Tag: Webb

Webb’s mid-infrared instrument restored to full operations

9:16 am

Engineers have figured out the issue on the mid-infrared instrument on the Webb Space Telescope that was causing increased friction during operations, and are now ready to return it to full operations.

The team concluded the issue is likely caused by increased contact forces between sub-components of the wheel central bearing assembly under certain conditions. Based on this, the team developed and vetted a plan for how to use the affected mechanism during science operations.

An engineering test was executed Wednesday, Nov. 2, that successfully demonstrated predictions for wheel friction. Webb will resume MIRI MRS science observations by Saturday, Nov. 12.

Webb has three other infrared instruments, looking at different infrared wavelengths, so this issue had not prevented the telescope from doing most of its observations. Losing MIRI however would have been a very bad blow, this soon after launch.

Leave a comment

Rate of micrometeorite impacts on Webb holding as expected

10:10 am

According to this Space.com article, the rate and size of micrometeorite impacts on the main mirror of the Webb Space Telescope has held steady at the rate and size expected, since the first surprisingly large micrometeorite impact in May that slightly dinged one mirror segment.

At this point, JWST has experienced a total of 33 micrometeoroid events, according to Smith’s slides. But the most damaging one came before JWST began science observations; in late May, a particularly large micrometeoroid struck the observatory’s mirror, leaving its mark on one golden hexagon. The team estimates that a strike of that size should occur about once a year, Smith said.

“So we got that at month five,” he said. “We haven’t seen another one yet, so it’s still consistent with the statistics that we expected.”

Smith noted that, at the current impact rate, Webb will still be meeting its five-year performance requirement 10 years into the mission. Scientists estimate that the observatory has enough fuel to operate for 20 years.

Meanwhile, one of Webb’s infrared cameras is not doing spectroscopy as engineers analyze the high levels of friction in a “grating wheel.” At this point it appears they still do not understand the cause of the friction, and thus have not come up with a plan for mitigating it.

Leave a comment

Webb takes infrared image of Hubble’s Pillars of Creation

10:28 am

The Pillars of Creation, as seen by Hubble and Webb
Click for original image.

Not unexpectedly, astronomers have quickly begun aiming the Webb Space Telescope’s infrared eye at some of the most famous targets previously imaged in optical wavelengths by the Hubble Space Telescope.

The newest example is shown to the right and reduced and labeled to post here. It shows what NASA officials dubbed “The Pillars of Creation” when Hubble first photographed this nebula in 1995, with a later 2014 Hubble optical image at the top and the new 2022 Webb infrared image on the bottom. From this image’s caption:

A new, near-infrared-light view from NASA’s James Webb Space Telescope, at [bottom], helps us peer through more of the dust in this star-forming region. The thick, dusty brown pillars are no longer as opaque and many more red stars that are still forming come into view.

While the pillars of gas and dust seem darker and less penetrable in Hubble’s view [top], they appear more diaphanous in Webb’s. The background of this Hubble image is like a sunrise, beginning in yellows at the bottom, before transitioning to light green and deeper blues at the top. These colors highlight the thickness of the dust all around the pillars, which obscures many more stars in the overall region.

In contrast, the background light in Webb’s image appears in blue hues, which highlights the hydrogen atoms, and reveals an abundance of stars spread across the scene. By penetrating the dusty pillars, Webb also allows us to identify stars that have recently – or are about to – burst free. Near-infrared light can penetrate thick dust clouds, allowing us to learn so much more about this incredible scene.

While the Hubble colors attempt to mimic the colors seen by the human eye, the colors in the Webb image are all false colors, chosen by the scientists to distinguish the different infrared wavelengths produced by different features in the picture.

2 comments

Shells of dust surrounding massive binary star

10:07 am

Webb infrared image of dust shells surrounding binary star system
Click for full image.

Cool image time! Using the Webb telescope, astronomers have detected a series of concentric shells surrounding the massive binary star dubbed Wolf-Rayet 140.

The infrared image to the right shows these shells quite clearly. As noted by astronomer Ryan Lau:

“On the night that my team’s Early Release Science observations of the dust-forming massive binary star Wolf-Rayet (WR) 140 were taken, I was puzzled by what I saw in the preview images from the Mid-Infrared Instrument (MIRI). There seemed to be a strange-looking diffraction pattern, and I worried that it was a visual effect created by the stars’ extreme brightness. However, as soon as I downloaded the final data I realized that I was not looking at a diffraction pattern, but instead rings of dust surrounding WR 140 – at least 17 of them.

“I was amazed. Although they resemble rings in the image, the true 3D geometry of those semi-circular features is better described as a shell. The shells of dust are formed each time the stars reach a point in their orbit where they are closest to each other and their stellar winds interact. The even spacing between the shells indicates that dust formation events are occurring like clockwork, once in each eight-year orbit. In this case, the 17 shells can be counted like tree rings, showing more than 130 years of dust formation. Our confidence in this interpretation of the image was strengthened by comparing our findings to the geometric dust models by Yinuo Han, a doctoral student at the University of Cambridge, which showed a near-perfect match to our observations.

