Since its launch in April 2018, NASA’s Transiting Exoplanet Survey Satellite (TESS) have mapped more than 93% of the entire sky, discovered 329 new alien worlds and thousands more exoplanet candidates.
An artist’s illustration of NASA’s Transiting Exoplanet Survey Satellite. Image credit: NASA’s Goddard Space Flight Center.
“The volume of high-quality TESS data now available is quite impressive,” said TESS project scientist Dr. Knicole Colón, an astronomer at NASA’s Goddard Space Flight Center.
“We have more than 251 terabytes just for one of the main data products, called full-frame images.”
“That’s the equivalent of streaming 167,000 movies in full HD.”
“TESS extracts parts of each full-frame image to make cutouts around specific cosmic objects — more than 467,000 of them at the moment — and together they create a detailed record of changing brightness for each one,” added Dr. Christina Hedges, lead for the TESS General Investigator Office and an astronomer at the University of Maryland, Baltimore County and NASA’s Goddard Space Flight Center.
“We use these files to produce light curves, a product that graphically shows how a source’s brightness alters over time.”
An artist’s impression of the planet AU Microscopii b. Image credit: NASA’s Goddard Space Flight Center / Chris Smith, USRA.
To find exoplanets, TESS looks for the telltale dimming of a star caused when an orbiting planet passes in front of it.
But stars also change brightness for other reasons: exploding as supernovae, erupting in sudden flares, dark star spots on their rotating surfaces, and even slight changes due to oscillations driven by internal sound waves.
The rapid, regular observations from TESS enable more detailed study of these phenomena.
This illustration sketches out the main features of the TOI-451 system. Image credit: NASA’s Goddard Space Flight Center.
Some stars give TESS a trifecta of brightness-changing behavior. One example is AU Microscopii, thought to be about 25 million years old — a rowdy youngster less than 1% the age of our Sun.
Spotted regions on AU Microscopii’s surface grow and shrink, and the star’s rotation carries them into and out of sight. The stormy star also erupts with frequent flares.
With all this going on, TESS, with the help of NASA’s now-retired Spitzer Space Telescope, discovered a planet about four times Earth’s size orbiting the star every 8.5 days.
Then, in 2022, scientists announced that TESS data revealed the presence of another, smaller world, one almost three times Earth’s size and orbiting every 18.9 days.
An artist’s impression of TOI-700d, c, and b planets and their host star. Image credit: Sci-News.com / NASA’s Goddard Space Flight Center.
In 2021, TESS discovered a trio of hot worlds larger than Earth orbiting a much younger version of our Sun called TOI-451, located about 400 light-years away.
TOI-700d was the first planet TESS found that orbits within its star’s habitable zone. That’s the range of orbital distances where liquid water potentially could exist on the planet’s surface.
In January 2023, astronomers announced this Earth-sized world was joined by another, TOI-700e, that also orbits in the star’s habitable zone.
An artist’s impression of TOI-700e (larger planet) and TOI-700d. Image credit: NASA / JPL-Caltech / Robert Hurt.
TESS has also observed hundreds of supernovae and thousands of other candidate transient, or short-lived, events so far.
“We’re celebrating TESS’s fifth anniversary at work — and wishing it many happy returns!” Dr. Colón said.
“New discoveries are waiting to be made within the huge volume of data TESS has already captured.”
