Complex sentence: The 2007 X PRIZE Cup also marked the rebirth of the Teacher in Space Project, when the Space Frontier Foundation and the United States Rocket Academy announced the rules and begin accepting applications for the first Teacher in Space "pathfinder" competition.
Split into simpler sentences: The 2007 X PRIZE Cup also marked the rebirth of the Teacher in Space Project. At the 2007 event, the Space Frontier Foundation and the United States Rocket Academy announced the rules and begin accepting applications for first Teacher in Space "pathfinder" competition.