“Farewell Rosetta, You Have Done The Job”

The European Space Agency’s (ESA) highly successful Rosetta Mission to Comet 67P/Churyumov-Gerasimenko came to its bittersweet end on September 30, as the spacecraft descended to its final resting place on the comet’s surface, 720 million km (447 million mi) away from Earth.

Comet 67P from an altitude of about 1.2 km (.75 m) using Rosetta’s OSIRIS narrow-angle camera at 10:14 UTC during the spacecraft’s final descent. Credit: ESA/Rosetta

During the 5 minutes leading up to impact confirmation, the team at ESA Operations in Darmstadt, Germany fell silent as they quietly watched the distinct signal from the spacecraft’s high-gain antenna disappear. This indicated that the orbiter had indeed touched down onto the comet, 40 light minutes prior, at a descending speed of 90 cm (3 ft) per second.

Sylvain Lodiot, Operations Manager for the mission, confirmed loss of signal (LOS) at 11:19 am UTC with the heartfelt words: “This is the end of the Rosetta mission. Thank you and goodbye.”

The 2-year science mission has already taught us more about comets than previously known. Water ice on the comet was found to have a different isotopic ratio than water here on Earth, lending to the idea that, contrary to prior speculation, comets like 67P may not have been a main source of water for our planet during its early formation.
Another key discovery
was that of the amino acid glycine, implying that comets may have played a key role in the origin of life on Earth.

Comet 67P from altitude of about 8.9 km (5.5 m) using Rosetta’s OSIRIS narrow-angle camera at 06:53 UTC. Credit: ESA/Rosetta

The comet was also revealed to have an internal porosity of over 70%, and according to data collected from Rosetta’s surface lander, Philae, only 50% porosity was detected at its surface, making 67P so light that it could float on water.

Let’s not forget about the extraordinary topography. The diversity of the landscape was appropriately described by Senior Editor for The Planetary Society, Emily Lakdawalla, as being akin to “the cover of a good pulp 70s science fiction novel.” Indeed, there are pits containing walls hundreds of meters high in these curious and fantastic landscapes and yet there are mountains and plains and fractured terrain. “It’s simultaneously familiar and strange,” says Lakdawalla.

Screenshot of the last packet of data received from Rosetta before the spacecraft crashed into Comet 67P. Credit: ESA

Despite the mission no longer being active, there is still a treasure trove of data for the team to analyze for generations to come. With over 672 scientific papers published since the launch in March of 2004, and an additional 50 in the works, the science is just now beginning. “We have decades of work to do on this data,” said Rosetta’s Project Scientist Matt Taylor,” so the spacecraft may end, but the science will continue.”

Screenshots before and after ESA Operations lost signal with Rosetta spacecraft. Credit: ESA

Soon after the impact was confirmed, Mission Manager Patrick Martin announced the name of the landing site stating, “The Rosetta Stone was originally located in Sais, and we shall name the impact point as such so that we can finally say that Rosetta has come home to Sais. Farewell Rosetta, you have done the job. That was space science at its best.”


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