Before crashing into the surface of Comet 67P/Churyumov-Gerasimenko in September 2016, which ended its successful 12-year mission, The Rosetta managed to capture one final image.
Rosetta's Last Hurrah
European Space Agency scientists initially thought they had recovered every image Rosetta had taken, but after analyzing the spacecraft's final transmission, they actually uncovered one more image: a blurry photo captured a few feet away from the comet's surface.
The image comes a year after Rosetta's crash-landing. The probe took the photo as it slowly descended toward the surface, approaching the Deir el-Medina, a pit 425 feet wide.
As it descended, Rosetta sent a series of images and measurements of the comet's gas, dust, and plasma.
Technically, the final complete image Rosetta sent to Earth was the one that arrived "back on Earth in one piece moments before the touchdown at Sais," said Holger Sierks. Sierks is the principal investigator of the OSIRIS camera in Germany's Max Planck Institute for Solar System Research.
But again, after looking into the telemetry packets further, the scientists figured out there could be another image altogether.
The final image actually has incomplete layers. Here's what that means: Before sending the final image back to Earth, Rosetta parsed it into six telemetry packets. But after sending three packets, the transmission was interrupted, sending over just half of what's supposed to be a complete image.
The automatic processing software failed to recognized the packets as an image, so it couldn't reconstruct them properly. But engineers at Max Planck Institute took it upon themselves to do the chore manually. They found out that Rosetta's compression software sent the images not pixel-by-pixel, but layer-by-layer, meaning they could recreate the image in full. But since half of the total packets were not sent, the resulting photo is blurry, with much of the detail missing.
Still, it's better than nothing. The final image was captured from a distance of 55 to 65 feet, which covers 10 square feet of the comet's surface — that's incredibly close. Had the rest of the packets been sent, the photo would have still been blurry, simply because the Rosetta wasn't designed to capture shots that close. Bummer.
Rosetta Crash Landing
Scientists decided to crash-land Rosetta back in 2016 because its solar panels wouldn't have been able to collect enough energy to go on. It was launched in March 2004 by the European Space Agency, en route to Comet 67P, passing by Mars and asteroids 21 Lutetia and 2867 Šteins on its way there.
Rosetta was the first spacecraft to ever orbit a comet nucleus and also the first to fly alongside a comet as it headed toward the inner solar system.