The ‘Happy Meal’ toy which is actually a space telescope

Touted as the follow-up to the Hubble Space Telescope, the James Webb Space Telescope (JWST) is the flag-bearer for NASA’s astrophysics division. The telescope, primarily built for improved detection of infrared radiation, is hailed ‘revolutionary’ due to its improved resolution which can allow it to detect wavelengths from galaxies far away, providing further insights into the origins of the galaxies and conditions in the universe billions of years ago.

JWST has had its share of hurdles. While planning started in 1996, the launch has been continuously delayed. 2007, 2018, 2020 and now slated to launch October 2021. Through these delays, it has also accumulated a budget significantly greater than the originally planned $500 million (it is now reported to cost in excess of $9 billion.)

Yet, despite the significant troubles, NASA unequivocally supports this telescope as the next-generation Hubble, mainly due to its unique design, greater resolution and the wide implications its findings could have across many fields.

JWST consists of four mirrors; the primary mirror is 6.5 metres in diameter (the largest yet, more than double the size of Herschel Telescope, the previous largest) and contains 18 hexagonal segments made of beryllium (for its strength and relatively light weight); the secondary and tertiary mirrors are designed to prevent optical aberrations through the use of active optics; the fourth mirror is fast steering to provide stabilization and avoid blurry imaging. All 4 mirrors are shown in Figure 1. The hexagonal shape of the primary mirror can be seen in the first image (the image shown is 1 segment of the 18-segment hexagonal piece). All the mirrors are coated in gold to improve reflection of infrared light (NASA).

Figure 1: Images of the four mirrors of JWST. Source: NASA

The telescope is made to orbit at the second Lagrange point (L2) of the Sun-Earth system. At a Lagrange point, the gravitational force of two bodies balances out the centrifugal force created by their motions. A telescope orbiting in a Lagrange point would therefore remain in a constant orbit, with very little course-correction required (“NASA Science”). L2 is not only fuel efficient but it also provides a cold environment due to the Sun and Earth being in the same part of the sky (the telescope will constantly remain on the ‘night’ side of the Earth.) This can potentially resolve a major concern for any infrared telescope: any heat radiation contains infrared radiation so any heated objects will emit light at infrared wavelengths. This includes the Sun, Moon, Earth and the telescope itself. To ensure that the telescope primarily only detects wavelengths from distant objects, it must be kept in a cool environment and L2 can provide such an orbit around the sun (“‘L2’ Will”).

This can create different problems for the JWST however. Primarily, L2 is located nearly 1.5 million km from Earth. This makes any maintenance and repair work on the telescope extremely difficult.

There are 4 primary instruments contained within the JWST: the Near Infrared Camera (NIRCam), which is the telescope’s primary imaging tool and is built to detect wavelengths from nearby stars and galaxies (particularly the Kuiper Belt objects) ; the Near-Infrared Spectrograph (NIRSpec) which can allow spectroscopy on distant objects, with new micro shutter cells which can allow study of upto 100 objects simultaneously; the Mid-Infrared Instrument (MIRI) which can allow study of distant galaxies and objects, and the Fine Guidance Sensor/ Near InfraRed Imager and Slitless Spectrograph (FGS-NIRISS) with a “guider” that can point the telescope to different regions, a tool particularly useful for exoplanet detections (“Programmatic Categories”).

In addition to all of these, JWST also contains a 5-layer sunshield the size of a tennis court. The shield radiates any heat collected from the Sun, Moon, Earth or even the telescope itself into space and can allow cooling of the telescope down to below 50 Kelvin. This cooling system also aims to prevent overheating of the NIRCam, NIRSpec and FGS-NIRISS instruments.

Using these instruments, there are many programs that JWST is planned to conduct within our solar system. One such program, led by Dr. Leigh Fletcher, aims to conduct reconnaissance of the Saturn system using MIRI, detect moons fainter than the ones discovered by the Cassini spacecraft using the NIRCam and detect deep spectra of selected moons using NIRSpec.

For the MIRI reconnaissance, the primary objective is to obtain three overlapping footprints of the northern summer hemisphere of Saturn. Prior observations from the Hubble have shown a slightly reddish colour over the northern hemisphere of Saturn. As the composition of the atmosphere, consisting of hydrogen, helium and hydrocarbons, give it a yellowish colour, NASA has attributed this change in detected colour as evidence of changing seasons, with the red detections resulting from increased sunlight causing heating. NASA continues extensive studies into the weather patterns of Saturn. The greater resolution of the JWST can reaffirm and provide further insights and observations into the northern hemisphere, providing further evidence into the weather systems of Saturn. The Cassini spacecraft has achieved great progress in this objective. During its long stay near Saturn, it observed long-term changes in the winds, temperatures and clouds of the planet. From this, a greater understanding of seasonal patterns was built. JWST can help support some of the findings and, with greater resolutions, provide precise images of seasonal phenomena.

