A Groundbreaking Software Fix

Researchers at the University of Sydney developed an innovative software solution that corrected blurriness in images captured by NASA’s multi-billion-dollar James Webb Space Telescope (JWST). Their breakthrough restored the full precision of one of the telescope’s key instruments, achieving what would once have required a costly astronaut repair mission.

This success builds on the JWST’s only Australian-designed component, the Aperture Masking Interferometer (AMI). Created by Professor Peter Tuthill from the University of Sydney’s School of Physics and the Sydney Institute for Astronomy, the AMI allows astronomers to capture ultra-high-resolution images of stars and exoplanets. It works by combining light from different sections of the telescope’s main mirror, a process known as interferometry. When the JWST began its scientific operations, researchers noticed that AMI’s performance was being affected by faint electronic distortions in its infrared camera detector. These distortions caused subtle image fuzziness, reminiscent of the Hubble Space Telescope’s well-known early optical flaw that had to be corrected through astronaut spacewalks.

Solving a Space Problem from Earth

Instead of attempting a physical repair, PhD students Louis Desdoigts and Max Charles, working with Professor Tuthill and Associate Professor Ben Pope (at Macquarie University), devised a purely software-based calibration technique to fix the distortion from Earth.

Their system, called AMIGO (Aperture Masking Interferometry Generative Observations), uses advanced simulations and neural networks to replicate how the telescope’s optics and electronics function in space. By pinpointing an issue where electric charge slightly spreads to neighboring pixels — a phenomenon called the brighter-fatter effect — the team designed algorithms that digitally corrected the images, fully restoring AMI’s performance.

“Instead of sending astronauts to bolt on new parts, they managed to fix things with code,” Professor Tuthill said. “It’s a brilliant example of how Australian innovation can make a global impact in space science.”

Sharper Views of the Universe

The results have been striking. With AMIGO in use, the James Webb Space Telescope has delivered its clearest images yet, capturing faint celestial objects in unprecedented detail. This includes direct images of a dim exoplanet and a red-brown dwarf orbiting the nearby star HD 206893, about 133 light years from Earth.

A related study led by Max Charles further demonstrated AMI’s renewed precision. Using the improved calibration, the telescope produced sharp images of a black hole jet, the fiery surface of Jupiter’s moon Io, and the dust-filled stellar winds of WR 137 — showing that JWST can now probe deeper and clearer than before.

“This work brings JWST’s vision into even sharper focus,” Dr. Desdoigts said. “It’s incredibly rewarding to see a software solution extend the telescope’s scientific reach — and to know it was possible without ever leaving the lab.”

Dr. Desdoigts has now landed a prestigious postdoctoral research position at Leiden University in the Netherlands.

Both studies have been published on the pre-press server arXiv. Dr. Desdoigts’ paper has been peer-reviewed and will shortly be published in the Publications of the Astronomical Society of Australia. We have published this release to coincide with the latest round of James Webb Space Telescope General Observer, Survey and Archival Research programs.

Associate Professor Benjamin Pope, who presented on these findings at SXSW Sydney, said the research team was keen to get the new code into the hands of researchers working on JWST as soon as possible.

These images confirm that the 9 km (~5.6 mile) wide Nadir Crater, lying about 300 meters (~1000 feet) below the ocean floor, was created when an asteroid slammed into Earth roughly 66 million years ago at the end of the Cretaceous period.

The timing matches that of the Chicxulub impact in Mexico, the colossal 200 km (~125 mile) wide crater linked to the extinction of the dinosaurs.

Using the new data, scientists have pieced together what unfolded immediately after the Nadir impact: the crater initially formed as a deep bowl, molten rock surged upward from below, a vast zone of fractured rock spread outward for thousands of square kilometers, and an enormous tsunami more than 800 meters (~2600 feet) high swept across the Atlantic.

The research was published in Nature Communications Earth & Environment.

66 million-year-old underwater imprint

Dr. Uisdean Nicholson of Heriot-Watt University first identified the Nadir Crater in 2022 while examining seismic reflection data from the Atlantic seabed off the coast of Guinea in West Africa.

The data revealed a circular depression measuring more than 8.5 km across, leading Dr. Nicholson to suspect it was the site of an ancient asteroid strike.

He then collaborated with experts in planetary science and geology from the UK and the USA to analyze the evidence. Early results suggested the crater was formed by an asteroid several hundred meters wide about 66 million years ago, but proof remained uncertain.

