SpaceX launches the alien planet-hunting TESS telescope today

Tess will look for so-called exoplanets

Knowing what we know today about what lies beyond our solar system, estimates that "thousands" exoplanets will be discovered by TESS seem conservative. SpaceX should also be broadcasting the launch, as well as its attempt to land the first stage of the Falcon 9 on a droneship in the Atlantic.

TESS should arrive in orbit around Earth — on a never-before-used, highly elliptical path that takes it close to the moon — about two months later. Scientists can determine the planet's mass by using the Doppler effect to measure the wobble the planet induces on its star. The launch will be aired on NASA TV.

TESS is expected to reveal 20,000 planets beyond our solar system, known as exoplanets, NASA said.

Still on the lookout from on high, Kepler alone has discovered more than 2,600 confirmed exoplanets.

Based on Kepler's observations, astronomers now believe that the Milky Way is home to at least two billion potentially habitable planets where conditions are neither too hot nor too cold for life-sustaining water to flow.

The Tess satellite will scan nearly the entire sky, staring at the brightest, closest stars in an effort to find any planets that might be encircling them.

This is where Tess comes in.

If all goes well with the launch and calibration phases of the mission, the first haul of new planets found by TESS could be announced later this year.

"So in the next few years we might even be able to walk outside and point at a star and know that it has a planet".

TESS itself will not detect life beyond Earth.

To identify them, TESS will probe faraway stars for interesting data about their brightness. The targets TESS finds are going to be fantastic subjects for research for decades to come.

"We're expecting to find 2,000-3,000 planets that are certainly below the size of our Jupiter and a lot of them below the size of Neptune; so, the ones that have the potential for being terrestrial, for being rocky", said Jennifer Burt from the Massachusetts Institute of Technology (MIT), which leads the mission.

Bigger and more powerful observatories of the future will scrutinise these prime candidates for potential signs of life. We now know that almost all stars have planets around them, and as our technology improves we keep finding more. "It's going to be a game-changer in our ability to study planets".

For most of the stars observed by Tess, this special distance will be a short one.

"Not only scientists will be following up these planets, but also amateur astronomers can use their own smaller telescopes to help confirm which planets are true, and which are not", said Diana Dragomir, a researcher at the Massachusetts Institute of Technology.