In April 2018, NASA launched the Transiting Exoplanet Survey Satellite (TESS), the successor to the Kepler Space Telescope that revolutionized the exoplanet studies field. Like its predecessor, TESS has been scanning almost the entire sky for five years for extrasolar planets using the Transit Method. This consists of monitoring thousands of stars for periodic dips in brightness, which may indicate a planet passing in front of the star relative to the observer. To date, TESS has made 243 confirmed discoveries, with another 4562 candidates – or TESS Objects of Interest (TOI) – awaiting confirmation.
On Monday, October 10th, fans of the TESS mission and the research it conducts got a bit of a scare as the observatory experienced a malfunction and had to be put into safe mode. Three days later, at around 06:30 PM EDT (03:30 PM PDT) on October 13th, NASA announced that their engineers had successfully powered up the instrument and brought it back online. While technicians at NASA are still investigating the cause of the malfunction, the spacecraft is now back in its fine-pointing mode and has resumed its second extended mission (EM2).
For reasons that are still unknown at this time, TESS had to be put into safe mode following a reset of its flight computer. This failsafe suspends science operations and places the telescope into a stable configuration until the mission team can determine the source of the problem. When in safe mode, any information that has not yet been downlinked to mission control will be safely stored aboard the space telescope’s computer for later retrieval.
TESS will survey the sky in a series of thirteen observing segments, each 27-days long. Credit: NASA/MIT
On October 12th, the TESS operations team reported that science data had been safely stored and that it could take several days before the telescope resumed normal operations. A day later, they announced that they had successfully restored power to the telescope and commenced recovery procedures. As of the latest update from NASA (Friday, October 14th), TESS has reportedly resumed normal science operations, and all the science data stored on board will be downlinked at the next available opportunity.
This hiccup happened during what has proven to be a promising year for the TESS mission. It began with the satellite being part of a Science Mission Directorate (SMD) Senior Review, an independent comparative review that NASA periodically conducts of its operational missions. This was the second time TESS was included in a Senior Review since it launched in 2018, the previous taking place in 2019. In both cases, TESS received high rankings for its many discoveries, including exoplanets and other cosmic phenomena like star-shredding black holes and stellar oscillations.
In addition, TESS entered Year 5 of its exoplanet-hunting campaign, which will run from September 2022 to September 2023. As part of this campaign, the exoplanet finder will scan five more sectors in the northern hemisphere, followed by nine more in the southern hemisphere. It will also provide 200-second full-frame images (FFIs) for each sector, compared to 10-minute FFIs in the first extended mission (EM1) and the 30-minute FFIs during its primary mission. This will create an unprecedented cadence of images for TESS’s full field of view and promises to lead to many exciting discoveries.
Illustration of the TESS field of view. Credit: NASA/MIT
For Year 6, TESS will complete its scan of the southern hemisphere, return to the ecliptic to scan three more sectors, then survey eleven more sectors in the northern hemisphere. The second mission extension (EM2) will then conclude by October 2024.
In the meantime, NASA engineers are still searching for the cause of the malfunction. Further updates will be posted on the NASA TESS mission page or the mission team’s page at MIT.
Further Reading: NASA