The NIRCam is expected to conduct time-series observations on Saturn, its rings, surrounding satellites and moons. These images will serve as a continuation of the images gathered from the Cassini mission (“Programmatic Categories”).

Study of Kuiper Belt objects are also on the agenda. Led by Dr. Dean C. Hines, the mission plans to make use of JWST’s sensitivity in the 1-5 micron region to investigate trans-Neptunian and Kuiper Belt objects. NIRSpec will be used to obtain the spectra along with MIRI. This data is expected to reveal the molecular structure of many icy objects, along with the histories of dwarf planets such as Pluto (particularly their collisional history.) Along with these studies, high resolution images and spectra of surface compositions of many of these objects, using MIRI, can reveal their historical journeys.

Alongside, study of relatively larger objects such as the moons of Neptune is also planned, mainly to study their temperature differences and composition, both severely understudied thus far. JWST’s ability to absorb light at a variety of wavelengths allows for these studies. For example, to observe Triton, the largest moon of Neptune, the longest imaging filters available will be used, since the flux (flow of photons) is larger at higher wavelengths, resulting in a greater amount of data being collected (“Programmatic Categories”).

While JWST is widely hailed as a successor to Hubble, there are in fact many differences in the two flagship telescopes. Firstly, JWST is primarily built to detect infrared wavelengths. Hubble is adept at detecting some infrared wavelengths (between 0.8 to 2.5 microns) though its focus remains on ultraviolet and visible light wavelengths. This by itself differentiates the two telescopes, since infrared light can travel through gas and clouds at longer distances, while visible light is blocked, allowing JWST to collect data from distant objects. Additionally, the light-collecting area of JWST is 6.25 times greater than that of Hubble, allowing for greater data collection.

The orbits of the two telescopes are also distinct. As mentioned earlier, to prevent overheating, JWST will take an L2 orbit, where the telescope is constantly on the ‘night’ side (lined up with the Sun and Earth) approximately 1.5 million km from Earth. Meanwhile, Hubble has a low-earth orbit at an altitude of around 570km from Earth. The orbits of the Hubble telescope and the JWST are shown in Figure 2. Because of this, rather than a successor to the Hubble telescope, the JWST can rather be called the successor to the Spitzer Space Telescope which also detects infrared light and has an orbit of around 570 km from Earth.

Figure 2: Diagram of the orbits of JWST and Hubble. Source: NASA

While it has the potential to be pathbreaking for detection of infrared radiation and the field of cosmology, JWST has many questioning the context under which the telescope is set to launch. The extremely large budget of the telescope has received large opposition. One of the causes of this over-budget result is due to the lack of information and knowledge on such a telescope back in 1996, when it was first being developed. Due to this, NASA signed unrealistic estimates for its budget. In 2001, after the main design for the telescope was proposed to NASA by the National Academies of Sciences, Engineering and Medicine, the budget estimate was $1 billion, already higher than NASA’s estimate but extremely modest compared to the technologies that would be required for the telescope. These technologies took time to develop. Engineers had to develop upto 10 new technologies before any construction could even begin. Not only did this add to the cost, but also resulted in the extensive delays.

On the other hand, it’s important to note that NASA receives $19 billion through the Annual Federal Budget, approximately half percent of the entire budget. The astrophysics division is allocated only $1 billion from this each year. While the budget is overrun, there are many other governmental agencies with larger budget concerns than NASA. Working on its limited budget, this telescope can potentially be path-breaking for the fields of astronomy (with its updated, higher resolution imaging of planets and exoplanets and study of the compositions of distant objects), astrophysics and cosmology (Grush).

So, is JWST worth all the trouble? Only time can tell.

Starting from the very beginning – inflation and inflatons

What is the beginning of the beginning of the beginning?

A few months ago, I had an engaging, yet extremely infuriating conversation with my friend Joey. He asked me, what came at the beginning, at the very beginning? Well, apart from the initial bewilderment at the ineptitude of the question, I cast my mind back to the beginning of my day. Perhaps he was asking about the fruit bowl I had for breakfast, or my train journey to work. I explained my morning to my friend, who scoffed at my response.

He even let out a “Pfft.”

“What, my answer not good enough for you?” I replied angrily.

“No, it’s just that I asked you about the beginning and you told me your morning routine.”

“Mate, can you be a bit more specific?? What the hell even is ‘the beginning’?”

“The beginning of life!”

“Oh, so now you want a biology lesson?”

“I said the beginning of life, not the beginning of your life!”

Appalled, I left the room.

The heated exchange, however frustrating, gnawed at me persistently. As I walked back home, I thought back. Like, way back. Countless history lessons from high school date back to 10,000 B.C. where developments in Africa and Eurasia were the headlines. But then I started thinking, what came before recorded history? Before all the dinosaurs, before any life? And what came before that? And what came before that before? And what about the before before the before before the before?

