Rosetta probe's final packets massaged into new snap of Comet 67P

Just 53 per cent of the image made it home, so software thought it couldn't be a photo

The European Space Agency (ESA) has been able to squeeze one last photo out of the Rosetta probe.

Rosetta crash-landed onto Comet 67P/Churyumov-Gerasimenko in September 2016 and the ESA revealed the last image it captured. That snap was thought to have been taken from an altitude of about 50m, but the agency now thinks it was taken between 23.3m and 26.2m from the comet's surface.

Now the agency has released a shot from between 17.9m–21.0m above 67P, thanks to some forensic trawling of its downloads.

The agency says that Rosetta's last minutes saw it transmit images in six packets of 23,048 bytes apiece. After the half-dozen packets of the last image was received, the probe managed to send another three, but because the ESA's image processing-software expected six packets it did not identify the last downloads as an image.

ESA boffins eventually trawled through the probe's telemetry, realised they had three packets to play with and therefore a chance of securing an extra snap. Their efforts were helped by the fact that Rosetta uploaded images in layers, rather than pixel-by-pixel, with each new layer adding more detail to an image.

The three packets therefore contained enough data to assemble an image, albeit at a notional compression rate of 1:38 instead of the usual 1:20.

And here is that image.

The last image from comet probe rosetta

Rosetta's last image of Comet 67P. © ESA/Rosetta/MPS for OSIRIS Team MPS/UPD/LAM/IAA/SSO/INTA/UPM/DASP/IDA

What are you looking at? Boulders. Perhaps with some organic molecules present, because Rosetta came down near some interesting holes that may or may not have been caused by stuff on 67P's surface warming up as it approached the sun.

We may never know what the boulders are made of, leaving the real lesson here that log files can sometimes reveal more than expected! ®


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