For a quick update for those uninitiated on the awesomeness that is Rosetta's comet, it is a comet believed to contain the building blocks of life, creates its own weather, and hasn't really changed in thousands upon thousands of years. The Rosetta itself is a space probe (built by the European Space Agency) and is currently completing a detailed study of comet 67P (aka Rosetta's Comet). It was launched in 2004. link
In early June, scientists established a theory as to why Rosetta's comet has two distinct 'lobes'. These 'lobes' are actually two distinct comets which, for eternity, are doomed to break up, then orbit one another, and smash back together again...and again.....oh yeah, and again.
A new modeling study of comet evolution, conducted by researchers at Purdue and U of Colorado Boulder first established this theory based on seeing two large cracks (notably, each longer than a football field). They surmise it is possible that this process of break-up and rearrangement has happened through the Rosetta's comet lifetime and that in actually may be a feature of many 'bilobed' comets.
However, over time (a lot of time) these repeated breakups might accelerate the comet's demise. Daniel Scheeres, a key researcher in the study comments, "“If a comet nucleus goes through this process a number of times it may eventually make one of the two lobes small enough so that it can escape once it spins to disruption again.”
The study will continue and will include other imaged comets. They are extending it to see if other bilobed comets (like Halley's) share this perpetual breakup and re-adjoining. It is possible our solar system is full of perpetually shapeshifting space rocks and that space is even more dynamic than we imagined.