The James Webb Space Telescope (JWST) has been busy. After reaching its final destination, the telescope has slowly been deploying its many instruments and mirrors, cooling down and preparing for its mission to better understand space. While early images have now come through, it will still be a while until we can expect to see anything concrete.
The successor to the Hubble Space Telescope, NASA’s new and much improved space observatory has several goals in mind for its trip into space. Not only will it be used to deepen our understanding of the Milky Way, but it will also peer at faraway exoplanets and celestial objects, and hunt for evidence of dark matter.
But what stage is the James Webb Space Telescope at now, how does it differ from Hubble and who is James Webb, the man the telescope is named after? We’ve answered these questions and more below.
Where is the James Webb Space Telescope now?
The James Webb Space Telescope is now in L2 Orbit – its final destination, about 1.5 million kilometers from Earth. This is a journey that took roughly a month to complete.
You can track its progress with NASA’s ‘Where is Webb’ feature. Not only does this show the current distance from Earth but also the telescope’s speed, temperature, how long it has been in orbit and what its next stage is.
What are the most recent updates on the JWST?
The JWST has been deploying its many instruments without any faults so far. Most recently, NASA announced that the team had completed the third of seven planned steps, eventually aligning 18 segments of the JWST’s mirrors. This is one of the more complicated processes in the set-up of the telescope, so it can take a while to complete.
With the completion of this most recent stage, the telescope is getting nearer to being able to take its first official photo, with the stars becoming much sharper in its field of view.
Images have already been sent back (more on that below), but these are very early indications of the telescope’s ability, showcasing what it can do during the alignment stages.
First images from the telescope
NASA has released the first images from the JWST, but as it is still in its early stages, these are by no means clear photos or even a hint at its full power. The first images came on 11 February and took a whole week to capture. It is a mosaic made up of 1,560 images amounting to 54GB of raw data.
As the telescope advances through its alignment, it is able to send back more detailed images. The team were able to create an image using 18 scattered dots of starlight, moved into a hexagonal shape (the same relative locations as the physical mirrors). The team refined each mirror’s image by making minor adjustments, while also changing Webb’s second mirror’s alignment.
These focused dots were then stacked on top of each other. During this process called image stacking, the team activated six mirrors at a time, commanding them to repoint their light to overlap until all dots of starlight overlapped each other. This results in one single clear image of a star.
What is the timeline of the JWST?
For a long time, all of the attention was on the launch of the telescope but now that is out of the way, we can look at what its timeline will look like. Luckily, NASA has given a full break-down of the telescope’s official timeline.
In the first month, the satellite was deploying its many components. In this stage, the telescope and instruments rapidly cooled, thanks to the sunshield, but it took a few more weeks for them to cool to stable temperatures. At this stage, mirrors are being deployed and tests will be made to be sure they move.
For the next couple of months after this, the satellite will begin its tests. Using the Fine Guidance Sensor, the JWST will be pointed at a bright star to demonstrate it can acquire and lock onto targets. Then, the long process of aligning the telescope optics begins.
After this, calibrations will be made on all of the scientific instrument’s different modes of operation. In this stage, observations will commence, tracking moving targets like asteroids, comets, moons and planets in our own Solar System. From this point onwards, Webb will begin its science mission, conducting routine tests and reporting back information.
When did the James Webb Space Telescope launch?
The telescope was launched into space on the 24th December 2021 – a nice Christmas Eve surprise for any fans of space! If you were too busy opening presents and enjoying a Christmas dinner to watch, you can view the launch on the JWST YouTube channel.
While the telescope has now officially launched, it saw a huge number of delays to get to this point. The observatory was originally expected to launch back in 2007. Since then, it has experienced over 16 launch delays with the pandemic extending the date way past the last expected date of March 2021.
The telescope was launched on the Ariane 5 rocket. This is a specialised rocket which is designed to take satellites and other payloads into transfer or low-Earth orbit.
Who is James Webb?
You might be thinking, who gets the honour of having such a historic telescope named after them? Well, that title goes to James Edwin Webb, the second administrator of NASA, best known for heading up Apollo – the first space programme to send humans to the Moon.
