New hi-res Rosetta comet images reveal its ancient past and violent future

23 Jan 2015

A section of the smaller of Comet 67P/G-P's two lobes as seen through Rosetta's narrow-angle camera from a distance of about 8 km to the surface on 14 October 2014. Image via ESA/Rosetta/MPS for OSIRIS Team MPS/UPD/LAM/IAA/SSO/INTA/UPM/DASP/IDA

Two months after it first achieved the historic landing on a comet, both the Rosetta craft and its Philae lander have returned detailed findings of Comet 67P C-G’s ancient past and violent future.

The world got their first up-close glimpse of the enormous chunk of space debris in August last year and while Philae’s landing, and its eventual downfall, were widely reported, Rosetta has remained in its orbit the last few months accurately measuring every nook and cranny of its surface.

According to recently released details from the European Space Agency (ESA) who achieved the feat, Rosetta’s OSIRIS camera has managed to capture detailed images of 70pc of the comet’s surface aside from the ever-elusive southern hemisphere which has not received the sun’s rays since the craft arrived.

Future Human


The 19 regions identified on Comet 67P/C-G are separated by distinct geomorphological boundaries. Following the ancient Egyptian theme of the Rosetta mission, they are named for Egyptian deities. Image via ESA/Rosetta/MPS for OSIRIS Team MPS/UPD/LAM/IAA/SSO/INTA/UPM/DASP/IDA

It’s certainly a weighty beast measuring in at 10bn tonnes with a density of 470 kg per cubed metre and despite its incredible weight, is rather weak with its loose-connecting clumps of ice and rock found to have a porosity of between 70 – 80pc.

While fragile to the intense power of solar radiation, the ice is believed to be protected by a deep layer of cosmic dust – as deep as 7m in places – that effectively insulates it, although not entirely given its emissions of a trail of water vapour.

The boulder-strewn, smooth Hapi region in Comet 67P/C-G’s neck, with the Hathor cliff face to the right. Image via ESA/Rosetta/MPS for OSIRIS Team MPS/UPD/LAM/IAA/SSO/INTA/UPM/DASP/IDA

Life on Comet 67P/G-P

So what would life be like on the comet, if you were crazy enough to want to live there?

Aside from trying to traverse the layers of dust, an entire day on the comet lasts 12.5 hours and completes an entire orbit of the sun over a period of 6.5 years.

Also, anyone habiting the comet’s surface must have to deal with the fact that things are only going to get hotter as it makes its closest approach to the sun on 13 August this year and is expected to release 1.2l of water vapour every second at this time.


Part of the Imhotep region on Comet 67P/C-G’s large lobe. Image via ESA/Rosetta/MPS for OSIRIS Team MPS/UPD/LAM/IAA/SSO/INTA/UPM/DASP/IDA

While a lot has been learned in the few months since our first encounter with the comet, the one mystery that remains is how it ended up having two lobes?

With a large crack measured at approximately 500m found between the two lobes, the two sections of the comet appear to be very similar compositionally which would suggest that it is one large body that has eroded to appear as a merged comet, however, ESA scientists are refusing to rule out the two-comet theory.

Speaking of these findings, the ESA’s Rosetta project scientist, Matt Taylor, said this is just the beginning, “We have already learned a lot in the few months we have been alongside the comet, but as more and more data are collected and analysed from this close study of the comet we hope to answer many key questions about its origin and evolution.”


Colm Gorey was a senior journalist with Silicon Republic