Great photograph of a dusty water jet on comet 67p. Or a dust devil or even a dusty plasma devil? So full of material is this dust jet that it forms a shadow on the comets rocky surface.
A plume of dust from Comet 67P/Churyumov–Gerasimenko, seen by ESA’s Rosetta spacecraft on 3 July 2016, provided evidence that the outburst was powered from deep inside the comet, perhaps released from ancient gas vents or pockets of hidden ice.
Comet plume in context | European Space Agency
Rosetta flew through jet stream and its instruments detected at least 18 KG of dust being emitted or created every second. With the plume potentially lasting up to an hour this could mean over 100 tons of surface material excavated.
Explanation: Where do comet tails come from? There are no obvious places on the nuclei of comets from which the jets that create comet tails emanate. Last year, though, ESA's Rosetta spacecraft not only imaged a jet emerging from Comet 67P/Churyumov-Gerasimenko, but flew right through it. Featured is a telling picture showing a bright plume emerging from a small circular dip bounded on one side by a 10-meter high wall. Analyses of Rosetta data shows that the jet was composed of both dust and water-ice. The mundane terrain indicates that something likely happened far under the porous surface to create the plume.
A Dust Jet from the Surface of Comet 67P | NASA
Last year, a fountain of dust was spotted streaming from Rosetta’s comet, prompting the question: how was it powered? Scientists now suggest the outburst was driven from inside the comet, perhaps released from ancient gas vents or pockets of hidden ice.
... We saw a bright plume of dust blowing away from the surface like a fountain,” explains Jessica Agarwal of the Max Planck Institute for Solar System Research in Göttingen, Germany, and lead author of the new paper. “It lasted for roughly an hour, producing around 18 kg of dust every second.” Alongside a steep increase in the number of dust particles flowing from the comet, Rosetta also detected tiny grains of water-ice.
... Initially, scientists thought that the plume might have been surface ice evaporating in the sunlight. However, Rosetta’s measurements showed there had to be something more energetic going on to fling that amount of dust into space. “Energy must have been released from beneath the surface to power it,” says Jessica. “There are evidently processes in comets that we do not yet fully understand.”
... “Rosetta scientists are now combining measurements from the comet with computer simulations and laboratory work to find out what drives such plumes on comets.”
Rosetta finds comet plume powered from below | ESA
When similar cometary like water and dust jets are found coming from active asteroids what will be the explanation then?
Are Comet 67P/Churyumov–Gerasimenko dusty jets a variation of the electric dust devils on Mars surface?
On 3 July 2016, several instruments on board ESA’s Rosetta spacecraft detected signs of an outburst event on comet 67P, at a heliocentric distance of 3.32 AU from the sun, outbound from perihelion. We here report on the inferred properties of the ejected dust and the surface change at the site of the outburst. The activity coincided with the local sunrise and continued over a time interval of 14 – 68 minutes. It left a 10m-sized icy patch on the surface. The ejected material comprised refractory grains of several hundred microns in size, and sub-micron-sized water ice grains. The high dust mass production rate is incompatible with the free sublimation of crystalline water ice under solar illumination as the only acceleration process.
Evidence of sub-surface energy storage in comet 67P from the outburst of 2016 July 3 (PDF)