This is an artist's rendering of a telescope. The largest component of the telescope is the sun shield.
Adriana Manrique Gutierrez is a NASA GSFC/CIL.
The telescope is going to be launched later this week. It will be the most powerful space telescope ever.
Scientists will use the telescope to peer back in time to the formation of the earliest galaxies in the universe, to study how our solar system evolved, and to look for gases that might signal habitability.
"It's going to be amazing and it's still a little mind-blowing to think about it," Jane Rigby, NASA project scientist for operations of the telescope, told NPR. She said that the light from these distant galaxies has traveled to Earth for 13 billion years.
The scientific instruments on the telescope need to be kept very cold. The sun shield is a crucial part of the telescope and protects it from the sun's heat.
James Cooper is the NASA James Webb Space Telescope Sun shield manager. There are no other telescopes that use this type of shield.
One of the main focuses of the launch is to make sure the equipment opens correctly.
A tennis court-sized shield is needed to block out heat.
The biggest part of the telescope is the sun shield, which has a primary mirror that is 6.25 times bigger than Hubble. The sun shield is the size of a tennis court when it's completely unfolded.
An imposing exact replica is stored in a massive clean room at a facility in Los Angeles County. The company is working with NASA.
Think about the sunscreen you put on at the beach to understand the purpose of the sun shield. Bill Ochs, the project manager for the James Webb Space Telescope, points out the features on the replica.
The sun shield is composed of five layers, each cooler than the one before it, and designed to minimize the amount of extraneous heat hitting the scientific instruments.
The layers are made of a material called Kapton that is coated in aluminum and has a special substance on the two outermost layers to reflect the sun's heat back into space. More and more heat is lost across the five kite-shaped layers, which can be seen in the gaps between them. The layer closest to the instruments will reach about - 389 degrees F.
Scientists hope the mission will last a decade. The sun shield is expected to be hit by debris over the course of those years. Each layer is a high-tech quilt. Scientists created each layer by stitching together 50 individual pieces with technology to prevent small holes or rips from getting too big.
Rip stops are that technology. If a micrometeorite hits a layer, it will tear a little bit. It will hit a ripstop and stop.
The level of durability is impressive, given how light a sample of the material feels. It looks like a silvery Mylar balloon from the grocery store, and it almost seems like it could be blown away with a light breeze.
The telescope needs to be cold.
To understand why the telescope needs a sun shield, it's important to know what kind of light the telescope is picking up and what kind of instruments are needed.
Scientists will use the telescope to study the light that comes from distant planets and galaxies, and the technology has to be kept very cold.
The temperature needs to be close to absolute zero. The telescope's scientific instruments have to be at an extreme temperature to work correctly and to minimize the noise from the sun's heat being picked up by the sensors.
The telescope is looking at light that came from distant galaxies. The total range of light on the spectrum is much larger than the light visible to humans. The light from these far reaches of the universe is no longer visible to the naked eye by the time it reaches the telescope.
"As light travels through the universe, the light waves change into heat, which is heat," explains Ochs. This process is called red shifting. It happens all the time as the universe expands.
The nearly $10 billion project hinges on the sun shield deploy correctly after launch because the scientific instruments on the telescope need to be kept so cold to operate. The telescope is being loaded into a rocket in French Guiana. Soon, it will launch into space, hurtling to about a million miles away from earth, where it will be in the sun. The frame of the sun shield will be unfurled by scientists after it passes the moon.
The sun shield deployment is the most difficult thing that we do. We all worry about this one. You worry about all of them, but this is the one we worry about the most.
The process is going to be methodical. There are many release mechanisms for the sun shield. NASA says scientists will deploy it for several days. The hope is that it will be proof that slow and steady really does win, and that the prize could be the history of the universe.
After spending the last few years testing out hundreds of contingency procedures, Ochs' big goal for deployment is to spend days feeling like he's watching grass grow. I hope that we have paid our penance in the development and that when we get on the moon, it will be boring.
The telescope will not be serviced in-person if the opposite happens. The replica of the James Webb Space Telescope will be used to test any issues that may arise.
