The ESA wants you to play ‘spot the difference’ to help study comets

6 May 2022

Rosetta images of Comet 67P as it approaches perihelion. Image: ESA/Rosetta/MPS for OSIRIS Team

By playing Rosetta Zoo, members of the public can help scientists understand the evolution of comets better.

The European Space Agency (ESA) is looking for the public to play a cosmic game of ‘spot the difference’ to help study surface changes on a comet that approached the sun around seven years ago.

Together with citizen science website Zooniverse, the ESA has launched Rosetta Zoo. This is a game where the public can help scientists in their quest to better understand comet 67P, which was studied by the Rosetta mission between 2014 and 2016.

Players of the game can browse through pictures of the comet, taken by the powerful Rosetta OSIRIS camera, and spot differences on its surface before and after perihelion – when 67P was closest to the sun at a distance of 186m kilometres.

‘We need more eyes’

Bruno Merín, head of the ESA’s ESAC Science Data Centre in Spain, said that the openly accessible Rosetta archive contains a vast amount of data that has “only been partially explored” until now.

Following the Rosetta mission, he said that astrophotographers and space enthusiasts have spontaneously identified changes and signs of activity in the images.

“Except for a few cases, though, it has not been possible to link any of these events to surface changes, mostly due to the lack of human eyes sifting through the whole dataset. We definitely need more eyes!”

Two side-by-side images of a comet's surface showing the movement of a boulder between May 2015 and Feb 2016.

Movement of a 30-metre-wide boulder over a distance of around 140 metres. Image: ESA/Zooniverse

Hosted on the Zooniverse website for citizen science, Rosetta Zoo invites volunteers to view images of roughly the same region side by side and identify a variety of changes, from large-scale dust transport to comet chunks that moved or even vanished.

Once enough people have played the game, scientists at the ESA will be able to produce maps of changes and active areas on the comet’s surface, with labels for each type of change.

‘Rewind the movie’ of cometary evolution

The ESA said that the study will help scientists develop “new models to link the physics of comet activity to observed changes”, such as lifted boulders or collapsed cliffs.

But the potential benefits don’t stop there. “We hope that by opening up this data to the public, we are improving the openness of our work, increasing citizen engagement in scientific research, and building stronger connections between science and society,” the ESA said.

Planetary scientist Jean-Baptiste Vincent from the DLR Institute of Planetary Research in Berlin, Germany, added that even though no one knows what a primitive comet looks like, volunteers can now play a crucial role in helping scientists understand how they evolve.

“We will be able to rewind the movie of cometary evolution all the way back to the origin of the solar system,” he said.

The ESA has been taking many steps to involve the public in its studies of the cosmos.

In March, it released an Android app, CAMALIOT, which when turned on and placed by a window overnight can record small variations in satellite signals and gather data on space weather patterns – turning the average smartphone into an instrument for crowdsourced science.

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Vish Gain is a journalist with Silicon Republic