NASA's Webb Measures the Temperature of a Rocky Exoplanet

 The amount of infrared light coming from TRAPPIST-1 b suggests that the planet is devoid of any significant atmosphere. Acting as a giant touch-free thermometer, NASA’s James Webb Space Telescope has successfully measured heat radiating from the innermost of the seven rocky planets orbiting TRAPPIST-1, a cool red dwarf star 40 light-years from Earth. With a dayside temperature of 450 degrees Fahrenheit, the planet is just about perfect for baking pizza. But with no atmosphere to speak of, it may not be the best spot to dine out. The result is the first from a comprehensive set of Webb studies of the TRAPPIST-1 system, and marks an important step in determining whether planets orbiting tiny but violent red dwarfs, the most common type of star in the Galaxy, can sustain atmospheres needed to support life.  An international team of researchers has used NASA’s James Webb Space Telescope to measure the temperature of the rocky exoplanet TRAPPIST-1 b. The measurement is based on the planet’s thermal emission: heat energy given off in the form of infrared light detected by Webb’s Mid-Infrared Instrument (MIRI). The result indicates that the planet’s dayside has a temperature of about 500 kelvins (roughly 450 degrees Fahrenheit) and suggests that it has no significant atmosphere. This is the first detection of any form of light emitted by an exoplanet as small and as cool as the rocky planets in our own solar system. The result marks an important step in determining whether planets orbiting small active stars like TRAPPIST-1 can sustain atmospheres needed to support life. It also bodes well for Webb’s ability to characterize temperate, Earth-sized exoplanets using MIRI.

“These observations really take advantage of Webb’s mid-infrared capability,” said Thomas Greene, an astrophysicist at NASA’s Ames Research Center and lead author on the study published today in the journal Nature. “No previous telescopes have had the sensitivity to measure such dim mid-infrared light.”

Rocky Planets Orbiting Ultracool Red Dwarfs

In early 2017, astronomers reported the discovery of seven rocky planets orbiting an ultracool red dwarf star (or M dwarf) 40 light-years from Earth. What is remarkable about the planets is their similarity in size and mass to the inner, rocky planets of our own solar system. Although they all orbit much closer to their star than any of our planets orbit the Sun — all could fit comfortably within the orbit of Mercury — they receive comparable amounts of energy from their tiny star.

TRAPPIST-1 b, the innermost planet, has an orbital distance about one hundredth that of Earth’s and receives about four times the amount of energy that Earth gets from the Sun. Although it is not within the system’s habitable zone, observations of the planet can provide important information about its sibling planets, as well as those of other M-dwarf systems.

“There are ten times as many of these stars in the Milky Way as there are stars like the Sun, and they are twice as likely to have rocky planets as stars like the Sun,” explained Greene. “But they are also very active — they are very bright when they’re young, and they give off flares and X-rays that can wipe out an atmosphere.”

Co-author Elsa Ducrot from the French Alternative Energies and Atomic Energy Commission (CEA) in France, who was on the team that conducted earlier studies of the TRAPPIST-1 system, added, “It's easier to characterize terrestrial planets around smaller, cooler stars. If we want to understand habitability around M stars, the TRAPPIST-1 system is a great laboratory. These are the best targets we have for looking at the atmospheres of rocky planets.”

Detecting an Atmosphere (or Not)

Previous observations of TRAPPIST-1 b with the Hubble and Spitzer space telescopes found no evidence for a puffy atmosphere, but were not able to rule out a dense one.

One way to reduce the uncertainty is to measure the planet’s temperature. “This planet is tidally locked, with one side facing the star at all times and the other in permanent darkness,” said Pierre-Olivier Lagage from CEA, a co-author on the paper. “If it has an atmosphere to circulate and redistribute the heat, the dayside will be cooler than if there is no atmosphere.”

The team used a technique called secondary eclipse photometry, in which MIRI measured the change in brightness from the system as the planet moved behind the star. Although TRAPPIST-1 b is not hot enough to give off its own visible light, it does have an infrared glow. By subtracting the brightness of the star on its own (during the secondary eclipse) from the brightness of the star and planet combined, they were able to successfully calculate how much infrared light is being given off by the planet.

Measuring Minuscule Changes in Brightness

Webb’s detection of a secondary eclipse is itself a major milestone. With the star more than 1,000 times brighter than the planet, the change in brightness is less than 0.1%.

“There was also some fear that we’d miss the eclipse. The planets all tug on each other, so the orbits are not perfect,” said Taylor Bell, the post-doctoral researcher at the Bay Area Environmental Research Institute who analyzed the data. “But it was just amazing: The time of the eclipse that we saw in the data matched the predicted time within a couple of minutes.”

The team analyzed data from five separate secondary eclipse observations. “We compared the results to computer models showing what the temperature should be in different scenarios,” explained Ducrot. “The results are almost perfectly consistent with a blackbody made of bare rock and no atmosphere to circulate the heat. We also didn’t see any signs of light being absorbed by carbon dioxide, which would be apparent in these measurements.”

This research was conducted as part of Webb Guaranteed Time Observation (GTO) program 1177, which is one of eight programs from Webb’s first year of science designed to help fully characterize the TRAPPIST-1 system. Additional secondary eclipse observations of TRAPPIST-1 b are currently in progress, and now that they know how good the data can be, the team hopes to eventually capture a full phase curve showing the change in brightness over the entire orbit. This will allow them to see how the temperature changes from the day to the nightside and confirm if the planet has an atmosphere or not.

