A peanut-shaped comet was spewing hundreds of pounds of fluffy ice chunks every second as a NASA spacecraft swung by it two weeks ago.

“To me, this whole thing looks like a snow globe that you’ve simply just shaken,” Peter H. Schultz, a Brown University professor working on the mission, said Thursday during a news conference.

The Deep Impact spacecraft passed within 435 miles of Comet Hartley 2 two weeks ago, producing a series of photographs that showed bright jets coming off a rough surface.

What fascinated the mission scientists most was that the chunks of water ice in the jets were not being lifted off the surface by the force of water vapor heated by the sun, but rather by jets of carbon dioxide. This was the first time that such carbon dioxide jets had been observed at a comet.