Launch date: Dec. 25, 2021.
Cost (at time of launch): $10 billion.
Orbit: JWST will orbit the sun, around the second Lagrange point (L2), nearly 1 million miles (1.5 million kilometers) from Earth.
Primary mirror size: 21.3 feet (6.5 meters) across.
Sun shield: 69.5 ft by 46.5 ft (22 meters x 12 meters).
Mass: 14,300 lbs (6,500 kg)
NASA's James Webb Space Telescope (JWST) is an infrared space observatory that launched on Dec 25, 2021, from ESA's launch site at Douro in French Guiana, at 7:20 a.m. EST (1220 GMT; 9:20 a.m. local time in Douro), aboard an Arianespace Ariane 5 rocket.
The $10 billion James Webb Space Telescope — NASA's largest and most powerful space science telescope — will probe the cosmos to uncover the history of the universe from the Big Bang to alien planet formation and beyond. It is one of NASA's Great Observatories, huge space instruments that include the likes of the Hubble Space Telescope to peer deep into the cosmos.
The first image contains a galaxy cluster’s past and recent star birth in more remote galaxies
JWST deep field image of SMACKS 0723 with lots of galaxies visible
It took astronomers mere days to dig insights out of the first public image from JWST, which shows a massive galaxy cluster called SMACKS 0723 and many more distant galaxies behind it.
Massimo Pascal wasn’t planning to study the galaxy cluster SMACKS 0723. But as soon as he saw the cluster glittering in the first image from the James Webb Space Telescope, or JWST, he and his colleagues couldn’t help themselves.
“We were like, we have to do something,” says Pascal, an astronomer at the University of California, Berkeley. “We can’t stop ourselves from analyzing this data. It was so exciting.”
Pascal’s team is one of several groups of scientists who saw the first JWST images and immediately rolled up their sleeves. In the first few days after images and the data used to create them were made public, scientists have estimated the amount of mass the cluster contains, uncovered a violent incident in the cluster’s recent past and estimated the ages of the stars in galaxies far beyond the cluster itself.
“We’ve been preparing for this for a long time. Myself, I’ve been preparing for years, and I’m not very old,” says Pascal, who is in his fourth year of graduate school. JWS “is really going to define a new generation of astronomers and a new generation of science as a whole.”
Cluster collision
When the image of SMACKS 0723 was released in a White House briefing on July 11, most of the focus went to extremely distant galaxies in the background (SN: 7/11/22). But smack in the middle of the image is SMACKS 0723 itself, a much closer cluster of galaxies about 4.6 billion light-years from Earth. Its mass bends light from even farther away, making more distant objects appear magnified, as if their light had traveled through the lens of another cosmic-sized telescope.
The light from the most distant galaxy in this image started its journey to JWS about 13.3 billion years ago — “almost at the dawn of the universe,” says astrophysicist Guillaume Mahler of Durham University in England, who is already using the picture as his Zoom background.
But the image can also fill in the history of the intervening galaxy cluster itself. “People sometimes forget about that — the galaxy cluster is also very important,” Pascal says.
Pascal’s and Mahler’s teams each started by taking inventory of the distant galaxies that appear stretched and distorted in the image. The light from some of those galaxies is warped such that multiple images of the same galaxy appear in different places. Mapping those multiply imaged galaxies is a sensitive probe of the way mass is spread around the cluster. That, in turn, can reveal where the cluster contains dark matter, the invisible, mysterious substance that makes up the majority of the mass in the universe (SN: 9/10/20).
Both teams found that SMACKS 0723 is more elongated than it appeared in previous observations. They also found a faint glow, called light, inside the cluster from stars that don’t belong to any particular galaxy. Together, those features suggest that SMACKS 0723 is still recovering from a relatively recent smash-up with another galaxy cluster, the teams report separately in a pair of papers submitted to arXiv.org on July 14.
A galaxy cluster that has been sitting on its own for eons should have a rounder distribution of matter and light, rather than SMACKS 0723’s oblong shape. The stars that emit the light were probably ripped from their home galaxies by gravitational forces during the collision.
“Two separate clusters have merged together, and it looks to us as if it’s not totally settled yet,” Pascal says. “What we might be looking at is an ongoing merger.”
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