Engage! Webb Telescope prepares to unlock the secrets of galactic evolution
The first galaxies in the universe are a mystery to us — but that could soon change.
The cosmos has come a long way (pun intended). But the most fantastic story of all time isn’t fully understood — especially the early chapters, ‘written’ in history during the first two to three hundred million years of the universe’s 13.8 billion-year existence.
The James Webb Space Telescope could be the key. The observatory can look about three times as far back in time than the iconic Hubble. The Webb will detect infrared wavelengths long enough to pierce through the dense smog of all the light and dust that sits between Earth and the furthest galactic posts, revealing information about the ancient universe where these wavelengths began their journey through space billions of years ago.
Although not quite yet ready to collect data, the Webb Telescope promises a level of perception made possible by its four instruments. These instruments can operate at the same time to siphon observations of objects like galaxies — maximizing the efficiency of the telescope.
James Webb Telescope: Mission update
On March 17, NASA announced that the Webb has started a new phase of its preparations to look deep into space and time: A six-week procedure called multi-instrument multi-field (MIMF) alignment. This process will help ensure all four of its science instruments go live by the summer of this year.
The process is a critical next step following the Webb’s most-recent triumph: Producing the mission’s first focused image, released by NASA on March 11, of a star. The image was made possible by carefully aligning all the Webb’s 18 mirror segments to work as a single unit — but this procedure is also still ongoing, Webb deputy senior project scientist Jonathan Gardner explains to Inverse.
In this image, Webb’s first in-focus image of a star, you can also see tiny, bright red dots — these are galaxies in the distant universe.
“We lined them up so that we can have a perfectly focused image in one of our four cameras, but now we need to change that alignment so that it's perfect across the whole field of view of all four instruments,” says Gardner.
The current alignment process will be followed by spending two months revising the different filters and modes of all four cameras on the telescope. Finally, the preparations will reach a crescendo in the summer when the mission releases its first scientific images. Gardner predicts these will be published in mid-July 2022.
What will the Webb detect?
One central area of study for the Webb will be early galaxies. These cosmic bodies are beacons for scientists investigating the early universe. Because Webb lets scientists operate more than one instrument at any given time, it can collect more precious drops of distantly-emanating galactic light from these far-off lanterns.
Webb interdisciplinary scientist Rogier Windhorst explains how it works: Imagine “a full circular pineapple slice with a hole in the middle” as a stand-in for Webb’s field of view.
Within that field of view, two of the four operational instruments can observe the sky at one time, Windhorst says.
Collecting data from two instruments at once enables scientists to reap twice as much information about the distant universe during a single window of time. For example, if someone snaps an image of two different non-adjacent regions of the early universe through the same filter. One shot, but twice the data.
“You have to plan it to make sure that the data is useful, but if you plan it right, you essentially double the data. Thereby observing two times as efficiently,” Windhorst says. This may be particularly useful for deep-field surveys, which look at a single field of view for a long time to collect as much data as possible for scientists to then sift through.
The image shows a central portion of the Hubble Deep Field, created from exposures taken in 1995. The Hubble Deep Field covers a piece of sky about one-thirteenth the diameter of the full Moon.
The Hubble Ultra Deep Field is one of the most significant feats accomplished by Webb’s predecessor. Hubble spent 592 hours creating that iconic cosmic landscape; Webb would take just 30 hours to do the same, says Windhorst.
“The parallel capability kind of comes with the design of the telescope,” Webb scientist Gardner explains.
“But in order to take any kind of data, the four instruments… have to be lined up to have a good sharp image in those instruments. And that’s the process we’re in right now.”
According to Windhorst, Webb’s Near-Infrared Camera (NIRCam) and Near-Infrared Imager and Slitless Spectrograph (NIRISS) are exceptionally efficient in tandem with one another because they are similar instruments, so the data from one compliments the other.
How Webb could explain galactic evolution
There’s another big reason this approach is helpful: Statistical analysis of galaxies helps us understand their evolution.
Galaxies are the islands of the universe where matter, dark matter, and light are concentrated. The stars and planets that coalesced into the earliest galaxies may have done so quickly enough in some places to produce supermassive black holes, now found at the center of almost every galaxy we’ve ever observed. Galaxies from the first few million years of the universe will be frequent targets of Webb’s amazing eyes; galaxies at the edge of Hubble’s capabilities that can bring researchers one step closer to understanding why the universe appears the way it does today.
The farthest objects we can see look to us like they appeared in the early universe when their light began traveling.
It’s a numbers game: Since galaxies evolve over tremendously long timescales of millions and billions of years, you can’t watch a single galaxy’s changes in real-time. Cosmologists studying the evolution of these structures can’t approach their research the way a horticulturist can study a single plant to glean its transformations.
“What we have to do with galaxies is we have to look at the most distant galaxies to see how galaxies start, and then we need to look at less distant galaxies to see the sort of average properties changing over time. We can’t do a one-to-one comparison,” says Gardner.
Scientists do deep-field surveys to try and spot these slow changes. Parallel data collection boosts the number of similarly-aged galaxies they can look at in different ways at one time, revealing more information about a particular chapter in the universe’s history.
Besides the primary target, Webb’s instruments could also collect observations of older or younger galaxies. This provides data of different evolutionary stages that may go unnoticed otherwise.
“It’s like archaeology or paleontology: As you dig deeper, you might see older and older layers, but you’re not seeing the same things,” Gardner says.
