James Webb Space Telescope turns 11: Why is it so amazing?

On December 14, 2022, Nature magazine named Jane Rigby, the project scientist of the James Webb Space Telescope, as the top 10 people of 2022 for her contribution to the successful operation of the Webb. The next day, Science magazine ranked the successful operation of the Webb as the top of the top ten scientific breakthroughs of 2022. What important results has the Webb achieved in just one year since its launch, so that it and the scientists who promoted it have received such an honor? Why is it so powerful? What enlightenment does its success have for us? This article will try to answer these questions.

Written by | Wang Shanqin

On December 14, 2022, Nature magazine announced the 2022 Person of the Year (Nature's 10). [1] Topping the list is Jane Rigby, an astrophysicist and project scientist for the James Webb Space Telescope (hereinafter referred to as Webb unless directly quoted in the original text).

Nature magazine dubbed Jane Rigby a "sky hunter" and called her a "pioneering astronomer." She was selected for her "key role in getting the James Webb Space Telescope up and running, providing vast new capabilities for studying the universe."[1]

Image: Screenshot of Nature's 10 website. Image source: [1]

On December 15, 2022, Science magazine listed the top ten scientific breakthroughs of 2022, with the successful operation of Webb ranking first. [2][Note 1] The top of the relevant webpage is an artistic image of a portion of Webb's main mirror.

Figure: Screenshot of the top of the Science magazine webpage introducing the top ten scientific breakthroughs of 2022. Image source: [2]

The honors Webb and the astronomers who drove it have received are a testament to its great success. So, just one year after its launch, what important achievements has Webb made that it and the scientists who drove it have received such honors? Why is it so powerful? What enlightenment does its success have for us?

Image: Webb’s artistic conception. Image source: [3]

What did Webb achieve?

Webb has spent a full year in space since its launch on December 25, 2021. During this year, scientists on the ground spent about half a year to make it transfer orbits, perform hundreds of operations and tests. After that, Webb entered the observation state, and astronomers processed the first batch of observation data it obtained into images, which were released on July 11 and 12, 2022.

This batch of images includes: long exposure photos of the sky area where the galaxy cluster SMACS J0723.3-7327 is located, light curve and transmission spectrum of WASP-96, the parent star of the exoplanet WASP-96b, images of the Southern Ring Nebula, images of the "Stephan's Quintet" composed of five galaxies, and images of a region of the Carina Nebula (NGC 3324). We have introduced this batch of results before, so we will not repeat them here. Interested readers can click to read "Billion-dollar investment pays off: How strong are the first batch of photos from the Webb Space Telescope?"

The quality and clarity of the first batch of images not only satisfied the public's aesthetic taste, but also met the requirements of professional astronomers, proving Webb's outstanding performance. It can be said that Webb's debut was the peak. After this peak, Webb did not go downhill, but continued to climb new peaks in different fields.

We can briefly summarize the first batch of results and the new results obtained so far by field.

In the "deep field" field, Webb observed different areas of the sky and photographed many high-redshift (distant) galaxies, some of which broke the record for the most distant galaxies previously observed by Hubble. In-depth research on these galaxies will directly deepen humanity's understanding of the properties of galaxies in the early universe. Webb's success in this regard makes people believe that it is expected to discover the first generation of galaxies and the first generation of stars in the universe, which were formed about 100-200 million years after the Big Bang.

Figure: A false-color infrared deep-field image obtained by Webb after observing the area observed by the Hubble Space Telescope's Ultra Deep Field project. Webb's Near Infrared Spectrometer (NIRSpec) obtained spectra of some of these galaxies, and the figure shows the redshifts of four of them: 13.20, 12.63, 11.58 and 10.38. At a redshift of 13.20, the universe is less than 400 million years old. Image source: [4]

In the field of galaxies, Webb has taken images of galaxies such as the Stephan Quintet, the Cartwheel Galaxy, and the active galaxy NGC 7469. The observation and study of these galaxies has provided important basis for people to understand the distribution of stars, gas and dust in these galaxies.

Image: A false-color image of NGC 7469, synthesized from data obtained by Webb's near-infrared camera. The apparent core causes a noticeable diffraction gleam in the image. Image source: [5]

In the field of nebulae, Webb took images of the Southern Ring Nebula, the Carina Nebula, the Tarantula Nebula, the Orion Nebula, and the "Pillars of Creation". These observations provide important support for astronomers' in-depth studies of the late stages of the evolution of low- and medium-mass stars, the properties of embryonic stars ("protostars"), and the relatively cold dust and gas disks around them.

