#Near-Infrared Camera (NIRCam)
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WASHINGTON, Jan 29 (Reuters) — A batch of newly released images captured by the James Webb Space Telescope show in remarkable detail 19 spiral galaxies residing relatively near our Milky Way, offering new clues on star formation as well as galactic structure and evolution.
The images were made public on Monday by a team of scientists involved in a project called Physics at High Angular resolution in Nearby GalaxieS (PHANGS) that operates across several major astronomical observatories.
The closest of the 19 galaxies is called NGC5068, about 15 million light years from Earth, and the most distant of them is NGC1365, about 60 million light years from Earth.
A light year is the distance light travels in a year, 5.9 trillion miles (9.5 trillion km).
The James Webb Space Telescope (JWST) was launched in 2021 and began collecting data in 2022, reshaping the understanding of the early universe while taking wondrous pictures of the cosmos.
The orbiting observatory looks at the universe mainly in the infrared.
The Hubble Space Telescope, launched in 1990 and still operational, has examined it primarily at optical and ultraviolet wavelengths.
Spiral galaxies, resembling enormous pinwheels, are a common galaxy type. Our Milky Way is one.
The new observations came from Webb's Near-Infrared Camera (NIRCam) and Mid-Infrared Instrument (MIRI).
They show roughly 100,000 star clusters and millions or perhaps billions of individual stars.
"These data are important as they give us a new view on the earliest phase of star formation," said University of Oxford astronomer Thomas Williams, who led the team's data processing on the images.
"Stars are born deep within dusty clouds that completely block out the light at visible wavelengths - what the Hubble Space Telescope is sensitive to - but these clouds light up at the JWST wavelengths.
We don't know a lot about this phase, not even really how long it lasts, and so these data will be vital for understanding how stars in galaxies start their lives," Williams added.
About half of spiral galaxies have a straight structure, called a bar, coming out from the galactic center to which the spiral arms are attached.
"The commonly held thought is that galaxies form from the inside-out, and so get bigger and bigger over their lifetimes.
The spiral arms act to sweep up the gas that will form into stars, and the bars act to funnel that same gas in towards the central black hole of the galaxy," Williams said.
The images let scientists for the first time resolve the structure of the clouds of dust and gas from which stars and planets form at a high level of detail in galaxies beyond the Large Magellanic Cloud and Small Magellanic Cloud, two galaxies considered galactic satellites of the sprawling Milky Way.
"The images are not only aesthetically stunning, they also tell a story about the cycle of star formation and feedback, which is the energy and momentum released by young stars into the space between stars," said astronomer Janice Lee of the Space Telescope Science Institute in Baltimore, principal investigator for the new data.
"It actually looks like there was explosive activity and clearing of the dust and gas on both cluster and kiloparsec (roughly 3,000 light years) scales.
The dynamic process of the overall star formation cycle becomes obvious and qualitatively accessible, even for the public, which makes the images compelling on many different levels," Lee added.
Webb's observations build on Hubble's.
"Using Hubble, we would see the starlight from galaxies, but some of the light was blocked by the dust of galaxies," University of Alberta astronomer Erik Rosolowsky said.
"This limitation made it hard to understand parts of how a galaxy operates as a system. With Webb's view in the infrared, we can see through this dust to see stars behind and within the enshrouding dust."
