The James Webb Space Telescope is going to be launched on Christmas Day of 2021, and a friend of mine wanted me to write about it. There has been extensive coverage of the telescope, especially of the incredible engineering achievement [1, 2, 3] and about what science the telescope would explore [1, 2, 3 and more]. I didn’t want to add another article to that pile, you should definitely go read or watch the links.
I was more interested in exploring why are astronomers so excited but also anxious about this specific telescope, even more so than usual. Especially knowing that many important space telescopes and planetary missions have been launched recently, and several multi-billion dollar (space and ground) telescopes are being constructed, and also the fact that some recent Nobel worthy discoveries, viz. The gravitational waves detection, the photo of the supermassive black hole, and the last year’s prize winning discovery of the presence of a supermassive black hole in the centre of the Milky Way, have all come from ground based observatories. So here are my thoughts.
NASA engineer Ernie Wright looks on as the first six flight ready James Webb Space Telescope's primary mirror segments are prepped to begin final cryogenic testing at NASA's Marshall Space Flight Center in Huntsville, Ala. Credit: NASA/MSFC/David Higginbotham
Hubble’s Heir
The JWST is the successor to the famous Hubble Space Telescope. The HST is a grand success. It has been involved in countless major discoveries, and revolutionized the way we explore physics and understand the Universe. Even after 25+ years of working, it is still one of the most sought-after telescope for observations among astronomers. Not only has it been a scientific success, it has also become a cultural phenomenon that transcended the confines of space astronomy and has become a household name. The famous images of the Pillars of Creation and the Deep Field Images have fascinated all. But more importantly, each new telescope has uncovered mysteries of the Universe that we previously had no knowledge of. As the scientific successor to Hubble, the JWST has very big boots to fill.
The aptly named Pillars of Creation, featured in this stunning Hubble image, are part of an active star-forming region within the nebula and hide newborn stars in their wispy columns. Credits: NASA, ESA and the Hubble Heritage Team (STScI/AURA)
Hubble showed us how stars are formed in nebulae and how galaxies evolved, and the JWST is designed to go a step further, to look farther back in time to see how the first stars and galaxies formed, and to study the light coming from exoplanets. To achieve this, JWST had to be designed differently. Hubble is an optical telescope, seeing the Universe in visible and ultraviolet light, which young stars emit. But this same light of the very young stars, coming from the early Universe when it was barely a few hundred million years old, gets stretched and shifted to the infrared. So to study this light from the youth of the Universe, the JWST will observe in the near- and mid-infrared bands. And to be able to catch the faint light from the early Universe or exoplanets, it has to be much bigger than the Hubble, a mighty 6.5 meters in diameter to HST’s paltry 2.4 meters, collecting five times as much light as the Hubble.
Space is difficult
These requirements have brought challenges of their own. Everything on the Earth glows bright in the infrared. You must have seen the thermal images of bodies glowing white-hot in a background of red and blue. To the very sensitive JWST, the Earth is a giant fireball, blinding its sensors. So it cannot be stationed in the same low-Earth orbit as Hubble at 500 km, but has to be placed at the Lagrange point L2 1.5 million kilometres away. Which also means it will get no servicing or repairs. We have to get everything right in the one and only try. There are no retakes.
Thanks to its low-Earth orbit, Hubble was serviced by astronauts multiple times, getting upgrades and adjustments, refilling the fuel, which has made it last for almost three decades. Without a possibility of servicing, the JWST’s lifetime depends completely on how much fuel we can put on it at the start. Due to this, the JWST is planned for an initial 5-year lifetime, with a possibility of another 5+ years if everything goes right. This comparatively short duration means it will be even more desired by astronomers for observation time. Although I should add that there are currently no plans for refuelling the telescope, some people are already exploring possible options for robotic refuelling which would extend the life of the telescope extensively.
But this isn’t the first time we have placed a telescope at the L2 Lagrange point, and it has been done very successfully. So why the extra worry for now? The JWST’s sheer size creates another set of complications. The diameter of the telescope mirror is 6.5 meters, and it is protected from solar radiation by large many-layered, tennis-court sized, but wafer-thin shields. But the Ariane 5 rocket which is going to launch it can only fit things smaller than 4 meters. And thus the 18-segmented, hexagonal mirror and the shields have to be folded up for launch and will unfold as they arrive at the destination. Even if the launch is successful and the telescope is placed in its orbit perfectly, it still has too many moving parts and hundreds of single-point-of-failure that would compromise the telescope. All astronomers will be keeping their fingers and toes crossed for weeks until the entire telescope deployment and calibrations are completed!
