- Astrophysicists anxiously await the upcoming launch of the James Webb Space Telescope, slated for December 18. Things can go wrong.
- This spectacular giant will be the most powerful space telescope ever built, opening new windows to nascent galaxies and stars from billions of years ago, as well as to planets circling other stars in our cosmic neighborhood.
- It will help us refine our own story — a story of our origins and how similar and different we are to the rest of the universe.
The history of science could be written as a history of instrumentation. From particle accelerators and microscopes to fMRIs and telescopes, as instruments become more powerful, they act as reality amplifiers: they magnify our view of the very small and the very large, allowing us a glimpse of what is invisible to the human eye.
It is hard to imagine that, up to 1609, all we knew about the skies depended on what we can see with the naked eye. When Galileo Galilei had the insight to aim his telescope at the night sky, he saw what no human had seen before: a new sky, full of surprises and possibility. This new sky would reveal a new world order: out with the Aristotelian view of an Earth-centered cosmos, a frozen sky where celestial objects were perfect and unchangeable, and in with a marvelously imperfect heaven — a moon full of craters and mountains, Jupiter with four orbiting moons (now we know there are about 79 and counting), a Saturn with “ears” (that is, the rings that his telescope could not yet resolve), and a Milky Way made of a countless number of stars. New instruments hold the promise of a worldview transformation: as we look deep into nature, our vision of reality and us in it changes.
It is then no surprise that the astrophysics community is nervously awaiting the launch of a new marvel of instrumentation, the James Webb Space Telescope (JWST). Even if often called the successor of the Hubble Space Telescope (HST), the JWST is a different kind of machine. The HST is, perhaps, the most successful instrument in astronomical history. Beyond its optical capability that reveals to us parts of the universe we could in principle see with our limited human vision (that is, the colors of the visible spectrum), it has additional infrared and ultraviolet instruments that have revolutionized the way we understand the cosmic history and the stunning wealth of galaxies spread throughout space. But the Hubble was launched in 1990, and it is time for a new instrument to step up and expand upon its groundwork, deepening our understanding of the universe near and far.
Two big missions for James Webb Space Telescope
The JWST is designed to capture mostly infrared light, which is of a longer wavelength than what our eyes can see. The focus on infrared comes from the two main missions for the telescope.
The first is to look into the very young universe by observing very far away objects, nascent galaxies and stars born about 13 billion years ago, which was only a few hundred million years after the Big Bang. (In cosmology, the science of our cosmic history, hundreds of millions of years is not a long time.) Contrary to Hubble, which had a near-Earth orbit, the JWST will be stationed far away, at 1.5 million kilometers from Earth at a spot known as a Lagrange point, where the gravitational attractions of sun and Earth cancel out — a peaceful cosmic parking spot.
After taking off inside an Ariane 5 rocket from the European Space Agency, the JWST will continue for another twenty-nine days until it gets to its final destination. The good thing about the Lagrange point is its remoteness and thus distance from interfering infrared sources near Earth. To make the shielding even more effective, the telescope comes with five layered sheets of Kapton foil, a sort of space umbrella to stop radiation interference. At the size of a tennis court, the shields are programmed to open during the telescope’s migration to its final position. The bad thing about being stationed so far away from Earth is that if something goes wrong, we cannot go there to fix it, as we had to with the Hubble Space Telescope. Anxiety rises.
The “eyes” of the telescope are made of 18 hexagonal, gold-coated, beryllium mirrors, making up a giant honeycomb the size of a large house. The mirrors will capture and focus light from distant sources that will then be sent off to the telescope’s four different instruments. The mirrors must also unfurl in space, another nerve-wracking step before astrophysicists can start to gather data.
The second big mission is to aim its sights on exoplanets, planets orbiting stars in our galactic neighborhood, for signs of life. A little over 20 years ago, astronomers detected the first alien worlds outside our solar system. Since then, the list has grown steadily to over four thousand confirmed exoplanets today. The essential question, of course, is whether some of these worlds may harbor life. We may not be able to travel across interstellar distances to see for ourselves, but our machines can scrutinize these worlds by detecting the chemical composition of their atmospheres in the hope of finding the telltale signs of life: mainly oxygen, water, carbon dioxide, and methane. Thus, JWST aims to map out other worlds that may resemble our own, addressing the age-old question of whether we are alone in the universe.
An early Christmas present
The current launch date is December 18, a week before Christmas. As with any space launch of a complex instrument, there are many things that could go wrong, although extensive testing has built up confidence that all will go smoothly. Regardless, we only will succeed in stretching the boundaries of knowledge by taking risks. The launch will be a gripping moment for humanity. What will a new window opening to the sky reveal about our story?
Unless you are lost to the power of wonder, a mission like this must capture your imagination. We all want this spectacular mission to succeed, astrophysicists and non-astrophysicists alike. We care about worlds so far away from us because the story this machine will tell is a mirror of our own. As we witness stars and galaxies being born, we learn about our galaxy and how our solar system emerged a little under five billion years ago. We learn about the myriad ways that gravity and chemistry conspired to bake matter into worlds, each different, some potentially thriving with life like our own. And with each discovery, we dive a little deeper into the mystery of who we are and of what makes us both alike and different from what is out there in the universe.