Goodbye Kepler, hello Tess: a new telescope will take over the baton in the search for planets

TESS was designed in such a way that it can discover planets very close to their star even if the stars are very bright, and thus among other things it will be able to locate planets in solar systems close to our own solar system and examine them in depth

An image of Kepler-10b, a planet orbiting one of the 150,000 stars tracked by the Kepler space telescope. NASA / Kepler mission / Dana Berry, CC BY
author
Jason Stephan
Assistant Professor of Physics and Astronomy, University of Nevada, Las Vegas

For centuries, humans have wondered about the possibility of planets orbiting distant stars. Perhaps some of these worlds will be inhabited by strange life forms or have unique histories. But it wasn't until 1995 that astronomers identified the first planets orbiting planets outside our solar system.

In the past decade, in particular, the number of planets known to orbit distant stars has grown from less than 100 to more than 2,000, with another 2,000 potential planets awaiting confirmation. Most of these new discoveries stem from one project - NASA's Kepler Space Telescope.

The number of happy planets continues to increase. NASA / Ames Research Center / Wendy Stanzel and University of Texas at Austin / Andrew Vanderburgh, CC BY

The Kepler space telescope is a satellite that carries a telescope with a diameter of one meter, and a digital camera of 95 megapixels. The instruments on the satellite detected tiny changes in the brightness of 150,000 distant stars, looking for the signal that comes when the planet blocks some of the star's light as it passes through the telescope's line of sight. The telescope is so sensitive that it can detect a buzzing fly hovering over one Chicago streetlight from orbit in space. He can see stars trembling and vibrating; He can see small stars like the moon.
Kepler's thousands of discoveries revolutionized the understanding of planets and planetary systems. Now, however, the spacecraft is running out of hydrazine fuel and will end its life sometime in the coming months. Luckily for planet hunters, NASA's next exoplanet search mission is right around the corner.

The history of Kepler
The Kepler mission was born in the early 2000s with an idea put forward by NASA scientist Bill Borkey, who was later assisted by his colleague David Koch. At that time there were no known planets outside the solar system. Kepler was eventually built in the 2009s and launched in March 2008. I joined the Kepler science team in XNUMX, eventually collaborating with the group studying the motions of stars led by Jack Lissauer.
Originally, the mission was planned to last three and a half years with possible extensions as long as the spacecraft's fuel, or camera, or other components last. Over time, parts of the camera began to fail but the mission continued. However, in 2013, when two of its four stabilizing gyroscopes stopped, the original Kepler mission ended.
Even then, with some sophistication, NASA was able to use the reflected light from the sun to help navigate the spacecraft. The mission was restarted as K2 and continued to find planets for another half decade. Now, when the fuel gauge runs out, its orbit around Earth will twist and the spacecraft will drift into the solar system. The final catalog of planet candidates from the original mission was completed late last year and is now processing the latest observations of K2.

Kepler's science
Extracting knowledge from Kepler will take many more years of reviewing data and pointing telescopes at planet candidates, but what we've seen so far has also amazed scientists.
We have seen several planets that orbit their host stars in a matter of hours, and are so hot that the rocks on their surface vaporize and float in space behind the planet like a comet's tail. Other systems have planets so close together that if you were to stand on one planet, the other planet would appear 10 times larger than the full moon. One system is so packed that eight planets are closer to their star than Earth is to the Sun. Many of these planets orbit their suns in the habitable zone - the area where water can exist in a liquid state on their surface.

In its four years of operation in its original form, Kepler stared at one area of ​​the sky and scanned it over and over again. TESS will use the same detection technique as Kepler, but instead of circling the Sun, it will "have a relationship" with the Moon, it will circle the Earth exactly twice in the entire orbit of the Moon. In addition, instead of staring at one part of the sky, Tess will scan almost the entire sky with the photo fields overlapping (much like the petals of a flower).

Following the knowledge we learned from Kepler, astronomers expect Tess to discover thousands of planetary systems. By scanning the entire sky we can discover systems where the planets orbit the stars 10 times closer and 100 times brighter than those Kepler could detect. In this way, we will be able to discover planets around the brightest stars closest to the solar system. This will open up new possibilities for measuring the mass of the planets and their density, studying their atmospheres, studying their host stars and learning about the nature of the systems in which the planets are located. This information, in turn, will tell us more about the history of our planet, how life began, what fate has been denied us and what is expected in the future. The quest to find our place in the universe continues as Kepler completes his part of the journey and TESS takes up the baton.

to the article on The Conversation website

More on the subject on the science website

• The space missions of 2018: from the world's most powerful launcher to the successor to the Kepler space telescope
• The Kepler data increase the likelihood of a widespread distribution of life in the universe
• "Operation Kepler" for the discovery of Earth twins (Hidan, 2001)