Figure: A false color image of the Pillars of Creation synthesized from data obtained by Webb's near-infrared camera (left) and a false color image of the Pillars of Creation synthesized from data obtained by Webb's mid-infrared instrument (right). Image source: [6]

In the field of celestial bodies in the solar system, Webb observed Jupiter, Mars, Neptune, Titan and other celestial systems. The images obtained by Webb confirmed that its ability in this area exceeded expectations. In the future, Webb's observations of celestial bodies in the solar system will deepen people's understanding of their properties and the origin of the solar system.

Figure: A false-color image of the Neptune system, based on data from Webb's near-infrared camera. The image shows Neptune's rings and seven of its 14 satellites: Triton, Galatea, Naiad, Thalassa, Despina, Proteus, and Larissa. Because Triton is point-shaped and bright, the hexagonal ridges caused by diffraction effects are very noticeable. Image source: [7]

In the field of exoplanets (planets outside the solar system), Webb used the transit method to photograph the light curve and transmission spectrum of WASP-96, the parent star of the exoplanet WASP-96b, and used direct imaging to photograph the exoplanet HIP 65426 b. Analysis shows that Webb's ability to detect planets using direct imaging is 10 times greater than expected. Although Webb is not the first, nor the only telescope that can use this method to take images of exoplanets, its unique advantage in infrared observations is not possessed by many other telescopes. In the future, Webb's observations of exoplanets will hopefully help people identify exoplanets similar to Earth.

Figure: Images of the exoplanet HIP 65426 b taken by Webb's Near Infrared Camera (NIRcam) and Mid-Infrared Instrument (MIRI) at four wavelengths: 3.067 microns, 4.397 microns, 11.307 microns, and 15.514 microns (small images below, from left to right). The large image shows the stars in the sky where the star HIP 65426 is located, as taken by the Digital Sky Survey (DSS). Image source: [8]

In the field of supernovae, Webb discovered 4 supernovae in 2022. [Note 2] In the current situation of fierce competition among various large-field telescopes, Webb, with a small field of view, will not have time to discover those nearby supernovae before other telescopes preempt it. Therefore, it can only discover very distant supernovae, which are so dim that other relatively small telescopes cannot detect them in time. Webb can discover more extremely distant supernovae in the future. [Note 3]

Why is Webb so powerful?

Webb's great success comes from the advanced functions of its primary mirror and instruments, as well as the positive experiences and negative lessons provided by the development process of many telescopes in the past.

First of all, Webb's primary mirror and instruments are very advanced. Its diameter (6.5 meters) is much larger than the diameter of the previous Hubble (2.4 meters) and the diameter of the Spitzer Infrared Space Telescope (0.85 meters).

Figure: From top to bottom, the sizes of Spitzer, Hubble, and Webb are shown. Although the diameter of Webb is marked as 6.6 meters, its equivalent aperture is 6.5 meters. Image source: [9]

Therefore, when observing the same infrared band, Webb's resolution is much higher than Hubble and Spitzer. Because of its much larger aperture, Webb needs much less observation time to observe the same target and obtain images of the same quality, so it is much more efficient.

Figure: Left and right are images of a region of the Large Magellanic Cloud (LMC) galaxy taken by the Infrared Array Camera (IRAC) on Spitzer and the Mid-Infrared Instrument (MIRI) on Webb. The two observation wavelengths are almost exactly the same (8.0 microns vs. 7.7 microns), but the resolution of Webb's image is obviously much higher than that of Spitzer. Image source: [10]

Webb is far away from the Earth. It has five layers of protective shields and its infrared equipment carries an additional refrigerator. Therefore, the observable wavelength limit (28 microns) is much larger than the observable wavelength limit of Hubble (no more than 2.5 microns). Therefore, it can discover many objects that Hubble cannot discover, such as protostars hidden deep in nebulae.

Figure: In the near-infrared image of a portion of the Carina Nebula obtained by Webb, astronomers found more than 20 jets and outflows that had not been discovered by the Hubble telescope and other telescopes before. The circled areas in the figure have been magnified and placed on the right. These areas all show molecular hydrogen outflows, and area 2 also shows a jet and a bow shock. Image source: [11]

Secondly, before Webb, humans had launched a large number of space telescopes, which covered all bands of electromagnetic waves except the radio band: gamma rays, X-rays, ultraviolet rays, optical (visible light), infrared rays and microwaves. [Note 4] Taking the infrared space telescope as an example, as early as 1983, humans launched the Infrared Astronomical Satellite (IRAS), which was the first infrared space telescope in human history. The technology accumulated during the development and launch of these space telescopes, especially the infrared space telescopes, provided Webb with a lot of positive experience.