Furthermore, the spectroscopy from Webb says these dust shells are carbon-enriched, showing that the dust released by these aged massive stars is a significant source of the carbon in the universe, the fundamental atom needed for life.

5 comments

Webb gets first direct infrared image of exoplanet

10:21 am

Exoplanet as seen in the infrared by Webb

Using the Webb Space Telescope, scientists have obtained that telescope’s first direct infrared image of an exoplanet, covering four different wavelengths.

The image to the right is from the wavelength image with the least distortion (formed by Webb’s own optics and the shape of its mirror and indicated by the faint ring surrounding the planet). The star indicates the masked location of the star itself.

The planet is about seven times the mass of Jupiter and lies more than 100 times farther from its star than Earth sits from the sun, direct observations of exoplanet HIP 65426 b show. It’s also young, about 10 million or 20 million years old, compared with the more than 4-billion-year-old Earth.

You can download the full research paper here.

One comment

Chandra takes an X-ray look at early Webb infrared observations

9:54 am

Chandra's X-ray vision of the Cartwheel Galaxy
Chandra’s X-ray view of the Cartwheel Galaxy

Webb's view of the Cartwheel Galaxy
Webb’s infrared view of the Cartwheel Galaxy
Click for full image.

Hubble's optical view of the Cartwheel Galaxy
Hubble’s optical view of the Cartwheel Galaxy. Click for original image.

Astronomers have now taken X-ray images using the orbital Chandra X-ray Observatory of four of the first Webb Space Telescope observations. The four targets were the Cartwheel Galaxy, Stephan’s Quintet, galaxy cluster SMACS 0723.3–7327, and the Carina Nebula.

The three images to the right illustrate the importance of studying astronomy across the entire electromagnetic spectrum. Each shows the Cartwheel Galaxy as seen by three of the world’s most important space-based telescopes, each looking at the galaxy in a different wavelength.

The top picture is Chandra’s new X-ray observations. As the press release notes,

Chandra data generally show higher-energy phenomena (like superheated gas and the remnants of exploded stars) than Webb’s infrared view. … X-rays seen by Chandra (blue and purple) come from superheated gas, individual exploded stars, and neutron stars and black holes pulling material from companion stars.

The middle picture was produced by Webb, shortly after the start of its science operations. It looks at the galaxy in the infrared.

In this near- and mid-infrared composite image, MIRI data are colored red while NIRCam data are colored blue, orange, and yellow. Amidst the red swirls of dust, there are many individual blue dots, which represent individual stars or pockets of star formation. NIRCam also defines the difference between the older star populations and dense dust in the core and the younger star populations outside of it.

The bottom picture was taken by the Hubble Space Telescope in 1995. I have rotated the image to match the others. It looks at the galaxy in optical wavelengths, the wavelengths that our eyes perceive.

Note how bright the central galactic region is in the infrared and optical, but is invisible in X-rays. Chandra is telling us that all the most active regions in the Cartwheel are located in that outer ring, not in its center.

2 comments

Initial Webb results revised because telescope wasn’t yet fully calibrated

10:02 am

The uncertainty of science: Though it appears that no results will have to be abandoned, the scientists who published some of the very first results from the Webb Space Telescope have been scrambling to adjust and revise their papers because the telescope is only now getting fully calibrated.

“This caused a little bit of panic,” says Nathan Adams, an astronomer at the University of Manchester, UK, who, along with his colleagues, pointed out the problem in a 9 August update to a preprint they had posted in late July3. “For those including myself who had written a paper within the first two weeks, it was a bit of — ‘Oh no, is everything that we’ve done wrong, does it all need to go in the bin?’”

To try to standardize all the measurements, the STScI is working through a detailed plan to point Webb at several types of well-understood star, and observe them with every detector in every mode for every instrument on the telescope4. “It just takes a while,” says Karl Gordon, an astronomer at the STScI who helps lead the effort.

In the meantime, astronomers have been reworking manuscripts that describe distant galaxies on the basis of Webb data. “Everyone’s gone back over and had a second look, and it’s not as bad as we thought,” Adams says. Many of the most exciting distant-galaxy candidates still seem to be at or near the distance originally estimated. But other preliminary studies, such as those that draw conclusions about the early Universe by comparing large numbers of faint galaxies, might not stand the test of time. Other fields of research, such as planetary studies, are not affected as much because they depend less on these preliminary brightness measurements.

Overall, it does not appear the more precise calibrations will change much of signficance, since most of the earliest observations were simply that, observations, not theoretical. Because the distance estimates remain largely unchanged however the theorists are left with the same conundrum: The age and apparent nature of the most distant objects does not seem to fit with what the theories had predicted Webb would see.

One comment

Hubble & Webb make first coordinated observations, tracking DART impact of Dimorphus

9:50 am

Webb and Hubble together look at DART impact of Dimorphus
Click for full image.

