As has been oft remarked on this blog, we are in a golden age of astrophysics and cosmology. The data is pouring down from the heavens, in large part from 14 state-of-the-art NASA space telescopes. However, this cornucopia of astronomy is about to come to a crashing stop. We are at the high-water mark, and the next few years are going to see a rapid decline in the number of observatories in space. In five years most, if not all, of these telescopes will be defunct (WMAP is already in the graveyard), and it's not clear what will be replacing them. This is brought into startling focus by the following plot:

The dotted line shows "today". In a few years, the only significant US space observatory may be the James Webb Space Telescope (assuming it's on budget and on time, neither of which are to be taken for granted). The reasons for the current "bubble" in resources, and the impending crash, are myriad and complex. These missions take many years, if not multiple decades, to plan and execute, and we are currently reaping the harvest of ancient boom times. But one aspect subtly implied by this graph is the impact of JWST on space funding. The cost of this mission is now over $5 billion, and continues to rise. Very optimistically, the mission will be in space in 2014, and will continue to consume major developmental resources until then. In an era of fiscal austerity, it is difficult to imagine that the immense ongoing cost of JWST leaves room for much else to be done. The community has gone through the painful exercise of winnowing down its "wish list" to a few key, high-impact missions (as detailed by Julianne here, here, and here; my summary here). It is not immediately apparent that even this fairly "modest" list is attainable given current budget realities. Astronomical data from space over the next decade will pale in comparison to the previous one. We are at a unique moment in the history of space astronomy; it is highly unlikely that we will have fourteen major space astrophysics missions flying again within our lifetimes. We need to make the most of what we have, while we still have it.