Last year Julien de Wit and colleagues discovered a system of seven new exoplanets using a prototype—and now they’re scaling-up the project, building new SPECULOOS telescopes to expand the search for habitable worlds.
In the last two decades, thousands of planets have been found beyond our solar system. Among them, a few dozen could potentially harbor surface conditions suitable for life. However, until now, we have only been able to speculate, as detecting life on these planets was totally out of reach. But the SPECULOOS project is changing the game by detecting terrestrial planets around nearby small stars that are well-suited for the detection of life with emerging technologies.
One of the most significant goals of modern astronomy is to discover if life exists on exoplanets circling other stars—and innovations in ground-based telescopes are paving the way to reach this goal within the next generation. Inexpensive and easy to deploy, these new small-diameter telescope projects offer an exciting opportunity to significantly boost the scientific returns of the next generation of advanced observatories, like the James Webb Space Telescope (JWST) launching in 2018.
Julien de Wit PhD ’14 (XII), a postdoctoral associate in the Seager Group in MIT’s Department of Earth, Atmospheric and Planetary Sciences (EAPS), is part of the team that announced the exciting discovery of three temperate, terrestrial planets orbiting a nearby small, ultra-cool star (TRAPPIST-1) in 2016. At just 40 light-years from Earth, TRAPPIST-1’s planets are among the strongest candidates to date in scientists’ search for life outside our solar system.
This seminal discovery, and the subsequent detection of four additional planets in the TRAPPIST-1 system, was a real game-changer in the quest to discover signs of life. Using a prototype 60cm robotic instrument focused on just 30 ultra-cool stars, the TRAPPIST project (TRAnsiting Planets and PlanetesImals Small Telescope)—with principal investigators Michaël Gillon and Emmanuel Jehin of the University of Liège, Belgium—proved that even the tiniest, coolest stars can amass enough orbital material to lead to the formation of planets, and that such stars are optimal targets for the discovery of exoplanets amenable to imminent habitability assessment.
TRAPPIST-1’s are the first exoplanets with conditions possibly hospitable to life that are suitable for thorough atmospheric studies with the JWST. Using the transit method to detect and study temperate terrestrial planets (characterized when planets cross in front of their host star), relatively dim ultra-cool stars allow for a substantial amplification of a planet’s signal—up to 100 times that found when studying larger Sun analogs.
Using the Hubble Space Telescope, de Wit, who plays a critical role in leading the atmospheric characterization of the newly discovered TRAPPIST-1 planets, got a first peek at the atmospheres of the two innermost planets, revealing them to be compact, much like Earth, Venus, or Mars. The pre-screening TRAPPIST enabled indicates that detailed follow-ups using the much more costly JWST can be optimized. De Wit, whose appointment as a future faculty member in EAPS was recently announced, is now focused on expanding a network of telescopes on Earth to continue the search for new potentially habitable TRAPPIST-1-like systems, with viewpoints from both the northern and southern hemispheres.
The TRAPPIST-1 discovery was achieved in the prototype phase of the project SPECULOOS (Search for habitable Planets Eclipsing Ultra-cOOl Stars) which aims to survey all the nearest and brightest ultra-cool stars for potentially habitable planets that would be well-suited for assessment with coming observatories—like the JWST—to detect the biosignatures that could indicate the presence of life. Michaël Gillon is also Principal Investigator on the SPECULOOS exoplanetary search project.
“The JWST will have a nominal lifetime of just 5-10 years, so it is vital for us to identify the most promising exoplanets now for further investigation. In addition, studying planets like TRAPPIST-1’s will also inform the development of tools for the characterization of non-transiting worlds like that recently found orbiting our Sun’s neighbor, Proxima Centauri,” says de Wit.
SPECULOOS is currently composed of a network of six 1-meter diameter telescopes, with five in Chile and one in Morocco. However, to optimize its potential for detecting planets like those orbiting TRAPPIST-1, efforts are underway to widen our view of the northern skies by installing more SPECULOOS telescopes in northern hemisphere astronomical sites. Each small telescope costs approximately $1M.
MIT and the University of Liège have already negotiated a draft agreement with Teide Observatory (Tenerife, Canary Islands) to install a first SPECULOOS telescope there, and work continues apace to garner seed funding to accomplish that goal. The agreement with Teide also reserves space to accommodate up to three additional instruments in future years to further expedite the monitoring of the close to 500 ultra-cool stars of interest within the estimated lifespan of the JWST.
TRAPPIST-1 is currently the only system with known temperate Earth-sized exoplanets whose atmospheres can be studied in depth with the Hubble Space Telescope and JWST, and is the best (and only known) system available to pursue the search for extra-solar habitats, and to perform Earth-sized comparative planetology. The discovery of the TRAPPIST-1 planetary system alone has catalyzed a storm of scientific studies worldwide, with over 60 papers already published.
“The door now stands open to expanding our understanding of planetary systems, habitats, life, and ultimately our own planet, through the discovery and study of new terrestrial exoplanets that can be characterized in depth,” says de Wit. “This is new. This has the potential to be paradigm-shifting.”
EAPS is grateful to Peter Gilman for his early support for the SPECULOOS project. If you would like to support MIT’s participation in SPECULOOS, please contact Angela Ellis at firstname.lastname@example.org or 617-253-5796.
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Story Image: High in the Chilean Atacama Desert at the European Southern Observatory’s Paranal site, SPECULOOS telescopes “Europa” and “Io” search the skies of the southern hemisphere for transiting exoplanets as part of a network of six instruments. EAPS future faculty Julien de Wit and his colleagues from the University of Liège are working to continue to expand the network of telescopes in the northern hemisphere at Teide Observatory in the Canary Islands. Image credit: P. Aniol/ESO/Paranal/SPECULOOS
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