The James Webb Space Telescope is finally ready to perform science

NASA will release the first images taken by the James Webb Space Telescope on July 12, 2022. It marks the beginning of the next era in astronomy, as Webb – the largest space telescope ever built – begins to collect scientific data that will help answer questions about the early moments of the universe and allow astronomers to study the exoplanets in more detail than ever before. But it took almost eight months of travel, setup, testing and calibration to get these most valuable telescopes ready for prime time. Marcia Ricci, an astronomer at the University of Arizona. The researcher in charge of one of the four webcams explains what she and her colleagues did to operate the telescope.

1. What has happened since the telescope was launched?

Following the successful launch of the James Webb Space Telescope on December 25, 2021, the team began the long process of moving the telescope to its final orbital location, opening the telescope, and while everything was cooling, the cameras and sensors on board calibrated.

The launch was as smooth as a rocket launch could happen. One of the first things my NASA colleagues noticed was that the telescope had more fuel on board than expected for future adjustments to its orbit. This allows Webb to work further from the original mission goal, which is 10 years.

The first task during Webb’s month-long journey to his last position in orbit was to open the telescope. This continued smoothly, starting with Lubricating the sunscreen with a white joint Helps cool the telescope, followed by adjusting the mirrors and activating the sensors.

As soon as the sunshade was opened, our team began monitoring the temperatures of four cameras and spectrophotometers on board, waiting for them to reach a low enough temperature so we could begin testing both 17 different modes the tools can operate.

NIRCam on Webb was the first tool to go online and help adjust 18 mirror clips.
NASA’s Goddard Space Center / Wikimedia Commons

2. What did you test first?

The cameras on Webb cooled down, as the engineers expected, and the first instrument the team turned on was the near-infrared camera – or NIRCam. NIRCam is designed to study dim infrared light from the oldest stars or galaxies in the universe. But before it could do that, NIRCam had to help align 18 separate segments of a web mirror.

When the NIRCam cooled to 280 degrees Fahrenheit, it was cold enough to detect light reflected from Webb mirror clips and produce the telescope’s first images. The NIRCam team was ecstatic when the first scans arrived. We were up and running!

These images showed that the mirror clips were: They all refer to a relatively small part of the sky The compatibility was much better than the worst case scenario we had planned.

Web’s precision control sensor also came into play at this time. This sensor helps hold the telescope firmly on target – just like image stabilization in consumer digital cameras. Using the star HD84800 as a reference point, I helped connect my NIRCam teammates to adjust mirror segments until they were almost perfect, much better than the minimum required for a successful mission.

3. Which sensors came to life?

When the mirror adjustment was completed on March 11, the near-infrared spectrometer – NIRSpec – and the near-infrared camera and spectrograph – NIRISS – finished cooling off and joined the party.

NIRSpec is designed to measure the intensity of different wavelengths of light coming from the target. This information can reveal the composition and temperature of distant stars and galaxies. NIRSpec does this by looking at the target object through an aperture that blocks other light.

NIRSpec has multiple slots that allow you to view 100 items at once. Team members began testing the location of the multiple targets, instructing the columns to open and close, and confirming that the columns responded correctly to commands. Future steps will measure and verify exactly where the cracks are pointing. Several targets can be observed simultaneously.

NIRISS is a non-splicing spectrophotometer that will also refract light in its various wavelengths, but is better at observing all things in the field, not just the things in the slits. It has several modes, including two specifically designed to study exoplanets that are particularly close to their parent stars.

So far, device checks and calibrations have gone smoothly, and the results show that both NIRSpec and NIRISS will deliver better data than engineers expected before launch.

The MIRI camera, the image on the right, allows astronomers to see the dust clouds incredibly clearly compared to previous telescopes such as the Spitzer Space Telescope, which produced the image on the left.
NASA / JPL-Caltech (left), NASA / ESA / CSA / STScI (right) / Flickr and CC BY

4. What was the last tool you used?

The last tool to launch on Webb was the mid-infrared instrument or MIRI. MIRI is designed to capture images of distant or newly formed galaxies, as well as faint small objects such as asteroids. This sensor detects the longest wavelengths of Web’s instruments and should be kept at 449 degrees Fahrenheit – only 11 degrees Fahrenheit above absolute zero. When it’s hotter, the detectors only absorb heat from the device itself, not from the interesting things in the room. MIRI Its cooling system, which needed more time to become fully functional before the unit could be used.

Radio astronomers have found evidence that galaxies exist precisely hidden in dust and undetectable by telescopes like Hubble, which capture wavelengths of light similar to those visible to the human eye. The extremely cold temperatures make MIRI incredibly sensitive to light in the medium-infrared range, which can more easily pass through dust. When this sensitivity is combined with Web’s large mirror, MIRI can cause these dust clouds to penetrate and reveal stars and structures for the first time in such galaxies.

5. What’s next for Webb?

As of June 15, 2022, all Web tools are operational and have created their first images. In addition, four imaging modes, three time series modes and three spectral modes were tested and approved, leaving only three modes.

NASA plans to release a collection of humorous notes on July 12. Describes web capabilities. These images will showcase the beauty of Web’s images and will also give astronomers a real taste of the quality of the data they receive.

After July 12, the James Webb Space Telescope will begin working full-time on its scientific mission. The detailed timeline for next year has not yet been announced, but astronomers around the world are eagerly awaiting the restoration of the first data from the most powerful space telescope ever built.

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