![]() “TESS is not going to be limited by any expendable or other aspects,” Ricker said. The mission is set to last two years, but could continue taking data almost indefinitely. At that point, it will be able to use the moon’s gravity to stabilize itself for decades in orbit without using extra fuel. It will take a few months for TESS to swing into its regular orbit before it begins collecting data. Webb will peer at the starlight filtering through planetary atmospheres to try to detect molecules that could be produced by something living on the surface. ![]() “This is one of the major questions that TESS is intended to answer: Where will we be pointing Webb?” said the mission’s principal investigator, MIT astronomer George Ricker, at the press conference. NASA’s James Webb Space Telescope, now scheduled to launch in 2020, will then check some of those planets for signs of life ( SN: 4/30/16, p. The size of the circles represents how easy the planets are to find. TESS (orange circles) will fill in the gap. Astronomers plan to measure masses for at least 50 TESS planets that are smaller than Neptune in the hopes that many of them will have rocky, and therefore potentially habitable, surfaces.īefore TESS, most known planets were more than 1,000 light-years away, with a few closer than 30 light-years (a parsec is 3.26 light-years). Ground-based telescopes will measure the gravitational tug of a planet on its host star to learn the planet’s density, which is a clue to its composition. For that, other telescopes will follow up. Once TESS finds a planet, astronomers will need more information to understand its qualities, such as whether it’s rocky or gassy (SN Online: 6/19/17). Measuring how much starlight is blocked can tell astronomers the size of the planet. NASA’s Goddard Space Flight Centerīut the way TESS will search for exoplanets is the same as Kepler: The satellite will watch stars for signs of dimming, which can indicate that a planet is transiting, or crossing in front of, the star. During the part marked in orange, it will transmit data back to Earth. During the part of the orbit colored blue, TESS will observe the sky. COASTING IN SPACE The TESS satellite’s unusual 13.7-day orbit uses the moon’s gravity to stabilize it, so it needs little fuel. Many of TESS’ planets won’t face the same uncertainty. A recent paper posted at showed that Kepler 452b, an Earth-sized planet that orbits a sunlike star at the same distance Earth orbits the sun, may be a mirage (SN: 8/22/15, p. And not all those confirmations may stick. Because Kepler’s stars were so far and so dim, some of its planet candidates were confirmed as actual planets only by statistics rather than by other telescopes. That follow-up will help TESS avoid some of Kepler’s pitfalls. “Photons are our currency - the more, the better,” she says. The brighter the star, the easier it is to determine its planet’s characteristics, such as its mass and whether it has an atmosphere, Seager says. TESS will focus on 200,000 stars that are a few hundred light-years away at most, and shine between 30 to 100 times brighter on average than Kepler’s. Most of the planets found by Kepler orbit stars 1,000 light-years away or farther.
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