One last look: Rosetta probe’s last surprise for scientists

CNN  — 

Scientists combing the last readings beamed home by the comet chaser Rosetta have discovered one final gift from the intrepid space explorer.

It’s grainy and a little out of focus, but this is the last image captured by Rosetta as it barreled toward the surface of Comet 67P last September.

While the probe’s OSIRIS camera was not designed to operate so close to the surface, engineers in Gottengen, Germany, were able to reconstruct a previously hidden image showing the unmistakable frozen, rocky surface right before impact.

“The last complete image transmitted from Rosetta was the final one that we saw arriving back on Earth in one piece moments before the touchdown at Sais (the designated impact site),” said principal investigator Holger Sierks.

Pioneering science

But to transmit images back to Earth, Rosetta has to compress them into data packets. The data for this unexpected picture was split into six packets, only three of which were fully transmitted.

Only receiving half of the image data made it harder for systems back on Earth to ID what Rosetta was sending home.

“Later, we found a few telemetry packets on our server and thought, wow, that could be another image,” Sierks added.

With the European Space Agency (ESA) taking lead, the Rosetta spacecraft was first launched back in 2004. It would spending a decade chasing the comet through the solar system before deploying its Philae lander to its surface in November 2014.

The Philae lander bounced across the comet on impact after failing to anchor. Rosetta's cameras were able to locate it later.

Among the rich scientific data gathered by Rosetta’s sister lander was the dramatic discovery of 16 “carbon and nitrogen-rich” organic compounds, supporting the theory that the building blocks of life could have been brought to Earth by comets.

Related: Rosetta and its mission

In September 2016, ESA controllers decided to end the mission when they determined the craft’s solar panels were ineffective because Rosetta was so far away.

Never designed to land on the comet, scientists opted to try a controlled descent and impact in the hopes of carrying out pioneering science right to the end.

The aim: to find out more about lumpy structures – so-called “goosebumps” – which they believe may be the original pieces of material that bonded together forming the comet’s body when the solar system was still in its infancy.

Rosetta’s legacy

After a 13-year odyssey in space, Rosetta had returned a treasure trove of groundbreaking data about the comet’s surface and its chemical composition, securing its legacy as one of the most successful missions of all time.

Astronomer Dan Brown, a lecturer at Nottingham Trent University in the UK, spoke to CNN at the conclusion of the mission last year, describing it as an “astonishing” engineering feat.

“The Rosetta mission has helped us gain an insight into the activity of comets, how comets were created and to some extent if they could have been the source for water on our early Earth,” he said last year.

“The presence of complex molecules, some of which previously unknown to exist on comets, still allows comets to be a possible source of introducing complex molecules and enable the formation of life on Earth.”