It's sort of the "Academy Awards" for deep space astronomy, except it only happens once every 10 years.
Last Friday a blue-ribbon National Academy of Sciences (NAS) committee released its recommendations for what types of telescopes astronomers should be building over the next decade. This offers to Congress, NASA and the National Science Foundation an exploration roadmap sanctioned by our nation's top researchers.
My colleague Nicole Gugliucci has a nice overview of the report's winners and runner-ups.
What's fascinating is that a decade ago, it would have been hard to predict what would have made it to the top of the list of cosmic mysteries now confronting astronomers.
In the 2001 NAS Decadal Survey report, the big questions were about the age, history and expansion of the universe; understanding the formation and evolution of black holes of all sizes; studying the formation of stars and their planetary systems; and understanding how the astronomical environment affects Earth. Significant inroads were made into some of these areas, or are awaiting pursuit by telescopes now under construction.
Taking a closer look at the top science goals for the upcoming decade, it seems that the fundamental physics of the universe takes center stage.
The top-ranked space mission, called the Wide Field Infrared Survey Telescope (WFIRST), would use three types of observations to characterize dark energy. Dark energy, an unimaginably weak energy field from the vacuum of space, is pushing the universe apart at an ever-faster rate. This "dark force" is so far from what would have been predicted that Mike Turner of the University of Chicago calls it "the most embarrassing number in physics." Therefore, it arguably is the most perplexing phenomenon ever to confront modern science.
As monumentally profound as this mystery is, I find it dissatisfying. Scientists are delighted at putting ever-tighter error bars around their observations. If built and launched for an estimated $1.5 billion, WFIRST will help physicists eliminate some theories for dark energy. We'll know what dark energy isn't. But the resulting dataset might never explain exactly what dark energy is. Turner has even confessed that we simply may never know.
WFIRST will also look for Earth-like planets in the far reaches of the galaxy using a technique called microlensing. This will build up the knowledge base for the abundance of Earth-sized planets in space. But, again, it's just statistics and error bars.
I also find this dissatisfying because the newfound planets won't be close enough to us for follow-on observations to see if they have habitable conditions. Such a telescope will not take us any closer to answering the "L" world: Life in space. The mega-space telescopes needed for that task won't be technologically ready for at least another decade, and the 2020 NAS survey report.
A brave new frontier that could burst open by the end of the decade is the ghostly realm of gravity waves. Spacetime should be ringing like a bell as black holes collide and supernova cores implode. Though gravity waves have not yet been detected in ground-based experiments, the NAS highly ranked the Laser Interferometer Space Antenna (LISA) because it would open up a whole new discovery space by detecting these whispers from massive objects gone wild.
But it will need a technological demonstrator precursor mission before anyone is willing to pony up approximately $3 billion for LISA. Planned for 2012 is the European Space Agency's LISA Pathfinder mission that will test a series of ultra-high precision technologies on a small single spacecraft.