“There was one target that I dreamed of having,” said Lagage, who worked on the development of the MIRI instrument for more than two decades. “And it was this one. This is the first time we can detect the emission from a rocky, temperate planet. It’s a really important step in the story of discovering exoplanets.”

The James Webb Space Telescope is the world's premier space science observatory. Webb will solve mysteries in our solar system, look beyond to distant worlds around other stars, and probe 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). MIRI was contributed by NASA and ESA, with the instrument designed and built by a consortium of nationally funded European Institutes (the MIRI European Consortium) and NASA’s Jet Propulsion Laboratory, in partnership with the University of Arizona.

James Webb Space Telescope's 1st year in space has blown astronomers away

Just one year after launch, the James Webb Space Telescope is exceeding all expectations, and astronomers are thrilled. Launched on Dec. 25, 2021, the $10 billion infrared observatory was designed to learn how galaxies form and grow, to peer far back into the universe to the era of the first galaxies, to watch stars be born inside their nebulous embryos in unprecedented detail, and to probe the atmospheres of exoplanets and characterize some of the closest rocky worlds. However, the complexity of the James Webb Space Telescope (Webb or JWST), including its fold-out, segmented 21-foot (6.5 meters) mirror and its delicate sun-shield the size of a tennis court, meant that astronomers were on tenterhooks as to whether the JWST would perform as hoped. It turns out, they needn't have worried. "I guess we really weren't expecting the results to be this good," Brenda Frye, an astronomy at Steward Observatory at the University of Arizona. "It's amazing," Steve Longmore, an astrophysicist at Liverpool John Moores University in the U.K., told Space.com. "It's delivering at least as well, and better in a lot of circumstances, than what we were expecting." And if it exceeds its own targets, it definitely surpasses those of its predecessors. "It's leaps and bounds better than what we've been able to see before," Susan Mullally, JWST's deputy project scientist from the Space Telescope Science Institute (STScI) in Maryland, which operates the observatory, told Space.com, adding that she is "blown away by the imagery, honestly. The images are beautiful."

The James Webb Space Telescope launched atop an Ariane 5 rocket from French Guiana on Dec. 25, 2021. (Image credit: NASA/Bill Ingalls)

The rings of Neptune

The main reason that JWST is performing so well is because of its superlative optics, which are able to achieve their maximum potential resolution for the majority of infrared wavelengths that the telescope observes in. This success means that JWST's images have a clarity to them that were unobtainable by the likes of the Hubble Space Telescope and NASA's retired Spitzer Space Telescope, or larger telescopes on the ground such as those at the Keck Observatory in Hawaii, whose vision is blurred by Earth's atmosphere.

But with JWST, individual stars so close together they were once indistinguishable can now be resolved; the structures of very distant galaxies are now discernible; and even something close by such as the rings of Neptune pop with the most detail seen in decades.

The James Webb Space Telescope's stunning view of Neptune, with its rings clearly visible. (Image credit: NASA/ESA/CSA/STScI)

"When the JWST's images of Neptune first came out, both Heidi [Hammel, an interdisciplinary scientist on JWST and an expert on the outer planets of the solar system] and myself looked at them, and then at each other, and asked, 'are we really looking at Neptune'?" Naomi Rowe-Gurney, an astronomer at NASA Goddard Space Flight Center in Maryland, told Space.com.

Although the Keck Observatory has imaged Neptune's rings, our most impressive view before JWST came from Voyager 2's flyby in 1989. "Heidi had not seen the rings [this well] since Voyager 2, and I had never seen the rings like this because Voyager was before I was born!" Rowe-Gurney said.

Normally, faint details or features around a bright object, such as the dark and tenuous rings around blue Neptune, are difficult to see against the glare of the bright object. To counteract this, an instrument is required to have the characteristic of "high dynamic range" to take in both the faint and the bright at the same time.

"We didn't realize that JWST would have this amazing dynamic range and be able to resolve really faint things like the rings of Neptune and the small moons and rings of Jupiter," Rowe-Gurney said.

Alien atmospheres

It's not only the planets of our solar system that JWST is scrutinizing. A key aim of the telescope is to detect the composition of exoplanets' atmospheres using a technique called transmission spectroscopy. As a planet transits its star, the star's light shines through the planet's atmosphere, but atoms and molecules within that atmosphere can block some of the light at characteristic wavelengths, which gives away the composition of the atmosphere.

The first exoplanet result released from JWST was the transmission spectrum of WASP-39b, which is a "hot Jupiter" exoplanet orbiting a sun-like star located 700 light-years away. JWST detected carbon dioxide in WASP-39b's atmosphere, the first time the gas has ever been detected on an exoplanet. Other gases present included carbon monoxide, potassium, sodium, water vapor and sulfur dioxide, the last of which can only be created through photochemistry when atmospheric gases react with the ultraviolet light from the planet's star — another exoplanet first.

The James Webb Space Telescope's analysis of the atmospheric composition of WASP-39b. (Image credit: NASA/ESA/CSA/J. Olmsted (STScI))

"I keep being amazed by what we're able to do with the exoplanet data, like the carbon dioxide and the photochemistry that was found in the atmosphere of WASP-39b," Mullally said. "That was really cool, and I don't remember people talking about [detecting photochemistry] ahead of time. I'm really looking forward to seeing what we can do with the terrestrial exoplanets orbiting the cool M-dwarfs and seeing what their atmospheres are made of."

