The biennial senior reviews are generally tasked to rank extended (post-primary-mission) support for a number of missions (and sometimes archive services) under the purview of NASA astrophysics, with regard to the likely science impact specifically of the proposed extended funding period. This year, they had to rank Swift, Chandra, GALEX, the warm extension for Spitzer, NASA funding for US investigators with XMM-Newton and INTEGRAL, operation of RXTE, two additional years of operation for WMAP, and extended analysis funds for GP-B (which ceased actual operations some time back). As I read the snippets of the review that have shown up around the web, the feeling (which I would have shared) was that it appeared unlikely that they could get a result from the additional 2 years or so which would be definitive (i.e. believed by anyone not on the team, to put things crudely). The decisions are often painful, but I agree that they are more fruitfully made by scientists than on other grounds.