Prepare for a brand new option to see the universe

The James Webb House Telescope (JWST) is NASA’s subsequent main observatory; consistent with the Hubble House Telescope, the Compton Gamma-Ray Observatory, the Chandra X-Ray Observatory and the Spitzer House Telescope. JWST combines the qualities of two of its predecessors, observing in infrared gentle, like Spitzer, with tremendous decision, like Hubble. Credit score: NASA, SkyWorks Digital, Northrop Grumman, STScI

James Webb Space Telescope is finally ready to do science – and it’s seeing the universe more clearly than even its own engineers hoped for.

NASA is scheduled to release the first images taken by the James Webb Space Telescope on July 12, 2022. They’ll mark the beginning of the next era in astronomy as Webb – the largest space telescope ever built – begins collecting scientific data that will help answer questions about the earliest moments of the universe and allow astronomers to study exoplanets in greater detail than ever before. But it has taken nearly eight months of travel, setup, testing, and calibration to make sure this most valuable of telescopes is ready for prime time. Marcia Rieke, an astronomer at the University of Arizona and the scientist in charge of one of Webb’s four cameras, explains what she and her colleagues have been doing to get this telescope up and running.

1. What has occurred for the reason that launch of the telescope?

Following the profitable launch of the James Webb House Telescope on December 25, 2021, the crew started the lengthy technique of transferring the telescope to its last orbital place, unfolding the telescope, and – as the whole lot cooled – calibrating the cameras and sensors. onboard sensors.

The launch went as easily as a rocket launch can get. One of many first issues my NASA colleagues observed was that the telescope had extra gasoline on board than anticipated to make future changes to its orbit. This may enable Webb to function for much longer than the mission’s authentic 10-year objective.

The primary activity on Webb’s month-long journey to its last location in orbit was to unfold the telescope. It went off with no hitch, beginning with the clean deployment of the sunshade that helps cool the telescope, adopted by aligning the mirrors and activating the sensors.

As soon as the sunshade was opened, our crew started monitoring the temperatures of the 4 onboard cameras and spectrometers, ready for them to achieve temperatures low sufficient that we may start testing every of the 17 totally different modes the devices can function in. operate.

NIR Cam

The NIRCam, seen right here, will measure infrared gentle from extraordinarily distant and historical galaxies. It was the primary instrument to come back on-line and helped align the 18 mirror segments. Credit score: NASA/Chris Gunn

2. What did you check first?

Webb’s cameras cooled because the engineers had predicted, and the primary instrument the crew turned on was the Close to Infrared Digicam – or NIRCam. NIRCam is designed to review the faint infrared gentle produced by the oldest stars or galaxies within the universe. However earlier than it may do this, NIRCam had to assist align the 18 particular person segments of Webb’s mirror.

As soon as NIRCam cooled to minus 280 F, it was cool sufficient to start detecting gentle mirrored from Webb’s mirror segments and producing the telescope’s first pictures. The NIRCam crew was thrilled when the primary vibrant picture arrived. We have been in enterprise!

These pictures confirmed that the mirror segments have been all pointing to a comparatively small space of ​​the sky, and the alignment was a lot better than the worst-case eventualities we had anticipated.

Webb’s tremendous steering sensor additionally entered service presently. This sensor helps hold the telescope pointed steadily at a goal, very like the picture stabilization in client digital cameras. Utilizing the HD84800 star as a reference level, my colleagues from the NIRCam crew helped dial within the alignment of the mirror segments till it was close to excellent, much better than the minimal required for a profitable mission. .

3. Which sensors then got here to life?

Because the mirror alignment wrapped up on March 11, the Close to Infrared Spectrograph – NIRSpec – and the Close to Infrared Imager and Slitless Spectrograph – NIRISS – completed cooling down and joined the social gathering.

NIRSpec is designed to measure the power of various wavelengths of sunshine coming from a goal. This info can reveal the composition and temperature of distant stars and galaxies. NIRSpec does this by viewing its goal object by a slit that blocks all different gentle from coming into.

NIRSpec has a number of slots that enable it to have a look at 100 objects directly. Group members began by testing the multi-target mode, commanding the slits to open and shut, and so they confirmed that the slits responded appropriately to instructions. The subsequent steps will measure precisely the place the slits are pointing and confirm that a number of targets could be noticed concurrently.

NIRISS is a slitless spectrograph that additionally breaks down gentle into its totally different wavelengths, however is extra environment friendly at observing all objects in a discipline, not simply these on the slits. It has a number of modes, together with two specifically designed to review exoplanets notably near their guardian stars.

To date, instrument checks and calibrations have gone easily, and the outcomes present that NIRSpec and NIRISS will ship even higher knowledge than what engineers predicted earlier than launch.

Webb MIRI and Spitzer Comparison Image

The MIRI digicam, picture on the best, permits astronomers to see by mud clouds with unbelievable readability in comparison with earlier telescopes just like the Spitzer House Telescope, which produced the picture on the left. Credit score: NASA/JPL-Caltech (left), NASA/ESA/CSA/STScI (proper)

4. What was the final instrument to gentle up?

The final instrument to begin on Webb was the Mid-Infrared Instrument, or MIRI. MIRI is designed to take photos of distant or newly shaped galaxies in addition to small faint objects like asteroids. This sensor detects the longest wavelengths of Webb’s devices and ought to be saved at minus 449 F – solely 11 levels F above[{” attribute=””>absolute zero. If it were any warmer, the detectors would pick up only the heat from the instrument itself, not the interesting objects out in space. MIRI has its own cooling system, which needed extra time to become fully operational before the instrument could be turned on.

Radio astronomers have found hints that there are galaxies completely hidden by dust and undetectable by telescopes like Hubble that captures wavelengths of light similar to those visible to the human eye. The extremely cold temperatures allow MIRI to be incredibly sensitive to light in the mid-infrared range which can pass through dust more easily. When this sensitivity is combined with Webb’s large mirror, it allows MIRI to penetrate these dust clouds and reveal the stars and structures in such galaxies for the first time.

5. What’s next for Webb?

As of June 15, 2022, all of Webb’s instruments are on and have taken their first images. Additionally, four imaging modes, three time series modes and three spectroscopic modes have been tested and certified, leaving just three to go.

On July 12, NASA plans to release a suite of teaser observations that illustrate Webb’s capabilities. These will show the beauty of Webb imagery and also give astronomers a real taste of the quality of data they will receive.

After July 12, the James Webb Space Telescope will start working full time on its science mission. The detailed schedule for the coming year hasn’t yet been released, but astronomers across the world are eagerly waiting to get the first data back from the most powerful space telescope ever built.

Written by Marcia Rieke, Regents Professor of Astronomy, University of Arizona.

This article was first published in The Conversation.The Conversation

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