Rosetta's Duck-shaped Comet 67p Continually Tears Itself Apart And Reforms

2 years ago
Comet 67P/Churyumov–Gerasimenko spins once every 12 hours at present
As its spin rate changes, the stress on its two giant lobes increases 
This causes the comet to regularly break up and then reform on its journey
Scientists estimate it would have a lifetime of 5,000 years as this erodes it 

That's the gist of it, read the original article for the full story Protection Status