#James Webb Space Telescope#spiral galaxies#Milky Way#Physics at High Angular resolution in Nearby GalaxieS (PHANGS)#NGC5068#NGC1365#light year#Hubble Space Telescope#Near-Infrared Camera (NIRCam)#Mid-Infrared Instrument (MIRI)#astronomy#space#universe#cosmos#Large Magellanic Cloud#Small Magellanic Cloud#Space Telescope Science Institute
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James Webb Space Telescope captures stunning images of actively forming stars
James Webb Space Telescope captures stunning images of actively forming stars
James Webb Space Telescope captures stunning images of actively forming stars. The James Webb Space Telescope has captured a stunning new image of two actively forming stars, collectively known as Herbig-Haro 46/47. The image shows the stars embedded in a disc of gas and dust, about 1,400 light-years away from Earth. James Webb Space Telescope has just captured a new image of actively forming…
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#000 years old#1#100#400 light-years away#accreting#amazing images#bow shock#Herbig-Haro 46/47#Herbig-Haro object#James Webb Space Telescope#natal cocoon#Near-Infrared Camera (NIRCam)#power of JWST#revolutionize our understanding of star formation#star formation#stunning image
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Webb Telescope Rules Out Thick Carbon Dioxide Atmosphere for TRAPPIST-1 c
NASA’s James Webb Space Telescope has conducted observations of the exoplanet TRAPPIST-1 c and made a significant discovery. Despite being similar in size to Venus and receiving comparable levels of radiation from its star, Webb’s findings indicate that TRAPPIST-1 c does not possess Venus’s thick carbon dioxide-rich atmosphere. If an atmosphere exists on TRAPPIST-1 c, it is likely to be very…
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#Ariane 5 rocket#Cosmic Microwave Background#Deep space observations#Exoplanets#Fine Guidance Sensor/Near InfraRed Imager and Slitless Spectrograph (FGS/NIRISS)#Galaxy formation#Hubble Space Telescope successor#Infrared Astronomy#Infrared detectors#James Webb Space Telescope (JWST)#Launch#Mid-Infrared Instrument (MIRI)#Mirror segments#Multi-object spectroscopy#NASA#Near InfraRed Spectrograph (NIRSpec)#Near-Infrared Camera (NIRCam)#Space telescope#Stellar populations#Sunshield#Transiting exoplanets#Universe formation and evolution#Webb Science Operations Center (JSOC)
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Astronomers used three of NASA's Great Observatories to capture this multiwavelength image showing galaxy cluster IDCS J1426.5+3508. It includes X-rays recorded by the Chandra X-ray Observatory in blue, visible light observed by the Hubble Space Telescope in green, and infrared light from the Spitzer Space Telescope in red. This rare galaxy cluster has important implications for understanding how these megastructures formed and evolved early in the universe.
How Astronomers Time Travel
Let’s add another item to your travel bucket list: the early universe! You don’t need the type of time machine you see in sci-fi movies, and you don’t have to worry about getting trapped in the past. You don’t even need to leave the comfort of your home! All you need is a powerful space-based telescope.
But let’s start small and work our way up to the farthest reaches of space. We’ll explain how it all works along the way.
This animation illustrates how fast light travels between Earth and the Moon. The farther light has to travel, the more noticeable its speed limit becomes.
The speed of light is superfast, but it isn’t infinite. It travels at about 186,000 miles (300 million meters) per second. That means that it takes time for the light from any object to reach our eyes. The farther it is, the more time it takes.
You can see nearby things basically in real time because the light travel time isn’t long enough to make a difference. Even if an object is 100 miles (161 kilometers) away, it takes just 0.0005 seconds for light to travel that far. But on astronomical scales, the effects become noticeable.
This infographic shows how long it takes light to travel to different planets in our solar system.
Within our solar system, light’s speed limit means it can take a while to communicate back and forth between spacecraft and ground stations on Earth. We see the Moon, Sun, and planets as they were slightly in the past, but it's not usually far enough back to be scientifically interesting.
As we peer farther out into our galaxy, we use light-years to talk about distances. Smaller units like miles or kilometers would be too overwhelming and we’d lose a sense of their meaning. One light-year – the distance light travels in a year – is nearly 6 trillion miles (9.5 trillion kilometers). And that’s just a tiny baby step into the cosmos.
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The Sun’s closest neighboring star, Proxima Centauri, is 4.2 light-years away. That means we see it as it was about four years ago. Betelgeuse, a more distant (and more volatile) stellar neighbor, is around 700 light-years away. Because of light’s lag time, astronomers don’t know for sure whether this supergiant star is still there! It may have already blasted itself apart in a supernova explosion – but it probably has another 10,000 years or more to go.
What looks much like craggy mountains on a moonlit evening is actually the edge of a nearby, young, star-forming region NGC 3324 in the Carina Nebula. Captured in infrared light by the Near-Infrared Camera (NIRCam) on NASA’s James Webb Space Telescope, this image reveals previously obscured areas of star birth.
