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April 27, 2016
Laura Betz
NASA Goddard Space Flight Center
NASA engineers recently unveiled the giant golden mirror of NASA’s James Webb Space Telescope as part of the integration and testing of the infrared telescope.
Standing tall and glimmering gold inside NASA’s Goddard Space Flight Center’s clean room in Greenbelt, Maryland is the James Webb Space Telescope primary mirror. It will be the largest yet sent into space. Credits: NASA/Chris Gunn
The 18 mirrors that make up the primary mirror were individually protected with a black covers when they were assembled on the telescope structure. Now, for the first time since the primary mirror was completed, the covers have been lifted.
Standing tall and glimmering gold inside NASA’s Goddard Space Flight Center’s clean room in Greenbelt, Maryland, this mirror will be the largest yet sent into space. Currently, engineers are busy assembling and testing the other pieces of the telescope.
Scientists from around the world will use this unique observatory to capture images and spectra of not only the first galaxies to appear in the early universe over 13.5 billion years ago, but also the full range of astronomical sources such as star forming nebulae, exoplanets, and even moons and planets within our own Solar System. To ensure the mirror is both strong and light, the team made the mirrors out of beryllium. Each mirror segment is about the size of a coffee table and weighs approximately 20 kilograms (46 pounds). A very fine film of vaporized gold coats each segment to improve the mirror’s reflection of infrared light. The fully assembled mirror is larger than any rocket so the two sides of it fold up. Behind each mirror are several motors so that the team can focus the telescope out in space.
This widely anticipated telescope will soon go through many rigorous tests to ensure it survives its launch into space. In the next few months, engineers will install other key elements, and take additional measurements to ensure the telescope is ready for space.
The James Webb Space Telescope is the scientific successor to NASA’s Hubble Space Telescope.
NASA/ESA/CSA Webb Telescope annotated
NASA/ESA Hubble Telescope
It will be the most powerful space telescope ever built. Webb will study many phases in the history of our universe, including the formation of solar systems capable of supporting life on planets similar to Earth, as well as the evolution of our own solar system. It’s targeted to launch from French Guiana aboard an Ariane 5 rocket in 2018. Webb is an international project led by NASA with its partners, ESA (European Space Agency) and the Canadian Space Agency.
NASA’s Goddard Space Flight Center is home to the nation’s largest organization of combined scientists, engineers and technologists that build spacecraft, instruments and new technology to study the Earth, the sun, our solar system, and the universe.
Named for American rocketry pioneer Dr. Robert H. Goddard, the center was established in 1959 as NASA’s first space flight complex. Goddard and its several facilities are critical in carrying out NASA’s missions of space exploration and scientific discovery.
How the biggest NASA mission of the decade will solve some of the Universe’s greatest mysteries.
“Now the world has gone to bed,
Darkness won’t engulf my head,
I can see by infrared,
How I hate the night.” -Douglas Adams
With every extra inch of aperture, every extra second of observing time, and every extra atom of atmospheric interference you remove from your telescope’s field-of-view, the better, deeper and more clearly you’re able to see the Universe. When the Hubble Space Telescope began operation in 1990, it ushered in a new era in astronomy: that of space-based astronomy.
NASA/ESA Hubble
No longer did we have to fight with the atmosphere; no longer did we have to worry about clouds; no longer was electromagnetic scintillation a problem. All we needed to do was point our telescope at the target, stabilize it, and collect photons. In the 25 years since, we’ve began to cover the entire electromagnetic spectrum with our space-based observatories, getting our first true glimpse of what the Universe really looks like in every wavelength of light.
Image credit: NASA / JPL, via Wikimedia Commons user Bricktop.
But as our knowledge has increased, so has our sophisticated understanding of what the unknowns are. The farther we look away in the Universe, the farther back in time we look as well: the finite amount of time since the Big Bang coupled with the finite speed of light ensures that there’s a limit to what we can see. Moreover, the expansion of space itself works against us, by stretching the wavelength of the emitted starlight as it travels through the Universe towards our eyes. Even the Hubble Space Telescope, which gives us the deepest, most spectacular view of the Universe we’ve ever uncovered, is limited in that regard.
Hubble is an amazing piece of equipment, but it’s fundamentally limited in a number of ways:
It’s only 2.4 meters in diameter, limiting its resolving power the farther away we look in space.
