The test even managed to continue as Hurricane Harvey hit the Texas coast.
When it launches, Webb will be the largest space telescope in the world.
When it is launched in 2019, it will be the world’s biggest and most powerful telescope, capable of peering back 200 million years after the Big Bang.
The team began to warm the chamber back up on September 27, before pumping air back in.
The telescope will be used to look back to the first galaxies born in the early universe more than 13.5billion years ago, and observe the sources of stars, exoplanets, and even the moons and planets of our solar system.