My head started spinning. I took a seat on the sidewalk nearby, trying to make sense of the epiphany I’d just had. I decided to take a dive headfirst into the depths of the universe, vowing to uncover the mysteries of the origin and pledging to have an answer to the seemingly dumb yet infinitely profound question Joey had asked. The following is my journey through time, and my attempt to figure out what came before the chicken and the egg.

Let’s start from the very beginning. The beginning of all beginnings. What was there when there was nothing? How was something born out of nothing? How did the ‘something’ grow when surrounded by nothingness? These aren’t just philosophical ramblings, but prudent inquiries that cosmologists spend their entire careers investigating. Cosmology is a branch of science which probes into the mysteries of the origin of the universe, what came after the bang and, more intriguingly, what came before it. Cosmologists are agents of this branch, championing their cause for finding science behind the unobservable proceedings.

How exactly can anyone answer the question Joey posed when the answer lies 14 billion years in the past? Well, the answer, according to inflationary cosmology, lies in the 10^(-35) seconds that preceded the big bang.

Yes, for 10^(-35) seconds before the big bang, out of a dense black hole spewed our universe. And in this time frame, the universe fanned out, spawning multiple galaxies making up countless solar systems and consisting of billions of stars. Then, after these first 10^(-35) seconds, the expansion stopped. Our universe stopped fanning out and ever since, has been expanding but at a minuscule rate. What followed this period, which we call inflation, was the standard big bang that we know of. Most of the galaxies have stayed in the exact same spots for the 14 billion years that followed.

Why did it slow down so drastically? Well, very simply, it’s because of gravity. Gravity is (primarily) attractive, which means it sucks objects nearby towards each other. Thinking about how your feet are attracted to the ground supports this claim. This discovery, made in the 18th Century, can be credited to Newton. Now, it’s not very clear whether the whole story of ‘the apple that fell on his head’ is true or not. But if there’s one thing we can say with certainty it’s that something (yes, maybe an apple) did lead Newton to describe the effects of gravity and how it’s an attractive force.

In fact, the discovery of gravity catalysed the discovery of the gravitational field which is one of the four main classical fields of physics. We’ll get to the other three in due time.

But if gravity slowed our expansion down, why wasn’t it there during inflation? To answer this, we first have to visualise the fact that inflation, this phenomenon that supposedly lead to this vast universe we have, originated from a dot, near the size of a speck of dust. Now imagine our entire universe (with billions of galaxies) compressed into this minuscule dot. Imagine the billions of stars in the billions of galaxies, now squashed into a shrunken tennis ball. All this leads to an extremely hot and dense state. For reference, temperatures are estimated to have reached up to 1000 trillion degrees Celsius at this point in time.

In this state, gravity too was clumped together, which lead to the birth of particles known as inflatons. These inflatons have one distinct property: they have what a non-scientist would call ‘negative pressure’. Think of it this way:

If I exert some pressure onto a tennis ball, forcing it to the ground, I am applying ‘positive pressure’ onto this ball. Gravity is the usual universal attractant which acts as this ‘pressure exerter’, pinning the ball, and everything else, to the ground. Instead of this positive pressure, now imagine the result of me extending ‘negative pressure’ onto a ball. Well, as logic would dictate, this negative pressure un-restricts the ball, in that it frees the ball of any limiting pressure that may be exerted on it.

Extrapolating this analogy by replacing the ball with our universe, you can see that gravity would cause positive pressure onto the universe, causing all its constituents to clump together. During inflation however, these inflaton particles exerted negative pressure. This caused all matter in the universe to spread out, thereby causing an expansion which resulted in the universe we know of today.

As it expanded, the universe also started to cool down (since everything wasn’t in such a hot, clumped-up mess). As temperature dropped, gravity started to exert its ‘positive pressure’, slowing down the expansion of the universe drastically.

And voila! We have the universe as we know it! Pretty simple, right? Well, no actually. While the non-scientific explanation I just provided does explain how inflation occurred and why it stopped, what we must be careful of is that all of this, in truth, is hypothetical.

Since we can’t peek back 14 billion years ago, all we have are theories. A theory might need countless agreements through experimental results to be proven, but only needs 1 dissimilar result to be disproven. Even the big bang theory is, in the end, a theory.

The inflaton particles I mentioned exist in the realm of quantum field theory (which I will delve into in a later post). They are hypothetical and therefore, require large assumptions.

As anti-climatic as that may sound, we still can’t discount the possibility of what I described as having actually happened. Cosmology is a field with constant ongoing research only boosted by innovations in quantum computing which allow for large-scale simulations of a time non-observable.

We’ll never be able to answer Joey’s question with absolute certainty, but we can get really bloody close to.