In particular, the TRAPPIST-1 planetary system of seven worlds orbiting an M-dwarf 40 light-years away is a key target of the JWST. Preliminary results, which failed to detect thick blankets of hydrogen surrounding some of the TRAPPIST-1 worlds, were released during a conference held at STScI in December, but we'll have to be patient for more comprehensive results from these planets, of which up to four could reside in their star's habitable zone.

WASP-39b was an easy first target because its star is bright and the planet's signal is strong. M-dwarfs like TRAPPIST-1 are much fainter, despite being closer.

"We have to wait until we can get enough transits of these guys to build up the signal-to-noise, because you can't do it with just one or two transits," Mullally said. "I think we're going to have to wait until at least the end of the cycle 1 observations [summer 2023] before anybody is going to be in a position to say if they've found anything really spectacular."

Star formation near and far

Another aspect of JWST's mission is to not only observe exoplanets, but to better understand how they, and their stars, form. Star formation in particular is a crucial process to understand it because it connects so many things in the universe both near and far.

Longmore is leading a study to use JWST to observe frantic star formation in a region at the center of our own Milky Way galaxy, called the central molecular zone, some 26,000 light-years from us. The center of our galaxy hosts the highest concentration of stars, and at our distance they all appear packed in — indistinguishable to the likes of the Hubble Space Telescope — while copious amounts of dust shroud most of them from view in optical light. Look with a large-aperture infrared telescope like JWST, however, and those two concerns are shoved aside.

"These are the JWST's two capabilities that are going to blow my field apart," Longmore said. The telescope's superb optics are able to resolve individual baby stars in the center of the galaxy, and infrared light will pass right through the dust to reach the observatory.

"Ordinarily, with Hubble, it's like trying to point your telescope at a brick wall and see through it," he added, "But the JWST is looking through a window in that wall and can count individual stars."

The star-forming Pillars of Creation, imaged in mid-infrared by the JWST in what will surely become an iconic picture. (Image credit: NASA/ESA/CSA/STScI/J. DePasquale (STScI)/A. Pagan (STScI))

It's taking longer to gather all the data from the center of the galaxy, but that's because it's such a complex environment, with bright, diffuse emission everywhere, and all that has to be disentangled from the relevant signal of star formation via determined and careful data processing.

"On all the projects I'm on, people are still fighting with calibration and things, but hopefully in the next six months that will change," Longmore said. He added an amusing story of how one of his team's observations had been blighted by a mysterious circle on the image. After deeper investigation, it turned out that this wasn't some mysterious new phenomenon, but that JWST had previously been looking at bright Jupiter, and the giant planet's after-image had not yet been properly flushed out of the instrument's electronic sensors!

Longmore and his colleagues are targeting the central molecular zone because it is the region in our galaxy that most resembles star-forming conditions in the early universe, when the star-formation rate was high and dense clusters of stars formed. In the Central Molecular Zone, the astronomers intend to measure a property called the initial mass function (IMF), which describes the range of stellar masses in a star-forming nebula.

Currently, astronomers do not understand what determines why stars form with the masses that they have, only that low-mass stars are much more common than luminous high-mass stars, at least in the local universe. Was this still the case over 13 billion years ago in the first galaxies? Answering that question could help explain both how galaxies formed and what ended the universe's dark ages.

Deep fields and the first galaxies

After she saw President Joe Biden reveal the first deep-field image from the JWST, of the galaxy cluster SMACS 0723, a "gravitational lens" whose massive gravity magnifies objects behind it, Frye and her student, Massimo Pascale at the University of California, Berkeley, raced to analyze the image.

"We didn't sleep for three-and-a-half days, and our paper was one of the first two papers submitted on JWST data," Frye said.

Together, they found 42 new gravitationally lensed images of 14 different high-redshift galaxies, galaxies located so far away that the expanding universe has stretched their light, making them appear redder. Further studies and more deep fields followed, and a host of high-redshift candidates were discovered by Frye's team and others, including some galaxies at record-breaking redshifts of 12, 13 and above; these redshifts mean that we see the galaxies as they existed less than 300 million years after the Big Bang.

These high-redshift galaxies have proven something of a surprise, in that they appear more luminous than models of galaxy formation predicted they should be.

"One possible explanation is that they're producing too many high-mass stars, that they have a top-heavy IMF," Longmore said, noting the importance of measuring the IMF in the central molecular zone to understand stellar masses in young neighborhoods.

Why the IMF would be different over 13.5 billion years ago is not understood, but then again the early universe seems to have been a far more intense place than it is today. "In the present day, galaxies in general are not forming stars so actively, but many galaxies formed stars more actively in the early universe," Frye said.

Frye is a member of the PEARLS (Prime Extragalactic Area for Reionization and Lensing Science) team. PEARLS is a JWST project to image a variety of deep fields, including two apparently sparse regions of sky and a number of galaxy clusters and proto-clusters, to observe the first few billion years of galaxy formation.  

The PEARLS field looking toward the North Celestial Pole. Inset are numerous types of galaxy, from interacting galaxies to ruby-red dusty star-forming galaxies. (Image credit: NASA/ESA/CSA/Rolf A. Jansen, Jake Summers, Rosalia O'Brien, Rogier Windhorst (ASU)/Aaron Robotham (UWA)/Anton M. Koekemoer (STScI)/Christopher Willmer (University of Arizona)/JWST PEARLS Team)

In December, the PEARLs team released their first dataset, of an extraordinary field of distant galaxies close to the North Ecliptic Pole. This region is directly above the main plane of the Milky Way and so is constantly visible to JWST, and it's also high above interfering features such as zodiacal dust.