The Carina Nebula clocks in at 7,500 light-years away, which means the light we receive from it today began its journey about 3,000 years before the pyramids of Giza in Egypt were built! Many new stars there have undoubtedly been born by now, but their light may not reach Earth for thousands of years.
An artist’s concept of our Milky Way galaxy, with rough locations for the Sun and Carina nebula marked.
If we zoom way out, you can see that 7,500 light-years away is still pretty much within our neighborhood. Let’s look further back in time…
This stunning image by the NASA/ESA Hubble Space Telescope features the spiral galaxy NGC 5643. Looking this good isn’t easy; 30 different exposures, for a total of nine hours of observation time, together with Hubble’s high resolution and clarity, were needed to produce an image of such exquisite detail and beauty.
Peering outside our Milky Way galaxy transports us much further into the past. The Andromeda galaxy, our nearest large galactic neighbor, is about 2.5 million light-years away. And that’s still pretty close, as far as the universe goes. The image above shows the spiral galaxy NGC 5643, which is about 60 million light-years away! That means we see it as it was about 60 million years ago.
As telescopes look deeper into the universe, they capture snapshots in time from different cosmic eras. Astronomers can stitch those snapshots together to unravel things like galaxy evolution. The closest ones are more mature; we see them nearly as they truly are in the present day because their light doesn’t have to travel as far to reach us. We can’t rewind those galaxies (or our own), but we can get clues about how they likely developed. Looking at galaxies that are farther and farther away means seeing these star cities in ever earlier stages of development.
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The farthest galaxies we can see are both old and young. They’re billions of years old now, and the light we receive from them is ancient since it took so long to traverse the cosmos. But since their light was emitted when the galaxies were young, it gives us a view of their infancy.
This animation is an artist’s concept of the big bang, with representations of the early universe and its expansion.
Comparing how fast objects at different distances are moving away opened up the biggest mystery in modern astronomy: cosmic acceleration. The universe was already expanding as a result of the big bang, but astronomers expected it to slow down over time. Instead, it’s speeding up!
The universe’s expansion makes it tricky to talk about the distances of the farthest objects. We often use lookback time, which is the amount of time it took for an object’s light to reach us. That’s simpler than using a literal distance, because an object that was 10 billion light-years away when it emitted the light we received from it would actually be more than 16 billion light-years away right now, due to the expansion of space. We can even see objects that are presently over 30 billion light-years from Earth, even though the universe is only about 14 billion years old.
This James Webb Space Telescope image shines with the light from galaxies that are more than 13.4 billion years old, dating back to less than 400 million years after the big bang.
Our James Webb Space Telescope has helped us time travel back more than 13.4 billion years, to when the universe was less than 400 million years old. When our Nancy Grace Roman Space Telescope launches in a few years, astronomers will pair its vast view of space with Webb’s zooming capabilities to study the early universe in better ways than ever before. And don’t worry – these telescopes will make plenty of pit stops along the way at other exciting cosmic destinations across space and time.
Learn more about the exciting science Roman will investigate on X and Facebook.
Make sure to follow us on Tumblr for your regular dose of space!
#NASA#astronomy#telescope#Roman Space Telescope#dark energy#galaxies#cosmology#astrophysics#stars#galaxy#Hubble#Webb#Chandra#Spitzer#space images#Youtube
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This image of the Horsehead Nebula from NASA’s James Webb Space Telescope focuses on a portion of the horse’s “mane” that is about 0.8 light-years in width. It was taken with Webb’s NIRCam (Near-infrared Camera). The ethereal clouds that appear blue at the bottom of the image are dominated by cold, molecular hydrogen. Red-colored wisps extending above the main nebula represent mainly atomic hydrogen gas.
Credit: NASA
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Looking Beyond the Veil This image from NASA’s James Webb Space Telescope’s NIRCam (Near-Infrared Camera) of star-forming region NGC 604 shows how stellar winds from bright, hot young stars carve out cavities in surrounding gas and dust.
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The Tarantula Nebula
A nursery of stars, caught in NASA's Webb.
In this mosaic image stretching 340 light-years across, Webb’s Near-Infrared Camera (NIRCam) displays the Tarantula Nebula star-forming region in a new light, including tens of thousands of never-before-seen young stars that were previously shrouded in cosmic dust. The most active region appears to sparkle with massive young stars, appearing pale blue.
