Scheduled to launch in 2017, the Transiting Exoplanet Survey Satellite (TESS) will monitor more than 500 000 nearby “Suns” for two years and is expected to discover at least 500 Earth-like planets orbiting them.
In the quest to find life beyond Earth, astronomers are looking for planets roughly the same size and also orbiting in the habitable, or Goldilocks, zone of their host stars. The hypothesis is simple: Extrasolar planets (also called exoplanets) with surface temperatures “not too hot and not too cold” might contain liquid H2O, an essential ingredient for life as we know it. (See the documentary below for more about what a habitable exoplanet might look it like and what life forms might be found on it.)
However, the best we can do is to observe these alien “twins” from a distance, through the lens of powerful telescopes and space-based cameras, since the nearest Sun-like star with an Earth-size planet is estimated to be at least 12 light years–or 70 trillion miles–away. Nonetheless, the search for exoplanets has heated up in the past decade, thanks in large part to NASA’s Kepler Space Telescope, which recently discovered its 1000th exoplanet—eight of the Kepler discoveries are believed to be “Goldilocks” planets.
Launched in 2009, the primary Kepler mission to discover exoplanets by scanning roughly 25% of the sky was thrown off target in 2012 by a mechanical failure of the telescope’s pointing system. (Since 2014, scientists, and citizen scientists, have been analyzing data collected by exploiting Kepler’s surviving capabilities.)
Last November, NASA gave the green light to an even more ambitious planet-hunting mission. Led by George Ricker at the MIT Kavli Institute for Astrophysics and Space Research, the Transiting Exoplanet Survey Satellite (TESS) will scan more than 90% of the sky looking for the nearest and brightest stars with Earth-like planets. The $200M mission is summarized in a paper appearing in the Journal of Astronomical Telescopes, Instruments, and Systems. Among the paper’s coauthors are John Johnson, an African American astronomer at the Harvard-Smithsonian Center for Astrophysics (CfA), and Keivan Stassun, a Hispanic astronomy professor at Vanderbilt University and adjunct professor at nearby HBCU Fisk University.
Like Kepler, TESS will indirectly detect exoplanets using the so-called Transit Method, which involves measuring the dimming of a star as an orbiting planet passes across it. According to NASA, TESS stars will be 30 to 100 times brighter than Kepler stars, making it easier for follow-up observations and analyses to determine the size, mass, and atmospheric properties of the orbiting exoplanets. TESS will employ four wide-field CCD cameras as detectors and will spend two years on a highly-elliptical orbit of Earth that’s timed to avoid the Moon, the Earth’s radiation belts, and their destabilizing effects.
Harvard’s Johnson, who is featured along with his graduate students in the YouTube video, “Exoplanets Explained” (see video at the bottom), is co-discoverer of three of the smallest exoplanets detected so far by Kepler. Vanderbilt’s (and Fisk’s) Stassun contributed to that research by helping to characterize the star that the three exoplanets orbit.
Both men play active roles in championing diversity in STEM. In a recent Q&A, Johnson notes that his efforts to guide young minority astronomers have led to a “slight uptick” in Black researchers at the CfA. Stassun is cofounder and codirector of the Fisk-Vanderbilt Masters-to-PhD Bridge Program, which provides full funding, mentoring, research experience, and fast-track admission to Vanderbilt for students who successfully complete their master’s degree in biology, chemistry, or physics at Fisk. That program has produced at least 16 PhDs to date, most of whom are Black or Hispanic.
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