Within the image are a whole host of galaxies. Some interact and some show a clear spiral structure; the collection exhibits a whole range of colors, from cobalt blue to ruby red. The latter are of great interest to Frye.

"We can now observe [in the PEARLS image] an abundance of red disk galaxies, which we think might be red spirals," Frye said. "This type of galaxy is very interesting because they are analogs of what the Milky Way might have looked like when it was younger."

The reddening is caused by huge amounts of dust in these galaxies; the dust is the result of rapid formation of massive stars that quickly die in supernova explosions and spill vast amounts of dust into space. Such galaxies are completely hidden from Hubble, but infrared light can pass through the dust and make the galaxies visible to JWST.

"The analogy is a New Year's Eve fireworks display," Frye said. "If you have a lot of fireworks going off then eventually they are obscured by dusty smoke."

The JWST has impressed scientists in the six months that it has been gathering data since becoming fully operational in June, but the real fireworks are still to come with major discoveries awaiting us.

It's slow going, requiring patience, Frye said. "There's too much for any one person to be able to study or understand on really short timescales, it's going to take us a long time to process all the data."

The results, though, will be worth it.

"It's going to completely change our understanding of our place in the universe, how the solar system formed and evolved, and how the very first stars and galaxies formed," Mullally said. "We've made great headway with this telescope, and it's going to do spectacular things."

 

James Webb Space Telescope sniffs out carbon dioxide around an alien world

The James Webb Space Telescope (JWST or Webb) has detected carbon dioxide in the atmosphere of an exoplanet in a breakthrough discovery that will usher in a new era of research on worlds outside our solar system. The detection came during the James Webb Space Telescope's first campaign focusing on exoplanets, which are planets orbiting other stars. The observations targeted a hot gas giant called WASP-39 b located some 700 light-years away from Earth in the constellation Virgo. The planet, about as massive as Saturn but larger than Jupiter in size, had previously been observed by the Hubble Space Telescope in optical wavelengths and the now-retired Spitzer Space Telescope, which like Webb observed heat-carrying infrared wavelengths. The previous observations revealed the presence of water vapor, sodium and potassium in the planet's atmosphere, but it wasn't until Webb that scientists caught the signature of carbon dioxide. "As soon as the data appeared on my screen, the whopping carbon dioxide feature grabbed me," Zafar Rustamkulov, a graduate student at Johns Hopkins University in Baltimore, USA and a member of the transiting exoplanet team which undertook this investigation, said in a statement (opens in new tab). "It was a special moment, crossing an important threshold in exoplanet sciences." Carbon dioxide has never been detected on any exoplanet before. But astronomers hope that the compound can help them better understand the formation history and evolution of the planets where it's found, scientists said.

"This unequivocal detection of carbon dioxide is a major milestone for exoplanet atmosphere characterisation," Laura Kreidberg, director of the Max Planck Institute for Astronomy in Germany and co-author of a paper describing the discovery, said in a statement (opens in new tab). "Carbon dioxide helps us measure the complete carbon and oxygen inventory of the atmosphere, which is highly sensitive to the conditions in the disk where the planet formed."

Such measurements can help identify how far from its star the planet formed and determine how much solid and gaseous material it accumulated as it migrated to its current location.

The discovery was made using Webb's NIRSpec instrument, a highly sensitive spectrograph that splits incoming light into barcode-like spectra that reveal how the observed objects absorb light. Neither Webb nor any other existing telescope can capture direct images of the exoplanet or its atmosphere; instead, researchers compare observations of the star's typical light to light seen through the atmosphere as the planet passes in front of it.

The measurements of WASP-39 b were gathered on July 10, two days before the first official release of Webb images.

The researchers believe the telescope will be able to detect carbon dioxide in the atmospheres of other types of planets, including Earth-like rocky bodies scattered across the galaxy.

"The exoplanet community has been searching for the signature of carbon dioxide for decades," Kreidberg said. "With the extraordinary new capability of JWST, it will be possible to routinely detect carbon dioxide for hot Jupiters, as well as smaller, cooler planets more like our own Earth."

WASP-39 b orbits extremely close to its parent star, WASP-39, at less than 1/20th the distance between Earth and the sun), completing one orbit about every four Earth days. The planet was discovered in 2011 and can only be observed through the transits it makes around WASP-39, which cause brief dips in the star's brightness.

A paper describing the research has been accepted for publication by Nature; a preprint of the paper is available on arXiv.org(opens in new tab).

NASA releases first color image from James Webb Space Telescope

A deep field of distant galaxies, some dating back to the first billion years after the Big Bang, is the first full-color image to come from the James Webb Space Telescope. The image, released at a White House event July 11 and called “Webb’s First Deep Field,” is a sneak preview of a broader set of early release observations that NASA and its European and Canadian partners on JWST plan to publish July 12. The White House event, attended by President Joe Biden and Vice President Kamala Harris, was announced with less than 24 hours’ notice. The image shows a galaxy cluster called SMACS 0723 about 4.5 billion light-years away. The cluster acts as a gravitational lens, bringing into view far more distant galaxies, some of which appear in the image as arcs. “We’re looking back more than 13 billion years,” said NASA Administrator Bill Nelson at the event. The NASA statement accompanying the image release didn’t give specifics on the more distant galaxies visible in the image, which involved 12.5 hours of images taken at several wavelengths. The Big Bang took place an estimated 13.8 billion years ago, meaning those distant galaxies date back to when the universe was less than a billion years old. The detail in the image comes from a very tiny part of the sky. “If you held a grain of sand on the tip of your finger at arm’s length, that is the part of the universe you’re seeing. Just one little speck of the universe,” Nelson said.

