Sydney, Oct 14 (The Conversation) After our family enjoyed Christmas dinner in 2021, we gathered around the television, riveted by the tense launch of NASA’s $10 billion James Webb Space Telescope, a groundbreaking advancement in telescope technology not seen since Hubble’s 1990 debut. The successful launch put our minds at ease after Webb navigated 344 potential failure points, leading to its deployment in space.
In July 2022, six months post-launch, Webb unveiled its inaugural images, capturing the most distant galaxies observed thus far. However, this milestone marked merely the onset of an intensive period of work for our team in Australia.
We planned to employ Webb’s highest-resolution mode, known as the aperture masking interferometer (AMI). AMI, a meticulously crafted piece of metal inserted into one of the telescope’s cameras, serves to enhance resolution.
Now, the fruits of our labor in testing and optimizing AMI are publicly available in two papers published in the open-access archive arXiv. These documents showcase its initial successful observations of stars, planets, moons, and black hole jets.
Working with a Distant Instrument
Unlike Hubble, which initially suffered from blurred vision due to an incorrectly ground mirror but was repaired in 1993 by astronauts aboard the Space Shuttle Endeavour, Webb presents a unique challenge. Stationed approximately 1.5 million kilometers away from Earth, Webb is beyond the reach of service missions.
This is where AMI plays a crucial role as the sole piece of Australian hardware aboard Webb, conceived by astronomer Peter Tuthill. It was intended to diagnose and assess any image blurring caused by distortions in Webb’s intricate system of mirrors and surfaces.
AMI utilizes a strategically structured pattern of holes within a metal plate to simplify the detection of optical misalignments. This innovative approach enables us to tackle any unwelcome blur that could obstruct our study of distant astronomical phenomena.
Tackling Blurry Pixels
Our ambition was to explore planetary birthplaces and material consumption by black holes using AMI, but initial findings revealed unexpected blurring at the pixel level. Brighter pixels seemed to bleed into adjacent darker ones, an inherent trait of infrared cameras that emerged as a significant hurdle for Webb.
This issue jeopardized Webb’s ability to discern distant planets thousands of times fainter than their nearby stars. Faced with this setback, our team embarked on a mission to rectify the situation.
Enhancing Webb’s Vision
Under the leadership of University of Sydney PhD student Louis Desdoigts, our team developed a computational model to address both optical and electronic distortions. This model integrates AMI’s optical physics with a machine learning-based “effective detector model” to simulate and correct the observed blurring.
After successful testing on known stars, the refined model allowed us to correct blurring in other observations, restoring AMI’s full capability without altering Webb’s operations in space. This approach brought clarity to previously faint targets, such as the faint planet orbiting star HD 206893 and the reddest-known brown dwarf.
Beyond Dots
In a complementary paper by University of Sydney PhD student Max Charles, we broadened our focus from dots to more intricate subjects, employing the highest resolution available with Webb. With enhanced corrections, we captured images of Jupiter’s moon Io, tracing its volcanic activity, and matched larger telescope images of the black hole jet in galaxy NGC 1068.
AMI also demonstrated its capacity to resolve detailed features like the dust ribbon around the stellar duo WR 137, aligning with theoretical predictions. The code developed for AMI serves as a precursor for Webb's future instruments and the upcoming Roman Space Telescope.
Despite the impossibility of achieving flawless optical calibration due to material constraints, our work illustrates that precise measurement and correction can propel us toward discovering Earth-like planets in distant galaxies. (The Conversation) GRS GRS
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