That confirmation has now arrived.

From a grainy ultrasound to a 3D image

High-resolution, three-dimensional seismic data collected by the global geophysical company TGS and shared with Dr. Nicholson provides clear evidence that an asteroid created the Nadir Crater.

Dr. Nicholson said: “There are around 20 confirmed marine craters worldwide, and none of them has been captured in anything close to this level of detail. It’s exquisite.

“Craters on the surface are usually heavily eroded and we can only see what is exposed, whereas craters on other planetary bodies usually only show the surface expression.

“These data allow us to image this fully in three dimensions and peel back the layers of sedimentary rock to look at the crater at all levels.

“One way to understand it is to think about a pregnancy ultrasound. A few generations ago, the ultrasound would show a grainy blob. Now you can see the baby’s features in 3D, in incredible detail — including all the internal organs.

“We’ve gone from 2D, fuzzy imaging to amazing high-resolution imaging of the Nadir Crater.”

Data reveals minute-by-minute chaos after collision

Dr. Nicholson said: “The new images paint a picture of the catastrophic event.

“We originally thought the asteroid would have been around 400m wide. We now think it was 450-500m wide, because of the larger crater size as shown by the 3D data.

“We can tell it came from about 20-40 degrees to the northeast, because of spiralling thrust-generated ridges surrounding the crater’s central peak — those are only formed following a low-angle oblique impact.

“And we think it would have hit Earth at about 20 km per second, or 72,000 km per hour, although we still need to confirm this with a new set of impact models.”

Using the data, the scientists created a timeline of what happened in the seconds and minutes after impact.

Dr. Nicholson said: “After the impact and the central uplift forming, the soft sediments surrounding the crater flowed inwards towards the evacuated crater floor, creating a visible ‘brim’.

“The earthquake shaking caused by the impact appears to have liquefied the sediments below the seabed across the entire plateau, causing faults to form below the seabed.

“The impact was also associated with large landslides as the plateau margin collapsed below the ocean.

“As well as this, we see evidence for a train of tsunami waves going away from, then back towards the crater, with large resurge scars preserving evidence of this catastrophic event.”

A natural laboratory for asteroid impact research

Dr. Nicholson points out that humans have never witnessed an asteroid of this size crashing into Earth.

“The closest humans have come to seeing something like this is the 1908 Tunguska event, when a 50-meter asteroid entered Earth’s atmosphere and exploded in the skies above Siberia.”

“The new 3D seismic data across the whole Nadir Crater is an unprecedented opportunity to test impact crater hypotheses, develop new models of crater formation in the marine environment and understand the consequences of such an event.

“We’ve applied to IODP3, which is a new international drilling program, to drill into the seabed and recover cores from the crater. These will give us more information about the shock pressures experienced during impact, and the precise age and sequence of events that occurred after this event.”

Unlike the moon, Earth’s craters erode

Collaborator Dr. Sean Gulick of the University of Texas at Austin, USA, a geophysicist and expert on impact processes, noted: “3D seismic images of a fully-preserved impact crater are a fantastic research opportunity that can allow us to consider how impact processes and craters scale with the size of the impactor both for understand the evolution of the Earth, and other worlds.”

Collaborator Dr. Veronica Bray of the University of Arizona, an expert in impact cratering across the solar system, commented: “We see pristine impact craters on airless bodies like the Moon, but don’t have subsurface structural information.

“On the Earth, that is reversed: we have structural data from seismics, field mapping and drill cores, but the craters are usually very eroded at the surface.

“The new 3D seismic imaging of Nadir gives us both. It’s a startlingly good look at an impact crater!”

Could an asteroid this size hit Earth soon?

The rubble pile asteroid Bennu is around 400m in diameter. It is considered the most hazardous object in near-Earth orbit. According to NASA scientists, its total impact probability through the year 2300 is about 1 in 1,750 (or 0.057%). The researchers were also able to identify September 24, 2182, as the most significant single date in terms of a potential impact, with an impact probability of 1 in 2,700 (or about 0.037%)

Why the Southern Ocean Matters So Much

The world’s oceans capture roughly one quarter of all human-produced CO₂ emissions. The Southern Ocean alone accounts for about 40 percent of that total, making it one of the planet’s most powerful natural defenses against global warming. This immense carbon sink functions through a complex circulation system: deep water rises to the surface, exchanges gases with the atmosphere, and then sinks again, carrying absorbed CO₂ back into the depths.

