Skip to main content

Three of James Webb’s four instruments are now aligned

The long process of getting the James Webb Space Telescope ready to begin collecting science data continues, and the Webb team has met another goal with the alignment of three out of its four instruments. The alignment process is a set of careful very small adjustments to each instrument to make sure they are in exactly the right location to receive light from the telescope’s large primary mirror. A few weeks ago the telescope’s mirrors were aligned with its main camera, called NIRCam, and now the telescope’s other instruments are being similarly adjusted.

Webb’s three near-infrared instruments (the Near-Infrared Slitless Spectrograph or NIRISS, the Near-Infrared Spectrometer or NIRSpec, and the Near-Infrared Camera or NIRCam) and its guidance sensor (the Fine Guidance Sensor or FGS) are now all aligned to its mirrors, leaving just the one mid-infrared instrument to go. The mid-infrared instrument (MIRI) takes longer to align because it uses a different type of sensor, which have to be cooled to an extremely low temperature of just 7 degrees kelvin. MIRI is still in the process of being cooled down to its operating temperature, and once it reaches this milestone then it too can be aligned.

Related Videos

The team had planned to make adjustments to the telescope’s secondary mirror — a smaller round mirror on the end of a boom arm — during the alignment process for the first three instruments, called phase six. However, it turned out that their alignments were so accurate that this wasn’t necessary, so they will wait until MIRI is fully cooled before making any final tweaks to the secondary mirror, in phase seven.

“As a general rule, the commissioning process starts with coarse corrections and then moves into fine corrections. The early secondary mirror coarse corrections, however, were so successful that the fine corrections in the first iteration of Phase Six were unnecessary,” said Chanda Walker, Webb wavefront sensing and control scientist at Ball Aerospace, in a NASA blog post. “This accomplishment was due to many years of planning and great teamwork among the wavefront sensing team.”

Once MIRI is cooled and all four instruments are aligned, there will be a second multi-instrument alignment phase to make any final small tweaks or adjustments. With alignment complete, the team will be able to move on to calibrating the instruments, getting them ready to begin science operations this summer.

Editors' Recommendations

James Webb Telescope catches a glimpse of young version of the Milky Way
This image shows an artist impression of our Milky Way galaxy in its youth. Five small satellite galaxies, of various types and sizes, are in the process of being accreted into the Milky Way. These satellite galaxies also contribute globular star clusters to the larger galaxy. The Sparkler galaxy provides a snap-shot of an infant Milky Way as it accretes mass over cosmic time.

Data from the James Webb Space Telescope has given a glimpse into what our galaxy was like in its formative years. Webb observed a galaxy called The Sparkler, which is analogous to what the Milky Way would have been like when it was young, when it had less mass and only a handful of globular clusters.

This image shows an artist impression of our Milky Way galaxy in its youth. Five small satellite galaxies, of various types and sizes, are in the process of being accreted into the Milky Way. These satellite galaxies also contribute globular star clusters to the larger galaxy. The Sparkler Galaxy provides a snapshot of an infant Milky Way as it accretes mass over cosmic time. James Josephides, Swinburne University.

Read more
A failed Webb telescope calibration leads to the discovery of this tiny asteroid
An asteroid roughly the size of Rome’s Colosseum — between 300 to 650 feet (100 to 200 meters) in length — has been detected by an international team of European astronomers using NASA's James Webb Space Telescope. They used data from the calibration of the MIRI instrument, in which the team serendipitously detected an interloping asteroid. The object is likely the smallest observed to date by Webb and may be an example of an object measuring under 1 kilometer in length within the main asteroid belt, located between Mars and Jupiter. More observations are needed to better characterize this object’s nature and properties.

With any new technology, there are bound to be failures -- and that's true of cutting-edge astronomy instruments like the James Webb Space Telescope as well. But failures can have a silver lining, as was demonstrated recently when an unsuccessful attempt to calibrate a Webb instrument to a well-known asteroid turned up a delightful surprise: the discovery of a new, different asteroid that is just a few hundred feet across.

An asteroid roughly the size of Rome’s Colosseum — between 300 to 650 feet in length — has been detected by a team of European astronomers using NASA's James Webb Space Telescope. They used data from the calibration of the MIRI instrument to serendipitously detect an interloping asteroid. The object is likely the smallest observed by Webb, and may be an example of an object measuring under 1 kilometer in length within the main asteroid belt, located between Mars and Jupiter.  ARTWORK: NASA, ESA, CSA, N. Bartmann (ESA/Webb), Martin Kornmesser (ESA), Serge Brunier (ESO), Nick Risinger (Photopic Sky Survey)

Read more
See a stunning field of galaxies captured by James Webb Space Telescope
A crowded field of galaxies throngs this Picture of the Month from the NASA/ESA/CSA James Webb Space Telescope, along with bright stars crowned with Webb’s signature six-pointed diffraction spikes. The large spiral galaxy at the base of this image is accompanied by a profusion of smaller, more distant galaxies which range from fully-fledged spirals to mere bright smudges. Named LEDA 2046648, it is situated a little over a billion light-years from Earth, in the constellation Hercules.

Stunning images from the James Webb Space Telescope continue to entrance, and recently the researchers using the telescope have shared a gorgeous image of a field of galaxies as part of the Webb Picture of the Month collection.

The image shows a spattering of different background galaxies, while the foreground shows bright individual stars and a bright spiral galaxy at the bottom called LEDA 2046648. Located around a billion light-years from Earth, this galaxy is relatively much closer to us than the far-off background galaxies which is why it is so prominent in the image.

Read more