Biden appeared pleased by what he saw and by the performance of JWST. “It symbolizes the relentless spirit of American ingenuity and it shows what we can achieve, what more we can discover,” he said of the space telescope, which finally launched last December after billions of dollars of cost overruns and years of schedule delays. JWST is now working better than expected at the Earth-sun L-2 point 1.5 million kilometers away. “These images are going to remind the world that America can do big things.”

“This telescope is one of humanity’s great engineering achievements,” added Harris. Both she and Biden emphasized the role of international cooperation in JWST’s development, including how, according to Harris, “a scientific endeavor can build upon the international rules and norms that govern our cooperation in space.”

The White House event started more than an hour later because, Biden said, he was busy preparing for an upcoming trip to the Middle East. Media were ushered out of the room and the webcast ended after only about 10 minutes.

Scientists and others were immediately impressed, though, with the image. “This is just a first glimpse of what Webb can do,” said Macarena Garcia Marin, ESA instrument scientist for a mid-infrared instrument on JWST called MIRI, in an ESA statement. “While we are truly in awe today of Webb’s first deep field, I can’t help but think of what images and science results are just around the corner in the many years to come.”

“The first image from the James Webb Space Telescope unveiled this evening is an incredible preview of its remarkable technology and scientific power,” said Rep. Eddie Bernice Johnson (D-Texas), chair of the House Science Committee, in a statement that featured bipartisan praise of the spacecraft from the committee’s leadership. “As a steadfast supporter of Webb and its mission, I am elated to see this image today — an image that has been 20 years of hard work in the making.”

The deep field image was originally scheduled to be released July 12 with the other early release observations. NASA and its partners will still release those other observations at that event. The other observations, announced by NASA July 8, include the Carina Nebula and Southern Ring Nebula within our own galaxy and the galaxy group Stephan’s Quintet about 290 million light-years away. NASA will also release spectra of the exoplanet WASP-96b, a “hot Jupiter” planet orbiting close to its star.

James Webb Space Telescope Passes Key Launch Clearance Review

The international James Webb Space Telescope has passed the final mission analysis review for its launch on an Ariane 5 rocket from Europe’s Spaceport in French Guiana. This major milestone, carried out with Arianespace, the Webb launch service provider, confirms that Ariane 5, the Webb spacecraft, and the flight plan are set for launch. It also specifically provides the final confirmation that all aspects of the launch vehicle and spacecraft are fully compatible. During launch, the spacecraft experiences a range of mechanical forces, vibrations, temperature changes, and electromagnetic radiation. All technical evaluations performed by Arianespace on the mission’s key aspects, including the launch trajectory and payload separation, have shown positive results. “We are thrilled to have passed this important step towards the launch of Webb and to have received the green light from Arianespace and NASA,” says Peter Rumler, ESA Webb project manager. Webb will be the largest, most powerful telescope ever launched into space. As part of an international collaboration agreement, ESA is providing the observatory’s launch service using the Ariane 5 launch vehicle. Working with partners, ESA was responsible for the development and qualification of Ariane 5 adaptations for the Webb mission and for the procurement of the launch service.

Artist’s impression of the James Webb Space Telescope (Webb), folded in the Ariane 5 rocket during launch from Europe’s Spaceport in French Guiana. Credit: ESA – D. Ducros

Ariane 5 will deliver the telescope directly into a precision transfer orbit towards its destination, the second Lagrange point (L2). After separation from the launcher, Webb will continue its four-week long journey to L2 alone. L2 is four times farther away than the Moon, 1.5 million km from Earth in the direction away from the Sun.

Mission analysis experts at ESA helped to compute the launch window, a complex issue because it involves ensuring that Webb can be inserted into its target orbit and at the same time the Ariane 5 upper stage will safely escape from Earth.

The telescope will observe the Universe in the near-infrared and mid-infrared – at wavelengths longer than visible light. To do so, it carries a suite of state-of-the-art cameras, spectrographs, and coronagraphs.

ESA plays a crucial role in the Webb mission. Aside from procuring the Ariane 5 launcher and launch services, ESA is contributing the NIRSpec instrument and a 50% share of the MIRI instrument, as well as personnel to support mission operations.

Webb is an international partnership between NASA, ESA, and the Canadian Space Agency (CSA). Webb’s partners are working towards the launch readiness date of October 31, 2021. The precise launch date following 31 October depends on the spaceport’s launch schedule and will be finalized closer to the launch readiness date.

NASA’s Webb Telescope Packs Its Sunshield for a Million Mile Trip

Engineers working on NASA’s James Webb Space Telescope have successfully folded and packed its sunshield for its upcoming million-mile (roughly 1.5 million kilometer) journey, which begins later this year. The sunshield — a five-layer, diamond-shaped structure the size of a tennis court — was specially engineered to fold up around the two sides of the telescope and fit within the confines of its launch vehicle, the Ariane 5 rocket. Now that folding has been completed at Northrop Grumman in Redondo Beach, California, the sunshield will remain in this compact form through launch and the first few days the observatory will spend in space. Designed to protect the telescope’s optics from any heat sources that could interfere with its sight, the sunshield is one of Webb’s most critical and complex components. Because Webb is an infrared telescope, its mirrors and sensors need to be kept at extremely cold temperatures to detect faint heat signals from distant objects in the universe. In space, one side of the sunshield will always reflect light and background heat from the Sun, Earth and Moon. Thermal models show that the maximum temperature of the outermost layer is 383 Kelvin, or about 230 degrees Fahrenheit. Meanwhile, the other side of the sunshield will always face deep space, with the coldest layer having a modeled minimum temperature of 36 Kelvin, or about minus 394 degrees Fahrenheit. Fully deployed, the telescope’s sunshield measures almost 70 feet by 47 feet (21 meters by 14 meters). When stowed inside the rocket for launch, the folded sunshield will be packaged in a very confined area in between other structures of the observatory to accommodate the limited space inside the 18-foot (5.4-meter) diameter rocket fairing.