For the first time scientists have used both the Hubble Space Telescope and the James Webb Space Telescope to observe the same astronomical event, in this case the impact of the DART spacecraft on the asteroid Dimorphus on September 26, 2022.

The two images to the right show the asteroid several hours after impact. Both telescopes also captured images before the impact as well. From the press release:

Observations from Webb and Hubble together will allow scientists to gain knowledge about the nature of the surface of Dimorphos, how much material was ejected by the collision, and how fast it was ejected. Additionally, Webb and Hubble captured the impact in different wavelengths of light – Webb in infrared and Hubble in visible. Observing the impact across a wide array of wavelengths will reveal the distribution of particle sizes in the expanding dust cloud, helping to determine whether it threw off lots of big chunks or mostly fine dust. Combining this information, along with ground-based telescope observations, will help scientists to understand how effectively a kinetic impact can modify an asteroid’s orbit.

When Webb was first conceived in the late 1990s, it was exactly for this reason, to combine Hubble’s optical vision with Webb’s infrared view. Though more than a decade late, it has finally happened.

It will be months before scientists begin to decipher the data produced by all the telescopes and spacecraft used to observe the DART impact. What we are seeing now are merely hints at what has been learned.

10 comments

Webb’s first infrared image of Neptune

9:30 am

Webb's infrared view of Neptune
Click for full image.

The science team for the James Webb Space Telescope today released that telescope’s first infrared image of Neptune.

That image is to the right, cropped and reduced slightly to post here. It is, as the press release touts, the best view in decades of Neptune’s rings. From the caption:

The most prominent features of Neptune’s atmosphere in this image are a series of bright patches in the planet’s southern hemisphere that represent high-altitude methane-ice clouds. More subtly, a thin line of brightness circling the planet’s equator could be a visual signature of global atmospheric circulation that powers Neptune’s winds and storms. Additionally, for the first time, Webb has teased out a continuous band of high-latitude clouds surrounding a previously-known vortex at Neptune’s southern pole.

The dots around the gas giant are the heat signatures of seven of its fourteen moons.

One comment

Webb instrument has technical issue partly preventing its use

9:31 am

Because a an issue with the mid-infrared instrument (MIRI) on the James Webb Space Telescope, the telescope’s engineering team has paused use of that instrument while it reviews the situation.

On Aug. 24, a mechanism that supports one of these modes, known as medium-resolution spectroscopy (MRS), exhibited what appears to be increased friction during setup for a science observation. This mechanism is a grating wheel that allows scientists to select between short, medium, and longer wavelengths when making observations using the MRS mode. Following preliminary health checks and investigations into the issue, an anomaly review board was convened Sept. 6 to assess the best path forward.

The Webb team has paused in scheduling observations using this particular observing mode while they continue to analyze its behavior and are currently developing strategies to resume MRS observations as soon as possible. The observatory is in good health, and MIRI’s other three observing modes – imaging, low-resolution spectroscopy, and coronagraphy – are operating normally and remain available for science observations.

I am quoting almost entirely NASA’s short announcement. The announcement is vague, confusing, and (quite typically) written to minimize the reality of the issue. I can’t figure out how MIRI’s other observing modes are available if they have paused use of a mechanism that allows them to choose modes.

Regardless, Webb is awful young to have this kind of problem.

Leave a comment

Webb takes its first infrared image of Mars

9:12 am

Webb's first infrared image of Mars
Click for full image.

Astronomers have now released the the James Webb Space Telescope’s first infrared image of Mars, taken on September 5, 2022.

The image to the right, cropped and reduced to post here, shows some of the data obtained. Because Mars is so close, it is actually too bright for Webb’s instruments. To get any data, the exposures were very very short, and still the brightest areas — as indicated by large areas of yellow — are overexposed. The cause of the different brightness of Hellas Basin, however, is not simply because the basin — the deepest point on Mars — is cooler.

As light emitted by the planet passes through Mars’ atmosphere, some gets absorbed by carbon dioxide (CO2) molecules. The Hellas Basin – which is the largest well-preserved impact structure on Mars, spanning more than 1,200 miles (2,000 kilometers) – appears darker than the surroundings because of this effect. “This is actually not a thermal effect at Hellas,” explained the principal investigator, Geronimo Villanueva of NASA’s Goddard Space Flight Center, who designed these Webb observations. “The Hellas Basin is a lower altitude, and thus experiences higher air pressure. That higher pressure leads to a suppression of the thermal emission at this particular wavelength range [4.1-4.4 microns] due to an effect called pressure broadening. It will be very interesting to tease apart these competing effects in these data.”

The NASA press release says the scientists are preparing a paper analyzing the spectral data and what it revealed about “dust, icy clouds, what kind of rocks are on the planet’s surface, and the composition of the atmosphere,” I suspect however that Webb’s capabilities for studying Mars are much more limited than implied, and that it will over time take much fewer images of the red planet, compared to Hubble.

