It’s not clear from where NASA takes that estimate, but it is likely the agency simply hopes two find an exoplanet in every other of the 200,000 starts it will be pointing the telescope at.
This is the first time in history when a space-borne all-sky transit survey will be conducted. Although it will not give us the answer to the question “are we alone,” the telescope will look for drops in star’s brightness, caused by planetary transits, to locate giant balls of rock, metal or gas.
As said, TESS will reach space via a Falcon 9 rocket. A few hours before the launch, Elon Musk tweeted a cryptic (or maybe not-so-much) preview of the launch:
“This is gonna sound crazy, but … SpaceX will try to bring rocket upper stage back from orbital velocity using a giant party balloon. And then land on a bouncy house.”
The upper stage of the Falcon 9 rocket is one of the parts SpaceX has not been able to recover so far. If his ballon-stunt works (it’s probably not a real party balloon, but since it’s Musk we’re talking about here, who knows), SpaceX would have become capable of recovering nearly the entire assembly.
The upper stage, or second stage, is powered by a single Merlin vacuum engine and is used to deliver the payload to the desired altitude. It ignites seconds after the booster separates and can be restarted multiple times to allow various orbit delivery.
This is gonna sound crazy, but …— Elon Musk (@elonmusk) 15 aprilie 2018
SpaceX will try to bring rocket upper stage back from orbital velocity using a giant party balloon— Elon Musk (@elonmusk) 15 aprilie 2018
And then land on a bouncy house— Elon Musk (@elonmusk) 16 aprilie 2018