How James Webb leapfrogged humanity’s quest for the stars

Space-based telescopes like the Hubble and Kepler have transformed our understanding of the universe. Each has surprised us by revealing unknown facets of the universe, whetting our curiosity to look deeper and farther in space. The recent James Webb Space Telescope (JWST or Webb) stands testimony to the giant leap humanity has taken in this quest.
Webb is the culmination of three decades of toil resulting in an engineering marvel that has etched its space in history for its iconic space feats.

Here’s a lowdown on Webb’s three-decade journey — from inception to accomplishment — from Webb’s ‘personal log’.

Standing on the shoulders of giants

The mid-to-late 1980s: The Hubble is getting ready. And even before the launch date is finalised, Nasa engineers summon me – the Next Generation Space Telescope. I am to capture the celestial happenings in greater depth and detail. Peer deep into space to the days when the universe was taking shape and see how the stars and galaxies were born back then.

The task is a humungous one. I have to gear up to perform magnificent space gymnastics unaided far away in space. Nevertheless, I am excited and raring to go.

September 1989: Around 130 astronomers and engineers gather for a workshop to discuss my mission objectives and technical details. The event, the Next Generation Space Telescope Workshop, is co-organised by Nasa and the Space Telescope Science Institute (STScI).

I learned that when the faraway primeval celestial bodies formed billions of years ago, they spewed intense radiation into space. The light travelled far into the ever-expanding space; in the process, the vast distances reduced the intensity. As a result, the light waves stretched, and the wavelength broadened to the infra-red range or weak heat signatures. Therefore, I must have an infrared vision to see these stars at their birth.

There’s a catch, though. My instruments must work under freezing temperatures (as low as -230 degrees Celsius) to capture these faint signals so that I can eliminate noise from other heat sources.

The mission outlay emerges:

• I will take a position in deep space, in a high orbit above the earth or on the moon

• I will have a huge mirror – as big as a house, and

• The mirror surface will be flawless – polished to perfection to capture the faint signals.
1996: An 18-member committee decided I would be stationed far beyond the moon – about 1.5 million kilometres from the earth in a particular orbit around the second Lagrange point L2. This spot in space will ensure that I will face no resistance from the earth’s and the sun’s gravitational pull. As a result, I can cruise in my orbit without high fuel usage. (This is a crucial aspect of the mission as there are no refuelling options).

I will get a 6.5m (about 22 feet) wide gold-plated mirror. (Gold is highly reflective at infrared wavelengths and hence will focus the incoming signals onto my sensitive instruments accurately).

It is exciting! At this position of L2, with infrared vision and a large mirror, I can see through dust and gas clouds, peek into the atmospheres of planets and exoplanets millions of lightyears away; I can travel back in time and give humanity visions of how the universe was– 50 to 500 million years after the Big Bang.

Whoopee!

Some realities and my christening

1997-2002: As I am on a never-before-attempted mission, the complexities of my suit of armour and instruments have escalated. The teams are taking extra precautions to enhance my ruggedness and robustness, for I am out of reach once I reach my destination. If I run into technical snags, no one can come to my rescue; my only option is to hang up my boots and turn into space junk.

They have renamed me James Webb Space Telescope in honour of Nasa’s erstwhile administrator who spearheaded the Apollo programs.

The project has now become a multi-national venture with the European and the Canadian Space Agencies contributing their expertise to ensure my success and safety.

I’m on a roll!

The clever idea

Several hurdles arise. No available rocket can accommodate a giant mirror. Moreover, I will need a big umbrella-like heat shield to block the reflected sunlight from the earth and moon to maintain the sub-zero temperatures. The rockets can’t accommodate such a shield, either.

So the engineers devised an alternative – to fold the mirror and the shield and pack them on the rocket. Brilliant! However, folding the mirror is possible only if it is divided into hexagonal segments in a honeycomb-like pattern. Also, the heat shield must be of superior quality thin fabric that can withstand the rigours of space.

These modifications will escalate the risks of the mission. Therefore, I must ramp up my efficiency manifold, performing each task autonomously with utmost precision at my post.

At L2, both the sun and the earth are in line. I will open my silver umbrella and shield myself from the sun and earth light to maintain the ultra-cold temperatures for my instruments. And facing my back to earth, I will unfold each segment of the golden optical mirror and realign them with nanoscale precision. Then I will point the mirror toward the vast expanse of cosmos.

It is humbling to know that over 1200 scientists, engineers and technicians across 14 countries are working arduously for my mission. Cutting-edge technology and ultra-precision motors will help me with the critical unfolding sequence. Nasa has even allocated funds for additional scientific studies to refine my technology requirements. (I eventually learned that my mission cost a whopping 11 billion dollars).

Piecing together

2003-2013: The demand for highly critical components has pushed the expected launch date by a decade. I will have two halves with the revised designs: The spacecraft and the optical telescope unit. My individual parts, manufactured across various facilities in Europe and America, begin to arrive at the Goddard Flight Centre. All 18 segments of the beryllium mirror coated with a thin layer of gold are ready and tested. They have passed cryogenic (temperature) tests to conform to the actual space situation.
Another team has begun work on the sun shield. It will be a five-layer Kapton E (a flexible tape-like material) with aluminium and doped-silicon coatings to reflect the sun’s heat into space. Unpacking the shield is a critical manoeuvre as it is difficult to control the behaviour of fabric in space. If any part of it does not respond as required, my entire mission will be a wasted effort.

The other scientific instruments – MIRI (Mid-infrared Instrument), NIRISS (Near-infrared Imager and Slitless Spectrograph) and Fine Guidance sensor arrived from Europe and Canada. Two others – NIRCam (Near-Infrared Camera) and NIRSpec (Near-Infrared Spectrograph) will follow soon.

2014-2018: They signed an agreement to launch me in 2018 atop Ariana 5. There is a frenzy of activity. The scientific instruments are assembled into the Integrated Science Instrument Module. Together they will go for the cryogenic tests. The secondary mirrors and the spacecraft components are also ready. I am in the final phase of testing.

I developed a snag and failed the vibration test. Dang!

The launch is cancelled and pushed to 2021.

2018-2021: The engineers refine my instruments further, and I go into the testing loops again. By 2019, the sun shield and bus pass the rigours in the thermal vacuum chamber and cryogenic units. Once again, my two halves are joined.

I go through several more dry runs of the folding-unfolding sequence. Finally, I am fully loaded and undergo one final round of checking to withstand the jolts and shakes from the rocket. This time I breeze through all of the tests unscathed. The optical parts are folded and stowed away at the launch site.
Hurray! I am ready and raring to go.

I take to the skies on December 25 2021 – a Christmas gift to the world. I have travelled the 1.5 million km in a month, traversing an S-like path. I park myself in my designated spot without a hitch. I have plenty of fuel reserves that will last for the next ten years.

Everything is going with clockwork precision; I settle down to unfold the universe for humanity.

July 12 2022: The first pictures are out. The world gushes.