What mission will NASA's TESS satellite perform and will it be launched aboard a Falcon 9 rocket?

If humans want to leave the solar system one day, it probably won’t be aimless. We will most likely set a course to some distant waypoint, perhaps another star system, to visit, study, or even settle there. And by then, there's a good chance our chosen destination will have been discovered by NASA's new "planet hunters."

The name of this "hunter" is the "Transiting Exoplanet Survey Satellite" (TESS), which will soon be launched on board SpaceX's "Falcon 9" rocket . There, TESS will lead our search for planets beyond our solar system from a highly unusual orbit that is even more ambitious than that of its predecessor, the Kepler Space Telescope, which was to search for planets in our own galaxy. Search for nearby rocky exoplanets—the kind that humans, or at least man-made probes, can reach within a lifetime.

TESS aims to find and study the exoplanets closest to Earth.

Like Kepler, TESS is designed to detect small dark spots in the light emitted by stars. Those dark spots indicate that the planet is passing by its parent star, blocking some of the light from reaching the detector, a phenomenon that astronomers call a "transit."

The Kepler telescope's use of the transit method has fundamentally changed our view of the universe. Thirty years ago, astronomers knew only nine planets in the solar system (now there are only eight planets left). Throughout the 1990s and early 2000s, scientists discovered a handful of planets orbiting other stars; but as recently as 10 years ago, we still didn't know whether so-called exoplanets were rare or common in the Milky Way. It is still unknown whether there are more or less potentially habitable planets - so-called habitable planets are celestial bodies like the Earth that are neither too hot nor too cold and can allow the existence of liquid water necessary for life.

However, the Kepler telescope launched in 2009 changed this situation to a great extent. It only observes a small area of ??the sky, but within it, Kepler has so far discovered more than 2,300 exoplanets, dozens of which may contain liquid water. Based on observations from the Kepler telescope, astronomers now believe that there may be more planets than stars in the Milky Way, and that there could be billions of potentially habitable planets.

What about TESS? It aims to find and study the exoplanets closest to Earth.

The Kepler telescope conducts what astronomers call a deep narrow survey; it only observes a small area of ??the sky, and the stars it observes are between hundreds and thousands of light-years away. In contrast, TESS's sky survey will be broad and shallow. It aims to use four 16.8-megapixel wide-field optical lenses to observe 85% of the sky, with an observation range 400 times larger than the Kepler telescope.

Each lens has 7 lenses, which will project light from the universe onto 4 CCD image sensors. A single lens can cover a sky area of ??24° in length and width. "It's a huge field of view, wide enough to accommodate Orion," said astrophysicist Padi Boyd, director of NASA's Astrophysics Sciences Division's Exoplanet and Stellar Astrophysics Laboratory. (Exoplanets and Stellar Astrophysics Laboratory), and concurrently serves as the director of the TESS Visiting Researcher Program.

By stacking the images taken by the four lenses, TESS can observe the sky area with an altitude of 96°, enough to cover the northern or southern celestial sphere at 90°. Every month TESS will focus on a different geographical area and focus all its attention there. It then turns to adjacent partition observations. Turn, observe, repeat. In this way, TESS will scan the sky for some 200,000 of the closest and brightest stars to us, and the planets it identifies will be between 10 and 300 light-years away from Earth. TESS will complete the southern celestial sphere in its first year of service, and then the northern celestial sphere in its second year.

"By doing this, we have completed a census of objects around the solar system," said astrophysicist George Ricker, director of the Kavli Object Research Institute at MIT. Senior researcher at the Kavli Institute for Astrophysics and Space Research and leader of the TESS mission. Rick and his team estimate that they will be able to include about 20,000 new exoplanets. They estimate that 500 of them will have a radius no more than twice that of Earth - a size that astronomers believe can be rocky and still have an atmosphere. The relative proximity of these planets to Earth will allow researchers to study their masses and atmospheric composition using ground-based instruments and future probes such as the James Webb Space Telescope in subsequent studies.

However, before this can become a reality, TESS will need to enter an unusual orbit around the Earth. The apogee of this orbit is close to the Moon's orbit around the Earth, and its orbital period is 14 days. As TESS gets closer to Earth, it will be able to transmit data back to the ground with higher bandwidth. When TESS is far from Earth, it will be sheltered from radiation and temperature fluctuations that could affect its performance. No spacecraft has ever entered such a high elliptical orbit before, and it will give TESS the best of both worlds.

“We are setting the stage for the future of exoplanet research, which is not just the 21st century, but the 22nd century and beyond,” said Rick. “Even 1,000 years from now, TESS will also be remembered for creating the best and brightest system around the solar system.

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