Exactly four centuries ago this year, Galileo sent a letter to the Grand Duchess of Tuscany to implore the powers-that-be of the time to accept the scientific fact that the Earth revolves around the sun and not the reverse.
It was not a new idea -- the ancient Greek Aristarchus made the same argument almost 2,000 years earlier, as did Copernicus in the 16th century -- but it was Galileo who finally had observations made with the newly invented telescope to prove the case.
Of course, that didn't save Galileo from persecution and spending the last decade of his life under house arrest, but eventually this fundamental idea became the foundation of astronomy and forever changed our view of the universe and our place in it.
Just as Galileo's telescope helped prove what had been suspected for centuries, now, exactly 400 years later, many scientists and observers believe a new generation of telescopes -- bothand planned for launch into space in the coming years -- will bring new discoveries that will again fundamentally alter humanity's view of our role in the wider cosmos. Specifically, it's believed these instruments could offer concrete evidence of what many suspect to be near a mathematical certainty: that we are not alone in the universe, that life exists in some form on other distant planets.
"I expect that in the next 10 to 20 years we might be able to determine with the future ground and space telescopes that some exoplanets are likely habitable or even habitable (not just potentially habitable) but not yet to confirm that any is inhabited; that might take longer than 30 years," Abel Méndez, who directs the Planetary Habitability Laboratory at the University of Puerto Rico at Arecibo, told CNET's Crave blog. "I hope I'm wrong and we do it earlier."
"(We are) embarking on the 'real search for alien life' by being the first generation capable of finding signs of life," Seager said on Twitter last year.
The new capability that Seager is referring to is the next generation of space telescopes that will succeed the likes of the Hubble, Kepler and Spitzer to better identify smaller, Earth-size planets and search for biosignatures emanating from their surfaces or atmospheres. NASA's(JWST), with a mirror almost three times larger than Hubble's, and the Transiting Exoplanet Survey Satellite (TESS) are scheduled for launch in 2018 and 2017, respectively, and will team up to identify and then study potentially habitable or even potentially inhabited exoplanets.
Since the 1990s, there has been a boom in data confirming that our galaxy, our universe and even the unexplored corners of our solar system are utterlyand other large chunks of rock, some hosting ice, water, lakes, oceans and the building blocks of life.
Most of these discoveries -- from the possibly warm "soda ocean" beneath the surface of Saturn's moonto , an Earth-size planet in the constellation Cygnus some 500 light-years away that may hold water -- have been made with telescopes and technology designed and built pre-Facebook and pre-iPhone. The , a veteran workhorse of space exploration, was built in the 1980s.
When it comes to searching the cosmos for signs of life, it's kind of like we're living in the age of Google, but still relying on the microfiche machine in the back of the library to help us find what we're looking for.
"If we want to study (many more) potentially habitable terrestrial planets around nearby stars, there are a couple of things that we need. First, if we plan to observe them with JWST we need to find planets eclipsing bright, nearby, low-mass stars," Heather Knutson, an assistant professor of planetary science at the California Institute of Technology, told CNET's Crave blog. "TESS is a crucial step in this process because it will find the closest, brightest transiting planet systems that will make ideal targets for JWST to characterize."
Astrobiologists won't look through the JWST and see real-lifeor waving back at us, but it will allow distant rocky planets and their characteristics to begin to come into focus, in a manner of speaking. Right now, Hubble has a hard time characterizing smaller planets, so this is an important step toward identifying far-off Earth cousins and their characteristics.
The next step to ID'ing E.T., even in microscopic form, would be to get a positive hit for biosignature gases -- such as methane, oxygen or carbon dioxide, just to name the familiar ones -- from one of these planets.
While Knutson believes "we certainly won't be able to detect biosignatures" with JWST, Seager is not quite so pessimistic, having said it could be the telescope's most exciting discovery, but would require good luck.
But we've mentioned just two of the planned new telescopes to come in the next decade. NASA's Wide-Field Infrared Survey Telescope (WFIRST); the European Space Agency's Gaia (launched 2013) and planned PLATO satellites; new ground-based telescopes in Hawaii, and elsewhere, as well as Seager's own Starshade project, which she explains in the TEDx talk embedded below, will all contribute to the search for distant life over the next 15 years or more.
Not surprisingly, much of this equipment will be far more powerful than what's been used to make the exciting exoplanet discoveries of the last few years, giving us exponentially more capability than ever before. But even optimists like Seager caution that there's still a scientific process to be performed before we can point to a star in the night sky and tell our children that it hosts life in its solar system (something she does believe she'll be able to do in her lifetime).
Once biosignatures have been detected on exoplanets, those atmospheres will need to be observed in more detail to eliminate "false positives," and that may require yet another generation of telescope technology.
Here's the illustration Mendez likes to use in his presentations showing how he expects the search to progress against a timeline of new telescope and satellite launches along the bottom:
Even if it took more than 40 years, that still puts us ahead of the schedule for first contact used in the "Star Trek" universe, where humans meet aliens for the first time in 2063.
NASA astronomer Kevin Hand is even more optimistic.elsewhere by 2034. After all, it seems increasingly likely that we may not have to scan all the heavens, using advanced telescopes to intricately discern the molecules floating around on planets light-years away. could find bacteria in Martian soil tomorrow. might spy biosignatures in Enceladus' plumes next week. Our own solar system looks livelier all the time. Perhaps it will turn out that it is literally so.
In a best-case scenario, the next decade could see near-simultaneous discoveries of life on-- thanks to NASA's planned mission to the Jovian moon -- and on a distant exoplanet emitting oxygen picked up by JWST.
Even if the most conservative estimates by scientists (and "Star Trek" creator Gene Roddenberry) that we're still decades away from discovering E.T. prove true, these are nonetheless exciting times to be conducting the search. It's the rapid and accelerating pace of discovery since the launch of Hubble in 1990 and the identification of the first exoplanet in the mid-1990s that really capture the imagination.
It took almost two centuries for the heliocentric model of the solar system proved by Copernicus and Galileo to be accepted by the powers that be, but these are very different times.
Consider that in just about two decades, we've gone from a universe in which we could point to not a single other planet like ours to keeping a catalog of them, a catalog it now seems could eventually contain billions of entries. And in just the past two years, we've made discoveries both about those distant planets and about the many fascinating rocks in our own solar system that prove that the building blocks of life, including , are much more abundant than we might have thought.
After millennia, we are just beginning to be able to see the true nature of the cosmos and our place within it. We are squinting at the universe right now, and at distant signs of potential life. The blurry visions we're currently grasping at are already pretty amazing, but in the next few years we will turn on telescopes and other technology that will allow us to finally bring this broader picture more clearly into focus.