Image: IRAS’s artistic conception. Image source: [12]

Taking technology borrowing as an example, the mid-infrared instrument (MIRI) on Webb uses the refrigerator mode that was used by Hubble's NICMOS between 2002 and 2008; Webb's mirror is coated with a thin layer of gold to enhance reflectivity, a solution previously used by the Infrared Telescope in Space (IRTS) and Akari satellite; Webb uses beryllium to cast the mirror blank to improve hardness, temperature adaptability and reduce weight, a solution previously used by the Spitzer telescope.

Image: Dave Chaney, chief optical test engineer at Ball Aerospace, inspects the six segments of Webb's primary mirror before performing X-ray and cryogenic tests. Image source: [13]

In addition to the above-mentioned solutions from space telescopes, Webb also borrowed the multi-mirror splicing technology of large ground telescopes. This technology is a common solution for 10-meter optical telescopes on the ground, and some 6-8-meter telescopes also use this solution. It is also one of the mainstream solutions for future 30-40-meter ground optical telescopes. Therefore, we can say that Webb is a giant standing on the shoulders of giants.

Figure: Webb's main mirror is made up of 18 regular hexagonal mirrors. Each mirror has a side length of about 0.75 meters and an area of ​​about 1.4 square meters. The total area of ​​the 18 mirrors is 25.4 square meters, which together form a mirror with an equivalent diameter of about 6.5 meters. Image source: [14]

The third factor that makes Webb so powerful is that it has fully absorbed some lessons from the past, especially the painful lessons of Hubble. A slight deviation when engineers were grinding Hubble's primary mirror caused the mirror of Hubble to be unable to focus accurately, thus affecting all instruments. This not only cost NASA hundreds of millions of dollars to repair Hubble, but also sacrificed an instrument for a long time (to install the optical corrector COSTAR), and also greatly affected Hubble's performance in the three years from 1990 to 1993. It was not until the end of 1993 that NASA astronauts implemented the maintenance plan, which allowed Hubble to redeem itself and become a legend.

Image: NASA astronauts Story Musgrave and Jeffrey Hoffman repair the Hubble in space in December 1993. Image source: [15]

The failure of Hubble for several years made Webb's research and development team extremely cautious. The launch date of Webb was repeatedly postponed, and its budget climbed to $10 billion. Such caution is necessary because Webb's orbital altitude is thousands of times higher than Hubble's, reaching more than 1 million kilometers, much farther than the moon. Once Webb has a problem, it is impossible to send people up to repair it. From the time Webb is launched to the time it starts working, it must perform 344 key steps under the remote control of ground engineers. Any mistake in any step will declare its death. Such caution and patience laid the most solid foundation for Webb to reach the peak of his debut.

The fourth factor that makes Webb so powerful is that engineers and scientists have developed a lot of new technologies. Webb is far more complex than any previous infrared space telescope. In fact, it is more complex than all telescopes and is one of the most complex devices ever built.

Image: The near-infrared camera (top) and mid-infrared device (bottom) on Webb. Image source: [16]

Due to its complexity, it is impossible to achieve the goal by simply piecing together some of the previous technologies, but it is necessary to continuously develop new technologies. From the design and manufacture of all the instruments inside it, to the design, manufacture, folding and unfolding of the five-layer sunshield, to the folding and unfolding of the main part of the telescope, to the focusing of each mirror, etc., all these processes are full of challenges, so some of the smartest engineers and scientists in the world have spent a lot of wisdom and effort.

Image: Engineers and technicians inspect Webb's five-layer sun shield. Image source: [17]

What enlightenment does Webb have?

The success of Webb is not only its own success, but also greatly inspires people's confidence in other space telescope projects. More importantly, its success will enlighten us in many aspects.

Webb's success tells all people and teams who aspire to achieve major results the simplest truth: sufficient patience, carefulness and wisdom are the basic requirements for achieving major results. This is true not only for Webb, but also for the Laser Interferometer Gravitational-Wave Observatory (LIGO). Several generations of physicists and engineers worked hard to make it the world's first instrument to detect gravitational waves.

