What the James Webb Telescope Images Mean for Space
TNASA’s James Webb Space Telescope scientists spent nearly 26 years trying to get patience, money, and time from NASA. It was in 1996 that a committee of astronomers working with the space agency first proposed a next-generation space telescope that would be capable of peering 13.6 billion light years away—detecting infrared light that has been traveling to us since just 200 million years after the Big Bang. The telescope, they promised, would be ready to launch by 2007 and would carry a price tag of just $500 million—cheap, as these things go.
It didn’t work out that way. That forecast 2007 launch didn’t happen until Christmas Day 2021, and as for that $500 million cost? This ballooned up to $10 billion. But the astronomers’ promise remained the same: the images the new telescope revealed would be spectacular.
That promise was kept this morning. NASA will present four brand new images from Webb at a press conference held at Goddard Space Flight Center Greenbelt. They are nebulae as well galactic clusters. The exoplanet is a huge, unknown-to-be-known, giant. That’s in addition to a gobsmacking picture of a galactic cluster known as SMACS 0723—a swarm of thousands of galaxies, including the most distant ones ever observed in the infrared spectrum—revealed at a White House press conference yesterday by NASA Administrator Bill Nelson, with President Joe Biden and Vice President Kamala Harris in attendance.
“These images are going to remind the world that America is capable of great things,” Biden said. “There is nothing beyond our possibilities.” The Webb telescope, he added, “symbolizes the relentless spirit of American ingenuity.”
NASA today will unveil four images, including the one unveiled yesterday. They are all of new objects that many people who don’t belong to the astronomy community may not have heard about. However they will gain an important place in cosmic historical records. They’re also SMACS0723.
- Carina Nebula is located at 7,600 lightyears away from Earth.
- WASP-96b is a huge gas planet that orbits a star 1150 light years away from Earth.
- The Southern Ring Nebula, a expanding cloud of gas that is nearly half an light-year wide around a dying star located 2,000 light-years distant.
- Stephan’s Quintet, a compact galaxy group, located 290 million light years from Earth, first crudely imaged in 1787.
It is in some ways, the smallest object the telescope imaged—the exoplanet WASP-96b—that will likely cause the greatest excitement. Until now, exoplanets, or planets circling other stars, were detectable in only one of two ways: The transit method, in which astronomers discern the small dimming of light in a parent star as an orbiting planet passes in front of it; and the radial velocity method—in which they look for the small wobble in the position of the star as the gravity of the orbiting planet tugs on it.
Astronomers have never been able to observe the planet. It would have been like trying to spot a tiny moth next to a streetlight, but standing blocks away from it. It would be impossible to see the small body. All by itself, the image of WASP-96b is thus historic—and it tees up Webb for perhaps even-more sensational discoveries: Now that astronomers can crisply image exoplanets, they can also look for signs of life on them, as the light from their parent planet streams through their atmosphere, revealing the make-up of the gasses and the possibility of the chemical fingerprints of biology.
As Vice President Harris said yesterday, with these photos we are entering a “new phase of scientific discovery.” These images offer a “new window into the history of our universe,” added President Biden.
Webb is remarkable for its ability to function as a telescope. Both its engineering and the location it occupies in space are unique. In 1990, the Hubble Space Telescope was launched. It orbits Earth at 547 km (345 mi). high, just above our atmosphere, and looks like, well, a telescope—a metal cylinder with its optics built inside and light streaming in from one end. Its conventional look is due to the fact that Hubble works in a conventional way—seeing principally in the visible spectrum. That means its mirrors need to be protected from stray light from the sun, the Earth and other objects it is not observing—hence tucking them away inside the telescopic body—allowing them to focus on the ones that it is.
Webb’s telescope instead operates in the invisible spectrum. It is an infrared wavelength that is one measure less of heat than light. Hubble would not have been able to see Webb’s 13.6 billion light year distance, as visible light from faraway is blocked by gas and dust in deep space. The interference is broken down by infrared light. In order to work, then, Webb needs to be protected from stray heat, which would blur its infrared optics just as stray light would blur Hubble’s visible-spectrum mirrors. The telescope should be kept at a minimum temperature. This allows for unusual architecture.
The Webb’s main mirror measures 6.5 m (21.6 ft.) across, and is made of 18 hexagonal segments, each of which can be adjusted in seven different axes with a precision down to the nanometer—or a billionth of a meter—allowing the overall mirror to be focused for maximum detail and clarity. The mirror remains exposed to space, since placing it in a housing like Hubble’s main mirror would trap heat. Also, it does not orbit Earth. The Earth’s constant day-night cycles would create its own temperature shifts. It is instead positioned at 1.6 million kilometers (one million miles). from the planet, where it station-keeps in what’s known as a Lagrange point—a spot in space where the gravity of the Earth and the sun cancel each other out, allowing objects to circle around the invisible point as if they were orbiting a solid body like a planet.
Still, there is the heat of the sun and even the remote Earth and moon to deal with, and for that reason, the mirror flies atop a protective sun-shield—perched on the shield like a sail on a boat. A sunshield that is as large as a tennis courts and roughly the shape of a kite, it is made up five layers of Kapton. The film has a thin foil-like layer with a thickness not greater than one human hair. On the outer layer—the side which always faces the sun, keeping the mirror in permanent shadow—the temperature is about 110º C (230º F). On the inner layer, closest to the mirror, it is -237º C (-394º F). Exceedingly cold temperatures like that allow the vanishingly faint, invisible heat of infrared signals from deep space to register on the telescope’s mirror, and be translated digitally into visible images.
Webb works as both an observatory and time machine. The farther into space a telescope can peer, the farther back in time it’s looking, since images from distant objects—even traveling at the speed of light—take a very long time to reach us. The image we see of a galaxy 13.6 billion light years away is thus not an image of how it looks today—but how it looked 13.6 billion years ago, during the universe’s infancy. The Hubble space telescope can see a maximum of 13.4 billion light years distant, and while the mere 200 million light-year advantage the Webb offers doesn’t seem like much, it’s in fact huge. There was a lot that happened over those 200 million years, and telescopes were blind to this until recently.
“The difference between what Hubble and Webb [see] is not like comparing someone who’s 70 years old to somebody who’s 71 years old,” said Scott Friedman, an astronomer with the Webb team, in a conversation with TIME last year. “It’s like comparing a baby who’s one day old to a baby who’s one year old, and that’s a huge difference.”
But the science Webb will be conducting over the years to come is for later—and already astronomers around the world are clamoring with proposals to book time on the Webb to study objects of interest over the coming years. The dazzle is what today’s for. It is possible to be awestruck by the universe’s beauty and scope. Webb is more impressive than any other observatory.
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