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The James Webb telescope is what we needed to see humanity's past and future

19 January 2022 7:15 PM
Digital technology

Long delays and massive costs aside, this is epic engineering

Most of the most influential services that we take for granted today got their start sometime between 2008 and 2011. I reckon it was a peak for disruption for Web 2.0 and potentially for the century although given the developments with our space efforts we may be in for more.

The reason for all that disruption was the launch of the smartphone. Apple unveiled the iPhone in 2007 and triggered an explosion of what could be done and what could be learnt about what users were doing and may want to do.

We now know there were big risks too and many of the bad scenarios have become reality.

Add the pandemic and the world feels like a worse place than we hoped going into 2000 and then as if to mark the changing of the guard for what the web was really for, Cloudflare reported that the traffic to TikTok exceeded the traffic to Google in 2021.

All business was now unusual and you may have been left wondering if it would ever return.

A crazy idea

One project from 1997 just may do that. It was a plan to build a telescope to surpass the Hubble telescope that was launched in 1990.

The James Webb Space Telescope was named after a former NASA administrator and was due to launch in the decade following its commissioning. The challenge was that the telescope was so ambitious, that some components and operations required technology and instruments that had not been developed yet.

The designers relied on global innovation to find the solutions they lacked and for those that the world did not provide they would create themselves.

Walk like an Egyptian

I would argue this is like ancient Egypt’s building of the Great Pyramids. Someone had the vision to build a massive pyramid despite not knowing how to build it and others who may have questioned why it was needed but devised a way to build it. No doubt the efforts improved with time and innovations and breakthroughs would have been discovered during their construction from acquiring the stone to transporting it and managing to set them one above the other in a way to allow them to stand for thousands of years.

Those with the vision for the telescope wanted to create an infrared telescope that would operate away from the light of the sun.

It would need to be as big as possible to collect as much light as possible to see the faintest and farthest objects.

Then because you can’t send a massive object into space, it had to collapse in a way to fit inside the fairing of one of the largest rockets being used. The Ariane 5 rocket flew for the first time in 1996 and so it too was developing along with the telescope.

Anyone for celestial tennis?

In the end the telescope would weigh over six tons and be as high as a multi-storey building. It would detect infrared light and so would need a sunshield which turned out to be about the size of a tennis court.

You can’t fit a double decker bus on a tennis court on top of a rocket. You certainly would also struggle to accelerate it to supersonic speeds and hope for anything to survive. So you need to make the largest, most expensive and complicated origami you can imagine.

It proved to be so complex that in the end there were 344 single-point failures. A single- point failure is one that scuppers the entire mission if the failure occurs.

Anyone who has seen Don’t Look Up will understand that throwing objects into the air high enough that they don’t fall back is not easy and when you have 24 years of effort and over $10 billion in spending then the reality that just a single electronic bolt release failing would render the entire mission a waste. Quite the responsibility on those building and overseeing it.

Artist conception of the James Webb Space Telescope. Credit: NASA GSFC/CIL/Adriana Manrique Gutierrez

Houston we have a problem

To illustrate how likely those chances of failure were, the sunshield ripped when being tested in 2018. The tennis-court-sized super thin film did not get pulled tight and so ripped when flexed. It was the reason the launch was delayed following a previous delay to ensure all systems could be tested and would function as needed.

Not only does the James Webb Space Telescope (JWST) have this enormous sunshield, it has five of them. Each cutting out more of the sun’s energy and transmitting the remaining energy into space.

The reason it needs so much shielding is that one of the infrared sensors is so sensitive that it could detect the light from a child’s night light when placed on the moon. It therefore needs to be so cold that it does not simply detect itself. More on that later.

All the systems and the incredible folding were complete in late 2021 and the telescope was shipped to South America where the rocket it would launch from was stationed. After a few more delays it was finally ready to fly on Christmas Day, it was a great present for humanity.

The rocket’s flight would determine how much fuel would be required to get the telescope to its final orbit around the Sun about 1,5 million kilometres from Earth at Lagrange point 2 (L2) to minimise the need to correct its orbit. Thanks to the near perfect launch the telescope will have more than the anticipated 5 to 10 years life with expectations for a 20-year-supply of fuel being expected.

Only going forwards because they can’t find reverse

Not that the spacecraft can turn around, doing so would damage the very light and heat sensitive instruments so it needs to travel to its destination in the same way you might drive up a hill without brakes. You need to reduce your thrust in such a way that gravity will slow you down just as you reach the top of the hill, too much and you go too far and can’t stop, too little and you stop too soon and have to use additional energy to get to the top. When you consider that it was doing over 1 000km/h after its initial thrust to L2 and would need to reduce its speed as it covers the 1,5 million kilometres to its destination, then you get another sense of just how much and how accurate the calculations needed to be to make this work.

Mirror mirror on the wall

The Hubble telescope has a 2,4m diameter mirror while the James Webb has 18 mirrors that together span 6,5m. Not only can it collect more light, it can see a bigger section of space and it can see further back in time. Its ability to see the past is down to just how big the universe is, light travels at about 300 000 km/s but even at that incredible speed objects are so far away that it takes light a long time to travel from those distant objects to us. This is why a unit of measure in space is a light year which is the distance light can travel in 365 days. The JWST will be able to look 13 billion years into our past which is almost back to the time of the big bang.

Will it find aliens?

Given how many stars there are and how many more planets orbit those stars it seems almost certain that life must exist elsewhere, yet despite our attempts to look for it for the last few hundred years we have seen nothing.

This is known as the Fermi Paradox and one explanation might be that things are very far away with our next nearest star being about 4 light years away, our galaxy is over 100 000 light years wide and the next major galaxy is 2,5 million light years away. Imagine if life that evolved on one of those distant worlds were to observe Earth, they would currently be seeing our development from tens of thousands of years ago if not hundreds of thousands or millions of years ago. A supernova collapse of a star observed in July last year was captured thanks to a method only available since 2018 even though that star actually exploded long before humans even existed.

So we don’t see aliens because even if they exist now it is likely the light we are able to see is from long before they were around. Until they can travel at light speed or faster we are unlikely to see them.

Who will use the JWST?

Amazingly, anyone. The $10 billion telescope will be available for astronomers and scientists to request time to make observations and look for objects. A fair bit of time will be to look for potentially habitable worlds besides our own and some time too will be to look for asteroids that may threaten Earth so take note if someone spots an asteroid and calls it Jennifer Lawrence.

For the next while the telescope will be aligning its mirrors to focus light exactly on the sensors. It can move the mirrors by increments that are the width of a hair and so it will take some time before we get the first picture, but is expected to be ready for pictures later in 2022. One image it can’t do is a selfie or a picture of Earth.

Follow the JWST via its homepage or its Twitter account.

This article first appeared on 702 : The James Webb telescope is what we needed to see humanity's past and future

19 January 2022 7:15 PM
Digital technology

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