Kepler’s Successor Scanning the Entire Sky
Launched April 18, 2018, NASA’s Transiting Exoplanet Survey Satellite (TESS) continues the exoplanet revolution started by Kepler, but with a different strategy: instead of staring at one small patch of sky, TESS scans 85% of the entire sky, monitoring 200,000+ stars for planetary transits. The mission focuses on nearby, bright stars (30-300 light-years away) whose planets can be studied in detail by ground telescopes and JWST.
Record-Breaking Discoveries
By 2023, TESS confirmed 400+ exoplanets with 6,000+ candidates awaiting verification. Notable finds include: TOI-700 d (Earth-sized planet in habitable zone 100 light-years away), LTT 1445 A b (rocky world orbiting nearby red dwarf), TOI-270 system (three planets ideal for atmospheric study), TIC 168789840 (six-planet system in gravitational resonance), and the youngest known exoplanet (TOI-1227 b, orbiting a 250-million-year-old star).
Follow-Up Goldmine
TESS’s genius is finding planets around bright nearby stars—targets easily studied by other telescopes. Ground-based spectrographs measure planet masses via radial velocity. JWST observes atmospheric compositions. This follow-up reveals planet densities (rocky vs. gaseous), temperatures, and atmospheric chemicals (water vapor, methane, carbon dioxide). TOI-700 d became one of JWST’s first targets, searching for biosignature gases.
Odd Worlds & Future Targets
TESS discoveries challenge planetary categories: Mini-Neptunes (between Earth and Neptune in size, the most common planet type in the galaxy but absent from our solar system), Hot Jupiters orbiting in days, Ultra-short-period planets with year-lengths measured in hours, Circumbinary planets (Tatooine-like worlds orbiting two stars). The mission extends through 2025, building a catalog of the best exoplanet targets for characterization by next-generation telescopes searching for life.
Sources:
- NASA TESS: https://www.nasa.gov/tess-transiting-exoplanet-survey-satellite
- Exoplanet catalog: https://exoplanetarchive.ipac.caltech.edu/
- Nature first discoveries: https://www.nature.com/articles/s41586-019-1676-3