Rosetta’s dust-analysing COSIMA (COmetary Secondary Ion Mass Analyser) instrument has made the first unambiguous detection of solid organic matter in the dust particles ejected by Comet 67P/Churyumov-Gerasimenko, in the form of complex carbon-bearing molecules.
While organics had already been detected in situ on the comet’s surface by instruments on-board Philae and from orbit by Rosetta’s ROSINA , those were both in the form of gases resulting from the sublimation of ices. By contrast, COSIMA has made its detections in solid dust.
Their presence was only ever hinted at in previous comet missions, which flew by their targets at high speed and, as a result, disrupted the particles, making characterisation challenging. But Rosetta is orbiting Comet 67P/C-G and can catch dust particles moving at low speed.
Optical image of two of the dust grains collected and analysed by COSIMA, named Kenneth and Juliette, which show the signature of carbon-based organics. They were collected in May and October 2015 respectively. Credits: ESA/Rosetta/MPS for COSIMA Team MPS/CSNSM/UNIBW/TUORLA/IWF/IAS/ESA/BUW/MPE/LPC2E/LCM/FMI/UTU/LISA/UOFC/vH&S/ Fray et al (2016)
“Our analysis reveals carbon in a far more complex form than expected,” remarked Hervé Cottin, one of the authors of the paper reporting the result that is published in Nature today. “It ...