spaceSpace and Physics

NASA Hopes To Find 20,000 Planets With Its New Planet-Hunting Spacecraft Launching Today


Jonathan O'Callaghan

Senior Staff Writer

Artist's impression of a rocky super-Earth, a type of planet that TESS could find. ESO/M. Kornmesser

Update: The launch has been delayed until Wednesday April 18 at the earliest. Our story as it originally appeared is below.

Later today NASA will launch one of its most anticipated missions yet, a telescope to find more worlds around nearby stars than ever before – including some potentially habitable planets.


Called the Transiting Exoplanet Survey Satellite (TESS), the spacecraft will be launched on a SpaceX Falcon 9 rocket from Cape Canaveral in Florida. The launch window opens today, April 16, at 6.32pm EST (11.32pm BST), and you can watch it live on NASA TV.

The mission is hugely exciting, as it’ll be studying 200,000 of the brightest stars near our Sun to hunt for new worlds. These will range from scorchingly hot gas giants in short orbits to Earth-like worlds that could support life.

“TESS… is the next step in the search for planets outside of our Solar System,” said NASA.

TESS has four cameras at its front. NASA

Over the past few years, most of our knowledge of exoplanets comes from NASA’s Kepler space telescope. Launched in 2009, it has since found thousands of worlds beyond our Solar System.


The Kepler mission will come to an end in a few months, though, as the spacecraft runs out of fuel. So it will be down to new missions like TESS, and Europe’s CHEOPS mission later this year, to continue its stellar work and find new worlds.

TESS will focus its gaze on stars 30 to 300 light-years from Earth, observing the dip in light as a planet passes in front – known as a transit. It is expected to find more than 20,000 planets, including hundreds that are less than twice the size of Earth and thus likely to be rocky.

Kepler found planets by staring at a relatively small region of the sky, but TESS will be the first space mission to search the entire sky. It will be placed in an unusual orbit around Earth that will make this possible, splitting the sky into 26 segments to observe an area 350 times larger than Kepler, 85 percent of the sky in total, over two years.

Focusing on bright stars, it’s hoped that many of the planets TESS finds will be prime targets for future study. Ground-based telescopes will be used to work out the masses of about 50 of the planets it finds (TESS can only see their size, not mass). But future telescopes could study more of them, including looking at their atmospheres in detail.


Frankly, TESS is going to be awesome. It’ll give us more planets to study than ever before, including some tantalizingly Earth-like worlds. So if you find yourself with some free time this evening, make sure you check out the launch.


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