Comet chaser Rosetta ends epic journey with suicidal crash
Image credit: European Space Agency
Comet-chasing spacecraft Rosetta ended its unique mission today after it was deliberately crashed on the surface of Comet 67P/Churyumov-Gerasimenko, taking close-up images until the moment of impact.
Operators at the European Space Operations Centre in Darmstadt, Germany, sent the comet on the collision course yesterday evening and then listened to its signal as it descended from an altitude of 19km.
Even though Rosetta's plunge was extremely slow, the spacecraft was not designed to survive the landing and ceased communicating with the Earth as expected at 11:19 GMT today upon impact.
"Rosetta has entered the history books once again," said Johann-Dietrich Wörner, Director General of the European Space Agency (ESA), which managed the mission.
"Today we celebrate the success of a game-changing mission, one that has surpassed all our dreams and expectations, and one that continues ESA's legacy of 'firsts' at comets."
The spacecraft was taking images throughout its descent as it flew past some scientifically significant features including pits in the Ma'at region on the comet's small lobe where it was destined to land.
These pits are of particular interest because they play an important role in the comet's activity and provide a unique window into its internal building blocks.
The controlled crash marks an end to an intense and ground-breaking two-year scientific endeavour, which has enabled scientists to reach an entirely new level of understanding of comets' geology and activity.
Comets, researchers say, provide a window into the earliest stages of the formation of the Solar System and studying them can answer many fundamental questions related to the life on Earth.
"Thanks to a huge international, decades-long endeavour, we have achieved our mission to take a world-class science laboratory to a comet to study its evolution over time, something that no other comet-chasing mission has attempted," said Alvaro Giménez, ESA's Director of Science.
Launched in 2004, Rosetta crossed a distance of more than 6 billion kilometres as it chased 67P. It finally arrived at its destination on 6 August 2014. Three months later, the mission achieved another historical first after the orbiter successfully deployed a small lander, called Philae, which became the first manmade object to soft-land on the surface of a comet.
Philae's landing, though a historical success, was marred with problems. Upon touch down, the lander's harpoon-like landing system failed to attach to the ground and the lander bounced of the surface. It landed in an unknown location under a cliff. Although the lander established contact with Rosetta, it stopped communicating after three days after its battery depleted. In its position, the lander didn't have a direct view of the Sun and therefore couldn't use its solar panels to recharge.
Controllers managed to briefly re-establish contact with Philae as the comet moved closer to the Sun. Miraculously, the lander was spotted in images obtained by Rosetta earlier this month stuck between rocks, only a few weeks before the mission's end. Although scientists had been able to receive Philae's signal, they had no idea where exactly the lander was.
"As well as being a scientific and technical triumph, the amazing journey of Rosetta and its lander Philae also captured the world's imagination, engaging new audiences far beyond the science community," said Mark McCaughrean, ESA's senior science advisor.
ESA decided to end the mission as the comet reaches more distant parts of the Solar System where Rosetta would struggle to get enough power through its solar panels.
The researchers also said that due to the extensive exposure to extreme environments, the spacecraft would likely fail in the near future.
"With the decision to take Rosetta down to the comet's surface, we boosted the scientific return of the mission through this last, once-in-a-lifetime operation," said mission manager Patrick Martin.
"It's a bittersweet ending, but in the end the mechanics of the Solar System were simply against us: Rosetta's destiny was set a long time ago. But its superb achievements will now remain for posterity and be used by the next generation of young scientists and engineers around the world."
While the operational side of the mission has finished today, the science analysis will continue for many years to come.