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NASA’s planet-hunting TESS satellite: What you need to know

NASA’s New Planet Hunter: TESS

Initially slated for a two-year mission, NASA’s Transiting Exoplanet Survey Satellite (TESS) soars in an elliptical, 13.7-day cycle around the Earth. It’s a unique and extreme orbit that’s never been used before, varying as close as 67,000 miles and as far away as 232,000 miles from its home planet. According to, the stable orbit will allow TESS to stay in space for decades without any need for course corrections.

And it gives the satellite a magical perspective.

Outfitted with four wide-angle cameras, TESS will observe 85 percent of the surrounding sky as it looks for exoplanets. The instruments on the spacecraft will map 26 different “sectors” of the sky over a two-year period. And with the first amazing image arriving in May, and a recent series of commissioning tests complete, the satellite’s future looks promising. Here’s everything you need to know about this amazing craft.

TESS begins hunting for exoplanets

We’re in operation! As of Friday, July 27, NASA reported that its exoplanet hunting satellite was fully operational and had begun scanning the skies for distant planets — and maybe, just maybe, spying signs of life outside of our galaxy.

“I’m thrilled that our new planet hunter mission is ready to start scouring our solar system’s neighborhood for new worlds,” said Paul Hertz, NASA Astrophysics division director at Headquarters, Washington. “Now that we know there are more planets than stars in our universe, I look forward to the strange, fantastic worlds we’re bound to discover.”

With the satellite in good health and all systems reporting healthy, NASA began the process of waking up TESS in May, with a goal of beginning science at the end of July. For a satellite, that means more than a shower and a cup of coffee: It entails a a commissioning period of testing and adjustments before scientists can truly rely upon the data being beamed back to Earth. According to NASA, “every new mission goes through a commissioning period of testing and adjustments before beginning science operations. This serves to test how the spacecraft and its instruments are performing and determines whether any changes need to be made before the mission starts observations.”

NASA's newest planet hunter, @NASA_TESS, the Transiting Exoplanet Survey Satellite, is currently undergoing a series of commissioning tests before it begins searching for planets.

— NASA_TESS (@NASA_TESS) July 11, 2018

In May, as the craft prepared for that final orbit, NASA’s latest satellite danced a funky little jig. “In one of the last passes, TESS performed a ‘break dance:’ rotating around to evaluate any stray light sources to characterize camera performance for the duration of the mission,” the space agency wrote on Twitter in June. How ’bout that?

Inside the exoplanet mission

What’s TESS all about anyway? The main purpose for this satellite is the quest for exoplanets, planets that lie outside of our solar system. But how to track down those tiny dots against the inky black background of deep space? TESS will be looking for a phenomenon called a “transit,” which occurs when a planet passes in front of its star. The resulting decrease in brightness can be observed and measured with spectroscopy, giving astronomers a better idea of the size and composition of the planet.


“TESS is opening a door for a whole new kind of study,” said Stephen Rinehart at Goddard Space Flight Center. “We’re going to be able study individual planets and start talking about the differences between planets. The targets TESS finds are going to be fantastic subjects for research for decades to come.”

TESS is replacing the aging Kepler telescope, which is running on fumes and will soon be unable to maneuver. Unlike TESS, Kepler is in a solar orbit and can make observations in just one direction. “TESS will cast a wider net than ever before for enigmatic worlds whose properties can be probed by NASA’s upcoming James Webb Space Telescope and other missions,” said Paul Hertz of NASA.

Kepler used the same methods to discover more than 2,600 exoplanets, but it was always observing the same area of space, and most of the planets were more than a thousand light-years away. TESS will set its sights on more nearby stars that are within 300 light-years of Earth.

The discoveries made by TESS may invite further study with the upcoming $8.8 billion James Webb Telescope planned for launch in 2020. “With those larger telescopes, we’ll be able to look for telltale signs in the atmospheres of those planets that might tell us what the planets are made of, and perhaps even whether they have the kinds of gases in their atmospheres that, on Earth, are an indication of life,” Hertz said at a news conference.

TESS may even moonlight at times to investigate other cosmic phenomenon it encounters besides exoplanets. Researchers will be invited to use the spacecraft as part of a “guest investigator” program, NASA said.

“I don’t think we know everything TESS is going to accomplish,” Rinehart added. “To me, the most exciting part of any mission is the unexpected result, the one that nobody saw coming.”

NASA’s Transiting Exoplanet Survey Satellite launched on Monday, April 16 aboard a SpaceX Falcon 9 rocket from Pad 40 at Cape Canaveral, Florida. The launch of the next-generation planet-hunting satellite was streamed live from the NASA website.

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