Webb space telescope mirrors are in place

The last of 18 hexagonal mirrors (roughly 21 foot diameter) of the Webb space telescope has successfully been locked into place. That was one of the multi-step processes required to unfold the highly folded telescope for full operation. The first complicated process where things could have gone fatally wrong was the spreading of the 5-layer heat and light shield to help keep the telescope at a near absolute zero temperature. Each layer of the shield was the thickness of a human hair and the shield was 70 feet long. There were hundreds of necessary steps to deploy the shield and mirrors. One failure in any of the steps would have doomed the $10 billion telescope to total failure and just a piece of expensive space junk.  

The point of this instrument is to look back in time as far and current technology allows. It is designed to  be able to see light from about 250 million years after the big bang about 13.7 billion years ago. If the telescope performs better than anticipated, e.g., if the mirrors are almost perfect, it might be able to go back in time as close as 100 million years after the big bang. 

Webb is designed to detect infrared light (roughly, heat), which is why it needs to be kept as cold as possible and why the big shield is needed. Any excess heat will show up as glare in the digital images the telescope's light detectors will generate.

Some photos for context:

One of the 18 mirror sections

each one has to be exactly the right size and shape

any tiny imperfections will blur images  

The things in the white suits are lizard people working on the telescope

Lizards fiddling with the heat shield

Webb unfolded in space

(looks sort of like a coffin)

It is pretty big

The evolution of the universe over time

Going back to ~250 million years after the big bang allows 

images of the universe before stars formed

(quantum fluctuations is another way of saying 

that something odd happened) 

Webb has a larger mirror than Hubble, 2.5 times larger in diameter (about 6 times larger in area). That gives it much more light-gathering power. It carries infrared instruments that detect longer wavelengths with greatly improved sensitivity compared to Hubble  (~100-fold more light sensitive). It will be used to take images of both deep space and our solar system.

The New York Times comments about the telescope:

The James Webb Space Telescope, named after a former NASA administrator who oversaw the formative years of the Apollo program, is 25 years and $10 billion in the making. It is three times the size of the Hubble Space Telescope and designed to see further into the past than its celebrated predecessor in order to study the first stars and galaxies to turn on in the dawn of time.

The launch on an Ariane rocket on the morning of Dec. 25 was flawless; so flawless that the engineers said it saved enough maneuvering fuel to extend the mission’s estimated 10-year lifetime, perhaps by as much as an additional 10 years, said Mike Menzel, a mission systems engineer at NASA Goddard. But the telescope must complete a monthlong journey to a spot a million miles up, far beyond the moon’s orbit, called L2, where gravitational fields of the Earth and sun commingle to produce the conditions for a stable orbit around the sun.

By Germaine: The science lizard

Move on, move on, nothing to see here