'One of the many amazing things that Kepler told us is that planets are everywhere and there are all kinds of planets out there. 'It was designed to look at 150,000 stars in a fairly wide field of view without blinking, for four years,' she told reporters on the eve of the launch. Kepler, the first planet-hunting mission of its kind, 'was launched to answer one single question: How common is a planet like Earth around a star like the Sun?' said Patricia 'Padi' Boyd, director of the TESS guest investigator program at NASA's Goddard Spaceflight Center. 'That is about 20 times what the Kepler mission was able to detect.'

'TESS is equipped with four very sensitive cameras that will be able to monitor nearly the entire sky,' said George Ricker, TESS principal investigator at the Massachusetts Institute of Technology (MIT). TESS will survey far more cosmic terrain than its predecessor, NASA's Kepler Space Telescope, which launched in 2009, taking in some 85 percent of the skies. NASA predicts that TESS could find more than 50 Earth-sized planets and up to 500 planets less than twice the size of the Earth. Its discoveries will be studied further by ground- and space-based telescopes for signs of habitability, including rocky terrain, a size similar to Earth and a distance from their sun - neither too close nor too far - that allows the right temperature for liquid water. TESS is expected to reveal 20,000 planets beyond our solar system, known as exoplanets, NASA said. These so-called 'transits' may mean that planets are in orbit around them. The $337 million washing machine-sized spacecraft is built to search the nearest, brightest stars for signs of periodic dimming. The Transiting Exoplanet Survey Satellite, or TESS, is poised to blast off at 6:32 pm (2232 GMT) aboard a SpaceX Falcon 9 rocket from a NASA launchpad in Cape Canaveral, Florida. This artist's rendition from NASA shows the Transiting Exoplanet Survey Satellite, or TESS, which launching on a mission to search for the nearest Earth-like planets in our cosmic neighborhood

Spacex launches nasa planet-hunting s