Lift-off of NASA's Transiting Exoplanet Survey Satellite (TESS) from Cape Canaveral in Florida is scheduled for 6:32 pm (2232 GMT).
While you wait for launch you can also watch my interview with one of the lead scientists from the TESS team, Sara Seager of MIT, in the video below.
The National Aeronautics and Space Administration (Nasa) is embarking on a new search for planets outside of the solar system, including those that could support life.
Adding to the anxiety will be the fact that TESS will be put into an orbit never attempted before, out as far as the moon and back to Earth, lasting 14 days at a time.
NASA has assured everyone that TESS is fine, so don't worry.
SpaceX's planned launch of NASA's Transiting Exoplanet Survey Satellite (TESS) has been delayed. The postponement of the launch was announced just before two hours after the launch.
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The mission begins a transition for SpaceX, which is launching its last new rocket in a version known as the "full thrust" or "Block 4" Falcon 9.
The spacecraft is meant to be maneuvered into an unusual Earth orbit that ranges in altitude from roughly 63,000 to 200,000 miles.
"TESS's legacy will be a catalog of the nearest and brightest stars hosting transiting exoplanets, which will comprise the most favorable targets for detailed investigations in the coming decades", NASA notes.
It promises an ability to resolve the atmospheres of some of the new worlds, to look for gases that might hint at the presence of life.
"But since then, we have found thousands of planets orbiting others stars and we think all the stars in our galaxy must have their own family of planets". "These types of planets that are close to us are much more easy to study, and we can measure their masses from telescopes here on Earth".
"Tess will tell us where and when to point", said Cheops' Esa project scientist, Kate Isaak. "By looking at such a large section of the sky, this kind of stellar real estate, we open up the ability to cherry-pick the best stars for doing follow-up science", said Burt.
"If you look at what Kepler found, nobody assumed there'd be a planet that might be made all of diamond, or all that there could be worlds that are all covered in water, or things like that", said Volosin.