#james webb space telescope#The Tarantula Nebula#NASA#nasa photos#nasa picture of the day#nasawebb#space#deep space#space telescope
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2023 November 9
M1: The Crab Nebula Image Credit: NASA, ESA, CSA, STScI; Tea Temim (Princeton University)
Explanation: The Crab Nebula is cataloged as M1, the first object on Charles Messier's famous 18th century list of things which are not comets. In fact, the Crab is now known to be a supernova remnant, debris from the death explosion of a massive star witnessed by astronomers in the year 1054. This sharp image from the James Webb Space Telescope’s NIRCam (Near-Infrared Camera) and MIRI (Mid-Infrared Instrument) explores the eerie glow and fragmented strands of the still expanding cloud of interstellar debris in infrared light. One of the most exotic objects known to modern astronomers, the Crab Pulsar, a neutron star spinning 30 times a second, is visible as a bright spot near the nebula's center. Like a cosmic dynamo, this collapsed remnant of the stellar core powers the Crab's emission across the electromagnetic spectrum. Spanning about 12 light-years, the Crab Nebula is a mere 6,500 light-years away in the head-strong constellation Taurus.
∞ Source: apod.nasa.gov/apod/ap231109.html
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Jupiter in ultraviolet
Auroras and hazes glow in this composite image of Jupiter taken by the James Webb Space Telescope’s Near-Infrared Camera (NIRCam). NIRCam has three specialized infrared filters that showcase details of the planet.
#astronomy#astrophotography#astro community#science#photography#cosmos#solar system#space#jupiter#james webb space telescope#nasa#nasa photos#nasa jpl
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Many of the gorgeous space images that you see from the James Webb Space Telescope come from the Near-Infrared Camera (NIRCam). It provides high-resolution imaging and spectroscopy for a wide variety of scientific investigations. What can NIRCam “see” in space? https://webbtelescope.pub/4dEjG67
#space#astronomy#stsci#science#nasa#universe#nasawebb#james webb space telescope#webb#webb telescope#webb space telescope#nircam
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NASA’s Webb provides another look into galactic collisions
mile for the camera! An interaction between an elliptical galaxy and a spiral galaxy, collectively known as Arp 107, seems to have given the spiral a happier outlook thanks to the two bright “eyes” and the wide semicircular “smile.” The region has been observed before in infrared by NASA’s Spitzer Space Telescope in 2005, however NASA’s James Webb Space Telescope displays it in much higher resolution. This image is a composite, combining observations from Webb’s MIRI (Mid-Infrared Instrument) and NIRCam (Near-Infrared Camera).
NIRCam highlights the stars within both galaxies and reveals the connection between them: a transparent, white bridge of stars and gas pulled from both galaxies during their passage. MIRI data, represented in orange-red, shows star-forming regions and dust that is composed of soot-like organic molecules known as polycyclic aromatic hydrocarbons. MIRI also provides a snapshot of the bright nucleus of the large spiral, home to a supermassive black hole.
The spiral galaxy is classified as a Seyfert galaxy, one of the two largest groups of active galaxies, along with galaxies that host quasars. Seyfert galaxies aren’t as luminous and distant as quasars, making them a more convenient way to study similar phenomena in lower energy light, like infrared.
This galaxy pair is similar to the Cartwheel Galaxy, one of the first interacting galaxies that Webb observed. Arp 107 may have turned out very similar in appearance to the Cartwheel, but since the smaller elliptical galaxy likely had an off-center collision instead of a direct hit, the spiral galaxy got away with only its spiral arms being disturbed.
The collision isn’t as bad as it sounds. Although there was star formation occurring before, collisions between galaxies can compress gas, improving the conditions needed for more stars to form. On the other hand, as Webb reveals, collisions also disperse a lot of gas, potentially depriving new stars of the material they need to form.
Webb has captured these galaxies in the process of merging, which will take hundreds of millions of years. As the two galaxies rebuild after the chaos of their collision, Arp 107 may lose its smile, but it will inevitably turn into something just as interesting for future astronomers to study.
Arp 107 is located 465 million light-years from Earth in the constellation Leo Minor.