Leave a comment

Webb’s infrared view of the Tarantula Nebula

9:55 am

Two views of the Tarantula Nebula by Webb
Click for original image.

The two images to the right, reduced and annotated to post here, were released today by the science team of the James Webb Space Telescope, and show two different views of the Tarantula Nebula, located 161,000 light years away in the Large Magellanic Cloud.

It is home to the hottest, most massive stars known. Astronomers focused three of Webb’s high-resolution infrared instruments on the Tarantula. Viewed with Webb’s Near-Infrared Camera (NIRCam) [top], the region resembles a burrowing tarantula’s home, lined with its silk. The nebula’s cavity centered in the NIRCam image has been hollowed out by blistering radiation from a cluster of massive young stars, which sparkle pale blue in the image. Only the densest surrounding areas of the nebula resist erosion by these stars’ powerful stellar winds, forming pillars that appear to point back toward the cluster. These pillars contain forming protostars, which will eventually emerge from their dusty cocoons and take their turn shaping the nebula.

…The region takes on a different appearance when viewed in the longer infrared wavelengths detected by Webb’s Mid-infrared Instrument (MIRI) [bottom]. The hot stars fade, and the cooler gas and dust glow. Within the stellar nursery clouds, points of light indicate embedded protostars, still gaining mass. While shorter wavelengths of light are absorbed or scattered by dust grains in the nebula, and therefore never reach Webb to be detected, longer mid-infrared wavelengths penetrate that dust, ultimately revealing a previously unseen cosmic environment.

As with all images from Webb, these are false color, as the telescope views the infrared heat produced by stars and galaxies and interstellar clouds, not the optical light our eyes see. Thus, the scientists assign different colors to the range of wavelengths each instrument on Webb captures.

These photos once again illustrate Webb’s value. It will provide a new layer of data to supplement the basic visual information provided by the Hubble Space Telescope, allowing scientists to better understand the puzzles we see in the optical.

8 comments

Webb obtains first direct infrared images of exoplanet

9:49 am

Webb's first infrared images of an exoplanet
Click for original image.

Using four different infrared instruments on the James Webb Space Telescope, astronomers have obtained the first infrared images of a gas giant with a mass about six to twelve times larger than Jupiter and circling about 100 times farther from its sun.

The montage to the right shows these four images. The white star marks the location of this star, the light of which was blocked out to make the planet’s dim light visible. The bar shapes on either side of the planet in the NIRCam images are artifacts from the instrument’s optics, not objects surrounding the planet.

This is not the first direct image of an exoplanet, as the Hubble Space Telescope has already done so, and done it in the visible spectrum that humans use to see. However, Webb’s infrared images provide a great deal of additional detail about this planet and its immediate surroundings that optical images would not. For example, the MIRI images appear to show us the outer atmosphere of this gas giant.

One comment

Webb’s infrared view of a face-on spiral galaxy

9:44 am

M74, as seen by Webb and Hubble combined
Click for original image.

Using the James Webb Space Telescope, astronomers have produced a false-color infrared view of M74, a face-on spiral galaxy located 32 million light years away.

The montage above shows that image to the right, with a Hubble optical image to the left. In the center both images are combined.

The addition of crystal-clear Webb observations at longer wavelengths will allow astronomers to pinpoint star-forming regions in the galaxies, accurately measure the masses and ages of star clusters, and gain insights into the nature of the small grains of dust drifting in interstellar space.

Because infrared can see through cold dust, it provides a much sharper view of this galaxy’s central regions.

7 comments

Webb detects carbon dioxide in atmosphere of exoplanet

8:42 am

Scientists using the James Webb Space Telescope have detected carbon dioxide in the atmosphere of a hot gas giant exoplanet about 700 light years away.

WASP-39 b is a hot gas-giant with a mass roughly one-quarter that of Jupiter (about the same as Saturn) and a diameter 1.3 times greater than Jupiter. Its extreme puffiness is partly related to its high temperature (about 900° Celsius or 1170 Kelvin). Unlike the cooler, more compact gas giants in our solar system, WASP-39 b orbits very close to its star – only about one-eighth the distance between the Sun and Mercury – completing one circuit in just over four Earth-days. The planet’s discovery, reported in 2011, was made based on ground-based detections of the subtle, periodic dimming of light from its host star as the planet transits or passes in front of the star.

Previous observations from other telescopes, including the Hubble and Spitzer space telescopes, revealed the presence of water vapour, sodium, and potassium in the planet’s atmosphere. Webb’s unmatched infrared sensitivity has now confirmed the presence of carbon dioxide on this planet as well.

This is only the beginning. Astronomers have told me repeatedly that the most important area of research in astronomy in the next few decades will be the study of known exoplanets and their make-up. Webb is now a new tool in that effort. Combined with other telescopes looking at other wavelengths scientists will be able to identify a whole range of molecules in the atmospheres of these transiting exoplanets. We will begin to get our first glimpse into what other solar systems are like.

