Particles from space have a long history of teaching us new physics, most recently recognised by the award of the Nobel Prize to Francis Halzen for the observation of high-energy neutrinos from space.

Measuring and modelling the collisions of high-energy particles with the atmosphere, or indeed polar ice, is tricky. In an attempt to improve our understanding specifically of high energy proton collisions with the atmosphere, the Large Hadron Collider loaded up with Oxygen nuclei a while ago, and smashed them up with protons (hydrogen nuclei, if you prefer). We measured the resulting mess in the ATLAS detector. Indeed we got more information, but, as this quote from Jesse indicates:

We thought that our data would help identify the best models for cosmic ray collisions. But surprisingly, we found that none of the models were very good.

… the modellers have work to do. They do now, thank to ATLAS and the LHC, have a some significantly better data to work with.