielding a trove of data as it orbited the Sun and monitored the comet’s changing activity levels. There were brief communications with Philae in mid-2015; however, it could not be fully reactivated.
As Rosetta’s mission neared its conclusion, the lander’s final resting place was revealed through orbital imagery, providing closure to one of the most impressive stories in the field of space exploration.
Looking Ahead: The Future of Comet Exploration
The legacy of Rosetta and Philae continues to inspire future missions aimed at exploring small celestial bodies. ESA has a history of innovative missions, beginning with Giotto’s flyby of Comet Halley in 1986, to the more recent Rosetta mission, which not only orbited a comet but also landed a probe on its surface. These successes paved the way for the forthcoming Comet Interceptor mission, which intends to explore a comet entering our Solar System for the first time, offering fresh insights into the early composition of our celestial neighborhood.
ESA is also engaging in asteroid exploration. The Hera mission aims to assess Dimorphos in the wake of NASA’s kinetic impact experiment designed to redirect its path—a practical application of planetary defense techniques. Other missions, such as Ramses and M-Argo, are set to investigate nearby asteroids, showcasing ESA’s commitment to expanding our understanding of these intriguing bodies.
The spirit of discovery initiated by Rosetta and Philae resonates with the scientists and enthusiasts who followed their extraordinary journey, as highlighted in a dedicated online exhibition celebrating the mission’s achievements.
Rosetta, a collaborative effort among ESA, its member states, and NASA, along with the Philae lander developed by a consortium led by DLR, MPS, CNES, and ASI, exemplifies the collaborative spirit that drives space exploration.
Source
www.esa.int