Despite being coated in reflective materials, it still spends all of its time in direct sunlight, which heats it. This heat means that it can’t observe wavelengths of light longer than about 1.6 microns, due to thermal effects.
And the combination of light-gathering limitations and the wavelengths to which it’s sensitive means that it can “only” see back to galaxies that are about 500 million years old.
Now, these galaxies are beautiful, distant and from when the Universe was just around 4% of its current age. But we know that stars and galaxies exist from even earlier times.
Hubble vs Webb. Image credit: NASA / JWST / HST team.
James Webb Space Telescope (JWST) is designed to overcome exactly these limitations: with a 6.5 meter diameter light-gathering area (grabbing more than seven times the light that Hubble can), the capability to do ultra-high resolution spectroscopy from about 600 nanometers to 6 microns (some four times the wavelength Hubble can grab), the ability to do mid-infrared observing to higher sensitivity than ever before, and to both passively cool everything down below the temperature of Pluto and to actively cool the mid-infrared instruments down to just 7 K, JWST should be able to do the science that no one else has been able to do.
In particular, this means:
observing the earliest galaxies ever to form,
seeing through the neutral gas and probing the first stars and the reionization of the Universe,
doing spectroscopic analysis of the very first stars (Population III stars) to form after the Big Bang,
and possibly some amazing surprises, like uncovering how the earliest supermassive black holes and quasars formed in the Universe.
The science we’re bound to learn from JWST is unlike anything else we’ve ever learned, and that’s why it was selected as the flagship NASA mission of this decade: the 2010s.
[Following is a stunning video of James Webb getting ready to go to work. You won’t want to miss it. It is worth downloading.]
JWST deployment sequence
Download mp4 video here .
From a technical standpoint, JWST is an incredible piece of work, and it’s all coming together beautifully. Those of you who’ve been following it for a long, long time might have, in the back of your mind, a distant memory of how the program went over budget and fell behind schedule, and was in danger of being cancelled. When new management stepped in, though, everything changed. The project was suddenly very tightly managed, allowances were made and budgeted for as far as mistakes, errors, setbacks and challenges, and thus far the JWST team has hit every single deadline and made every single deliverable on schedule and within budget. They’re slated for launch in 2018, and they’re not only on schedule, they’ve got a nine month cushion for when they planned to have everything assembled and launch-ready. There are four main pieces to JWST, and here’s the status on each one.
1.) The Optical Assembly. This includes all the mirrors; most spectacularly the eighteen primary, segmented gold mirrors that will be used to gather the distant starlight and focus it for the instruments to analyze. These mirrors are currently all complete and flawless, and are right on schedule as far as installation goes. When it’s all complete, these mirrors will be folded up into a packaged array, launched more than a million kilometers from Earth to the L2 Lagrange point, and then robotically unfolded to create that honeycomb-like structure that will gather that ultra-distant light for years to come. It’s truly a thing of beauty and the successful result of a herculean effort by many.
2.) The science instruments. There are four of these, and they are all 100% complete! They are:
The Near Infrared Camera, James Webb’s primary imaging camera. Extending over an order of magnitude of wavelengths, from visible, orange light deep into the infrared, it should be able to give us unprecedented views of the earliest stars, the youngest galaxies in the process of formation, young stars in the Milky Way and nearby galaxies, hundreds of new objects in the Kuiper Belt, as well as being optimized for directly imaging planets around other stars.
Known objects in the Kuiper belt beyond the orbit of Neptune. (Scale in AU; epoch as of January 2015.)
This will be the main camera used by most observers on JWST.
The Near Infrared Spectrograph, which not only breaks the light from individual objects apart into its individual wavelengths, it’s designed to do this for more than 100 separate objects at once, in a single image! This workhorse will be Webb’s all-purpose spectrograph, capable of three distinct modes of spectroscopy. It was built by the European Space Agency, but with many components, including the detectors and multi-shutter array, provided by Goddard Space Flight Center/NASA. This instrument has been robustly tested and is complete.
