One of the concepts for a Terrestrial Planet Finder would have used an array of spacecraft that pooled their observations using a technique known as interferometry. The concept was mothballed due to NASA's financial woes.
Hundreds of planets are being found beyond our solar system, including some that just might be habitable. But can we ever confirm signs of alien life beyond our solar system? It's theoretically possible — but in a new book about exoplanetology, "Five Billion Years of Solitude," science journalist Lee Billings suggests that the task may be beyond humanity's financial capabilities.
The good news is that this is shaping up to be a golden age of astronomy — thanks in part to the Hubble Space Telescope, the data from the Kepler planet-hunting telescope, the yet-to-be-launched James Webb Space Telescope and a host of next-generation ground-based telescopes that will be coming online. The prospects have never been better for finding Earth-size planets in Earth-type orbits around sunlike stars.
However, it's not enough to find those alien Earths. Those discoveries just open the way to a bigger question: Does life exist on those distant worlds?
Sniffing out life
In his book, Billings traces how scientists have worked out ways to detect life's signature: For example, you might see an anomalous abundance of oxygen and methane in a planet's atmosphere. Or you might pick up a whiff of gases that are harder to detect, such as nitrous oxide or dimethyl sulfide.
Making the case for life on extrasolar planets would probably require putting more than one next-generation telescope into outer space, Penn State geoscientist James Kasting told Billings.
Science journalist Lee Billings
"For any interesting planets we'd find at first, there could be a whole series of follow-up missions done at greater and greater expense of time and money to nail down what exactly is being seen," Kasting said. "It could go on for 50 years, a century, who knows."
NASA already has committed itself to following up on the planet quest, with a $200 million mission known the Transiting Exoplanet Survey Satellite, or TESS, due for launch in 2017 — plus the $8.8 billion Webb telescope, now scheduled for a 2018 launch. The quest will also involve ground-based telescope projects such as the High Accuracy Radial Velocity Planet Searcher, the Automated Planet Finder and the European Extremely Large Telescope. Will all that be enough?
"I fear it's just going to leave us on the cusp," Billings told NBC News.
In "Five Billion Years of Solitude," Billings traces the successes and the setbacks in the search for life among the stars. He delves into five decades of ups and downs in SETI, including the financial challenges that have dogged the Allen Telescope Array in California. He analyzes the reasons why an ambitious mission known as the Terrestrial Planet Finder fizzled. And he highlights the hopes that surround potential future missions — ranging from the low-cost ExoplanetSat project to a grand scheme to use the sun as the gravitational lens for a cosmic-scale telescope capable of imaging an exoplanet's expressways.
Follow the money
The problem is finding the money to take the planet quest to the next level — especially in an era of tighter budgets, and in the wake of the cost overruns and schedule slips that have plagued the James Webb Space Telescope. Billings wishes there were extra money to build and launch a separate starshade for the Webb telescope, which would help scientists reduce the glare of alien stars when they look for planets. But that kind of add-on just isn't in the budget.
"Five Billion Years of Solitude: The Search for Life Among the Stars" is Lee Billings' first book.
"If I could gather the astronomical community in a room, I would implore them to consider the fact that the golden age of astronomy in which we all live has no guarantees of continuing," Billings said. "It's not going to be around forever, and it depends on the largesse of taxpayers and the politicians who pull the strings."
The way Billings sees it, finding and characterizing other Earths should be at the top of the priority list for space science — and although it's possible to draw upon the generosity of billionaire philanthropists and crowdsourcing campaigns, it's impossible to pursue the quest without NASA.
"If we're going to be dependent on the largesse of billionaires to answer these scientific questions, these existential questions — you gotta wonder, what the heck is NASA for? Now everyone is trying to find any way but NASA to do it," Billings said. "We aren't going to find alien Earths and life beyond the solar system through the fantasies of multibillion-dollar Kickstarter campaigns. That's a non-starter."
More about the planet quest:
Alan Boyle is NBCNews.com's science editor. Connect with the Cosmic Log community by "liking" the NBC News Science Facebook page, following @b0yle on Twitter and adding +Alan Boyle to your Google+ circles. To keep up with NBCNews.com's stories about science and space, sign up for the Tech & Science newsletter, delivered to your email in-box every weekday. You can also check out "The Case for Pluto," my book about the controversial dwarf planet and the search for new worlds.
First published October 16 2013, 3:46 PM