James Webb Space Telescope Offers Earliest View Of Universe
HOUSTON—President Biden unveiled the first image marking the start of the James Webb Space Telescope’s (JWST) long-anticipated initial science campaign on July 11 that featured a stirring, full-color view of the now-vast universe from its earliest and not previously witnessed era.
There is more to follow the president’s 10-min. White House curtain-raiser, as representatives from NASA and its European and Canadian space agency partners plan to publicly lift the veil on four additional images at 10:30 a.m. EDT on July 12. Both events are meant to display the JWST’s scientific promise over potentially two decades to come.
Joined by Vice President Kamala Harris and NASA Administrator Bill Nelson, Biden presented an image of SMACS 0723, or “Webb’s First Deep Field.” It is a vast scattering of small, bright, multicolored galaxies against a dark background, all more than 13 billion light years distant. Nelson characterized them as the oldest, most distant and faintest galaxies that humans have ever witnessed.
“Today is an historic day,” Biden proclaimed. “This telescope embodies how America leads the world. These images are going to remind the world that America can do big things and remind the American people, especially our children, that there is nothing beyond our capacity. We can see possibilities no one has ever seen before. We can go places no one has ever gone before.”
“This is a very exciting moment,” added Harris, who chairs the White House National Space Council.
“Now we enter a new phase of scientific discovery. Building on the legacy of Hubble, the James Webb Space Telescope allows us to see deeper into space than ever before and in stunning clarity. It will enhance what we know about the origins of our universe, our Solar System and possibly life itself,” she said. “This was made possible by a partnership among nations and is an example of how the scientific endeavor can build up the international rules of and norms that govern our cooperation in space. This telescope is one of humanity’s great engineering achievements.”
The JWST’s promise spans sharper, more detailed views of a vast universe in the wake of its violent beginnings an estimated 13.8 billion years ago to the formation of the first stars, galactic evolution and possible chemical evidence for biological activity locked in the atmospheres of extrasolar planets. Though costly and among the most challenging space endeavors ever, the $10 billion observatory was fashioned to build on past endeavors, including the now 32-year-old Hubble Space Telescope (HST). It also complements NASA’s Nancy Grace Roman Space Telescope planned for launch in 2027 and the best ground-based observatories. JWST fills in the blanks of how the first stars and galaxies formed and evolved to include planets while generating the chemistry and resources that made life on at least one destination within the expanding realm possible.
HST, for instance, is equipped to observe the cosmos in the visible and small portions of the shorter ultraviolet and longer infrared wavebands. Among Hubble’s achievements was detection of the universe’s expansion under a force called dark energy and ever faster at greater distances. With its expansion, the most distant fainter objects can only be witnessed at the longer infrared wavelengths that JWST was specifically developed to observe. NASA’s breakthrough but less capable Spitzer Space Telescope offered a glance of the infrared realm, including light from the first extrasolar planets, over a more than 16-year mission that came to an end in early 2020.
The JWST partnership announced on July 8 the names of the first five observations that had been selected by scientists to best illustrate the new observatory’s capabilities. They are being unveiled July 11-12 at the White House and NASA’s Goddard Space Flight Center (GSFC) with support from the Space Telescope Science Institute (STSI) of Baltimore, which will manage JWST observations. Those slated to take the stage on July 12 are:
—The Carina Nebula, one of the largest and brightest cradles for star birth, including many massive stars much larger than the Sun and located about 7,600 light-years away.
—WASP-96b, a giant extrasolar planet, about half the mass of Jupiter and composed primarily of gas. About 1,150 light-years from Earth, WASP-96b orbits its star every 3.4 days.
—Southern Ring Nebula. Also known as “Eight Burst,” the planetary nebula is an expanding cloud of gas that surrounds a dying star. Nearly a half light-year in diameter, the Southern Ring Nebula is located about 2,000 light-years from Earth.
—Stephan’s Quintet, about 290 million light-years away, is the first compact galaxy group discovered. Located in the constellation Pegasus, four of the five galaxies in the group are “locked in a cosmic dance of repeated close encounters.”
—The first cycle, or year, of JWST observations as outlined by the STSI will span just more than 6,000 hr., with observation campaigns led by principal investigators from 22 countries and 26 U.S. states.
Initially estimated to cost between $1 billion and $3.5 billion and to launch between 2007 and 2011, the JWST lifted off on Dec. 25, 2021 from the European spaceport in French Guiana.
The European-provided Ariane 5 rocket delivered the observatory to its new home, the gravitationally stable, L2 Earth/Sun Lagrange point about 1 million mi. from Earth, with enough fuel-saving efficiency to potentially double its initially estimated 10-year life span.
The observatory’s scientific prowess was developed under the supervision of GSFC and the telescope’s prime contractor, Northrop Grumman. Contributions from international partners and academic and scientific institutions are concentrated in four primary instruments:
—The Near-Infrared Camera (NIRCam) for high-resolution imaging and spectroscopy. Coronagraphs block bright light sources, allowing scientists to image nearby faint, dim objects of interest.
—The Near-Infrared Spectrograph (NIRSpec), the first space spectrograph designed to observe 100 objects simultaneously as well as specific targets.
—The Near-Infrared Slitless Spectrograph and companion Fine Guidance Sensor (NIRISS/FGS) provides high-resolution imagery of bright objects. FGS serves to point and stabilize its companion spectrograph through the detection and identification of guide stars to lock onto over long periods of time until the observations are complete.
—Mid-Infrared Instrument (MIRI), a combination of a camera, coronagraphs, spectrographs and an integrated field unit that enables the observatory to capture and map spectra across an entire field of view. MIRI detectors are cryocooled to temperatures of 7K, or minus 447F.
In order to carry out its challenging mission, the JWST is equipped with a 21.5-ft. (6.5-m) primary mirror fashioned from 18 carefully crafted smaller segments, each strong and lightweight. The design enabled the large mirror to be folded to fit within its rocket fairing for liftoff and unfurled and precisely aligned during the lengthy post-launch commissioning phase.
In order to gather the longer wavelength infrared radiance that hold the discoveries astronomers are seeking, the observatory’s large mirror must be chilled to less than minus 370F. That was accomplished with a carefully engineered, five-layer sunshield roughly the size of a tennis court.
Each layer is separated from the next to prevent heat from the Sun from being transferred onto the mirrors and science instruments. The layer facing the Sun warms to 230F, while the cold side facing the mirrors and instrumentation chills to as cold as minus 394F.