The James Webb Space Telescope is the world’s premier space science observatory. Webb is solving mysteries in our solar system, looking beyond to distant worlds around other stars, and probing the mysterious structures and origins of our universe and our place in it. Webb is an international program led by NASA with its partners, ESA (European Space Agency) and CSA (Canadian Space Agency).
TOP IMAGE: This composite image of Arp 107, created with data from the James Webb Space Telescope’s NIRCam (Near-Infrared Camera) and MIRI (Mid-Infrared Instrument), reveals a wealth of information about the star-formation and how these two galaxies collided hundreds of million years ago. Credit NASA, ESA, CSA, STScI
LOWER IMAGE: This image of Arp 107, shown by Webb’s MIRI (Mid-Infrared Instrument), reveals the supermassive black hole that lies in the center of the large spiral galaxy to the right. This black hole, which pulls much of the dust into lanes, also display’s Webb’s characteristic diffraction spikes, caused by the light that it emits interacting with the structure of the telescope itself. Credit NASA, ESA, CSA, STScI
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Crab Nebula, taken by the James Webb Space Telescope’s NIRCam (Near-Infrared Camera) & MIRI (Mid-Infrared Instrument)
Published by NASA 10/30/23
#photography#space#telescope#james webb space telescope#nebula#crab nebula#universe#stars#infrared#astronomy#galaxies#discovery#science#nasa
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An image captured by the James Webb Space Telescope shows Arp 107, a pair of interacting galaxies. The spiral galaxy UGC 5984 (or PGC 32620) and the elliptical galaxy MCG +05-26-025 (or PGC 32628) will eventually merge. The Arp 107 pair was already studied several times with various telescopes but the combination of the MIRI (Mid-Infrared Instrument) and NIRCam (Near-Infrared Camera) instruments allowed to capture many new details of the star formation activity triggered by the interaction between the two galaxies.
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James Webb Telescope Unveils Cosmic Seahorse and Gravitational Lensing
Webb Gravitational Lensing
NASA’s James Webb Space Telescope has captured a mesmerizing image that reveals a cosmic phenomenon known as gravitational lensing. In this captivating image, distant galaxies are magnified, distorted, and brightened due to the gravitational pull of a foreground galaxy cluster. Among the intriguing features highlighted in the image is a galaxy nicknamed the “Cosmic Seahorse,” presenting a long,…
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#Ariane 5 rocket#Cosmic Microwave Background#Deep space observations#Exoplanets#Fine Guidance Sensor/Near InfraRed Imager and Slitless Spectrograph (FGS/NIRISS)#Galaxy formation#Hubble Space Telescope successor#Infrared Astronomy#Infrared detectors#James Webb Space Telescope (JWST)#Launch#Mid-Infrared Instrument (MIRI)#Mirror segments#Multi-object spectroscopy#NASA#Near InfraRed Spectrograph (NIRSpec)#Near-Infrared Camera (NIRCam)#Space telescope#Stellar populations#Sunshield#Transiting exoplanets#Universe formation and evolution#Webb Science Operations Center (JSOC)
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Quirks and features of the James Webb Space Telescope
The James Webb Space Telescope (JWST) is a ten billion dollar space telescope that weighs 14,000 pounds, is the size of a bus, and took decades to construct. It's been in the news recently, you might have heard about it.
The development, launch and deployment of the JWST were fraught with unexpected setbacks, terror and frights, 344 "single-point failures", any one of which that, if they failed during deployment, could doom the entire spacecraft to uselessness, since it orbits far out beyond where any current manned spacecraft could even attempt a repair job.
The fact that it came online as smoothly as it did was something of a surprise to the people in charge. Given the miracle of it making it to space at all, the press coverage of JWST has focused on the positives. But a stroll through the JWST user documentation by a curious reader reveals much that is interesting, or interestingly broken. Such as..
