This week NASA released the long-awaited first images and scientific data from the James Webb Space Telescope. JWST's dramatically detailed images of a stellar nursery, a dying star, a cluster of galaxies, and JWST’s first ‘deep field’ follow on similar images from the Hubble Space Telescope over its 32-year run as the Earth’s premier space telescope. While this new release doesn’t represent a major leap in knowledge beyond what we have from HST and other telescopes, it promises that JWST will soon provide dramatic new findings about the history of our universe.
Starting in 1995, HST began a series of lengthy exposures into seemingly empty corners of the universe that revealed large numbers of galaxies billions of light years away. These images, known as Hubble Deep Fields, have taken us to within a billion years of the Big Bang that marked the beginnings of our universe about 13.8 billion years ago. Hubble’s cameras took exposures of roughly a week in length to obtain these revolutionary images, and more recent Deep Fields have exploited gravitational lensing, where galaxies bend light from objects that are behind them and farther away.
JWST is designed to look farther out in distance and farther back in time than HST by observing in infrared wavelengths. Objects that are moving away from us at high speeds, such as distant galaxies and other objects, are found at infrared wavelengths because of their movement away from us. (HST observes mainly in optical wavelengths familiar to humans.)
The JWST Deep Field image released this week is similar to Hubble Deep Field images, but it required only a few hours of exposure because of its much larger light gathering capability compared to Hubble. That means we will soon be contemplating JWST Deep Fields that go well beyond the Hubble Deep Fields and this week’s JWST Deep Field. We will see how our universe evolved very early in our history, learning about the processes that amongst other things led to our own creation.
Along with four dramatic images, the scientists running JWST released a chart that shows evidence of water in the atmosphere of a planet known as WASP-96 orbiting a star 1,150 light years away. While WASP-96 is too hot and located too close to its star to host any form of life, the precision and wealth of information JWST gathered about its atmosphere shows that JWST will be able to advance the search for habitable planets by observing smaller planets in locations more friendly for life.
The instrument used to find this data is JWST's Near-Infrared Imager and Slitless Spectrograph (NIRISS) which was built by Canadian scientists and engineers with the support of the Canadian Space Agency. This week’s first release of data from NIRISS marks a major step forward for Canadian astronomy.
While Canadian astronomers have made observations with HST and other space telescopes, Canada was not a formal partner in HST, which was built by NASA and the European Space Agency. With its contribution of NIRISS and JWST’s Fine Guidance Sensors, which aim the telescope and also provide scientific data of their own, Canada has taken a central role in the most ambitious space astronomy program of this century.
Most astronomers do not rely on images to explore the cosmos. Spectrographs such as NIRISS take the 'fingerprints' of stars, planets, nebulae and other objects, providing information about their chemical makeup, temperature, mass and distance, amongst other things. JWST’s gigantic segmented mirror will allow JWST to provide more precise information about more objects in space than any other instrument. While there are larger telescopes on Earth, our atmosphere blocks many wavelengths of light, which is why astronomers get more information from space telescopes.
While writing my book about Hubble,
Not Yet Imagined, I often traveled to the HST control centre at NASA’s Goddard Space Flight Center near Washington D.C. There I was also able to follow the construction of JWST before it was moved to the launch pad.
Although Hubble is nearing the end of its lifetime, it is far from being replaced by JWST. In fact in the coming months, JWST and HST will work in tandem with each other to produce coordinated sets of observations that will cover wide ranges of wavelengths.
Planning for JWST began more than 30 years ago, even before Hubble was launched. It took 20 years to build, and cost more than US $10 billion. Along the way, JWST encountered many problems that nearly led to its cancellation. But it was finally launched into space last Christmas Day, and in the weeks that followed, it successfully unfolded and aligned its 18 mirror segments and its tennis-court-sized sunshield that helps chill JWST’s instruments to operate at the low temperatures required to find infrared light. This week JWST's scientific payoff began.
HST and other telescopes of its time turned humanity’s understanding of our universe on its head, and raised as many questions as they answered. This week we learned that JWST has the technological chops to further revolutionize astronomy. Stay tuned for some major scientific surprises.