He was also instrumental in the two crewed space programmes that followed on from Apollo: Mercury and Gemini. While Webb did eventually die in 1992, aged 85, he left a massive legacy behind, deserving of a telescope named after him.
“It is fitting that Hubble’s successor be named in honour of James Webb. Thanks to his efforts, we got our first glimpses at the dramatic landscape of outer space,” said former NASA administrator Sean O’Keefe about the observatory’s name. “He took our nation on its first voyages of exploration, turning our imagination into reality.”
The telescope hasn’t always been named after Webb. It started its life being known as the Next Generation Space Telescope which, realistically, isn’t the most imaginative name we’ve ever heard!
How big is the James Webb Space Telescope?
Billed as the successor to the Hubble Space Telescope, the JWST is the largest space observatory ever built. Its gigantic sunshield base measures a massive 22m by 12m, roughly the same size as a tennis court.
Although nearly twice as big as Hubble (which is only 13m long), the JWST is almost half the weight at 6,500kg.
The JWST’s gold-plated mirrors have a total diameter of 6.5m, much larger than Hubble’s 2.4m diameter plate. Overall, the JWST will have approximately a 15 times wider view than Hubble.
How far can the James Webb Space Telescope see?
Using its infra-red telescope, the JWST observatory will examine objects over 13.6 billion light-years away.
Because of the time it takes light to travel across the Universe, this means that the JWST will effectively be looking at objects 13.6 billion years ago, an estimated 100 to 250 million years after the Big Bang. This is the furthest back in time ever observed by humanity.
Where will the James Webb Space Telescope orbit?
After launching into space, the JWST will orbit the Sun, flying up to 1.5 million kilometres from Earth in temperatures reaching -223°C.
For comparison, the Moon is 384,400km away, while the Hubble Space Telescope flies only 570km above our planet. As the JWST will operate so far away from Earth, it will not be able to be serviced by astronauts if any faults arise.
What is the James Webb Space Telescope’s mission?
As the JWST is a product of an international collaboration between NASA, the European Space Agency (ESA), and the Canadian Space Agency (CSA), it has many mission goals.
These include:
- Examine the first light in the Universe and the celestial objects which formed shortly after the Big Bang.
- Investigate how galaxies form and evolve.
- Study the atmospheres of distant exoplanets.
- Capture images of planets in our own solar system.
- Locate evidence of dark matter.
The JWST is expected to operate for five years after its launch. However, NASA hopes the observatory will last longer than 10 years.
Unfortunately, the observatory won’t be able to operate forever: although mostly solar-powered, the JWST needs a small amount of finite fuel to maintain its orbit and instruments.
How is the James Webb Space Telescope different to Hubble?
The James Webb is seen in many ways as an improved successor to the Hubble telescope which was launched way back in 1990. But are they similar or are these two telescopes drastically different?
Firstly, both telescopes see light in different ways. The Hubble’s main focus is on both visible and ultraviolet light. While it can observe a very tiny portion of the infrared spectrum, it is nowhere near the extent to which the JWST can.
The JWST is specifically designed to focus on the infrared spectrum. It can’t see in ultraviolet light like the Hubble but it will be able to focus on bright objects like very distant galaxies.
The James Webb Telescope is also much larger than the Hubble, mostly due to its large sunshield. This is used on all space telescopes but is especially important with the James Webb due to its infrared cameras. If it isn’t kept cool, it could risk blinding itself to the lights of objects it is trying to observe.
One other key difference between the two satellites is the distance that they will be kept. The Hubble telescope orbited above Earth’s atmosphere but was near enough to be approached if repairs needed to be done.
The JWST on the other hand will be far away, around 1.5 million kilometres away! That’s both further than any human has ever travelled and too far for anyone to ever go repair the satellite if something goes wrong.
It will be this far out for a few reasons. It will be in a place where the gravity of the Sun and Earth work together to help keep the satellite in place, plus it will be far away from the reflected radiation of the Earth, helping keep it cool.
Authors
Alex is a staff writer at BBC Science Focus. He has worked in technology and science journalism since graduating in 2018 with an interest in consumer tech, robotics, AI and future techology.
#Space | https://sciencespies.com/space/james-webb-space-telescope-everything-you-need-to-know-about-the-hubble-successor/
No comments:
Post a Comment