The space launch will be live streamed from Cape Canaveral, Florida, courtesy of NASA TV.
What is TESS?
TESS stands for The Transiting Exoplanet Survey Satellite, billed by NASA as the “first ever space borne transit survey that will observe the whole sky”.
The fact-finding space vessel will spend two years observing 200,000 stars “from Earth-sized to gas giants” to search for evidence of life and to learn more about their properties.
NASA has located solar systems beyond ours with thousands of planets that orbit other stars.
These are known as exoplanets and scientists are keen to learn more about them.
Previous mission Kepler informed the space agency of the existence of exoplanets with TESS now ready to find out more.
NASA expert Dr Martin Still said: “We expect to find a whole range of planet sizes between planets the size of Mercury or even the moon, our moon, to planets the same size as Jupiter and everything in between.
“The most interesting thing about these TESS discoveries is gonna be how close they are and the fact that their host stars are gonna be bright relative to those Kepler stars.
And so, this means that these stars and planets are gonna be much easier to follow up, both with ground based telescopes and with future space telescopes like James Webb [Space Telescope] where we’ll be able to characterize the properties of those planets and their host stars far more readily than we can with the planet population that we already know.”
The mission is expected to locate around 50 planets close to Earth’s size.
When is the mission launch?
Spacecraft designer and rocket launcher SpaceX is providing a Falcon 9 rocket for the launch, which is now taking on Wednesday, April 18 after it was delayed.
SpaceX tweeted earlier: “Standing down today to conduct additional GNC analysis, and teams are now working towards a targeted launch of @NASA_TESS on Wednesday, April 18.”
A live stream of the launch will start about 15 minutes before lift-off.
Social media fans expressed their disappointment at the delay.
But @CalinWay tweeted: “Always best to launch when you are ready. A rocket on the pad is better than a payload at the bottom of the ocean.”
The mission is said to cost around £200 million, excluding launch costs.
They are an additional $87 million, according to NASA officials quoted by Space.com.
After the launch, SpaceX will aim to land its rocket on a robotic ship in the Atlantic Ocean.
Previous missions have experienced much success, with around half of the boosters landing on “drone ships” and the rest returning to dry land.