Projects are not guaranteed to come to fruition. All four are part of a newly established Pioneers program that promises to help relatively new researchers conduct experiments, but only as long as the mission hits a $ 20 million cap. While this is inexpensive compared to many NASA missions, there is a chance that the new concepts selected will lose out if they go over budget.
However, this challenge is part of the problem. Ideally, NASA can not only increase research in astrophysics with limited funding, but also encourage more creative ways to conduct science. This could reduce its dependence on conventional satellites and giant rockets used to put them into orbit.