One comment

Another Webb infrared image of Jupiter released

8:53 am

Jupiter as seen in the infrared by Webb
Click for original image.

The science team for the James Webb Space Telescope today released another infrared false-color image of Jupiter, this time processed for science instead of calibration of the telescope after launch.

That image is to the right, reduced to post here. From the caption:

Several exposures in three different filters were assembled to create this mosaic, after being corrected for the rotation of the planet. The combination of filters yields an image whose colors denote the height of the clouds and the intensity of auroral emissions.

The F360M filter (mapped to the red-orange colors) is sensitive to light reflected from the lower clouds and upper hazes. The red features in the polar regions are auroral emissions, caused by ions excited through collisions with charged particles at altitudes up to 1000 km above the cloud level. Auroral emission in red is evident in the northern and southern polar regions and reaches high above the limb of the planet. In the F212N filter (mapped to yellow-green colors), the gaseous methane in Jupiter’s atmosphere absorbs light; the greenish areas around the polar regions come from stratospheric hazes 100-200 km above the cloud level. The stratospheric haze that appears green in this composite is also concentrated in the polar regions, but extends down to equatorial latitudes and can also be seen along the limbs (edges) of the planet. The cyan channel holds the F150W2 filter, which is primarily sensitive to reflected light from the Jupiter’s deeper main cloud level at about one bar.

The Great Red Spot, the hazy equatorial region and myriad small storm systems appear white (or reddish-white) in this false-color image. Regions with little cloud cover appear as dark ribbons north of the equatorial region. Some dark regions — for example, those next to the Great Red Spot and in cyclonic features in the southern hemisphere — are also dark-colored when observed in visible wavelengths.

This image is part of the telescope’s early release science program.

7 comments

First Webb infrared image of Cartwheel Galaxy

9:13 am

Webb's view of the Cartwheel Galaxy
Click for full image.

Scientists today have released a new infrared image of the Cartwheel Galaxy, taken by two instruments on the James Webb Space Telescope. That image is to the right, reduced to post here. From the caption:

In this near- and mid-infrared composite image, MIRI data are colored red while NIRCam data are colored blue, orange, and yellow. Amidst the red swirls of dust, there are many individual blue dots, which represent individual stars or pockets of star formation. NIRCam also defines the difference between the older star populations and dense dust in the core and the younger star populations outside of it.

The galaxy, located about a half billion light years away, is one of the more well known astronomical objects due to its unusual shape, believed caused by a collision with a smaller galaxy sometime in the past. Earlier this year for example astronomers discovered a supernovae had exploded in the galaxy sometime in 2021. To see a 1995 Hubble optical image, go here.

This Webb image reveals many new details previously obscured by dust.

2 comments

Another Webb galaxy found even closer to the Big Bang

9:54 am

A galaxy formed only 250 million years after the universe formed

Using data from the first Webb deep field, astronomers have identified another galaxy in that image that apparently was able to form less than 250 million years after the the Big Bang, the theorized beginning of the universe.

Like the distant galaxies described last week, it also appears to have the equivalent of a billion Suns of material in the form of stars. The researchers estimate that it might have started star formation as early as 120 million years after the Big Bang, and had certainly done so by 220 million years.

You can read the actual research paper here [pdf]. The image of the galaxy to the right is taken from figure 4 of the paper. From its abstract:

We provide details of the 55 high-redshift galaxy candidates, 44 of which are new, that have enabled this new analysis. Our sample contains 6 galaxies at z≥12, one of which appears to set a new redshift record as an apparently robust galaxy candidate at z≃16.7.

The speed in which this galaxy formed places a great challenge on the Big Bang theory itself. 220 million years is an instant when it comes to galaxy formation, which has been assumed to take far longer. Either galaxy formation is a much faster process than expected, or something is seriously wrong with the timing of the Big Bang theory itself.

7 comments

The earliest galaxy so far seen?

10:37 am

Earliest galaxy?

Scientists using the James Webb Space Telescope now think they have identified a galaxy formed only 330 million years after the Big Bang.

The red smudge in the centre of this image [to the right] is thought to be a galaxy with a redshift of around z=13, as seen by the NIRCam instrument on the James Webb Space Telescope. This redshift estimate is based on photometry so the object remains a candidate rather than a confirmed high-redshift galaxy, but if confirmed spectroscopically this would be the highest-redshift galaxy yet observed.

You can read the research paper itself here [pdf]. The galaxy is actually very young, and its nature, along with a second also described by the research, appears to contradict expectations. From the paper’s abstract:

These sources, if confirmed, join GNz11 in defying number density forecasts for luminous galaxies based on Schechter UV luminosity functions, which require a survey area > 10× larger than we have
studied here to find such luminous sources at such high redshifts. They extend evidence from lower redshifts for little or no evolution in the bright end of the UV luminosity function into the cosmic dawn epoch, with implications for just how early these galaxies began forming. This, in turn, suggests that future deep JWST observations may identify relatively bright galaxies to much earlier epochs than might have been anticipated. [emphasis mine]

In other words, this early data from Webb suggests that galaxies formed much faster than expected after the Big Bang. This either means all the theories describing the Bang are wrong, or that it might not have even happened.