Fun and games with infrared
Specifically, the JWST is an infrared telescope, designed to collect light that's redder than red. The two dedicated imaging instruments are the Near Infrared Camera (NIRCam) collecting light from 0.6 micrometers to 5.0 micrometers and the Mid-Infrared Instrument (MIRI) collecting light from 5.6 micrometers to 25.5 micrometers. (Though with significant light collected past 25.5 um by filter F2550W)
The wonderful thing about infrared astronomy is that everything emits blackbody radiation, and the hotter it is the more infrared it emits. The unfortunate thing about infrared astronomy is that everything emits blackbody radiation, including your telescope, and self-emission from your telescope can swamp the faint signal from astronomical sources. (Like building a camera out of glowsticks.)
The equilibrium temperature for an object in Earth orbit is about 300 Kelvin. (26C) Everything on the other side of the sunshield passively cools down to 40K, and MIRI is actively cooled by the cryocooler down to a chilly 6K (-267C, -449F) This extends MIRI's seeing range deeper into infrared.
But the mirror is still warm! At the far end, MIRI is significantly compromised by thermal self-emission: (Note log scale!)
This is more graphically illustrated by one of the MIRI commissioning images:
Check out that background glare!
(This is somewhat unfair: the calibration target here is a star, which emits comparatively little light in far-infrared. MIRI is really meant for nebulae and extra-galactic high-redshift objects)
("Why not actively cool the mirror?" Mechanical cryocoolers operate on the very limit of what heat engines are capable of. The MIRI cryocooler draws a fat 180 watts to move 78 milliwatts of heat. Previous infrared telescopes used a fixed amount of expendable coolant (liquid helium or solid hydrogen) to cool the entire instrument package... at the cost of a much smaller primary mirror and a telescope that flat out just stopped working when it ran out of coolant.)
There's something else you might notice about the above series of photographs...
Thanks a lot, Lord Rayleigh
John William Strutt, 3rd Baron Rayleigh was a typical early physicist in that he has a great big pile of "discoveries" by virtue of being the first person to 1) notice something and 2) actually write it down. One of them is the fundamental theorem for the angular resolution of an optical system, the Rayleigh criterion. It is dead simple:
Resolution is roughly equal to 1.22 times the wavelength of the light you're looking at, divided by the diameter of the aperture. Bigger the opening at the front of light bucket, the higher the resolution. Smaller the wavelength of light, the higher the resolution.
(Fun fact: the former Arecibo radio observatory, once the largest single telescope in the world with a 305 meter wide dish, had about the same angular resolution in radio waves as the human eye does in visible light.)
You can imagine the effect this has on an infrared telescope. And sure enough, in the user documentation for the two imaging sensors, it states a pixel scale of 0.031 arcseconds for 0.6 to 2.3 micrometers light wavelength, 0.063 arcsec/px for 2.4-5.0 µm, and a squishy 0.11 arcsec/px for 5.6-25.5 µm.
But this is just how many pixels are on the detector. The resolution gets much worse at long wavelengths, as you can see in the commissioning image, where the extra pixels oversample a progressively vaguer blob. The Rayleigh criterion holds that the 6.5 meter wide JWST primary mirror should manage 0.206 arcsec at 5.32 µm, falling to 0.42 arcsec at 10.85 µm, 0.747 arcsec at 19.29 µm, and an unfortunate 1.014 arcsec at 26.2 µm. One wonders why the designers went to heroic lengths to cool MIRI down to 7 kelvin, instead of using that cryocooler mass and power budget for more detector surface area.
Knowing this, you can spot how the JWST's press team works around the limitations of the telescope. Like how a "look at how good our infrared telescope" commissioning photo happens to use the 7.7 µm mode:
Or how if you browse the photos on the webbtelescope.org site, you will see lots of NIRcam output in the "oooh, ah, new desktop background" category, but not so much MIRI.
(Another amusing detail of MIRI is that bright objects leave afterimages ("latents") on the sensor, so once a week they warm the sensor up to a tropical 20 kelvin before cooling it down again, a "MIRI anneal". You can see when anneals are performed, as well as what the telescope is looking at right now, by viewing the public schedule.)
But this is Webb operating right up to its full specifications. How about something that's actually broken?
NIRSpec my beloved
The Near-Infrared Spectrograph (NIRSpec) instrument takes incoming light and runs it through a diffraction grating to produce a spectrum. When scientists say that the Sun is 0.77% oxygen, 0.29% carbon, etc, it's not because someone flew a spacecraft over to it and collected a bucket of solar plasma, it's because you can look at the absorption lines in the spectra to figure out its composition.
