TESS mission cleared for next development phase

This is a conceptual image of the Transiting Exoplanet Survey Satellite (TESS). 

Credit: MIT

NASA has officially confirmed the Transiting Exoplanet Survey Satellite (TESS) mission, clearing it to move forward into the development phase.

This marks a significant step for the TESS mission, which would search the entire sky for planets outside our solar system, known as exoplanets.

Designed as the first all-sky survey, TESS would spend two years of an overall three-year funded science mission searching both hemispheres of the sky for nearby exoplanets.

"This is an incredibly exciting time for the search of planets outside our solar system," said Mark Sistilli, the TESS program executive from NASA Headquarters, Washington.

"We got the green light to start building what is going to be a spacecraft that could change what we think we know about exoplanets."

"During its first two years in orbit, the TESS spacecraft will concentrate its gaze on several hundred thousand specially chosen stars, looking for small dips in their light caused by orbiting planets passing between their host star and us," said TESS Principal Investigator George Ricker of the Massachusetts Institute of Technology, Cambridge, Massachusetts.

During the third year, ground-based astronomical observatories would continue monitoring exoplanets identified earlier by the TESS spacecraft.

TESS is expected to find more than 5,000 exoplanet candidates, including 50 Earth-sized planets.

It will also find a wide array of exoplanet types, ranging from small, rocky planets to gas giants.

Some of these planets could be the right sizes, and orbit at the correct distances from their stars, to potentially support life.

"The most exciting part of the search for planets outside our solar system is the identification of 'earthlike' planets with rocky surfaces and liquid water as well as temperatures and atmospheric constituents that appear hospitable to life," said TESS Project Manager Jeff Volosin at NASA's Goddard Space Flight Center in Greenbelt, Maryland.

"Although these planets are small and harder to detect from so far away, this is exactly the type of world that the TESS mission will focus on identifying."

Now that NASA has confirmed TESS, the next step is the Critical Design Review in 2015. This would clear the mission to build the necessary flight hardware for launch.

"After spending the past year building the team and honing the design, it is incredibly exciting to be approved to move forward toward implementing NASA's newest exoplanet hunting mission,"Volosin said.

TESS is designed to complement several other critical missions in the search for life on other planets.

Once TESS finds nearby exoplanets to study and determines their sizes, ground-based observatories and other NASA missions, like the James Webb Space Telescope, would make follow-up observations on the most promising candidates to determine their density and other key properties.

By figuring out a planet's characteristics, like its atmospheric conditions, scientists could determine whether the targeted planet has a habitable environment.

"TESS should discover thousands of new exoplanets within two hundred light years of Earth," Ricker said. "Most of these will be orbiting bright stars, making them ideal targets for characterization observations with NASA's James Webb Space Telescope."

"The Webb telescope and other teams will focus on understanding the atmospheres and surfaces of these distant worlds, and someday, hopefully identify the first signs of life outside of our solar system," Volosin said.

NASA TESS: Exoplanet Mission to Hunt Down Earth-sized Worlds

Set to launch in 2017, NASA's Transiting Exoplanet Survey Satellite (TESS) will monitor more than half a million stars over its two-year mission, with a focus on the smallest, brightest stellar objects.

During its observations, TESS is expected to find more than 3,000 new planets outside of our solar system, most of which will be possible for ground-based telescopes to observe.

"Bright host stars are the best ones for follow-up studies of their exoplanets to pin down planet masses, and to characterize planet atmospheres," said TESS principal investigator George Ricker, of the Massachusetts Institute of Technology's Kavli Institute for Astrophysics.

"TESS should be able to find over 200 Earths and super-Earths, defined as being twice the size of Earth," said Peter Sullivan, a physics doctoral student at MIT.

"Ten to 20 of those are habitable-zone planets.”

Sullivan, who works with Ricker on TESS, led an analysis of the number of planets TESS would likely find based on the number and types of planets found by NASA's Kepler mission.

Kepler focused on a single region of the sky and studied all transiting planets within it.

TESS, on the other hand, will examine almost the entire sky over its two-year mission, but capture only the brightest stars, many of which are expected to host terrestrial planets.

NASA's Transiting Exoplanet Survey Satellite (TESS) mission is scheduled to launch in 2017 to hunt for Earth-size alien worlds.

Credit: MIT KAVLI Institute for Astrophysics and Space Research

TESS will travel around Earth in a highly elliptical orbit that will range as distant as the moon.

Along the way, it will use four cameras to observe a swatch of sky running from the celestial equator to the poles.

TESS will observe each swatch for approximately a month before switching to the next region.



Courtney Dressing, a doctoral student at the Harvard-Smithsonian Center for Astrophysics, compares the satellite's observations to peeling an apple in vertical cuts that overlap near the stem.

Because of the overlap, stars near the pole will be observed for more than 100 days, while stars near the equator will be observed for only 27 days.

Dressing worked on a second model, based on Sullivan's work, that predicts the number of planets near Earth that pass between the sun and their host star.

"We predicted there should be about 100 transiting planets within 20 parsecs [about 65 light-years], and that roughly three of them should lie within the habitable zone of their host stars," Dressing said.

Not all of these planets will be detectable to the TESS mission. According to Dressing, the new telescope will be most sensitive to small planets orbiting stars 20 to 50 percent the size of our sun.