In its fifth year in space, NASA’s TESS (Transiting Exoplanet Survey Satellite) satellite is enjoying incredible success. TESS cameras mapped more than 93% of the sky, discovered 329 new worlds and thousands of candidates, and provided new insights into a wide variety of cosmic phenomena, from stellar pulsations and stellar explosions to supermassive black holes.

Using four cameras, TESS observes large areas of the sky, called sectors, for about a month. Each sector is 24 by 96 degrees, about the size of a human hand at arm’s length, and stretches from horizon to apex. The cameras capture 192 million pixels in every full-frame image. TESS took one of these images every 30 minutes during its primary mission, but this data flow increased over time. Cameras now record every sector every 200 seconds.

This mosaic combines more than 900 images from all 24 by 90 degree sectors surveyed by NASA’s Transiting Exoplanet Survey Satellite (TESS) through October 2022. The mosaic covers 93% of the sky and was created in chronological order to show the progress of the mission. for the last five years. A notable feature of the mosaic is the Milky Way, a bright U-shaped band that represents the bright central plane of our galaxy.

“The amount of high-quality TESS data currently available is pretty impressive,” said Nicole Colon, mission project scientist at NASA’s Goddard Space Flight Center in Greenbelt, Maryland. “We have more than 251 terabytes of space for just one of the main data products, called full-frame images. That’s the equivalent of 167,000 movie streams in Full HD.”

“TESS extracts parts of each full-frame image to make cutouts around certain space objects – there are more than 467,000 so far – and together they create a detailed record of how the brightness of each changes,” said Christina Hedges, TESS’s president. Office of Principal Investigator and Research Associate, University of Maryland, Baltimore County and Goddard. “We use these files to create light curves, a product that graphically shows how a source’s brightness changes over time.”

To find exoplanets or worlds outside our solar system, TESS looks for the visible dimming of a star caused by passing in front of an orbiting planet. But stars’ brightness also changes for other reasons: explosions as supernovas, flash explosions, dark patches of stars on their rotating surfaces, and even subtle changes from oscillations caused by internal sound waves. Rapid, regular observations with TESS allow us to examine these phenomena in more detail.

Some stars give TESS a triple brightness change behavior. One example is AU Microscopii, a turbulent teenager less than 1% of the age of our Sun, thought to be about 25 million years old. The speckled areas on the AU Mic’s surface get larger and smaller as the star’s rotation brings them into view and loses sight. The stormy star also shines in frequent bursts. All the while, TESS, using NASA’s now decommissioned Spitzer Space Telescope, discovered a planet about four times the size of Earth, orbiting its star every 8.5 days. Then, in 2022, scientists announced that TESS data had revealed the existence of another smaller world, about three times the size of Earth and rotating every 18.9 days. These discoveries have made the system a cornerstone for understanding how stars and planets form and evolve.

TESS is a NASA Astrophysical Explorer mission led and managed by the Massachusetts Institute of Technology in Cambridge, Massachusetts and operated by NASA’s Goddard Space Flight Center. Additional partners include Falls Church, Va. based in Northrop Grumman; NASA’s Ames Research Center in California’s Silicon Valley; Harvard-Smithsonian Center for Astrophysics in Cambridge, Massachusetts; MIT Lincoln Lab; and the Space Telescope Science Institute in Baltimore. More than a dozen universities, research institutes and observatories worldwide participate in the mission.