The balance depends on how much natural CO₂ from ancient deep waters resurfaces. When more carbon-rich water from below reaches the surface, it limits how much new, human-made CO₂ the ocean can take in. This interplay is governed by the layering, or stratification, of different water masses and by the strength of ocean currents.

Ancient Waters and Strengthening Winds

The deep water that resurfaces in the Southern Ocean has been isolated for centuries or even millennia, accumulating large amounts of CO₂. Climate models predict that stronger westerly winds, a result of human-driven climate change, will bring more of this carbon-rich water to the surface, reducing the ocean’s capacity to absorb CO₂ in the long term.

However, despite these stronger winds, data collected over recent decades show that the Southern Ocean remains a strong carbon sink. The new AWI research helps explain why: ocean layering has changed in a way that keeps much of the deep carbon locked away.

The Invisible Barrier Holding Carbon Below

“Deep water in the Southern Ocean is normally found below 200 meters,” says Dr. Léa Olivier, AWI oceanographer and lead author of the study. “It is salty, nutrient-rich and relatively warm compared to water nearer the surface.”

This deep water contains large stores of dissolved CO₂ that entered the ocean long ago. In contrast, near-surface water is cooler, less salty, and holds less CO₂.

As long as this density layering remains strong, the CO₂-rich deep water stays sealed off. But if the boundary between layers weakens, that trapped carbon could more easily reach the surface and escape into the atmosphere.

Stronger Winds, Rising Risks

“Previous studies suggested that global climate change would strengthen the westerly winds over the Southern Ocean, and with that, the overturning circulation too,” says Léa Olivier. “However, that would transport more carbon-rich water from the deep ocean to the surface, which would consequently reduce the Southern Ocean’s ability to store CO₂.”

Although such wind intensification has been observed and linked to human activity, measurements still show no major decline in the ocean’s carbon uptake — at least not yet.

Freshwater Inputs Strengthen Ocean Layers

Long-term monitoring by AWI and other research institutions shows that climate change is already altering the characteristics of both surface and deep waters. “In our study, we used a dataset comprising biogeochemical data from a large number of marine expeditions in the Southern Ocean between 1972 and 2021. We looked for long-term anomalies, as well as changes in both circulation patterns and the properties of water masses. In doing so, we only considered processes related to the exchange between the two water masses, namely circulation and mixing, and not biological processes, for example,” explains Léa Olivier. “We were able to determine that, since the 1990s, the two water masses have become more distinct from one another.” The Southern Ocean’s surface water salinity has reduced as a result of increased input of freshwater caused by precipitation and melting glaciers and sea ice. This “freshening” reinforces the density stratification between the two water masses, which in turn keeps the CO₂-rich deep water trapped in the lower layer and prevents it from breaking through the barrier between the two layers.

A Temporary Shield Against Climate Change

“Our study shows that this fresher surface water has temporarily offset the weakening of the carbon sink in the Southern Ocean, as model simulations predicted. However, this situation could reverse if the stratification were to weaken,” summarizes Léa Olivier. Strengthening westerly winds are already pushing the deep water closer to the surface. Since the 1990s, the upper boundary of the deep water layer has risen by about 40 meters.

As CO₂-rich water replaces more of the surface layer, the boundary between them becomes more vulnerable to mixing, likely caused by those same winds. Once mixing increases, stored CO₂ could begin to leak upward and escape into the atmosphere.

Warning Signs Beneath the Waves

Recent research suggests that this process may already be starting. If more carbon from the deep ocean reaches the surface, the Southern Ocean’s role as a global carbon sink could weaken, accelerating climate change.

“What surprised me most was that we actually found the answer to our question beneath the surface. “We need to look beyond just the ocean’s surface, otherwise we run the risk of missing a key part of the story,” says Léa Olivier.

“To confirm whether more CO₂ has been released from the deep ocean in recent years, we need additional data, particularly from the winter months, when the water masses tend to mix,” explains Prof. Alexander Haumann, co-author of the study. “In the coming years, the AWI is planning to carefully examine these exact processes as part of the international Antarctica InSync program, and gain a better understanding of the effects of climate change on the Southern Ocean and potential interactions.”