The Just Wait Space Telescope
Everybody wishes for any space mission to succeed, and even when they don’t, the failures do not carry a somewhat existential threat to the field. So what’s different with the JWST, and why is everyone so worried about its launch?
The JWST was being planned before the Hubble was even launched, just as right now, many astronomers are drawing the plans for the successor to the JWST. In its original conception, it was supposed to launch in 2007 and would cost about $500 million. But already in the early years, things started to go off the track. In 2001, the telescope had to be downsized by a third from its original size. Each subsequent year, the planned launch date was delayed, so that by 2006, the launch was postponed to 2014, and the budged ballooned to $4.5 billion. The US Congress Appropriations Committee called it "billions of dollars over budget and plagued by poor management", and suggested cancelling the project entirely, but the telescope was saved after strong support from some prominent scientific and political figures.
The construction started only around 2004 and struggled to quickly develop key technologies necessary for its operation. It also suffered several setbacks, when technicians damaged it by using the wrong solvent to clean the propulsion valves, or when the screws came loose during the testing, leading to more delays. The constant delays became a meme on its own, most prominently the cartoon from ever-insightful Randall Munroe’s XKCD. After all the delays, testing and quality control, the JWST will finally be launched on the verge of 2022, with the budged of almost $10 billion!
The evolution of the expected launch date was not so linear, and we finally got the launch well before the linear extrapolation. :)
This budget overflow came at a high cost. The initial cost estimates were outlandishly low, and came from the 1990s era NASA philosophy of ‘faster, better, cheaper’, and the telescope was designed when NASA budget was growing a few percent per year. But in the 2000s, the US Govt started reducing the overall NASA budget and the increased cost ate into the already shrinking pie, and pushed many other, smaller telescopes out of consideration. It is quite likely that if the costs had been clear, the priorities might well have been different. A secondary cost of the JWST delays is the derailment or termination of several careers, which were planned around the successful launch.
Some astronomers have commented that Hubble was also originally delayed and cost much more than the initial expectation, and yet it has been a success story. The overall launch, repair, servicing and operations cost for the HST comes to be around $7 billion in today’s money. But we must also remember that when launched in 1990, Hubble was an absolute disaster. Its primary mirror was not built correctly, causing the images to be blurred. It had to be fixed by an expensive repair mission. There will be no such second chances for the JWST, and a failure would affect astronomy for generations.
Honestly, what are we doing?
The ballooning cost of JWST did not come out of nowhere. Space telescopes are inherently more expensive by their nature. Because repairs and upgrades are expensive or impossible, the space telescopes have to be designed and tested for everything that could go wrong. Some early estimates in the 1980s calculated the cost of the next generation infrared telescope would be around $7 billion. A smaller and technologically comparatively modest European cousin of JWST, the Herschel infrared telescope, launched in 2009, also cost about $1 billion. The original estimate of 0.5 – 1 billion dollars for JWST was completely unrealistic, and may have come from the combination of the overly optimistic ‘faster, better, cheaper’ philosophy, and lowballing the cost to get the project accepted and hoping the inertia and ‘too-big-to-fail project’ difficult to cancel.
This practice of ‘overpromise and under deliver’ is not restricted to the space telescopes. The next generation radio telescope, the Square Kilometre Array (SKA), was originally planned to have 4000 dishes of 10 meter diameter with a total collecting area of one kilometre-squared, and expected to complete in 2020, costing 1.5 billion Euro. It has been cut, chopped and scaled back multiple times, and its phase 1, with only 10% of the original capacity, costing 650 million Euro, will not be completed before 2027, and the full-SKA has become a pipe-dream.
Artist’s impression of what the SKA Phase-1 will look like. The image is a composite of the two SKA sub-parts, located in Australia and South Africa. Credit: SKAO www.skatelescope.org
These examples are an exception, rather than common practice, and most astronomy instruments, whether ground or space based, run on time and within budget, and often last significantly beyond their planned operation, providing heaps of returns beyond the original plan. But we must be cautious that the phenomenon of ‘overpromise and under deliver’ should not become regular practice, lest the government and the public lose faith in the scientific merit of such projects.
And more importantly, it is vital to consider this in the context of overall scientific budgets. In the 21st century, and especially since the 2007 financial market crash, the science budgets of almost all countries have declined. As a result, the competition between projects has drastically increased. But the overall NASA or NSF budget is a tiny fraction of annual US Govt spending. You could build a JWST every year with just 1% of the US military budget, where trillions of dollars are spent over dubious wars. So when we are penny-pinching science projects, we should also question where our priorities lie.
Fingers Crossed
With all this in mind, we keep our fingers crossed for a successful launch and deployment of the JWST and get ready to have our minds blown with gorgeous images and fantastic science results that will revolutionize astronomy! A lot depends on its success!