It is even more “calm” in space, NASA arranges “shading” equipment for the Webb telescope

On January 4th, Hubble's successor, the James Webb Space Telescope (JWST), completed a very important and complex step in space — unfolding a huge sun visor. For NASA, it's an "incredible milestone."

Why are sun visors so important? Let's start with the mission of JWST.

JWST launched on December 25, 2021, after about 25 years of development. Astronomers hope to use JWST to explore every stage of cosmic history—from the interior of our solar system to the most distant observable galaxies in the early universe, and everything in between, helping humanity understand the origin of the universe, galaxy evolution, and Our place in it.

▲ Fully expanded JWST (art rendering). Image credit: NASA

That said, we can expect to observe the early states of the visible universe today, seeing the first galaxies that formed only a few hundred million years after the Big Bang.

Observing in the infrared spectrum is a key technology to achieve this, so the JWST is equipped with high-sensitivity infrared electrical sensors, spectrometers, and more. The temperature of the observation module must be kept below 40K (-233.15°C) to see faint infrared light.

The sunshade is what controls the temperature.

Otherwise, the target's signal would be drowned out in infrared radiation from the telescope itself, the sun, the Earth and the moon.

But the telescope is too large to be launched directly into space in its full form, and can only be deployed after launch, and the sun visor becomes part of the deployment mission.

▲ The sun visor was tested on the ground before launch. Image credit: NASA

On December 28, three days after launch, the JWST team began deploying the visor remotely, and on January 4 at approximately 11:59 a.m. EST.

The visor consists of five layers of polyimide film coated with silicon and aluminum, each as thin as a hair, protecting the telescope from the light and heat of the Sun, Earth and Moon, allowing it to cool to the extremely low temperatures required.

NASA notes that with the combined effect of five layers of materials, more than 200 kilowatts of solar energy can be reduced to a fraction of a watt.

The complication of unfolding the visor is that each joint must be executed perfectly for the visor to be opened. The entire JWST has as many as 344 single points of failure, and the visor contains a significant portion of them.

A single point of failure is a component in a system that, if it fails, will render the entire system inoperable. In other words, a single point of failure is an overall failure, showing how tight the sun visor deployment is. Accidental tearing of the film during testing in 2018 was also one of the factors that delayed the project.

▲ The sun visor was tested on the ground before launch. Image credit: NASA

The entire process involved 139 release mechanisms, 70 hinge assemblies, 8 deployment motors, approximately 400 pulleys, and 90 individual cables totaling approximately a quarter of a mile in length.

When unfolded, each layer of visors is 70 feet long and 47 feet wide, the size of a tennis court, and they are finally fully tensioned and secured in place, similar to adjusting a sail.

The deployment of the visor took more than a week to complete, slightly longer than originally planned, during which there were minor issues with equipment such as the solar array, visor motor, etc., but it was ultimately successful. "Some of the most gripping moments have passed, with 70 to 75 percent of the single point of failure officially complete," NASA said.

After completing the visor, JWST still has a lot of work to do, including deployment of the secondary and primary mirror wings, alignment of the telescope optics, and calibration of scientific instruments. When everything is ready, JWST, which has cost nearly ten billion dollars in total, will provide its first images and begin collecting light from distant galaxies for humans.

Grapes are not the only fruit.

#Welcome to pay attention to the official WeChat account of Aifaner: Aifaner (WeChat: ifanr), more exciting content will be brought to you as soon as possible.

Love Faner | Original link · View comments · Sina Weibo