SETI), the Allen Array, is going offline for lack of money is a sobering reminder of the challenges faced by high risk science. It seems to be the result of a confluence of cuts and declines in both federal funding of the observatory site from the National Science Foundation and the drastic belt-tightening of a virtually insolvent state of California.
Others have written about all the great science that the Allen Array can be used for in addition to hunting for artificial signals. Paul Gilster at Centauri Dreams gives a pitch perfect discussion of this. I think it's also important to remember that SETI has helped pioneer voluntary distributed computing with their SETI@Home project. This began in 1999, the veritable stone age of what we might now call "crowdsourcing". Next time you fire up your iPhone or Android for information on local hot-dog stands you should think about that. By most standards SETI has produced very significant spin-offs along the way since it began in modern form in the early 1960's.
What about the root motivation for SETI though? Is there simply insufficient enthusiasm among scientists and the public to sustain an effort like this, even if it's to the tune of a just few million dollars a year? [A note to cynical misers; American Idol rakes in over $1 billion each year for its various interested parties. You could finish building the Allen Array and fund SETI in perpetuity for significantly less than that].
I feel that SETI has always been a hard sell. Spend an hour talking to one of its key proponents like Jill Tarter and one comes away utterly convinced that this is a vital thing for humanity to pursue. But over the following days and weeks then in all honesty doubt does tend to creep back in. This doubt is multi-faceted. There is the high-risk nature of the endeavor, the risk being the perception that as remarkable as a detection would be, the odds of actually getting it are so very small. Then there is the problem that there are so many unconstrained parameters involved, which just exacerbates the risk assessment question.
Things are changing though. Twenty years ago there was essentially no evidence that planets existed around any star other than our Sun. Sure, it would have been pretty bizarre and unsettling if ours were the only planetary system in a galaxy of 200 billion stars, but we just didn't know. Now we are in the happy situation of being able to argue about exactly how many small rocky worlds there should be, and even how many of them might be terrestrial analogs. The general answer is "lots". This really does change a big piece of the SETI equation as it is employed. Suddenly there is not only a way to improve the estimates of the number of potential targets, but to actually identify those targets. Hence the plans that were in place to use the Allen Array to monitor Kepler planets.
The more difficult questions are those that revolve around some of the implicit (and even explicit) assumptions in SETI. These are to do with the nature of "intelligent" or "technological" life, and the presumed or hoped for motivations of other worlds, other species. It's a quagmire. The problem is that we just don't know, not even a teeny bit, whether the example of humanity is a reasonable template or not. Even arguing about the equally sophisticated but non-technological evolution of dolphins or ants ignores the fact that all of life on Earth is the product of intimate co-evolution across 4 billion years. Similarly fraught are arguments about the longevity and placement of civilizations in cosmic time. The risks for success or failure with SETI are almost impossible to compute, one way or the other.
No. I think the real argument for SETI is that no-one can say whether or not there is another species in our galaxy sending out recognizable signals, and that is precisely why we should be listening.
Long before we had modern astrophysics humans looked out into the universe eyes wide open. There was certainly motivation to understand those objects or phenomena that we had already discovered. But there was also motivation to simply gather knowledge by finding, well, by finding whatever was out there. Modern SETI as performed by the Allen Array is well set up to capture all manner of natural signals as well as those of artificial origin. The transient phenomena of the universe represent one of the next great challenges for astronomy. Projects like the $400 million Large Scale Synoptic Telescope are aiming for precisely this regime. Part of the motivation is to simply discover things that we could not have found before.
Regardless of what it finds, or doesn't, the Allen Array needs to keep operating or else we lose out on the beautiful mysteries waiting for us out there in the cosmos. Let's go help it.