The Mid-Infrared Instrument will be the one most useful for wide-field broadband imaging, meaning that it will return the most visually striking pictures of all of Webb’s instruments. Scientifically, it will be most useful for the measurement of proto-planetary disks around incredibly young stars, measuring/imaging Kuiper Belt objects to unprecedented accuracy, and dust that has been warmed by starlight. This will be the only instrument that’s cryogenically (i.e., with extra on-board coolant) cooled: down to 7 K. This will improve on what, for example, the Spitzer Space Telescope saw by about a factor of 100.
NASA/Spitzer
And the last of the four instruments, the Near-InfraRed Imager and Slitless Spectrograph (NIRISS), will allow Webb to perform wide-field spectroscopy at near infrared wavelengths (1.0–2.5 microns); single-object grism spectroscopy over visible and infrared wavelengths (0.6–3.0 microns); aperture-masking interferometry between 3.8–4.8 µm (where we expect to see the first stars and galaxies); and broad-band imaging across its entire field of view. This is the lone instrument that was built by the Canadian Space Agency, and after passing cryogenic testing, it, too, is complete and integrated within the entire instrument module.
3.) The Sunshield. This is new! This is one of the scariest parts of any mission: the brand new stuff. Rather than cooling the entire spacecraft actively, with some type of disposable/consumable coolant, JWST uses a brand new technology: a 5-layer sunshield, which will deploy and block the heat from the Sun from the entire spacecraft. These five 25-meter-long sheets will be held taut, in place, by titanium rods that will deploy when the entire spacecraft unfolds. The Sunshield was tested extensively in 2008 and 2009, and full-scale models for laboratory testing have passed everything they’ve been subjected to here on Earth. It’s truly an innovative thing of beauty.
This is also an incredible concept: you don’t just block the light from the Sun and place the telescope in shadow, you make sure that all the heat is radiated away in the direction opposite to the telescope! The five-layered structure in the vacuum of space means that each progressive layer gets cooler and cooler as it approaches equilibrium. While the outermost layer is going to be quite a bit warmer than the Earth’s surface temperature — somewhere around 350–360 K — by time you get to the end of the fifth layer, the temperature should be down to right around 37–40 K, or cooler than the surface of Pluto during the night.
In addition, there are some tremendous precautions in place to protect against the catastrophic environment of deep space. You see, one of the things everyone needs to worry about are tiny rocks — pebble-sized, grain-of-sand-sized, dust-mote-sized and even smaller — that are flying about through interplanetary space at tens or even hundreds of thousands of miles per hour. These micrometeroids can rip and punch tiny, microscopic holes in everything they encounter: spacecraft hulls, astronaut suits, telescope mirrors and more. While the mirrors would only be dented or dinged, slightly reducing the amount of “good light” available, the sunshield could develop a tear that runs from end-to-end, rendering an entire layer useless. So they did something brilliant to fight this.
They compartmentalized every bit of the sunshield, so that if a small tear emerges in one, or two, or even three pieces, it won’t necessarily render the entire layer useless by spreading, the way a crack in your car’s windshield might spread. Instead, the sectioning should keep the general structure intact, an important precaution against degradation. And finally…
4.) The spacecraft bus, assembly and control systems. This is actually the most routine component, as all space telescopes and science missions need these. JWST’s will be unique, but this is also completely ready. All we need to do is finish the sunshield, finish installing the mirrors, put the whole thing together with the appropriate testing, and we’ll be ready for launch in two years.
If things go right, we’re in for the next great scientific leap forward. The curtain of neutral gas — currently obscuring our view of the earliest stars and galaxies — will be pulled back by this telescope’s infrared capabilities and huge light-gathering power from space. It will be the greatest, most sensitive telescope over a huge wavelength range, from 0.6 microns to about 28 microns (where the human eye can see from about 0.4 to 0.7 microns), ever constructed. If it launches, deploys and operates properly, as it’s expected to, we could get a full decade of observations out of it. According to NASA:
Webb’s mission lifetime after launch will be between 5–1/2 years and 10 years. The lifetime is limited by the amount of fuel used for maintaining the orbit, and by the lifetime of the electronics and hardware in the harsh environment of space. Webb will carry fuel for a 10-year lifetime; the project will do mission assurance testing to guarantee 5 years of scientific operations starting at the end of the commissioning period 6 months after launch.
