I've just got this news via cosmicvariance. The US National Academy of Science has just released its recommendations to NASA and the DoE for the Beyond Einstein program - see here for the press release. The basic conclusion they came to is that a Joint Dark Energy Mission should be first off, given that it will be using pretty much proven technologies and a mission could be easily put together, whereas the space-based gravitational wave detector LISA requires more technological testing before they could place it top of the list for recommending. It does, however say that LISA should become the flagship mission in the future. What all this means in practical terms for the US side of LISA funding I'm not sure? LISA has been pushed back with regards to a potential launch date due to technological and funding issues for ages, but this could lead to yet more delays (although not entirely unexpected.) This is obviously a bit of a disappointment for a gravitational wave researcher like me, and I honestly think that the science return from LISA would be more than one of the JDEM missions could give - I mean they're only trying to understand what potentially makes up 70% of the universe, so who cares about that? ;) But seriously LISA has the potential to do very good cosmology as well as provide loads of other fundamental astrophysics with possible completely new discoveries being made - it just has a little bit more risk attached to pull off the mission, but many people are working very hard to make it as sound as possible. As Sean at cv notes maybe ESA should consider finding a more reliable partner for LISA - China, Japan, India what are your thoughts?
[Update: Apparently, according to my boss, the US recommendations are pretty much a match for the timescale that ESA was planning for LISA anyway, so they shouldn't really cause any significant extra delays. Not so bad really then.]