After Christmas dinner in 2021, our family was glued to the television, watching the nail-biting launch of NASA’s US$10 billion (AU$15 billion) James Webb Space Telescope.
It’s a tiny piece of precisely machined metal that slots into one of the telescope’s cameras, enhancing its resolution.
We can finally present its first successful observations of stars, planets, moons and even black hole jets.
Working with an instrument a million kilometers away Hubble started its life seeing out of focus—its mirror had been ground precisely, but incorrectly.
The code built for AMI is a demo for much more complex cameras on Webb and its follow-up, Roman space telescope.
When NASA’s US$10 billion (AU$15 billion) James Webb Space Telescope was set to launch in 2021, our family was riveted to the TV after Christmas dinner. Since the launch of Hubble in 1990, telescope technology had not advanced to this degree.
Webb had to avoid 344 possible points of failure on its way to deployment. Fortunately, the launch proceeded more smoothly than anticipated, and we were able to breathe easy.
The first pictures of the farthest galaxies ever seen by Webb were released six months later. But the work was just getting started for our team in Australia.
AMI, or aperture masking interferometer, is Webb’s highest-resolution mode, which is what we would be using. It is a small, finely machined metal component that fits into one of the telescope’s cameras to improve resolution.
We have now published two papers on the open-access archive arXiv that present our results of meticulously testing and improving AMI. Finally, we are able to report the first successful observations of black hole jets, planets, moons, and stars.
Utilizing a device located a million kilometers away.
Because its mirror had been precisely but incorrectly ground, Hubble began its life seeing out of focus. It was possible to determine a “prescription” for this optical error and create a lens to compensate by examining known stars and contrasting the ideal and measured images—exactly like optometrists do.
In 1993, seven astronauts had to fly up on the Space Shuttle Endeavor to install the new optics in order to make the correction. Astronauts are able to reach Hubble, which orbits the Earth only a few hundred kilometers above it.
We must be able to resolve problems without replacing any hardware because Webb is approximately 1.5 million kilometers away and we are unable to visit and service it.
AMI can help with this. Designed by astronomer Peter Tuthill, this is the only Australian hardware aboard.
In order to identify and quantify any blur in its pictures, it was installed on Webb. Images from Webb’s 18 hexagonal primary mirrors and numerous internal surfaces will be sufficiently blurred by even nanometers of distortion to make it difficult to study planets or black holes, where sensitivity and resolution are crucial.
Using a carefully planned pattern of holes in a basic metal plate, AMI filters the light to make it much simpler to detect optical misalignments.
hunting for pixels that are blurry.
We intended to observe planet birth sites and material being sucked into black holes using this mode. However, AMI revealed that Webb wasn’t functioning exactly as planned before all of this.
An electronic effect caused brighter pixels to leak into their darker neighbors, making all of the images somewhat blurry at very fine resolution—at the level of individual pixels.
This was a basic feature of infrared cameras that proved to be surprisingly serious for Webb, not an error or defect.
Its limitations were more than ten times worse than anticipated, as my colleagues promptly demonstrated. This was a deal-breaker for seeing far-off planets that were thousands of times fainter than their stars just a few pixels away.
Thus, we started working to fix it.
How Webb’s vision was sharpened.
In a recent study headed by Ph.D. A. Louis Desdoigts, a student, taught us how to simultaneously correct optical and electronic distortions by looking at stars with AMI.
To replicate the optical physics of AMI, we constructed a computer model that allows for customization of the aperture and mirror shapes as well as the star colors.
In order to represent the electronics using an “effective detector model”—where we are only concerned with how well it can replicate the data, not why—we linked this to a machine learning model.
Following training and validation on a few test stars, this configuration enabled us to compute and remove the blur in additional data, bringing AMI back to full functionality. Instead of altering Webb’s actions in space, it fixes the data while it is being processed.
The star HD 206893, which is home to the reddest known brown dwarf (an object between a star and a planet) and a faint planet, worked flawlessly. Before this correction, they were well-known but out of Webb’s grasp. Now, both of the tiny .s were clearly visible in our updated system maps.
Due to this adjustment, it is now possible to use AMI to prospect for undiscovered planets at resolutions and sensitivities that were previously unattainable.
It’s not limited to dots.
In a related study, Ph. D. We used this to look at more than just .s, even if they are planets, and create intricate images at the highest resolution possible using Webb, according to student Max Charles. We tested the telescope’s performance by returning to well-studied targets that strain it.
We were able to focus Jupiter’s moon Io with the new correction, and we were able to observe its volcanoes clearly during an hour-long timelapse.
Images from much larger telescopes closely matched the jet that was launched from the black hole at the center of the galaxy NGC 1068 as seen by AMI.
In agreement with theory, AMI can finally sharply resolve a ribbon of dust surrounding a pair of stars known as WR 137, a faint relative of the spectacular Apep system.
For the much more sophisticated cameras on Webb and its successor, the Roman space telescope, the code developed for AMI serves as a demonstration. These instruments require an optical calibration that is so fine that it is only a fraction of a nanometer, which is greater than what any known material can provide.
Our research demonstrates that we can still search for Earth-like planets in the outermost regions of our galaxy if we can measure, manipulate, and adjust the materials we do have at our disposal.
