Transiting Exoplanet Survey Satellite

TESS: Searching for New Worlds

Transiting Exoplanet Survey Satellite (TESS), launched by NASA in 2018, is a revolutionary space telescope dedicated to discovering exoplanets—planets beyond our solar system. Using the highly effective transit method, TESS monitors the brightness of nearby stars, searching for the tiny dips in light that occur when a planet crosses in front of its host star. This technique has already unveiled a treasure trove of alien worlds.

• Wide-Field Cameras: TESS is equipped with four powerful wide-angle cameras that enable it to scan over 85% of the sky. Each camera observes a different section of space, and together they provide a broad field of view—ideal for covering large areas and spotting planetary transits that might otherwise go unnoticed.
• Orbit and Coverage: TESS orbits in a unique highly elliptical 13.7-day orbit, known as a P/2 resonant orbit with the Moon. This orbit allows the satellite to maintain a stable environment, free from Earth’s interference, and conduct two-week-long observations of different sky sectors. Over time, TESS builds a dynamic, time-lapse map of exoplanetary activity across the sky.
• Planetary Discoveries: Since its launch, TESS has identified thousands of exoplanet candidates, known as TESS Objects of Interest (TOIs). These range from Earth-sized rocky planets in habitable zones to gas giants in tight orbits. Many of these candidates are now being confirmed through follow-up observations by ground-based telescopes and other space missions like the James Webb Space Telescope (JWST).

Scientific Impact and Legacy

By 2025, TESS has become a cornerstone of exoplanetary science. Unlike earlier missions such as Kepler that focused on a small patch of sky, TESS surveys nearly the entire celestial sphere, providing a much broader catalog of planets orbiting bright, nearby stars. These stars are ideal targets for follow-up study because their relative brightness allows detailed atmospheric characterization using spectroscopic methods.

TESS’s discoveries have already led to the identification of super-Earths, mini-Neptunes, and potentially habitable-zone planets. Some of these worlds exhibit the right conditions for life as we know it—making them prime targets for JWST’s infrared observations, which aim to detect signs of biosignatures in their atmospheres.

Beyond exoplanets, TESS has contributed to stellar astrophysics by capturing valuable data on variable stars, eclipsing binaries, and even transient phenomena like supernovae and tidal disruption events. Its frequent, high-cadence observations offer a unique window into the dynamic universe.

The Road Ahead

As of 2025, TESS continues to scan the skies with remarkable efficiency. Its mission extensions are planned to revisit previous sectors and refine earlier detections, improving accuracy and uncovering multi-planet systems previously hidden in the noise. Its partnership with JWST, the Extremely Large Telescope (ELT), and other observatories makes it a vital part of the exoplanet detection and confirmation pipeline.

TESS is opening the door to new worlds, expanding our search for life beyond Earth.

With each passing day, TESS strengthens humanity’s quest to answer one of the oldest questions: Are we alone in the universe? From nearby red dwarfs to sun-like stars, the planets uncovered by TESS are bringing us closer than ever to finding a second Earth—and perhaps, signs of life itself.