I learned the following sentence from 100 Greatest Science Discoveries of All Time by Kendall Haven:
Marie Curie's studies rank as one of the great turning points of science. Physics after Curie was completely different than before and focused on the undiscovered subatomic world. She cracked open a door that penetrated inside the atom and has led to most of the greatest advances of twentieth-century physics.
I don't understand the sentence in bold. Why can two verbs, "cracked" and "open", be put together in this sentence? Or do I misunderstand the part of the speech here?