(CN) — NASA publicly released the first deep-space images taken by the James Webb Space Telescope on Tuesday, after giving President Joe Biden the chance to unveil a preview of them Monday.
The pictures, captured using the $10 billion telescope's onboard infrared cameras, reveal stars and galaxies that were previously too faint to be seen.
"We're making discoveries and we really haven't even started trying yet," said Eric Smith, program scientist for the James Webb Space Telescope Program and chief scientist for NASA's Astrophysics Division. "The promise of this telescope is amazing."
The James Webb Space Telescope was launched on Christmas Day 2021. It is the product of collaboration between NASA, the European Space Agency and the Canadian Space Agency, with the primary construction contractor being the aerospace and weapons technology manufacturer Northrop Grumman Corporation.
It is intended to succeed the aging Hubble Telescope as NASA's flagship space-based telescope. Hubble was launched in April 1990, and its orbit several hundred miles above Earth's surface is slowly decaying due to atmospheric drag.
The James Webb Telescope, in contrast, revolves around the sun at close to a million miles from Earth, beyond the moon's orbit. It operates at what's known as the second Lagrange Point in the Sun-Earth system, one of five points in space where the gravitational forces of the Earth and Sun are in equilibrium. This placement allows the telescope to remain in a relatively stationary position relative to the Earth's own orbit.
The distance from Earth frees Webb from the atmospheric interference that plagues Hubble, and helps it to see objects too distant or faint for Hubble to detect. The composite images released by NASA on Tuesday included celestial bodies more than 13 billion light years away from Earth, providing a look back in time to when the universe was still in its infancy.
"Light from the farthest galaxy shown traveled 13.1 billion years before Webb’s mirrors captured it," a press release describing the image of the distant galaxy cluster SMACS 0723 said. "These observations mark the first time these particular emission lines have been seen at such immense distances – and these are only Webb’s initial observations. There may be even more distant galaxies in this image!"
Webb is able to capture such distant bodies not only due to its position, but through its extensive use of infrared spectroscopy tools. As opposed to Hubble, which functions primarily in the spectrum of light visible to the naked human eye, Webb's 21-foot wide array of 18 imaging mirrors primarily captures light in the infrared spectrum. The long wavelengths of Infrared light penetrate dust and gas more easily than visible light, allowing Webb to detect faint and low-energy objects such as brown dwarves and stars inside nebulae. The long-exposure infrared data is then compiled into visible-color images.
"What we do with Webb is not making up colors, or doing something odd with them... we use what's called chromatic order," Webb Project Scientist Klaus Pontoppidan said. "We assign to the blue color an infrared color that... has shorter wavelength, and a red color. And so we always maintain that order. Blue color means shorter wavelength, red color means longer wavelength."
Hubble still holds the record for the most distant objects ever imaged; its Ultra Deep Field image, based on data collected between 2003 and 2004, included light from galaxies that existed a mere 500 million years after the Big Bang. But Webb Operations Scientist Jane Rigby said Tuesday that the images Webb has produced are already of an unprecedently high quality.
"What's remarkable is just how good the spectra are... We're used to barely being able to tell the red-shift and instead we have a spectrum that has so many lines, you can say, 'Oh I can tell you how many oxygen atoms there are in that galaxy,'" Rigby said.
She added that these first images are only "proof that it works," and that she was confident Webb would eventually be able to see deeper than Hubble's Ultra Deep Field. One estimate by NASA puts Webb's imaging limit at about 200 million years after the Big Bang.
"As far as deeper images than the UDF, that's based on examining the images and figuring out, what is the deepest, what is the faintest blob that we're seeing," Rigby said. "And we're confident that that's deeper than images that Hubble has taken in the same wavelength. And honestly it's not hard to do that. A couple of hours and you beat Hubble in those wavelengths."
Besides the infrared images released on Tuesday, NASA also released spectroscopic data Webb captured from observing the exoplanet gas giant WASP 96-b. Orbiting a star more than a thousand light years from Earth, the planet has no analogue in our own solar system. Less than half as massive as Jupiter but about 20% larger in diameter, it revolves around its star at only one-ninth the distance between the Sun and Mercury, completing a full circuit once every 3.5 Earth days. Webb's observation of the strange planet revealed tell-tale signs of water in its atmosphere.
"What you've seen with WASP 96 were prominent water vapor absorption features," said Knicole Colón, the James Webb Space Telescope deputy project scientist for exoplanet science. "So those bumps upwards actually indicate there's water in the atmosphere, absorbing starlight."
She added Webb scientists would use a similar spectroscopy techniques for observing the atmospheres of smaller, rockier exoplanets, including those that may be habitable. Webb, she said, would also carry out direct visual observation of exoplanets as well as search for exoplanets yet to be discovered.
The scientists working with the Webb telescope said they looked forward to making further discoveries as it began its career, which is expected to last at least five years but could be extended by more than a decade. Its lifetime is limited only by the amount of hydrazine fuel it expends to maintain its orbit - it launched with a full tank of 240 liters - and by the rate at which its instruments degrade in the harsh environment of deep space.
"Seeing to the edge of the universe, it's really understanding where we come from," Pontoppidan said.
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