Pic Scientists at the European Space Agency (ESA) got lucky when the Rosetta probe, currently orbiting Comet 67P, picked up a massive outgassing from the frozen body.
On February 19, the comet suddenly started to emit dust and gas in an unprecedented display, as Rosetta was orbiting 35 kilometers away. Nine of the probe's instruments were turned on and facing the comet at the time, allowing for the entire burp to be caught and analysed.
"Over the last year, Rosetta has shown that although activity can be prolonged, when it comes to outbursts, the timing is highly unpredictable, so catching an event like this was pure luck," said Matt Taylor, ESA's Rosetta project scientist.
"By happy coincidence, we were pointing the majority of the instruments at the comet at this time, and having these simultaneous measurements provides us with the most complete set of data on an outburst ever collected."
The results of the data have now been accepted by the Monthly Notices of the Royal Astronomical Society, and the data collected have allowed scientists to decipher exactly what happened to cause the eruption.
Boffins pinpoint landslide spot
Rosetta's camera caught the first hint of the incident at 0940GMT when the halo of dust surrounding the comet began to glow. A few hours later, the temperature of the comet's gases rose 30°C and the brightness of the sunlight reflected off the body rose sixfold.
By 1115GMT, the probe was hit by a cloud of particles that was blown off the surface of the comet, with Rosetta's dust detector registering 200 hits an hour, compared to the normal rate of three to ten impacts for other days. Some of the dust was moving so fast it registered as trails during exposure to the instruments.
"From Rosetta's observations, we believe the outburst originated from a steep slope on the comet's large lobe, in the Atum region," said Eberhard Grün of the Max Planck Institute for Nuclear Physics. "As a result, we think the outburst must have been triggered by a landslide at the surface, rather than a more focused jet bringing fresh material up from within the interior, for example." ®