Until now, information about the James Webb Space Telescope’s first full-color images and science data – which will be publicly released on July 12th – has been a closely guarded secret. But during a media briefing on June 29th, scientists and officials shared a few enticing details.
First, there won’t be just one image, as has been common in “first light” releases for previous telescopes.
“We will have a package that will consist of a number of full-color images,” said Klaus Pontoppidan, JWST project scientist at the Space Telescope Science Institute (STScI) in Baltimore, home to Webb’s science and mission operations. “Each of them will reveal different aspects of the infrared Universe in unprecedented detail and sensitivity.”
One of those images will be the deepest image of our universe that has ever been taken, said NASA Administrator Bill Nelson. “Just think about that,” he pondered, “this is farther than humanity has ever looked before. And we're only beginning to understand what Webb can and will do.”
So, think of the previous deepest image, the Hubble Space Telescope’s Ultra Deep Field – which revealed over 10,000 previously unseen distant galaxies in a tiny region of the sky thought to be devoid of objects. These ancient galaxies existed between 400 and 800 million years after the Big Bang. But as the universe expands and the older and most distant galaxies speed away from us, their light gets redshifted farther into the infrared, making them dimmer and invisible to the capabilities of previous telescopes.
That’s why JWST was built.
Its ability to see longer wavelengths in the infrared with incredible sharpness will bring those early stars and galaxies into focus, revealing details of how our universe began and formed.
“In comparison to Hubble, Webb does go deeper and certainly sharper in the infrared, especially the longer wavelengths like mid-infrared, bringing the universe into high definition,” said Jonathan Gardner, Webb deputy senior project scientist, at NASA’s Goddard Spaceflight Center. And in terms of the visual appeal of the images, Gardner added, if you like looking at Hubble images, you’re going to REALLY like seeing the new Webb images.
“But the real difference is the new scientific information,” he said, “and opening up the universe in a way that we've really never seen before.”
In another surprise at the briefing, Thomas Zurbuchen, associate administrator for NASA’s Science Mission Directorate, revealed what to expect for the first non-image science data from JWST.
“I can confirm that part of the July 12th release, we will share Webb’s first exoplanet spectrum,” Zurbuchen said. “Right from the beginning, we are going to be looking at these worlds out there, the ones that keep us awake at night as we look into the starry sky and wonder if there is life elsewhere.”
When Webb was initially designed, scientists had only found a few exoplanets — planets that orbit other stars. Now, we know of over 4,000 exoplanets, and one of Webb’s major focuses will be to study the atmospheres of these distant worlds. Webb’s instruments can look for signatures of water, carbon dioxide, and even methane, all of which could point to the possibility of life.
And Pontoppidan revealed even more details of what awaits: Webb’s first images will also show colliding galaxies, and how these cataclysmic collisions drive the process of star formation. There will be images of young stars being born in their natal clouds of gas and dust, as well as stars dying spectacularly in a supernova.
“I'm really looking forward to revealing the first color images to the world,” Pontoppidan said. “But I also want to emphasize this is really only the beginning; we're only scratching the surface, we have in the first images, just a few days’ worth of observations. We’ll have many more years of observations, and we can only imagine what that will be. The next exciting phase is really to get the data out to the thousands of scientists around the world so they can dig into it. And then we can start a shared journey of discovery.”
Careful planning for Webb’s first full-color images and data release has been underway for a long time, conducted in secret by a small committee. In fact, Massimo Stiavelli, head of the Webb telescope mission office at STScI told me just a few months ago that even he didn’t know what the proposed targets would be. All he knew was that the main goal of the first images would be to illustrate the capabilities of the new observatory, showcasing the telescope’s powerful instruments and previewing the science mission to come.
The committee is made up of members from the international partnership behind the telescope: NASA, ESA, the Canadian Space Agency, and STScI. One of the challenges of planning the first images far in advance is that Webb can only see certain parts of the sky at a given time. The timeline of what Webb would be seeing when the instruments were finally ready to start taking data would depend on what day the spacecraft launched from Earth.
Additionally, the committee had to account for the possibility of any snafus in the telescope’s month-long journey to Lagrange point 2, 1.5 km (1 million miles) from Earth, or the six-month-long period of aligning the 18 segments of the 6.5 meters (21 feet) wide mirror and commissioning the four science instruments. (In case you haven’t been following the news, the entire process has gone perfectly.)
The committee came up with a potential list of 70 targets, taking inspiration from what previous space telescopes like Hubble and the Spitzer Space Telescope have done before. Could possible targets be the Pillars of Creation in the Eagle Nebula, the Crab Nebula, Andromeda, or the Sombrero Galaxy?
“The committee essentially prioritized this list in such a way that once we knew when we would be able to take the data,” Pontoppidan explained, “We could go down that prioritized list and make the highest prioritized targets that were visible at that time.”
The first science images were actually taken on the summer solstice, June 20th, and the team is still gathering images and data with the new telescope. But taking images with Webb is nothing like taking a picture with your smartphone. It includes a complex process of commanding the telescope to get in position, acquire the data, send the data to Earth, process that data, then assemble them into colorful images.
“We have a team of absolutely amazing people, of experts, who have been working round the clock on this project,” Pontoppidan said, “so that we can deliver a fantastic package on July 12.”
What will we see on July 12? NASA Deputy Administrator Pam Melroy said she had a chance to preview just a few of the images that will be showcased. “What I have seen just moved me,” Melroy said, “as a scientist, as an engineer, and as a human being.”
Zurbuchen said he was moved to tears.
"It’s really hard to not look at the universe in a new light and not have a moment that is deeply personal," he said. "It’s an emotional moment when you see nature suddenly releasing some of its secrets. And I would like you to imagine and look forward to that."