After Christmas dinner 2021, our family was glued to the TV watching exciting launch from NASAthat's 10 billion dollars James Webb Space Telescope. There has not been such a leap forward in telescope technology since then. Hubble was launched in 1990.
On the way to deployment, Webb had to successfully pass 344 potential points of failure. Fortunately, the launch took place better than expectedand we could finally breathe again.
We will use the highest resolution Webb mode called aperture masking interferometer or Abbreviated as AMI. This is a tiny piece of precision-machined metal that is inserted into one of the telescope camerasincreasing its resolution.
Our results from painstaking testing and improvement of the AMI are now published in the open access archive arXiv. in pairs documents. We can finally present our first successful observations of stars, planets, moons and even jets of black holes.
Working with a tool a million miles away
Hubble began his life seeing out of focus – his mirror was polished precisely, but incorrectly. By looking at known stars and comparing ideal and measured images (just as optometrists do), it was possible to figure out the “recipe” for this optical error and design a lens to compensate for it.
Correction required seven astronauts will fly on the space shuttle Endeavor in 1993 new optics were installed. Hubble orbits Earth just a few hundred miles above the surface, and astronauts can reach it.
In contrast, Webb is about 1 million miles (1.5 million km) away—we can't visit it and service it, and we need to be able to fix problems without changing any equipment.
This is where AMI comes to the rescue. This is the only Australian equipment on board, designed astronomer Peter Tuthill.
It was installed on Webb to diagnose and measure any blurring in the images. Even nanometers of distortion in Webb's 18 hexagonal primary mirrors and many internal surfaces will blur images enough to make it difficult to study planets or black holes, where sensitivity and resolution are key.
AMI filters light using a carefully structured pattern of holes in a simple metal plate, making it much easier to detect if there are any optical abnormalities.
Hunting for blurry pixels
We wanted to use this mode to observe the birthplaces of planets, as well as the material sucked into black holes. But above all, AMI showed that Webb was not working quite as well as we would like.
At very high resolution – at the individual pixel level – all images were slightly blurred due to an electronic effect: brighter pixels bleeding into their darker neighbors.
This is not a bug or a flaw, but a fundamental feature of infrared cameras that turned out to be unexpectedly serious for Webb.
This was an obstacle to observing distant planets. many thousands of times dimmer than their stars at a distance of several pixels: my colleagues quickly showed that its limits were more than ten times worse than expected.
So we decided to fix it.
How we sharpened Webb's vision
IN new document supervised by a graduate student at the University of Sydney Louis Dedoiswe looked at stars with AMI to simultaneously study and correct optical and electronic distortions.
We built computer model to simulate AMI optical physics with flexibility in mirror shapes and apertures, as well as star color.
We coupled this with a machine learning model to represent electronics using an “effective detector model” – where we only care about how well it can reproduce the data, not why.
After training and testing on some test stars, this setup allowed us to calculate and deblur other data, restoring full AMI functionality. This doesn't change what Webb does in space, but rather adjusts the data during processing.
It worked great – star HD 206893 contains a faint planet and the reddest known brown dwarf (an object between a star and a planet). They were known but not available to Webb prior to this amendment. Now both small dots appeared clearly on our new maps of the system.
This amendment opened up the possibility of using AMI to search for unknown planets with previously impossible resolution and sensitivity.
This doesn't just work with dots
IN accompanying paper University of Sydney PhD student Max Charleswe applied this not only to viewing points – even if those points are planets – but also to forming complex, highest-resolution images created with Webb. We revisited well-studied objects that enhance the telescope's capabilities by testing its performance.
Thanks to the new correction, we focused Jupiter's moon Io, clearly tracking its volcanoes as it rotated over an hour-long time frame.
According to AMI observations, a jet launched from the black hole at the center of the galaxy NGC 1068 is very similar to images from much larger telescopes.
Finally, AMI can clearly discern a ribbon of dust around a pair of stars called WR 137, a faint relative of the star. impressive Apep systemaccording to theory.
The code generated for AMI is a demonstration of much more complex cameras on Webb and its subsequent versions. Roman space telescope. These instruments require optical calibration so precise that it is mere fractions of a nanometer, exceeding the capabilities of any known materials.
Our work shows that if we can measure, control and adjust the materials we work with, we can still hope to find Earth-like planets in the far reaches of our galaxy.
This edited article is republished from Talk under Creative Commons license. Read original article.
