Mar 22, 2017 02:04 PM EDT By Anne Collins, UniversityHerald Reporter

The Rosetta spacecraft witnessed the collapse of cliffs at two locations on the Comet 67P. After two years of orbiting the 4km-wide comet the European probe documented the breakdown of 2,000 tons of rubble that slid away on the surface that was probably driven by exposure to sunlight. Details of the event were presented at the Lunar and Planetary Science Conference (LPSC).

According to lead researcher Dr Maurizio Pajola, an astronomer from the Nasa Ames Research Centre in California, the volume that fell down was equivalent to around nine full Olympic size pools.

Daily Mail reported, Rosetta was launched in 2004 and travelled more than six billion kilometers to reach comet 67P.  It first entered orbit around Comet 67P or Churyumov-Gerasimenko in September 2014. Comet 67P was discovered in 1969 by the Soviet astronomers Klim Churyumov and Svetlana Gerasimenko.

The spacecraft enabled researchers to capture multiple high-resolution images of the comet's surface. The mission allowed them to study its features and how it changed for two years said lead author Mohamed El-Maarry from University of Colorado, Boulder.

Researchers found that repeated heating and cooling can tease the surface materials apart and erode. The team observed cliff collapses at two regions on the comet called Ash and Seth.

In the Khonsu region of 67P, a massive boulder was seen to move a distance of 140m. It could have been caused by the erosion of the slope surface or it could have been moved by an outburst of gas and dust from within the comet.

The surface changes occurred around perihelion, when Comet 67P was at the point in its orbital path closest to the Sun. It suggested that the events were driving by exposure to sunlight.

However, the changes in the neck region were connected to an increase in the comet's spinning rate. Most of changes are localised said Dr. El-Maarry.

The LPSC is scheduled from March 20-24 in the Woodlands, Texas. The study was published in the journal Science and a companion paper on surface changes will be released in the journal Nature Astronomy according to BBC.

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