Skip to main content

James Webb’s MIRI instrument has both a heater and a cooler

The long process of getting the James Webb Space Telescope ready for science operations continues, with the ongoing alignment of three of its instruments.

Webb recently reached the major milestone of aligning its mirrors with its NIRCam instrument, in a successful step that promises great results to come. “Webb’s alignment at the NIRCam field showed some spectacular diffraction-limited images, producing a tantalizing glimpse of the capabilities this observatory will carry for its science program,” wrote two Webb researchers, Michael McElwain, Webb observatory project scientist, and Charles Bowers, Webb deputy observatory project scientist, both at NASA Goddard, in a recent blog post. “This was a major milestone because it required nearly all of the observatory systems to be functioning as designed. It all worked as well as we dared to hope, and it was certainly a moment to celebrate.”

Now, the Webb team is working on aligning two more of the instruments — the Near-Infrared Slitless Spectrograph (NIRISS) and Near-Infrared Spectrometer (NIRSpec) — as well as the guider, called the Fine Guidance Sensor (FGS). This process is expected to take around six weeks and will ensure that all of the instruments can work together. Along with NIRCam, these comprise Webb’s near-infrared instruments.

While the three near-infrared instruments are passively cooled — meaning that heat is dispersed from the telescope and into space using design elements like heat sinks which require no power — the fourth instrument, MIRI, works in the mid-infrared wavelength and requires active cooling. Because MIRI uses a different type of detector than the other instruments, and these detectors need to be at an extremely low temperature of less than 7 kelvin to work properly, the instrument needs to be fitted with a cryocooler. This refrigeration system uses helium gas and includes pumps that require power but must produce very little vibration to avoid interfering with instrument readings.

In addition to this cooling system, MIRI is also fitted with heaters so that the cooldown process can be carefully managed to prevent ice from forming on the components. The heaters will shortly be turned off, allowing the cooling system to bring the instrument down to its operating temperature.

With the cooling of MIRI underway, it will take a few weeks until the final instrument gets cool enough to be ready for alignment. Then, with all four of the instruments aligned, the Webb team can move onto the next phase of commissioning — optical stability tests and instrument performance measurement — to get the telescope ready for science operations this summer.

Editors' Recommendations

Georgina Torbet
Georgina is the Digital Trends space writer, covering human space exploration, planetary science, and cosmology. She…
James Webb photographs two potential exoplanets orbiting white dwarfs
Illustration of a cloudy exoplanet and a disk of debris orbiting a white dwarf star.

Even though scientists have now discovered more than 5,000 exoplanets, or planets outside our solar system, it's a rare thing that any telescope can take an image of one of these planets. That's because they are so small and dim compared to the stars that they orbit around that it's easier to detect their presence based on their effects on the star rather than them being detected directly.

However, thanks to its exceptional sensitivity, the James Webb Space Telescope was recently able to image two potential exoplanets orbiting around small, cold cores of dead stars called white dwarfs directly.

Read more
See 19 gorgeous face-on spiral galaxies in new James Webb data
This collection of 19 face-on spiral galaxies from the NASA/ESA/CSA James Webb Space Telescope in near- and mid-infrared light is at once overwhelming and awe-inspiring. Webb’s NIRCam (Near-Infrared Camera) captured millions of stars in these images. Older stars appear blue here, and are clustered at the galaxies’ cores. The telescope’s MIRI (Mid-Infrared Instrument) observations highlight glowing dust, showing where it exists around and between stars – appearing in shades of red and orange. Stars that haven’t yet fully formed and are encased in gas and dust appear bright red.

A stunning new set of images from the James Webb Space Telescope illustrates the variety of forms that exist within spiral galaxies like our Milky Way. The collection of 19 images shows a selection of spiral galaxies seen from face-on in the near-infrared and mid-infrared wavelengths, highlighting the similarities and differences that exist across these majestic celestial objects.

“Webb’s new images are extraordinary,” said Janice Lee of the Space Telescope Science Institute, in a statement. “They’re mind-blowing even for researchers who have studied these same galaxies for decades. Bubbles and filaments are resolved down to the smallest scales ever observed, and tell a story about the star formation cycle.”

Read more
James Webb snaps a stunning stellar nursery in a nearby satellite galaxy
This image from the NASA/ESA/CSA James Webb Space Telescope features an H II region in the Large Magellanic Cloud (LMC), a satellite galaxy of our Milky Way. This nebula, known as N79, is a region of interstellar atomic hydrogen that is ionised, captured here by Webb’s Mid-InfraRed Instrument (MIRI).

A stunning new image from the James Webb Space Telescope shows a star-forming region in the nearby galaxy of the Large Magellanic Cloud. Our Milky Way galaxy has a number of satellite galaxies, which are smaller galaxies gravitationally bound to our own, the largest of which is the Large Magellanic Cloud or LMC.

The image was taken using Webb's Mid-Infrared Instrument or MIRI, which looks at slightly longer wavelengths than its other three instruments which operate in the near-infrared. That means MIRI is well suited to study things like the warm dust and gas found in this region in a nebula called N79.

Read more