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Jan. 23, 2026
NASA's TESS Returns to Science Observations
NASA's TESS (Transiting Exoplanet Survey Satellite) entered safe mode Jan. 15 and returned to normal science operations Jan. 18.
The operations team determined the issue arose when TESS slewed to point at a target, but its solar panels did not rotate to remain pointed at the Sun relative to the spacecraft's new direction. The off-Sun angle of the solar arrays resulted in a slow discharge of TESS's batteries. As designed and planned for in situations of this kind, the satellite entered a safe mode after detecting the low-power condition.
At the time of the safe mode, TESS was conducting a week-long observation of comet 3I/ATLAS and resumed those observations Jan. 18. Data from TESS is publicly available through archives at the Mikulski Archive for Space Telescopes.
May 7, 2024
NASA's TESS Returns to Science Operations
NASA's TESS (Transiting Exoplanet Survey Satellite) returned to science operations May 3 and is once again making observations. The satellite went into safe mode April 23 following a separate period of down time earlier that month.
The operations team determined this latest safe mode was triggered by a failure to properly unload momentum from the spacecraft's reaction wheels, a routine activity needed to keep the satellite properly oriented when making observations. The propulsion system, which enables this momentum transfer, had not been successfully repressurized following a prior safe mode event April 8. The team has corrected this, allowing the mission to return to normal science operations. The cause of the April 8 safe mode event remains under investigation.
The TESS mission is a NASA Astrophysics Explorer operated by the Massachusetts Institute of Technology in Cambridge, Massachusetts. Launched in 2018, TESS has been scanning almost the entire sky looking for planets beyond our solar system, known as exoplanets. The TESS mission has also uncovered other cosmic phenomena, including star-shredding black holes and stellar oscillations