Spectrometry is also used to measure redshift, a close proxy to distance. When a press release says that a galaxy is "ten million lightyears away", it's not because NASA has a really long tape measure they haven't told anyone about, it's because a spectrometer measured how much cosmological redshift has moved a spectrum line. Naturally, it's not quite as easy as pointing a sensor at a object and getting back a single, unambiguous result. Distant objects are also dim objects, so the spectra will be noisy and chewed up by dust and other contamination its endured in the millions of years its traveled to arrive at our telescopes. Bleeding edge astronomy is thus the practice of designing statistical models to fit to noisy, fragmented data, and then arguing with other astronomers about r^2.
In any event, it's a handy thing to have on a telescope. Naturally, JWST has more than one. In fact every instrument has a spectroscopy mode. Besides the dedicated NIRISS and NIRSpec instruments, both NIRcam and MIRI include diffraction gratings in their filter wheels that smear out incoming light, like looking through a prism:
Pointing the JWST at an object is relatively expensive, since it requires rotating ("slewing") the entire darn spacecraft, and an amusingly complex alignment procedure with the fine guidance sensor and fine steering mirror. Considering how long it would take to shoot a hundred spectra with a conventional fixed slit rigidly mounted to the telescope frame, you can see the appeal of gathering a hundred spectra in a single exposure with "slitless" spectroscopy.
(Longtime space telescope nerds might hear the word "slewing" and involuntarily twitch, recalling that the reaction wheels and gyroscopes were a problem point on the Hubble, requiring several servicing missions, and also significantly affecting operations on the Kepler space telescope. Fortunately, JWST switched to a gyroscope type that has no moving parts, and used some mass budget to install six reaction wheels, up from Hubble's four, giving it three spares.)
You can also see the big downside in the image above, which is there's a hard tradeoff between how long a spectrum can be (and thus its resolution!) before it'll overlap its neighbors and be useless. Most of the slitless modes therefore have two gratings at two different angles, (GRISMR and GRISMC above) but wouldn't it great if you could just block out all that other light?
Thus, the Micro Shutter Array, as seen above. The best of both worlds! Capture many spectra at the same time, while blocking off light you don't want from contaminating the field, using a configurable array of nearly a quarter million microscopic, individually actuated moving shutters.
Lots and lots and lots of tiny little moving parts, installed in the guts of a spacecraft that's orbiting out past the Moon, impossible to access or replace.
Yeah, a bunch of them broke:
When it was handed over to NASA for installation into Webb in 2007, the MSA already had 150 shutters that no longer responded to opening commands in just one of the four submodules.
By the time JWST emerged from commissioning and was declared fully operational in 2022, 15,893 shutters, 7% of the total, had "failed closed." Hilariously, 904 of those failed during post-launch testing, and the authors of that paper note that, on average, if you tell 100 shutters to close, 4 of them will jam shut and no longer work.
This is unfortunate, but fairly easy to work around. What's worse are the shutters that are stuck open:
These permanently open shutters then compromise big chunks of the sensor. Commissioning testing jammed two more of them open, taking the total up to 22. You can imagine that if a few dozen more of these fail-open during routine operation then the entire microshutter array observation mode won't be much more useful than regular slitless spectrography.
And this, right here, sums up the essentially "interim" nature of JWST. After all, it was only supposed to cost $500 million and take a mere nine years from design to launch. All becomes clear in that light. Why give it a shutter array that falls apart in use? Why have the mirror exposed to space, where it gets hit with micrometeoroids? Why only design it to carry ten years worth of fuel? Because it was supposed to be half the price of Hubble!
The 90s was the era of "faster, better, cheaper". JWST was going to be an incremental improvement on a long series of previous infrared telescopes, and a stepping stone to the next one. It wasn't supposed to be an eternal monument to Science, and a financial black hole consuming NASA's entire budget.
So what went wrong?
We shouldn't have built one JWST.
Those 344 single points of failure. Any single one of them can end the mission. There's just one telescope, no backups, no trying again. Bureaucrats are harshly punished for failure, lightly rewarded for success. It's always easier to wait, do more tests, delay the schedule a bit more at a hint of trouble. Engineers can get you to 90% reliable no problem, but getting to 99% reliable takes another decade and nine billion more dollars.
