Key members of the James Webb Space Telescope team offered a preview of what to expect in the first images from Webb, which are scheduled to drop on July 12.
“We will have a package that will consist of a number of full-color images,”
Klaus Pontoppidan, project scientist with the Webb Mission Office at the Space Telescope Science Institute and technical principal investigator for Webb’s Early Release Observations, said in a press conference on Wednesday. “Each of them will reveal a different aspect of the infrared universe in unprecedented detail and sensitivity.”
Pontoppidan and his colleagues said that the first images, called the Early Release Observations, will showcase each of Webb’s instruments and each of the observatory’s four main science themes: the early universe, galactic evolution, stellar life cycles, and exoplanets. Until now, NASA and other agencies involved with the Early Release Observations have been unusually secretive about what the images will contain, but Wednesday’s press conference offered some unexpected clues.
Here’s what we can look forward to on July 12:
05 The most distant galaxies ever observed
This Hubble Ultra Deep Field image shows 28 galaxies that formed when the universe was less than a billion years old.
The first color images from Webb will include the deepest look into the universe any telescope has ever taken. Webb’s infrared instruments were designed to look at the furthest, oldest objects in the universe, and the space telescope will show off that capability with its first deep field image.
“This is farther than humanity has ever looked before,” NASA administrator
Bill Nelson said during Wednesday’s press conference.
But the team preparing Webb’s Early Release Observations can’t say exactly how far into the distant universe — and how far back in time—– Webb will take us. Amid the rush to process the data and images for release to the public, the team doesn’t have time for their own analysis of the data, and that includes things like calculating redshift.
Redshift measures how much the light waves from an object have been stretched out as the object moves away from us in space. The universe is accelerating as it expands, so things that are further away also move faster, appearing redder when breaking down their light. Redshift can tell astronomers how distant an object is. Because more distant things are also older, redshift can also offer clues about an object’s age.
“What is also really exciting is that I know that this is not a record that will stand for very long,” Pontoppidan said. “Scientists out in the world will very quickly beat that record and go even deeper.”
04 Merging galaxies
These Hubble photos depict several pairs of galaxies at different stages of merging.
We’ll get to see the dramatic merger of two galaxies in Webb’s first images.
“These cataclysmic collisions between galaxies drive the process of star formation,” Pontoppidan said. Collisions like the one Webb will reveal on July 12 also helped produce most of the large galaxies we see in the nearby universe today. The first generation of galaxies were small and dim, but eventually merged to form larger, brighter ones.
But don’t expect an epic galaxy-sized explosion in the Webb images, warned
Jonathan Gardner, deputy senior project scientist for the James Webb Space Telescope.
galaxies collide, he said, “They don't go bang; they go splosh.” That’s because most of the space in galaxies is just that: empty space between stars. But clouds of gas within the galaxies do collide, triggering waves of star formation. 03 New stellar births
The Spitzer Space Telescope used its infrared instruments to view the star-forming nebula W51 in this false-color image.
The evolution of stars will be an important part of Webb’s first year of science, and the Early Release Observations will capture both the beginning and the end of a star’s life.
“We'll see a couple of examples from the life cycle of stars, starting from the birth of stars where Webb can reveal new, young stars emerging from their natal cloud of gas and dust,” Pontoppidan said.
Stars usually form in enormous clouds of gas and dust, where all that material can fuel their growth. Such clouds also hide stellar nurseries from prying eyes, because they block most light in the wavelengths our eyes can see. But infrared telescopes like James Webb can see right through the surrounding clouds to study newborn stars — and even stars that haven’t quite gathered enough mass to kickstart their inner thermonuclear reactors yet.
02 An alien exoplanet atmosphere
Exoplanets orbit the small, cool star Kepler-11 in this artist’s illustration.
Webb’s first data will include the spectrum of an exoplanet’s atmosphere, which could reveal information about the chemical makeup of the planet’s atmosphere — and possibly even signs of life.
“Right from the beginning, we'll look at these worlds out there that keep us awake at night as we look into the starry sky and wonder, ‘is there life elsewhere?’” Thomas Zurbuchen, associate director of NASA’s Science Mission Directorate, said. “What are these worlds out there we have [identified] 5000 plus of?”
Different chemical elements reflect, absorb, and give off light at different wavelengths. One of Webb’s instruments, the Near Infrared Spectrometer or NIRSpec, will separate light from the exoplanet’s atmosphere into its different wavelengths. That spectrum of light will tell scientists what chemicals are floating around in the
“It turns out that a lot of these small molecules that we're looking at, whether it's CO2 or it's ozone, all have vibrational spectra that happen to be in the [infrared] range that we're looking at,” Zurbuchen said.
NASA hasn’t revealed which exoplanet’s atmosphere Webb will study first, or even whether it’s a rocky world like Earth or a massive “hot Jupiter” gas giant.
01 A dying star
Nebulae like the Helix Nebula, pictured in this Hubble Telescope image, are the debris scattered into space by supernovae.
We’ll get to see some cosmic fireworks in Webb’s first images, in the form of “a dying star seeding the galaxy with new elements and new dust that may one day become part of new planetary systems,” Pontoppidan said.
That could mean a red giant or the nebula left behind by a supernova.
All of us owe our lives to dying stars. Elderly massive stars spend their final stages of evolution fusing lighter elements into elements like oxygen, sodium, calcium, and iron. And everything in the universe that’s heavier than iron — zinc, silver, and gold, for instance — it was forged by the tremendous heat and pressure of a supernova, the explosive death of a massive star.
But there are still unanswered questions about the physics of stellar evolution, and Webb’s team hopes its data will help astrophysicists answer some of those questions.
Some of the images and data for the Early Release Observations are already in the hands of Webb project scientists and engineers here on Earth. NASA has already deemed 13 of Webb’s 17 observing modes fit for duty, and those 13 modes have been busily gathering data for the last couple of weeks. As the final stages of commissioning continue, Pontoppidan says Webb will probably finish the last of its first batch of images just days before they’re scheduled to be released.
Meanwhile, the observatory also started doing its first round of actual science observations on June 21.
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