As reported by engadget,
The projects aren’t guaranteed to come to fruition. All four are part of a recently established Pioneers program that promises to help relatively new researchers conduct experiments, but only so long as the mission fits under a $20 million cost cap. While that’s inexpensive compared to many NASA missions, there is a chance the newly selected concepts might lose out if they run over budget.
However, that challenge is part of the point. Ideally, NASA can not only eke more astrophysics research out of limited funding, but encourage more creative ways to conduct science. It might reduce its reliance on conventional satellites and the giant rockets used to get them to orbit.