Our techne is just bad at producing flawless machines first try. For the price of one reliable JWST we could have put twenty into orbit... but the first five would have been embarrassing failures. Spars sticking in place, sunshields jamming, thrusters misfiring. To save the shame of $0.5 billion wasted, NASA happily spent $9.5 billion. Why not? Because money spent is invisible, but failure is painfully apparent.
A critical third party can draw unflattering parallels. The crowning achievement of NASA, the Moon Landing... required eleven Apollo launches and twenty Surveyor launches before a single man set foot on lunar regolith! Quite a few of those spacecraft pancaked into the Moon and exploded on the launchpad before we figured out this "space" thing. Three men died! But NASA was on a hard deadline, with a fixed budget, and the only way to get a home run is to take a lot of swings at the ball.
Another comparison is the Space Launch System, NASA's attempt to make the Saturn V again. So far $27 billion has been lit on fire to put exactly one test load into orbit, with the primary contractor now desperate to get out of its contact. Slow, careful, incremental development has completely failed to produce a working launch system.
Meanwhile, SpaceX produced a series of public, embarrassing failures... resulting in the world's only reusable launch system, and as a result has put far more mass into orbit than any country in the world.
The only way to develop a flight system is flight tests.
Space telescope deploy mechanisms meant to work in zero gravity can't be tested on the ground.
They can only be tested in space.
NASA administrators who didn't work during Apollo are too stupid to understand this. Fire them all!
These geriatrics have happily sacrificed science in order to play it safe and secure their own easy retirement. Do we want 15 risky JWST telescopes by 2010, or do we want one reliable one by 2022? The answer is obvious!
For the money we wasted making Webb more reliable, we could have launched a space telescope far outside the disk of dust in the inner solar system, allowing it to see deeper into space than Webb ever could. ESA put an astrometry space telescope just outside Earth orbit, measuring angles between stellar objects, which is the only way to directly measure the distance to the stars. Great first step. The obvious next step is to send more of these telescopes out past Neptune's orbit, to capture better observations with a vastly larger baseline, something that can never be done by an Earthly observatory. Are there any plans to do this? No!
Space exploration is paralyzed by boomers, mired in the mental tarpit of the 1970s, where each gram to orbit is terribly expensive and must be counted on punched cards and summed with slide rules. Meanwhile, SpaceX Starship is on its way to orbit, and each one can carry sixteen JWSTs with room to spare!
The old paradigm is done. Telescopes don't need folding mirrors and exotic materials, they need to be mass produced. There is no excuse not to have a hundred more JWST-class telescopes lined up next to the Texas launch pad waiting for Starship to come online. But as far as I know not a single space mission even mentions it-- that's how afraid they are of risk!
The JWST, with its myriad of fragile components and its staggering price tag, stands as a monument not to our ingenuity but to our inability to let go of outdated ideals.
We must abandon the notion that space is a realm reserved for the flawless and the infallible. Instead, we should embrace the chaos, the unpredictability, the sheer messiness of exploration. Let us launch a thousand telescopes, each a patchwork of parts, each destined to fail in its own spectacular way. For it is only in this embrace of the ephemeral that we can find out what actually works!
Let the JWST be the last of its kind, a relic of a bygone era. The future is unwritten, and it is ours to fill with a symphony of failures, each note a step closer to the stars.
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NASA’s James Webb Space Telescope has observed the well-known Ring Nebula in unprecedented detail. Formed by a star throwing off its outer layers as it runs out of fuel, the Ring Nebula is an archetypal planetary nebula. This new image from Webb’s NIRCam (Near-Infrared Camera) shows intricate details of the filament structure of the inner ring. There are some 20,000 dense globules in the nebula, which are rich in molecular hydrogen. In contrast, the inner region shows very hot gas. The main shell contains a thin ring of enhanced emission from carbon-based molecules known as polycyclic aromatic hydrocarbons (PAHs).
Credit: ESA/Webb, NASA, CSA, M. Barlow (University College London), N. Cox (ACRI-ST), R. Wesson (Cardiff University)
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