Figure: The exterior of the ground-based parts of the two LIGO devices located in Livingston and Hanford. Image source: [18]

Webb's success also further proves the value of Big Science. Over the past 100 years, the cost of scientific research related to observation and experiment has become increasingly high, and the teams serving it have become increasingly large. It is not uncommon for a laboratory to involve hundreds or even thousands of people, which has led science to the era of Big Science.

In the fierce competition of science and technology, different countries are faced with a difficult choice: should they choose a project with low risk and stability, or a big science project with high risk and high return? This poses a challenge to a country's decision-making in the field of science and technology. Webb's success has given people more confidence in big science projects that are full of risks and hope.

Webb's success also sets a benchmark for more ambitious goals. In the future, people can use better vehicles to launch larger infrared space telescopes and space telescopes that observe other bands.

We hope that the data obtained by Webb in the next decade will reshape our understanding of the celestial bodies in the solar system and the formation mechanism of the solar system, and deepen our understanding of the formation and explosion of exoplanets and extraterrestrial life, galaxies, various celestial bodies, and the universe itself. We also hope that in the future there will be more powerful telescopes than Webb flying in space, further sublimating the human knowledge system.

Image: The last time humans saw Webb. Image source: [19]

Notes

[Note 1] Chinese article from the Science magazine WeChat public account (
https://mp.weixin.qq.com/s/I6kBfXwS24dDSG3le65zWg) called Webb "NASA's star-level new space telescope", which is not a rigorous statement, because Webb is not owned solely by the National Aeronautics and Space Administration (NASA), but is jointly invested and built by NASA, the European Space Agency (ESA) and the Canadian Space Agency (CSA).

[Note 2] Webb discovered supernova AT2022owj on June 22, 2022, the first supernova it has ever discovered.

[Note 3] For example, the AT 2022qmm it discovered had a magnitude of 24.1 when it was discovered, far dimmer than the limit that most other telescopes can observe (generally no dimmer than magnitude 21).

[Note 4] The reason why people have not launched radio telescopes into space is that most radio telescopes on the ground are basically unaffected by the atmosphere, and a few radio telescopes with very high requirements can also work well in dry plateau deserts. In addition, radio telescopes need much larger apertures to obtain the same resolution as optical telescopes, and before and now, launching radio telescopes with apertures of tens of meters into space is unrealistic.

References/Image sources

[1]https://www.nature.com/immersive/d41586-022-04185-3/index.html

[2]https://www.science.org/content/article/breakthrough-2022#section_breakthrough

[3] Northrop Grumman

[4]IMAGE: NASA, ESA, CSA, M. Zamani (ESA/Webb), Leah Hustak (STScI), SCIENCE: Brant Robertson (UC Santa Cruz), S. Tacchella (Cambridge), E. Curtis-Lake (UOH), S. Carniani (Scuola Normale Superiore), JADES Collaboration

[5] ESA/Webb, NASA & CSA, L. Armus, AS Evans

[6]SCIENCE: NASA, ESA, CSA, STScI, IMAGE PROCESSING: Joseph DePasquale (STScI), Anton M. Koekemoer (STScI), Alyssa Pagan (STScI) (left); SCIENCE: NASA, ESA, CSA, STScI, IMAGE PROCESSING: Joseph DePasquale (STScI), Alyssa Pagan (STScI) (right)

[7]IMAGE: NASA, ESA, CSA, STScI, IMAGE PROCESSING: Joseph DePasquale (STScI), Naomi Rowe-Gurney (NASA-GSFC)

[8]DSS; NASA/ESA/CSA, A. Carter (UCSC), the ERS 1386 team, and A. Pagan (STScI)

[9] IMAGE: STScI, 3D MODEL: NASA, ESA, STScI

[10]NASA/JPL-Caltech (left), NASA/ESA/CSA/STScI (right)

[11]NASA, ESA, CSA, STScI, SCIENCE: Megan Reiter (Rice University), IMAGE PROCESSING: Joseph DePasquale (STScI), Anton M. Koekemoer (STScI).

[12] NASA/JPL

[13]NASA/MSFC/David Higginbotham

[14] NASA

[15] NASA

[16]Lockheed Martin (top); Science and Technology Facilities Council (bottom)

[17] Northrop Grumman Aerospace Systems

[18]https://www.ligo.caltech.edu/LA

[19] NASA, ESA

Produced by: Science Popularization China

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