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NASA’s newest planet-hunting space telescope – the Transiting Exoplanet Survey Satellite, aka TESS – has just completed its primary mission, the space agency said on August 11, 2020. Its initial sky survey lasted two years. At that time, TESS helped revolutionize our knowledge of exoplanets, the worlds orbiting distant stars, continuing where the Kepler Space Telescope, NASA’s first planet chaser, left off.
TESS’s main mission officially ended on July 4, 2020. After that, TESS will continue with its extended mission phase.
During the two-year investigation, TESS photographed around 75% of the sky and has so far found 66 new confirmed exoplanets and nearly 2,100 additional candidates awaiting confirmation. Patricia Boyd, Project TESS Scientist at NASA’s Goddard Space Flight Center, said in a statement:
TESS produces a torrent of high-quality observations providing valuable data on a wide range of scientific topics.
In the first year, TESS observed 13 different sectors of the sky as seen from the southern hemisphere, then turned its attention to the northern sky in the second year. Each sector is a 24 x 96 degree strip of the sky, and TESS spends about a month surveying each sector.
Sky view of the southern hemisphere from TESS. You can see the light strip of our Milky Way galaxy (left), the Orion Nebula (top), and the Great Magellanic Cloud (center). Dark lines are spaces between the detectors in the TESS camera system. Image via NASA / MIT / TESS / Ethan Kruse (USRA).
Patricia Boyd, Project Scientist for TESS at the Goddard Space Flight Center. Image via NASA / Goddard Space Flight Center.
Now TESS has returned to observing the northern skies as he entered his extended mission. According to NASA, this change also leads to other changes and improvements.
TESS now collects data faster and more efficiently than during the main mission, NASA said. Telescope cameras can now capture a full frame every 10 minutes, three times faster than on the main mission. Moreover, using a new fast mode, TESS can measure the brightness of thousands of stars every 20 seconds. Previously, the telescope took similar measurements every two minutes. These upgrades are not only good for planet hunting, they also help TESS better resolve changes in brightness caused by stellar oscillations and observe explosive eruptions of active stars in more detail.
This extended mission phase will continue until September 2022. TESS will spend the next year observing the southern sky and then return again to surveying the northern sky for a period of 15 months. These surveys will include observations along the ecliptic – the plane of Earth’s orbit around the sun – which TESS has not yet imaged.
How does TESS find exoplanets?
Like many other telescopes, TESS uses the transit method to detect exoplanets. In other words, its instruments are designed to detect slight decreases in the brightness of stars as planets pass in front of these stars as seen from Earth. These temporary drops in brightness are very tiny, but TESS is able to see them and determine if they’re caused by a planet (in most cases, according to NASA, they are).
Last January, NASA announced that TESS had discovered its first Earth-sized planet, TOI 700 d, in the habitable zone of its red dwarf star. The habitable zone is the region around a star where temperatures on a rocky planet could allow liquid water to exist. The planet was then confirmed by NASA’s Spitzer Space Telescope. This planetary system is just over 100 light years away in the constellation Dorado. According to Paul Hertz, director of the astrophysics division at NASA headquarters in Washington:
TESS was designed and launched specifically to find Earth-sized planets orbiting nearby stars. Planets around nearby stars are easier to track with larger telescopes in space and on Earth. The discovery of TOI 700 d is a key scientific discovery for TESS. Confirming the size of the planet and habitable zone status with Spitzer is another victory for Spitzer as the end of science operations nears in January.
Artist’s concept of TOI 700 d, the first Earth-sized exoplanet discovered by TESS in the habitable zone of its star. This planetary system is 100 light years away in the constellation Dorado. Image via Goddard Space Flight Center / Wikipedia.
TOI 700 d is the outermost of the three known planets in the system and the only one in the habitable zone. It is 20% larger than the Earth, revolves around its red dwarf star every 37 days, and receives from its star 86% of the energy the sun provides to the Earth.
TESS is expected to find many more Earth-sized worlds, including those that are potentially habitable.
In June, scientists reported that TESS found a Neptune-sized planet, AU Mic b, orbiting a very young red dwarf star. Bryson Cale, doctoral student at George Mason University, said:
AU Mic is a young nearby M dwarf star. He’s surrounded by a vast disc of debris in which moving clumps of dust have been tracked, and now, thanks to TESS and Spitzer, he has a planet with direct size measurement. There is no other known system that checks all of these important boxes.
The star is only 10 to 20 million years old, and the planet completes an orbit in just 8.5 days.
TESS also recently discovered its first circular planet – one that orbits two stars – called TOI 1338 b. The two stars revolve in orbit every two weeks. One is about 10% more massive than our sun, while the other is cooler, darker and only 1/3 the mass of the sun. The planet is approximately 6.9 times the size of Earth, between the size of Neptune and that of Saturn.
TESS is also good at multitasking, NASA said, and has studied more than just exoplanets. He observed the explosion of a comet in our own solar system, as well as many exploding stars. He also found surprise eclipses in a well-known binary star system, solved a mystery about a class of pulsating stars, and explored a world of star-modulated seasons.
TESS even caught a black hole in a distant galaxy tearing apart a sun-like star with its enormous gravity! Thomas Holoien, of Carnegie Observatories, is the lead author of a paper that described the findings on September 27, 2019 in The astrophysical journal. Holoien said:
TESS data allows us to see exactly when this destructive event, named ASASSN-19bt, started to get clearer, which we have never been able to do before. Because we quickly identified the tidal disturbance with the All-Sky Automated Ground Survey for Supernovae (ASAS-SN), we were able to trigger multi-wavelength tracking observations within the first few days. The first data will be extremely useful in modeling the physics of these explosions.
Last November, it was also announced that TESS would team up with Breakthrough Listen (which is part of Breakthrough Initiatives) in the search for alien intelligence, aka SETI. Basically, TESS will identify objects of interest, such as potentially habitable exoplanets, for other telescopes to point and look for radio signals or other signs of advanced technology, called technosignatures.
In just the first two years of its mission, TESS not only found thousands of new exoplanets, but observed and observed a wide variety of incredible cosmic objects and phenomena. What else will he find in the years to come?
Artist illustration from TESS. The Planet Hunting Space Telescope has now completed its primary mission and is now heading towards its extended mission. He has already found nearly 2,100 exoplanet candidates and 66 new confirmed worlds. Image via NASA / Goddard Space Flight Center.
Conclusion: NASA’s planet-hunting space telescope, TESS, has completed its primary mission.
Via NASA
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