If humans ever leave this solar system, they probably will not do so without a fixed course. Most likely they will set a course for a distant reference point, perhaps another solar system, to visit, study or even settle down. And when they do, there's a good chance that the destination they choose has been discovered by NASA's new planetary search spacecraft.
Called Transiting Exoplanet Survey Satellite, the instrument will soon be hooked into space aboard one of SpaceX's Falcon 9 rockets. There, from a very unusual orbit, TESS will lead the search for planets beyond our solar system even more ambitious than the one set up by its predecessor, the Kepler Space Telescope, in search of alien rocky worlds in our immediate galactic neighborhood: the types of places that humans, or at least the probes of human engineering, could reach within the life of a human being.
Like Kepler, TESS is designed to detect small depressions in light emanating from stars. These falls can serve as clues that a planet in orbit moves across the face of its parent star, preventing part of its light from reaching the spacecraft in a phenomenon that astronomers call transit.
Kepler's use of the transit method fundamentally changed our view of the universe. Thirty years ago, astronomers knew only nine (now eight) planets, which make up our solar system. Throughout the 1990s and early Aughts, scientists found a handful of planets orbiting other stars; But only a decade ago, it was still unclear if the so-called exoplanets were rare or common in the galaxy. The prevalence of potentially habitable worlds is also unknown: celestial bodies that, like Earth, were neither too hot nor too cold to hold liquid water to sustain life.
But Kepler, which was launched in 2009, changed that big time. He examined only a small piece of sky, but within that small patch, Kepler found, according to the last account, more than 2,300 exoplanets, of which tens could hold liquid water. According to Kepler's sampling, astronomers now believe that the planets of the Milky Way could outnumber their stars, and that our galaxy could harbor billions of potentially habitable worlds.
And TESS? TESS is designed to search and study the exoplanets closest to Earth.
Kepler did what astronomers call a deep and narrow study of the heavens; He peered into a small segment of the sky, at stars that were several hundred and several thousand light-years away. Instead, the TESS survey will be broad and shallow. It is designed to inspect 85 percent of the sky – an area 400 times larger than that monitored by Kepler – with four wide-field optical cameras of 16.8 megapixels.
Each camera has seven lenses that channel light from the sky towards four CCD image sensors. A single chamber can cover a piece of sky 24 degrees wide by 24 degrees high. "It's a huge field of vision, wide enough to fit the Orion constellation," says astrophysicist Padi Boyd, chief of the NASA's Exoplanet and Astrophysical Astrophysics Laboratory in the Division of Astrophysical Sciences and director of the guest-researchers program. of TESS.
Stacking the images of the four chambers gives TESS a view of the sky of 96 degrees of height, enough to cover an entire latitudinal segment of 90 degrees of the northern or southern hemisphere. Each month, TESS will direct its gaze to a different segment of the sky and absorb everything that needs to be seen. Then it will turn to an adjacent segment and look. Turn and look. Turn and look. In this way, TESS will scan most of the sky for the approximately 200,000 brightest and closest stars; Any planet it identifies will be between 10 and 300 light years from Earth. It will cover the southern hemisphere during its first year of operation and the northern hemisphere during its second year.
"Do that, and you'll get a census of the solar neighborhood," says astrophysicist George Ricker, principal investigator at MIT. Kavli Institute of Astrophysics and Space Research and leader of the TESS mission. He and his team hope to catalog some 20,000 new exoplanet candidates. Anticipate that 500 of them will have radios less than twice those of Earth, small enough, according to astronomers, as rocky, but large enough to hold an atmosphere. The proximity of these planets to Earth will allow researchers to study their masses and atmospheric compositions in follow-up studies, using terrestrial instruments and future spacecraft such as the James Webb Space Telescope.
But before TESS makes this possible, it will have to enter an unusual orbit around the Earth. Your path will stretch almost as far as the moon before retreating to a close passage of the planet once every 14 days. When TESS approaches Earth, it will transmit data at a greater bandwidth. When it is far away, it will prevent radiation and temperature changes that may impede its performance. This highly elliptical orbit – which has never been tested by a spacecraft – will allow TESS to have the best of both worlds.
"We are setting the stage for the future of exoplanet research, not just for the 21st century, but for the 22nd century and beyond," says Ricker. "Even 1,000 years from now, TESS will be remembered for establishing the best and brightest systems in our solar neighborhood."
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