16 comments

The May micrometeoroid impact on Webb’s mirror

9:37 am

Figure 3 from report

In a detailed report [pdf] of Webb’s overall excellent operational status following its in-space commissioning, the science team also included an analysis of the May 2022 micrometeoriod impact on one segment of Webb’s mirror.

The image to the right, taken from figure 3 of the report, shows the remaining alignment error of Webb’s entire mirror, after alignment. Except for that one bright spot in the segment to the lower right, all of the segments show excellent alignment, well within the range predicted before launch. The bright spot however is from the impact, and suggests that one mirror segment is significantly damaged. From the report:

The micrometeoroid which hit segment C3 in the period 22—24 May 2022 UT caused significant uncorrectable change in the overall figure of that segment. However, the effect was small at the full telescope level because only a small portion of the telescope area was affected. After two subsequent realignment steps, the telescope was aligned to a minimum of 59 nm rms, which is about 5-10 nm rms above the previous best wavefront error rms values 7 . It should be noted that the drifts and stability levels of the telescope mean that science observations will typically see telescope contribution between 60 nm rms (minimum) and 80 nm rms (where WF control will typically be performed). Further, the telescope WFE combines with the science instrument WFE to yield total observatory levels in the range 70-130 nm (see Table 2), so the slight increase to telescope WFE from this strike has a relatively smaller effect on total observatory WFE.

In plain English, the impact while damaging has not seriously reduced the telescope’s predicted capabilities.

However, to be hit with this size impact so soon after launch is very worrisome, especially because Webb’s mirror is not housed in any protective tube like Hubble or most telescopes. From the report:

It is not yet clear whether the May 2022 hit to segment C3 was a rare event (i.e. an unlucky early strike by a high kinetic energy micrometeoroid that statistically might occur only once in several years), or whether the telescope may be more susceptible to damage by micrometeoroids than pre-launch modeling predicted.

The science team is presently trying to anticipate what might happen if the impact rate turns out to be much higher than expected, and what can be done to mitigate the degradation of the mirror should more impacts occur.

8 comments

Webb infrared image of Jupiter & Europa

3:36 pm

Jupiter and Europa as seen by Webb
Click for full image.

During the commissioning phase after deployment, the James Webb Space Telescope took images of Jupiter and several asteroids in order test the telescope’s instruments. The photo to the right, cropped and reduced to post here, shows both Jupiter and its moon Europa to the left.

Fans of Jupiter will recognize some familiar features of our solar system’s enormous planet in these images seen through Webb’s infrared gaze. A view from the NIRCam instrument’s short-wavelength filter shows distinct bands that encircle the planet as well as the Great Red Spot, a storm big enough to swallow the Earth. The iconic spot appears white in this image because of the way Webb’s infrared image was processed.

…Clearly visible at left is Europa, a moon with a probable ocean below its thick icy crust, and the target of NASA’s forthcoming Europa Clipper mission. What’s more, Europa’s shadow can be seen to the left of the Great Red Spot. Other visible moons in these images include Thebe and Metis.

The false color differences indicated differences in heat but it is not explained whether brighter is colder or warmer in this photo.. As one of my readers below correctly notes, Europa’s shadow tells us that darker is cooler. This one image shows that the Red Spot and Jupiter’s equatorial regions and poles are generally warm.

13 comments

First science image released from Webb

3:40 pm

Webb's first deep field image
Click for original image.

The first science image from the James Webb Space Telescope has now been unveiled.

That image is to the right, reduced to post here. From the press release:

Known as Webb’s First Deep Field, this image of galaxy cluster SMACS 0723 is overflowing with detail. Thousands of galaxies – including the faintest objects ever observed in the infrared – have appeared in Webb’s view for the first time. This slice of the vast universe covers a patch of sky approximately the size of a grain of sand held at arm’s length by someone on the ground.

This deep field, taken by Webb’s Near-Infrared Camera (NIRCam), is a composite made from images at different wavelengths, totaling 12.5 hours – achieving depths at infrared wavelengths beyond the Hubble Space Telescope’s deepest fields, which took weeks.

The image shows the galaxy cluster SMACS 0723 as it appeared 4.6 billion years ago. The combined mass of this galaxy cluster acts as a gravitational lens, magnifying much more distant galaxies behind it. Webb’s NIRCam has brought those distant galaxies into sharp focus – they have tiny, faint structures that have never been seen before, including star clusters and diffuse features.

The smeared concentric arrangement of many reddish objects surrounding the picture’s center strongly suggests we are seeing distortion by the gravity of this galaxy cluster.