Both sides of the James Webb Space Telescope's sunshield were lifted vertically in preparation for the folding of the sunshield layers. Credits: NASA/Chris Gunn

“There is nothing really analogous to what we are trying to achieve with the folding up of a tennis court-sized sunshield, but it is similar to packing a parachute,” said Jeff Cheezum, a lead sunshield design engineer at Northrop Grumman. “Just like a skydiver needs their parachute packed correctly in order to open perfectly and to successfully get back to Earth, Webb needs its sunshield to be perfectly stowed to ensure that it also opens up perfectly and maintains its shape, in order to successfully keep the telescope at its required operating temperature.”

                                        

During the sunshield folding process for the James Webb Space Telescope, a team of technicians carefully fold each layer in a zigzag pattern to create accordion-like stacks of membranes on either side of the telescope.

Credits: NASA/Chris Gunn

The month-long process of folding the sunshield began with laying the five layers as flat as possible. In its deployed state, the sunshield resembles a multilayered silver ship, so its inherently curved surfaces added a degree of complexity to this step. Afterwards, the layers were lifted vertically and propped onto special support equipment so that they could be properly restrained for folding. A team of technicians then carefully folded each layer in a zigzag pattern to create accordion-like stacks of membranes on either side of the telescope.

The first layer of the sunshield is two-thousandths of an inch (0.005 centimeters) thick, while the other four layers are only one-thousandth of an inch thick. For the team, a built-in challenge was the delicacy of folding such thin layers. The folding process also had to account for components such as the sunshield’s 90 different tensioning cables, which must be stowed in a specific manner to ensure the sunshield deploys smoothly.

With the successful completion of sunshield folding, the engineering team has prepared the sunshield for its complex deployment in space. The sunshield will unfold at the end of the telescope’s first week in space after launch, stretching out to its full size and then separating and tensioning each of its five layers. Testing for this unfolding and tensioning procedure was completed for the final time on Earth in December 2020.

The James Webb Space Telescope’s final sunshield deployment and tensioning tests were completed in December 2020.

Credits: NASA/Chris Gunn

“Think of it backwards; we want the deployed sunshield to achieve a specific shape so we get the performance we need. The whole folding process was designed with that in mind. We have to fold cleanly and carefully the same way each time, to ensure the unfolding occurs exactly the way we want it,” said James Cooper, lead sunshield engineer at NASA’s Goddard Space Flight Center in Greenbelt, Maryland.

For instance, one of the most intricate aspects of the folding process involved aligning the membrane stacks. Each of the sunshield’s layers has hundreds of intentional holes, which are deliberately arranged to avoid light and heat from passing to the optical elements of the telescope when the sunshield is fully deployed. These holes must be lined up during folding so that Webb technicians can insert “pins” through the holes in each membrane stack. The 107 “pins,” or membrane release devices, will help restrain the layers for launch, but release to unfold the sunshield once the telescope is in space.

“It’s a very methodical process that we use to make sure everything is aligned correctly,” said Marc Roth, mechanical engineering lead at Northrop Grumman. “Our team has been through multiple training cycles, and we’ve implemented many lessons learned from the previous times we’ve done this process, all culminating in this last sunshield fold.”

Over the next three months, engineers and technicians will finish stowing and securing the packed sunshield. This process will involve installing the membrane release devices, rigging and securing all of the sunshield cables, and stowing covers for the sunshield membranes. It will also include stowing the two “arms” of the sunshield — the Mid-Boom Assemblies — which will horizontally extend the sunshield outwards during deployment, as well as stowing the two pallet structures that hold the sunshield in place.

The James Webb Space Telescope previously deployed its primary mirror in March 2020. Its folded sunshield is also visible in this image.

Credits: Northrop Grumman

The observatory will additionally undergo a final mirror deployment before it is shipped to its launch site in French Guiana, South America.

The Webb engineering team continues to follow personal safety procedures in accordance with current Centers for Disease Control and Prevention and Occupational Safety and Health Administration guidance related to COVID-19, including mask-wearing and social distancing.

The James Webb Space Telescope will be the world's premier space science observatory when it launches in 2021. Webb will solve mysteries in our solar system, look beyond to distant worlds around other stars, and probe 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 the Canadian Space Agency.

Both halves of NASA's Webb Telescope successfully communicate

For the first time, the two halves of NASA's James Webb Space Telescope - the spacecraft and the telescope--were connected together using temporary ground wiring that enabled them to "speak" to each other like they will in flight. Although it was a significant step forward for the program, this test was an optional "risk reduction" test that took advantage of an opportunity to connect the two halves of the observatory together electrically months earlier than planned. If any issues had been found, it would have given engineers more time to fix them and without causing further delays. As a bonus, it also provided a jumpstart for the separate spacecraft and telescope test teams to begin working jointly as they will when the whole observatory is put together in one piece next year. The James Webb telescope is both an exceedingly complex and rewarding undertaking for NASA and its international partners. Scientists anticipate its findings to rewrite textbooks on astronomy by providing revolutionary observations of the cosmos, while engineers and involved technicians forecast that its challenging design will enable and influence future spacecraft architecture for years to come.Each piece of Webb has undergone rigorous testing throughout various historic and state of the art facilities across the United States. This ensures the entire observatory is prepared to survive the inherent harshness of a rocket launch to space, and years of continuous exposure to the extremes encountered on a mission nearly a million miles away from Earth.

