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Image credit: NASA's Goddard Space Flight Center
An illustration of the TESS orbiting telescope checking for alien planets. The instrument may launch as soon as April 16.

Editor's note: A version of this article was previously published on the author's blog.

As early as April or as late as June, NASA plans to launch the next generation planet finder, an orbiting telescope called the Transiting Exoplanet Survey Satellite or TESS, which will have a field of view 400 times that of the Kepler instrument. Since its launch on March 6, 2009, Kepler has discovered 3,705 confirmed planets with 612 in multiple-planet systems and 4,496 candidate planets, according to the latest count.

The new orbiter promises to open the heavens in terms of planetary research.

"TESS will survey the entire sky over the course of two years by breaking it up into 26 different sectors, each 24 degrees by 96 degrees across," states a NASA fact sheet. "The powerful cameras on the spacecraft will stare at each sector for at least 27 days, looking at the brightest stars at a two-minute cadence." As with Kepler, the new satellite will look for transiting exoplanets whose presence is deduced when starlight periodically dims.

The stars TESS will examine are 30 to 100 times brighter than those studied by the Kepler project, allowing follow-up studies to more readily confirm or discount candidates. "TESS will also cover a sky area 400 times larger than that monitored by Kepler," the NASA fact sheet continues.

Although the survey will encompass a much larger region than Kepler's, this does not equate to 400 times the number of stars because Kepler stared at myriad stars during its four-year prime effort and more in the later K2 project. TESS will examine 200,000 of the brightest and nearest stars, says NASA (more than twice that, according to an MIT estimate), while Kepler studied 150,000 dimmer stars in its main program.

According to a March 6 advisory inviting media representatives to cover the launch, TESS will blast off from Cape Canaveral aboard a Space-X Falcon 9 rocket possibly as soon as 4:32 p.m. MDT, April 16.

Kepler's main project has been to stare at stars in the same quadrant, and most of the stars that were examined were dim, which made detection and verification difficult. TESS won't be as limited, which should make those jobs easier.

"The technology involved in TESS is mind-boggling," said Seth Jarvis, director of Salt Lake's Clark Planetarium at The Gateway. "Just the orbital mechanics employed to get it to its position in space from where it will perform its observations make you marvel at how much precision can be applied to an object so distant, so delicate, and moving so quickly."

According to the Massachusetts Institute of Technology's Kavali Institute for Astrophysics and Space Research, one of the project partners, TESS may record more than 3,000 planet candidates. (The institute also says the satellite will monitor more than 500,000 stars, compared to NASA's 200,000 estimate.) The discoveries may include about 500 Earth-size and super-Earths (up to twice our planet's diameter).

"TESS will detect small rock-and-ice planets orbiting a diverse range of stellar types and covering a wide span of orbital periods, including rocky worlds in the habitable zones of their host stars," the institute predicts.

Jarvis said, "Searching for exoplanets by using the tiny dimming of stars created by a transiting planet involves receiving zillions of bits of brightness data, not knowing if within that cacophony of ones and zeros there is a signal that can be teased-out, and then applying ferocious amounts of math and computer power to see if there's a needle hidden in all that hay."

Another aspect to consider, Jarvis said, is that the transiting method can't possibly detect all the planets orbiting the stars it studies. Undoubtedly, most of these will not happen to glide between the star and the satellite. The star is a small point as seen from Earth, and only coincidence would bring one of its planets exactly in line with TESS.

Kepler and other detectors have shown that the Milky Way may host 1 trillion stars, Jarvis said. TESS will help refine our knowledge and improve our estimates about the likelihood of life on alien planets.

"I cannot think of a more terrifying question for us to explore than, 'Are we alone?'" he added. "Think of the implications associated with knowing the answer to that question, whether it's 'yes' or 'no,' with certainty."

Jarvis said an answer that we are alone would raise many questions, including, "How is that even possible?" But an answer that we aren't alone also raises confounding new questions, he said.

Comment on this story

"Yikes! Where are they? How far away are they? Are they anything like us? What can we know about them? Do they know about us? Do they have the same history, questions, dreams, and problems that we do? What could we possibly say to each other? Can we communicate with them? Should we?" Jarvis said.

Determining whether we are the only intelligent life in the galaxy is one of the most important goals of astronomy. The answer, if it can be found, will have a profound effect on our civilization.

Jarvis said humanity is hard-wired to explore, and that failing to look for that answer "would be a betrayal of our intelligence."