After completing the self-assembly of the 18-segment primary mirror, the telescope took outstanding images of ordinary stars to test its performance.
Known as HD84406, the star is 100 times fainter than what the human eye can see. The star itself is a beautiful image, but we are not interested in it.
Astronomers are attracted to a spray of tiny dots scattered in the background. Each of them is a distant galaxy and for the first time we have captured them.
In a virtual briefing, NASA officials expressed great joy and relief at what these first images represent.
“We said last fall that we would know that the telescope is working properly when we have an image of a star that looks like a star,” says Lee Feinberg, Webb optical telescope element manager at NASA’s Goddard Space Flight Center. “Now you’re seeing that image.
And I’m pleased to say that the optical performance of the telescope is absolutely exceptional, it is really working extremely well. The work is as good if not better than our most optimistic prediction.”
Why Are These Images Called Engineering Images?
The images captured by Webb are not scientific but actually they are engineering images, designed to test how easily all the parts of this engineering marvel are working together.
The US $10 billion dollar telescope is comparatively complex in design, and the stakes are high as where the Hubble telescope orbits the Earth, within our reach to service, James Webb sits approximately 3000 times further away, orbiting the Sun.
This wonderfully expands our understanding of the deep universe while at the same time implying our inability to adjust or repair when problems arise.
The need to ensure that all components of a telescope are perfect before they can be launched into space is enormous, resulting in significant delays.
Did James Webb Telescope Take Its Selfie?
A new “selfie” was created using a special pupil imaging lens inside the NIRCam device designed to image a portion of the primary mirror instead of an image of the sky. This configuration is not to be used during scientific work and is for design and coordination purposes only.
Thiis image shows all 18 Webb primary mirror segments simultaneously collecting light from the same star. Also, since the December 2021 launch, every step of the release has been flawless.
How Is James Webb Telescope Doing In Space?
The telescope’s main mirror is 6.5 m wide and consists of 18 hexagonal segments that assemble independently in space. Aligning each of these segments to produce a single, smooth reflective surface requires nanometer precision.
So far, we haven’t been able to see how well the process has gone, and our expectations for this first image are shaky. The reliefs that accompany this star portrait are almost tangible.
“Currently the performance of the telescope is all we can expect,” says Jane Rigby, research scientist at Goddard’s Webb Operations Project. “The images we see today are as sharp and clear as the images Hubble can take, but with wavelengths of light that Hubble can’t see at all. This makes the invisible universe very, very clear.”
What Is The Significance Of This Image?
This first image not only confirms that the telescope is running smoothly, but also clearly demonstrates James Webb’s abilities.
One hundred times more sensitive than Hubble, and operating in the realm of infrared, James Webb is already capturing galaxies far more distant than any we have before.
“There’s no way that Webb can look for 2,000 seconds at any point in the sky, and not get an incredibly deep field,” Rigby says. “This is going to be the future from now on. Wherever we look, it’s a deep field.
Without even really breaking a sweat, we’re seeing back in time to galaxies that we’re seeing the light as it looked billions of years ago. And the process has only just begun.”
How Is NIRCam So Necessary?
James Webb has four scientific rigs on board, but only one NIRCam (near infrared camera) that helped take these first images is now working. NASA believes the remaining three will be operational and ready to begin the scientific imaging process in June or July.
This image captures galaxies in the early universe, only a few hundred million years after the Big Bang, potentially changing our understanding of galaxy formation and evolution.
“The James Webb Space Telescope is going to shed light on the universe in a few different ways,” says Dr Rebecca Allen, from the Swinburne University of Space Technology and Industry Institute. “It will be able to capture the distant starlight from galaxies that have been redshifted from UV wavelengths to the infrared meaning we can literally see further back when the universe was younger to understand more about how the first galaxies formed and grew.
What Are The Other Observations JWST Is Going To Help Us With?
It’s not all about looking far away, says Allen. “The telescope’s infrared instruments are also perfectly suited to helping us reveal more about the nearby universe by studying planets outside our solar system. I’m very excited to see the telescope take spectroscopy of distant worlds as they pass in front of their stars and hopefully confirm the existence of water beyond Earth.”
Why Space Dust Isn’t A Problem Anymore?
The James Webb Space Telescope is known to astronomers as a “dust buster”. “Where planets and stars form, there are piles of dust both near and far,” Allen explains. Because over time, stars make heavier elements in their cores, enriching the universe.
Dust is annoying because it likes to absorb the bright light of stars, obscuring our view of these important regions and making distant galaxies less visible.
But the light is emitted again at longer wavelengths that JWST can see, which can tell us more about how planetary systems like ours formed