While nothing in this image appears at first glance to be different than many earlier Hubble images, it looks at objects in the infrared that are much farther away than anything ever seen before, farther than Hubble in the optical could see. To understand the new discoveries hidden in such an image will likely take several years of further research. For example, before astronomers can understand what this image shows they need to determine the red shift of each galaxy, thus roughly determining its distance and the overall 3D structure of the objects visible. Moreover, the consequences of the gravitational lensing must be unpacked.

The White House briefing itself was somewhat embarrassing to watch, as Vice President Kamala Harris, President Joe Biden, and NASA administrator Bill Nelson all struggled to explain what this image shows, and failed miserably. Moreover, the briefing had technical problems, started very late, and it appeared that Bill Nelson especially had no idea what he was looking at. The briefing also ended very abruptly when it shifted to reporters’ questions.

11 comments

NASA announces the targets picked for Webb’s first science images

10:20 am

NASA today announced the astronomical targets scientists have chosen for the first infrared science images taken by the James Webb Space Telescope which will be unveiled on July 12, 2022.

  • Carina Nebula. The Carina Nebula is one of the largest and brightest nebulae in the sky, located approximately 7,600 light-years away in the southern constellation Carina. Nebulae are stellar nurseries where stars form. The Carina Nebula is home to many massive stars, several times larger than the Sun.
  • WASP-96 b (spectrum). WASP-96 b is a giant planet outside our solar system, composed mainly of gas. The planet, located nearly 1,150 light-years from Earth, orbits its star every 3.4 days. It has about half the mass of Jupiter, and its discovery was announced in 2014.
  • Southern Ring Nebula. The Southern Ring, or “Eight-Burst” nebula, is a planetary nebula – an expanding cloud of gas, surrounding a dying star. It is nearly half a light-year in diameter and is located approximately 2,000 light years away from Earth.
  • Stephan’s Quintet: About 290 million light-years away, Stephan’s Quintet is located in the constellation Pegasus. It is notable for being the first compact galaxy group ever discovered in 1877. Four of the five galaxies within the quintet are locked in a cosmic dance of repeated close encounters.
  • SMACS 0723: Massive foreground galaxy clusters magnify and distort the light of objects behind them, permitting a deep field view into both the extremely distant and intrinsically faint galaxy populations.

That only the last image is focused on distant deep space cosmology, the scientific research that Webb’s infrared instruments are optimized for suggests that NASA wishes to highlight the telescope’s other observational possibilities.

The images will be released one by one during a press conference beginning at 10:30 am (Eastern) on July 12th. It is once again important to note that though the images are likely to be spectacular, they will be false color infrared images measuring the heat produced by the objects, not optical images that we could see with our eyes.

One comment

Webb gets its first large micrometeoroid impact

9:18 am

In a carefully worded press release this week, NASA revealed that one segment of the primary mirror of the James Webb Space Telescope had been hit by a micrometeoroid.

Between May 23 and 25, NASA’s James Webb Space Telescope sustained an impact to one of its primary mirror segments. After initial assessments, the team found the telescope is still performing at a level that exceeds all mission requirements despite a marginally detectable effect in the data. Thorough analysis and measurements are ongoing. Impacts will continue to occur throughout the entirety of Webb’s lifetime in space; such events were anticipated when building and testing the mirror on the ground.

The reason such events were expected is because — unlike most telescopes (including Hubble) — Webb’s mirrors are not enclosed in a tube for protection. To do so would have made the telescope far too expensive to build or launch.

After describing in great detail all the work done prior to launch to anticipate such hits and deal with them, the press release then mentioned this fact almost as an aside:

This most recent impact was larger than was modeled, and beyond what the team could have tested on the ground.

Localized damage to the primary mirror of any telescope is not unusual. With ground-based telescopes such issues are not infrequent and easily worked around. The same applies to Webb. The engineers will calculate how to calibrate this particular segment to minimize distortion from the impact.

However, that the telescope experienced a hit larger than ever modeled, so soon after launch, suggests that those models were wrong, and that larger and more frequent hits can be expected. If so, this could be very worrisome, as over the long run it could shorten the telescope’s life in space significantly.

9 comments

Webb to release first science images July 12th

9:41 am

The science team for the James Webb Space Telescope announced today that the first infrared science images from the telescope will be released on July 12, 2022.

The first images package of materials will highlight the science themes that inspired the mission and will be the focus of its work: the early universe, the evolution of galaxies through time, the lifecycle of stars, and other worlds. All of Webb’s commissioning data – the data taken while aligning the telescope and preparing the instruments – will also be made publicly available.

In many ways this first release will likely mirror the first release of images from the Hubble Space Telescope in 1993, after its serious focus problem had been solved. Then, the science team and NASA picked images for the press conference that, to them, would pass what they called the “grandmother test,” whereby an ordinary person not familiar with space objects would still instantly recognize the object imaged.

