The Crisis in Astrophysics and Planetary Science: How Commercial Space   and Program Design Principles will let us Escape
  Astrophysics and planetary science are in crisis. The large missions we need for the next generation of observations cost too much to let us do more than one at a time. This spreads the science out onto a generational timescale, inhibiting progress in both fields. There are two escape paths. In the long run, but still well within our planning horizon, commercial space will bring mission costs down substantially allowing parallel missions at multiple wavelengths or to multiple destinations. In the short run, adopting prudent principles for designing a research program will let us maintain vitality in the field by retaining breadth at a modest cost in depth. 
Martin Elvis
astro-ph.IM