In February, Webb made an important, and symbolic step forward in its path to completion when all primary flight components of the observatory came to reside under the same roof at Northrop Grumman in Los Angeles, California. This is where all flight hardware is undergoing final assembly and testing until cleared to launch from the Guiana Space Centre near Kourou in French Guiana.

"What we did now was make electrical connections between the flight telescope and flight spacecraft to understand all the nuances of the electrical interface. Specifically in this test, the spacecraft commanded mirror motion on the telescope, and the telescope replied back with telemetry confirming it.

Even though we have tested each half with a simulator of the other half during their parallel construction, there is nothing exactly like connecting the real thing to the real thing. While the sunshield was being reassembled to get back into its environmental testing, we took advantage of the time and did a flight-to-flight electrical dry run right now to reduce schedule risk later," said Mike Menzel, Webb's Mission System Engineer.

"The full complement of electrical and software tests will be run next year when the observatory is finally fully assembled for flight."

The James Webb Space Telescope will be a giant leap forward in our quest to understand the universe and where humans fit in the great cosmic expanse. Webb will examine every phase of cosmic history: from the first luminous glows after the big bang to the formation of galaxies, stars, and planets to the evolution of our own solar system.

Allowing for unprecedented scientific observation and discovery worldwide. Webb will broaden and enrich the discoveries achieved by the great space observatories Hubble, Spitzer, and Chandra.

"This test also afforded us an early chance to ensure that the two teams, who had been working separately over the years building and testing the two separate halves of Webb respectively, were able to operate as a single observatory test team.

"We are enthused that the early communications and commanding risk reduction test has been successfully executed. The procedure was designed and executed by an integrated set of team members from Goddard Space Flight Center, Northrop Grumman, and Ball Aerospace," said Jeff Kirk, Test Operations Lead.

Technicians Ensure James Webb Space Telescope's Sunshield Survives Stresses Experienced During Liftoff

The sound associated with a rocket launch creates extreme vibrations that can adversely affect any satellite or observatory, so engineers put spacecraft through simulations to ensure they will remain operational. In this photo, technicians delicately inspect stowed sunshield membranes of NASA's James Webb Space Telescope on the forward side of the spacecraft. Acoustic testing exposes the spacecraft to similar forces and stress experienced during liftoff, allowing engineers to better prepare it for the rigors of spaceflight. The sunshield separates the observatory into a hot, sun-facing side (reaching temperatures close to 230 degrees Fahrenheit), and a cold side (approximately minus 400 degrees Fahrenheit) where the sunlight is blocked from interfering with the sensitive telescope instruments. The James Webb Space Telescope will be the world's premier space science observatory. Webb will solve mysteries of our solar system, look beyond to distant worlds around other stars, and probe the mysterious structures and origins of our universe and our place in it.

Webb is an international project led by NASA with its partners, the European Space Agency (ESA) and the Canadian Space Agency (CSA).

Astronomers Concerned with Proposed Cancellation of Space Telescope

Sharing alarm voiced by other scientists, leaders of the American Astronomical Society (AAS) are expressing grave concern over the administration's proposed cuts to NASA's astrophysics budget and the abrupt cancellation of the Wide Field Infrared Survey Telescope (WFIRST). "We cannot accept termination of WFIRST, which was the highest-priority space-astronomy mission in the most recent decadal survey," says AAS President-Elect Megan Donahue (Michigan State University). "And the proposed 10% reduction in NASA's astrophysics budget, amounting to nearly $1 billion over the next five years, will cripple US astronomy." WFIRST, the successor to the 28-year-old Hubble Space Telescope and the forthcoming James Webb Space Telescope, is the top-ranked large space-astronomy mission of New Worlds, New Horizons in Astronomy and Astrophysics, the National Academies' Astro2010 decadal survey, and is an essential component of a balanced space astrophysics portfolio. Cutting NASA's astrophysics budget and canceling WFIRST would leave our nation without a large space telescope to succeed Hubble and Webb.

Yet just last year another National Academies report, Powering Science: NASA's Large Strategic Missions, found that "large strategic missions are critical for balance and form the backbone of the disciplines" of NASA's Science Mission Directorate (SMD), which includes astrophysics. The same report further recommended that "NASA should continue to plan for large strategic missions as a primary component for all science disciplines as part of a balanced program that also includes smaller missions."

"The AAS has long supported community-based priority setting as a fundamental component in the effective funding, management, and oversight of the federal research enterprise," says AAS Executive Officer Kevin B. Marvel.

"This process has been tremendously successful and has led to US preeminence in space science through missions that are now household names, like Hubble." Marvel continues, "Not only is WFIRST a top decadal-survey priority in astronomy and astrophysics, but the mission has also undergone rigorous community, agency, and Congressional assessment and oversight and meets the high expectations of an astrophysics flagship."

