A year after Rosetta was intentionally crashed on Comet 67P/Churyumov-Gerasimenko, scientists continue to discover new science in the data from the European Space Agency’s spacecraft.
The latest results, announced at the AVS 64th International Symposium and Exhibition, focus on the detailed analysis of the comet’s atmosphere also known as its coma. Researchers used Rosetta's sophisticated on-board mass-spectrometer to work out the different elements and where they assembled. The ice appears to have formed long before the Sun began to shine.
“What we found is amazing: Cometary ice is mostly older than the solar system, having survived its formation as ice,” Professor Kathrin Altwegg, from the University of Bern, said in a statement. “This means the abundant organics found in the cometary coma are also probably older and therefore as such ‘universal’ – not specific to the solar system. If comets contributed to the emergence of life on our Earth, similar processes could have happened or could happen elsewhere in the universe.”
Recently, a theoretical study suggested that the organic materials in comets could be formed in the so-called diffuse interstellar bands (DIBs), regions of organic material across the stars. These new results strengthen this idea, although they are not the final word on the nature of comets. The researchers blame the unfortunate accident of Rosetta’s lander Philae for the lack of constraints. Upon landing, Philae bounced unexpectedly and ended up where it couldn’t use its solar panel to recharge itself.
“We are missing the ground truth, as, due to the hopping of the lander Philae, the two mass spectrometers on Philae could not measure in their nominal modes,” Altwegg, who presented the results, added.
Understanding comets might also help us understand the origin of life on Earth. Comets are believed to be responsible for about 1 percent of the water on our planet. So by understanding their compositions, we can work out how much organic material they delivered. This is estimated using xenon, a noble gas.
“By looking at xenon isotopes we can also quantify how much organics they brought,” Altwegg said. “The unexpected richness of organics found in the cometary coma together with the results from xenon tell us that comets could have played an important role in sparking life on Earth.”
A future landing mission would extend these measurements to the surface and maybe below, giving us a better understanding of where and when comets come from.