The result of that criteria was that some of Hubble’s best ground-breaking first images were not included, such as its first sharp picture of the exploding star Eta Carinae. While the images shown were beautiful, they did not immediately demonstrate what Hubble was going to accomplish. The Eta Carinae picture did however.

Hopefully this time the scientists will be more daring, and have a greater respect for the general public, and include some infrared images that are not familiar to non-scientists. It is such data that is almost always the most exciting.

One comment

Webb’s coldest instrument reaches operating temperature

1:32 pm

The engineering team announced today that the mid-infrared instrument on the James Webb Space Telescope has now cooled to its operating temperature of -447 degrees Fahrenheit, less than 7 kelvin degrees above absolute zero.

On April 7, Webb’s Mid-Infrared Instrument (MIRI) – a joint development by NASA and ESA (European Space Agency) – reached its final operating temperature below 7 kelvins (minus 447 degrees Fahrenheit, or minus 266 degrees Celsius).

Along with Webb’s three other instruments, MIRI initially cooled off in the shade of Webb’s tennis-court-size sunshield, dropping to about 90 kelvins (minus 298 F, or minus 183 C). But dropping to less than 7 kelvins required an electrically powered cryocooler. Last week, the team passed a particularly challenging milestone called the “pinch point,” when the instrument goes from 15 kelvins (minus 433 F, or minus 258 C) to 6.4 kelvins (minus 448 F, or minus 267 C).

Before science operations can begin the instruments still need further calibration and testing. Expect the first infrared images sometime in the next month or so.

4 comments

Alignment of segments in Webb’s primary mirror completed

3:06 pm

Alignment image
Click for full image.

Astronomers and engineers have now successfully completed the alignment of the eighteen segments in the primary mirror of the James Webb Space Telescope.

On March 11, the Webb team completed the stage of alignment known as “fine phasing.” At this key stage in the commissioning of Webb’s Optical Telescope Element, every optical parameter that has been checked and tested is performing at, or above, expectations. The team also found no critical issues and no measurable contamination or blockages to Webb’s optical path. The observatory is able to successfully gather light from distant objects and deliver it to its instruments without issue.

The picture to the right shows that alignment, focused on a single star. As noted in the caption:

While the purpose of this image was to focus on the bright star at the center for alignment evaluation, Webb’s optics and NIRCam are so sensitive that the galaxies and stars seen in the background show up.

After many years delay and an ungodly budget overrun, thank goodness Webb appears to be working better than expected.

It will still be several months before actual science observations begin. Further more precise alignment adjustments need to be done for all its instruments and mirrors.

11 comments

First image from Webb released

8:52 am

Webb's first released alignment image

It ain’t pretty, nor is it in optical wavelengths, but the first alignment image from the James Webb Space Telescope has been released by NASA.

That image, reduced slightly to post here, is to the right. It shows 18 different near-infrared images of the same star, each image taken by a different segment of Webb’s primary mirror. At the moment the mirrors are not perfectly aligned, so that each segment’s star image shows up at a slightly different place. The goal now will be to adjust those mirror segments so that future images will show only one star, all focused to the same spot.

This alignment process is expected to take about a month.

The image is significant however because it shows that each segment is producing a relatively sharp image, even though the telescope has not yet cooled to its operating temperature. It thus appears that, unlike Hubble, Webb’s mirror segments were ground correctly, and it will be able to take sharp images right off the bat.

4 comments

Webb mirror alignment begins with first photons detected by instrument

2:19 pm

With the detection by one instrument of the first photons traveling through all of the mirrors of the James Webb Telescope the alignment of its many mirror segments begins.

This week, the three-month process of aligning the telescope began – and over the last day, Webb team members saw the first photons of starlight that traveled through the entire telescope and were detected by the Near Infrared Camera (NIRCam) instrument. This milestone marks the first of many steps to capture images that are at first unfocused and use them to slowly fine-tune the telescope. This is the very beginning of the process, but so far the initial results match expectations and simulations.

The article at the link provides a very detailed description of the step-by-step process used by engineers to align the eighteen segments of the primary mirror.

12 comments

Webb successfully inserted in final orbital position at the Sun-Earth Lagrange point

3:01 pm

The James Webb Space Telescope today successfully completed a five minute firing of its engines to place it at the Sun-Earth Lagrange point dubbed L2.

Webb’s orbit will allow it a wide view of the cosmos at any given moment, as well as the opportunity for its telescope optics and scientific instruments to get cold enough to function and perform optimal science. Webb has used as little propellant as possible for course corrections while it travels out to the realm of L2, to leave as much remaining propellant as possible for Webb’s ordinary operations over its lifetime: station-keeping (small adjustments to keep Webb in its desired orbit) and momentum unloading (to counteract the effects of solar radiation pressure on the huge sunshield).

Engineers will spend the next three months aligning the segments of Webb’s large primary and secondary mirrors, while they wait for the telescope to cool down to the ambient very cold temperatures required for it to detect the tiny infrared heat emissions from very faint very very very distant objects.

8 comments
1 2 3 4 5