TESS planet hunter snaps test photo showing 200,000 stars

An initial image from NASA’s new exoplanet-hunting TESS spacecraft shows more than 200,000 stars captured in a two-second exposure. The first science-quality image is expected next month. Credit: NASA

One of four cameras at the heart of the planet-hunting Transiting Exoplanet Survey Satellite – TESS – has snapped a stunning test photo showing an estimated 200,000 stars cantered on the southern constellation Centaurus.

The image was released by NASA shortly after Tess flew within about 8,000 kilometres (5,000 miles) of the moon 17 May for a gravity assist to nudge the spacecraft toward its intended 13.7-day orbit. A final rocket firing is planned 30 May to fine tune the trajectory.

Launched from Cape Canaveral on 18 April, TESS features four 16.8-megapixel cameras, each equipped with four state-of-the art CCD detectors. If all goes well, the spacecraft will spend at least two years mapping the sky, on the lookout for the tell-tale dimming that occurs when an exoplanet moves in front of its star as viewed from Earth.

The goal is to map 85 percent of the sky, identifying as many exoplanet candidates as possible with an emphasis on finding Earth-size to super-Earth-size terrestrial worlds orbiting in the habitable zones of their stars where the temperature would allow water to exist as a liquid – a requirement for life as it’s known on Earth.

The two-second exposure released Friday shows a multitude of stars, but it’s just a sampling of what’s to come.

TESS’s four cameras will shoot 24-degree-wide squares stretching from the celestial equator to the poles, taking 27 days to collect a single 96-degree long sector. Then another sector will be imaged, then another until nearly the entire sky has been mapped over the course of the two-year primary mission.

During each 27-day observing run, TESS will monitor the brightness of every visible star every 30 minutes. Some 15,000 stars in each sector, selected before launch, will be monitored every two minutes. It will take a year to collect the 13 sectors needed to map the southern sky and another year to map its northern counterpart.

NASA says TESS should be ready to begin science operations in mid June.