The Future of Exoplanets: The Next 20 Years of Exploration
Artist conception of the James Webb Space Telescope
Image Credit: ESA (C. Carreau)

Twenty years ago this month, the detection of the first planet orbiting a Sun-like star was announced by the team of Didier Queloz and Michel Mayor of  the Geneva Observatory in Switzerland on October 6, 1995. Less than a week later, the team of Geoff Marcy and Paul Butler from San Francisco State University  confirmed this planet, 51 Pegasi b, on October 12. As we celebrate the anniversary of this historic discovery, we look ahead to see what discoveries we will make in the next twenty years and how we will make those discoveries.
Our understanding of exoplanets has come a long way since 1995. The first planets discovered were large, hot Jupiters orbiting scorchingly close to their parent stars. Such planets had not been predicted and their very existence threw out our understanding of what was possible with the formation of planets and the structure of solar systems. 
Detection techniques become more numerous and refined and more observatories became capable of detecting these strange new worlds. Teams of astronomers competed to make more discoveries, and discover they did, each new solar system adding to our understanding of what is possible in the universe. Telescopes such as NASA's Hubble Space Telescope, the French and European Space Agency's COROT, Keck, SuperWASP, Gemini, and more all turned their steady gaze to distant star systems looking for telltale wobbles or blips in light curves indicating the presence of increasingly smaller exoplanets. With the launch of Kepler in 2009 the rate of discoveries exploded, with thousands of confirmed planets and thousands more exoplanet candidates in its wake, with more discoveries still coming in the next phase of its life, the K2 mission. Kepler finally confirmed what had long been suspected-there are indeed Earth-sized worlds orbiting in the habitable zones of other stars. In less than twenty years we have come from discovering strange hot giant world inhospitable to life to planets that may very well hold all the ingredients for life as well know it...if we can just increase the power of our instruments to detect those signs of possible life!
One of the first next generation instruments that will have advanced exoplanet detection techniques will be the James Webb Space Telescope (JWST). When it is launched in 2017, the JWST will probe the edges of the universe to answer questions of about moments after the big bang...and it will also be able to focus closer to home, looking at the atmospheres of exoplanets in nearby solar systems to determine what the composition of their atmospheres.  The JWST will be able to directly image larger exoplanets as well through the use of a coronagraph, a device which blocks the bright light from a star and allowing astronomers to image dim objects such as brown dwarfs, planets, and dust clouds in orbit around the star. The Wide-Field Infrared Survey Telescope (WFIRST) will be launched sometime after the JWST and will have a coronagraph allowing it to also take image images of gas and ice giants orbiting other stars. 
image of the TESS space telescope

Artist concept of the upcoming TESS mission looking for planets around other stars.
image credit: MIT/TESS team

The European Southern Observatory has recently begin observation of the skies with the Next-Generation Transit Survey (NGTS), installed near the Very Large Telescope (VLT) in Chile to take advantage of the outstanding clarity of the thin atmosphere at the top of the Andes Mountains. NASA's Transiting Exoplanet Survey Satellite (TESS) is due to launch in 2017. Both TESS and NGTS are to target bright nearby stars for evidence of exoplanets outside of the limited field of view of the Kepler mission and will serve to "tag" interesting exoplanets for followup studies by the James Webb and other powerful telescopes. These next-generation missions are expected to find thousands more planets around nearby stars. 
image of a Starshade prototype
Photo of a Starshade mockup tested by JPL
Image credit: NASA/JPL
One innovative technique which may be used in future missions is to orbit a large device called a starshade. This would be deployed at a precise location thousands of miles away from the orbit of a space telescope and would precisely block the light from the target star, allowing the space telescope to image planets much smaller and closer to their suns than possible with even a coronograph. A starshade couple with a powerful enough telescope may even allow us to directly image terrestrial worlds in the habitable zone of their stars, and even possibly to analyse their atmospheres to find signs of life. 

image of three planets orbiting a star
Discovery image of 3 planets around the star HR 8799. 
Credit Gemini Observatory/NRC.AURA; Christian Marois et al.
Exoplanet research will not be limited to space, however. Just like now many important discoveries will be made by ground-based observatories using the most advanced techniques couples with the most advanced cameras and giant mirrors to find out even more about these distant worlds. The Gemini Planet Imager, installed on the Gemini Southern Observatory, has already directly imaged exoplanets in it commissioning phase, and similar projects such as the Subaru Coronagraphic Extreme Adaptive Optics imaging system are in the works as add-on instruments to enhance the abilities of already extant observatories. Many of these systems use coronagraphs to block the bright light from the central star, as well as adaptive optics systems, which allow the imaging system to adjust for turbulence in the atmosphere. Observatories such as the Giant Magellan Telescope (GMT), the Thirty Meter Telescope (TMT) and the European Extremely Large Telescope (E-ELT) with their record-breaking mirrors will allow for unprecedented levels of sensitivity. 
Instrumentation is not the only tool that advances as the years progress: our mathematical techniques used to scan and analyse data continue to advance as well. The data e have already collected can even yield new discoveries! For example, the datasets of the Kepler mission are open to anyone to analyse. New statistical analysis techniques can tease out even more possible exoplanets from the millions of light curves collected by Kepler. Data containing the positions of stars and their spectra from earlier observations by other observatories can be researched and analysed as well, teasing out more information about previously-discovered planets, to confirm suspected planet candidates, and even can be used to find undiscovered planets!  

The Night Sky Network recently hosted a telecon with Dr. Charles Beichman of NASA's Exoplanet Institute, and you can find his presentation and a recording of his presentation on the future of exoplanet science on our dedicated telecon page. NASA's PlanetQuest website offers a huge amount of information for use by the public, educators, and amateur astronomers, and more technical information can also be found on NASA's Exoplanet Exploration Program website. 
An entire generation has now grown up knowing that there are indeed other lanes orbiting other Suns like our own.  Will the next generation be the first that grows up knowing that life exists around other worlds?  Will we find another "pale blue dot" in the universe, as Carl Sagan so fervently hoped? What else will we discover?  Astronomers and space agencies from around the world have joined forces to construct some of the largest, most powerful and advanced telescopes and computers known to man just to answer these questions. The next twenty years will prove to be exciting, indeed!


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