TESS has resumed normal operations

In April 2018, NASA launched the Transit exoplanet survey satellite (TESS), the successor to the Kepler space telescope who have revolutionized the field of exoplanet research. Like its predecessor, TESS has been scanning almost the entire sky for extrasolar planets for five years using the transit method. This consists of monitoring thousands of stars for periodic dips in brightness, which may indicate a planet is passing in front of the star relative to the observer. To date, TESS has made 243 confirmed discoveries, with an additional 4562 candidates – or TESS Objects of Interest (TOI) – awaiting confirmation.

On Monday, October 10th, fans of the TESS mission and the research it was conducting got a bit of a scare when the observatory malfunctioned and had to be put into safe mode. Three days later, around 6:30 p.m. EDT (3:30 p.m. PDT) on October 13, NASA announced that its engineers had successfully booted the instrument and brought it back online. While NASA technicians are still investigating the cause of the malfunction, the spacecraft is now back in fine-pointing mode and has resumed its second enhanced mission (EM2).

For reasons that are still unclear, TESS had to be put into safe mode after resetting the flight computer. This failover interrupts scientific operations and places the telescope in a stable configuration until the mission team can determine the cause of the problem. In safe mode, any information that has not yet been transmitted to mission control is securely stored on the space telescope’s computer for later retrieval.

On October 12, the TESS operations team reported that the scientific data was safely stored and that it could be several days before the telescope resumed normal operations. A day later, they announced that they had successfully restored power to the telescope and had begun recovery procedures. With NASA’s latest update (Friday, October 14), TESS has reportedly resumed normal science operations and all science data stored on board will be downlinked at the next available opportunity.

This hiccup came in a promising year for the TESS mission. It started with the satellite being part of a Senior Review by the Science Mission Directorate (SMD), an independent comparative review that NASA regularly conducts for its operational missions. This was the second time that TESS was included in a senior review since its inception in 2018, the previous one being in 2019. In both cases, TESS received high rankings for its many discoveries, including exoplanets and other cosmic phenomena such as star-ripping black holes and stellar oscillations.

In addition, TESS has entered the fifth year 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 30-minute FFIs during its main mission. This will generate an unprecedented cadence of images for the entire field of view of TESS and promises to lead to many exciting discoveries.

For Year 6, TESS will complete its scan of the southern hemisphere, return to the ecliptic to scan three more sectors, and then survey eleven more sectors in the northern hemisphere. The second mission extension (EM2) will then end until October 2024.

Meanwhile, NASA engineers are still searching for the cause of the malfunction. Further updates will be posted on the NASA TESS mission page or the MIT mission team page.

Further reading: NASA