Indeed, after Astro2010, scientific and technological advancements enabled an enhanced WFIRST that would be 100 times more powerful than Hubble. Follow-on National Academies' reports in 2013 and 2016 reaffirmed the significant scientific merit of the enhanced WFIRST mission, and their recommendations for careful monitoring of potential cost and schedule drivers led to NASA's commissioning of the WFIRST Independent External Technical / Management / Budget Review (WIETR) last fall.

Neither the commissioning of the WIETR nor the content of its findings are an indication that WFIRST is experiencing or will experience the cost overruns that the Webb telescope experienced. In fact, the opposite is true.

As Thomas Young, former director of NASA's Goddard Space Flight Center and former president and chief operating officer of Martin Marietta Corp., testified to the House Science Subcommittee on Space in December 2017, that WFIRST has undergone extensive scrutiny is "no cause for panic. What is transpiring is a perfectly healthy process to assure that the scope, cost, and risk are appropriately defined."

NASA's SMD Associate Administrator, Thomas Zurbuchen, fully agreed with the WIETR recommendations to match mission cost with appropriate resources as part of a balanced astrophysics portfolio.

After undergoing a redesign over the last several months, WFIRST would once again fit both within the February 2016 budget approved by NASA at the onset of its mission formulation phase and within the notional five-year budget profile the administration requested for NASA astrophysics in its FY 2018 budget less than one year ago. Put another way, the lifecycle cost for WFIRST is the same now as it was two years ago and has been described as both reasonable and credible by numerous review panels.

Marvel worries that the administration's proposal to scale back federal investment in the nation's exploration of the universe and terminate WFIRST risks undermining future decadal surveys and other community-based priority-setting processes.

"These efforts to achieve community consensus on research priorities are vital to ensuring the maximum return on public and private investments in the astronomical sciences," Marvel says. "The cancellation of WFIRST would set a dangerous precedent and severely weaken a decadal-survey process that has established collective scientific priorities for a world-leading program for a half century. Such a move would also sacrifice US leadership in space-based dark energy, exoplanet, and survey astrophysics. We cannot allow such drastic damage to the field of astronomy, the impacts of which would be felt for more than a generation."

The AAS will defend the important role of the decadal surveys in helping set federal spending priorities, to explain the scientific promise of the top-ranked WFIRST mission, and to share our excitement for the field of astrophysics, which has never been more ripe for discovery from the search for life elsewhere in the universe to understanding where we came from and where we're going. "We look forward to working with Congress to restore funding for WFIRST and for NASA astrophysics overall," Donahue concludes.

A new 'atmospheric disequilibrium' could help detect life on other planets

As NASA's James Webb Space Telescope and other new giant telescopes come online they will need novel strategies to look for evidence of life on other planets. A University of Washington study has found a simple approach to look for life that might be more promising than just looking for oxygen. The paper, published Jan. 24 in Science Advances, offers a new recipe for providing evidence that a distant planet harbors life. "This idea of looking for atmospheric oxygen as a biosignature has been around for a long time. And it's a good strategy - it's very hard to make much oxygen without life," said corresponding author Joshua Krissansen-Totton, a UW doctoral student in Earth and space sciences."But we don't want to put all our eggs in one basket. Even if life is common in the cosmos, we have no idea if it will be life that makes oxygen. The biochemistry of oxygen production is very complex and could be quite rare." The new study looks at the history of life on Earth, the one inhabited planet we know of, to find times where the planet's atmosphere contained a mixture of gases that are out of equilibrium and could exist only in the presence of living organisms - anything from pond scum to giant redwoods. In fact, life's ability to make large amounts of oxygen has only occurred in the past one-eighth of Earth's history.

By taking a longer view, the researchers identified a new combination of gases that would provide evidence of life: methane plus carbon dioxide, minus carbon monoxide.

"We need to look for fairly abundant methane and carbon dioxide on a world that has liquid water at its surface, and find an absence of carbon monoxide," said co-author David Catling, a UW professor of Earth and space sciences.

"Our study shows that this combination would be a compelling sign of life. What's exciting is that our suggestion is doable, and may lead to the historic discovery of an extraterrestrial biosphere in the not-too-distant future."

The paper looks at all the ways that a planet could produce methane - from asteroid impacts, outgassing from the planet's interior, reactions of rocks and water - and finds that it would be hard to produce a lot of methane on a rocky, Earth-like planet without any living organisms.

If methane and carbon dioxide are detected together, especially without carbon monoxide, that's a chemical imbalance that signals life. The carbon atoms in the two molecules represent opposite levels of oxidation. Carbon dioxide holds as many oxygen molecules as it can, while the carbon in methane lacks oxygen and instead has oxygen's chemical adversary, hydrogen.

"So you've got these extreme levels of oxidation. And it's hard to do that through non-biological processes without also producing carbon monoxide, which is intermediate," Krissansen-Totton said.

"For example, planets with volcanoes that belch out carbon dioxide and methane will also tend to belch out carbon monoxide."

What's more, carbon monoxide tends not to build up in the atmosphere of a planet that harbors life.

"Carbon monoxide is a gas that would be readily eaten by microbes," Krissansen-Totton said.

"So if carbon monoxide were abundant, that would be a clue that perhaps you're looking at a planet that doesn't have biology."

The authors agree that oxygen is a good way to look for signs of life, but think that this new combination is at least as likely to pop up through the new telescopes' sights.

"Life that makes methane uses a simple metabolism, is ubiquitous, and has been around through much of Earth's history," Krissansen-Totton said.

"It's an easy thing to do so it's potentially more common than oxygen-producing life. This is definitely something we should be looking for as new telescopes come online."