(WHTM) — After months of slowly cooling instruments to their working temperature (a smidge above absolute zero) and carefully adjusting mirrors to bring 18 separate images together, NASA’s James Webb Space Telescope is now fully aligned.
A NASA blog post states “The optical performance of the telescope continues to be better than the engineering team’s most optimistic predictions.” The term they’re using for the image quality is “diffraction-limited,” meaning it’s as good as it can possibly get-and the only way to get anything better would be to send up a larger telescope.
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Last week NASA released a photomosaic showing images produced by the four main instrument clusters- The Near Infrared Camera (NIRCAM), the Mid-Infrared Instrument (MIRI), the Near-Infrared Imager and Slitless Spectrograph (NIRISS), and the Near-Infrared Spectrograph (NIRSPEC), as well as the FGS (Fine Guidance Sensor) whose main purpose is to help aim the telescope.
You’ll note that the images are primarily red. The main reason for that is to produce the best possible contrast so that the human eyes looking at the pictures could figure out if the images are as sharp as possible. (It helps that the images are infrared, the part of the red spectrum which is just out of our visual range.) As the NASA blog notes, “Colors in space telescope images sometimes recreate the way our eyes see; other times they are selected to highlight features of an object.”
So with the focus fine-tuned, what comes next?
For the next few months, the Webb will undergo a process known as science instrument commissioning. Each of the instrument packages has unique equipment, such as lenses and filters, to perform the tasks for which they are designed. Each of them has to be checked and double-checked (at the bare minimum) before they can be put into service.
If that all goes as planned, the commissioning process will take about two months. Then, sometime this summer, the serious scientific imaging will begin.
To see a set of videos comparing the resolution of the Webb images to other telescopes, click here.