REAL LIFE NEWS: COMET 67P BLEW OFF WHILE ROSETTA WATCHED
by Hazed
The Rosetta probe lucked out by being in just the right place, with its instruments pointed in the right direction, on July 3 2016. This was when Comet 67/P belched out a fountain of dust from a hole on its surface, spewing all kinds of stuff into space.
In fact, it gets better: not only was Rosetta watching when it happened, it then flew through the resulting plume and was able to analyse it. The results have just been published.
The plume originated from a 10 m-high wall around a circular dip in the surface. During the ejection, which lasted between 14 and 68 minutes, it pumped out between 6,500 and 118,000kg of material.
The plume contained a lot more dust than ice, which scientists find strange because it leaves the question of what powered the plume unanswered – evaporating ice on its own couldn’t have provided the energy needed to shoot all that dust into space.
They have two theories. One is that there’s a gas-filled pressurised cavity inside the comet, and evaporation caused a crack through which the plume of gas, dust and water ice emerged.
The second theory suggests that there was “amorphous ice” that seldom saw the sun, perhaps because it was underground, which was then exposed by some kind of collapse of nearly rocks or ice. When it was revealed to the sun it vaporised, then re-condensed, which produced enough energy to create the fountain of stuff.
There’s probably no way to know which theory is correct without close-up observation of more comets. So roll on the next comet mission!
Source: http://www.theregister.co.uk/2017/10/30/rosetta_analysis_of_comet_67p_plume/
