TESS Live Tracker
NASA's Transiting Exoplanet Survey Satellite, launched 18 April 2018 on a SpaceX Falcon 9 from Cape Canaveral. TESS is the first and only spacecraft ever to fly a P/2 lunar-resonant orbit, sweeping between 108,000 km and near-lunar distance every 13.7 days. Its four wide-field cameras have already confirmed more than 600 exoplanets around the brightest, nearest stars.
TESS Uncovers Seven-Planet System Around Nearby M-Dwarf
A stellar survey by TESS has uncovered a compact system of seven small planets orbiting a nearby red dwarf, three of them inside the star's habitable zone. The planets were confirmed through follow-up radial-velocity observations and are among the most promising targets yet for atmospheric characterisation.
The Only Full-Sky Exoplanet Surveyor Flying
TESS is the direct successor to Kepler, the mission that first showed exoplanets were common. Where Kepler stared at a small patch of sky for years, TESS surveys the entire sky in 26 sectors, watching the brightest and nearest stars where planet atmospheres can be followed up by JWST. Its 13.7-day orbit is unique in spaceflight.
How TESS Sees the Whole Sky
TESS uses four identical wide-field cameras aimed in a stack to cover a 24° by 96° strip from horizon to zenith. As the spacecraft rotates every 13.7-day orbit, that strip sweeps across an entire hemisphere over roughly a year.
8 Years, Six Milestones
What TESS Has Actually Found
Eight years of full-sky staring has turned TESS into the deepest catalogue of transiting exoplanets around nearby, bright stars, precisely the ones we can follow up in detail.
TESS vs Kepler, Hubble and JWST
TESS operates in the same optical waveband as its predecessor Kepler and its cousins Hubble and JWST, but its survey strategy and unique orbit set it apart from all three.
Why TESS Flies Where Nothing Else Has
TESS was designed to solve a specific problem left over from Kepler. Kepler proved planets are common by staring at a hundred thousand faint stars for four years. But most of its planets were too dim and too far away for detailed follow-up. TESS's answer: cover the entire sky, and only look at the brightest, closest stars. Its four wide-field cameras deliver photometric precision on stars 10× closer than Kepler's, exactly the ones whose atmospheres can be probed by JWST spectroscopy.
The P/2 lunar-resonant orbit
TESS flies a completely unique 13.7-day orbit chosen so its period is exactly half the Moon's. That resonance keeps TESS gravitationally stable for decades without needing station-keeping burns. Perigee at 108,000 km sits well above the geosynchronous belt, so TESS never crosses busy operational orbits. Apogee near lunar distance keeps the spacecraft in a benign radiation environment and allows a clean, uninterrupted 13-day observation of every target sector.
The extended mission story
TESS finished its two-year primary mission in July 2020 and has been running on extended missions ever since. Its third extended mission runs through 2028. Every additional year of coverage catches longer-period planets that transit their star less often, and lets the survey re-observe high-priority targets already flagged as candidates.
What comes next
ESA's PLATO mission, due for launch in 2026-2027, will pick up the survey with a much larger focal plane. NASA's next dedicated exoplanet mission, ARIEL, targets 2029. Between them and JWST atmospheric spectroscopy, the TESS-discovered planet catalogue will remain the foundation for the entire field for the next decade.
TESS, Frequently Asked
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