The primary limiting factor is the amount of on-board fuel, required to keep the telescope operating, in orbit, and pointing accurately at its targets. When that fuel runs out, it will drift away from the L2 Lagrange point, entering a chaotic orbit in the vicinity of Earth.
Lagrange Points
[In celestial mechanics, the Lagrangian points (/ləˈɡrɑːndʒiən/; also Lagrange points, L-points, or libration points) are positions in an orbital configuration of two large bodies where a small object affected only by gravity can maintain a stable position relative to the two large bodies. The Lagrange points mark positions where the combined gravitational pull of the two large masses provides precisely the centripetal force required to orbit with them. There are five such points, labeled L1 to L5, all in the orbital plane of the two large bodies. The first three are on the line connecting the two large bodies and the last two, L4 and L5, each form an equilateral triangle with the two large bodies. The two latter points are stable, which implies that objects can orbit around them in a rotating coordinate system tied to the two large bodies.]
Other things that could fail are:
degradations of the mirrors, which will impact the amount of light gathered and will create image artifacts, but which will still allow the telescope to be usable,
failure of part or all of the sunshield, which will increase the telescope’s temperature and narrow the usable wavelength bands to the very near infrared (out to only 2–3 microns),
and the coolant on the mid-IR instrument, which is consumable; this would render the mid-IR instrument unusable but wouldn’t affect the other instruments (from 0.6 to 6 microns).
The nightmare scenario is that the telescope doesn’t launch or deploy properly, and that’s exactly what the tests being done (and passed, by the way) ensure against.
If JWST works as expected, it’s carrying enough fuel on-board that it should operate from 2018 through 2028, and although it’s never been done, the potential exists for a robotic (or crewed, if the technology gets developed by then) re-fueling mission to L2, which could increase the telescope’s lifetime by another decade. Just as Hubble’s been in operation for 25 years and counting, JWST could give us a generation of revolutionary science if things work out as well as they could. It’s the future of astronomy, and after more than a decade of hard work, it’s almost time to come to fruition. The future of space telescopes is almost here!
“Starts With A Bang! is a blog/video blog about cosmology, physics, astronomy, and anything else I find interesting enough to write about. I am a firm believer that the highest good in life is learning, and the greatest evil is willful ignorance. The goal of everything on this site is to help inform you about our world, how we came to be here, and to understand how it all works. As I write these pages for you, I hope to not only explain to you what we know, think, and believe, but how we know it, and why we draw the conclusions we do. It is my hope that you find this interesting, informative, and accessible,” says Ethan
Inside a massive clean room at NASA’s Goddard Space Flight Center in Greenbelt, Maryland the James Webb Space Telescope team used a robotic am to install the last of the telescope’s 18 mirrors onto the telescope structure.Credits: NASA/Chris Gunn
The 18th and final primary mirror segment is installed on what will be the biggest and most powerful space telescope ever launched. The final mirror installation Wednesday at NASA’s Goddard Space Flight Center in Greenbelt, Maryland marks an important milestone in the assembly of the agency’s James Webb Space Telescope.
“Scientists and engineers have been working tirelessly to install these incredible, nearly perfect mirrors that will focus light from previously hidden realms of planetary atmospheres, star forming regions and the very beginnings of the Universe,” said John Grunsfeld, associate administrator for NASA’s Science Mission Directorate in Washington. “With the mirrors finally complete, we are one step closer to the audacious observations that will unravel the mysteries of the Universe.”
Using a robotic arm reminiscent of a claw machine, the team meticulously installed all of Webb’s primary mirror segments onto the telescope structure. Each of the hexagonal-shaped mirror segments measures just over 4.2 feet (1.3 meters) across — about the size of a coffee table — and weighs approximately 88 pounds (40 kilograms). Once in space and fully deployed, the 18 primary mirror segments will work together as one large 21.3-foot diameter (6.5-meter) mirror.
“Completing the assembly of the primary mirror is a very significant milestone and the culmination of over a decade of design, manufacturing, testing and now assembly of the primary mirror system,” said Lee Feinberg, optical telescope element manager at Goddard. “There is a huge team across the country who contributed to this achievement.”
While the primary mirror installation may be finished on the tennis court-sized infrared observatory, there still is much work to be done.
“Now that the mirror is complete, we look forward to installing the other optics and conducting tests on all the components to make sure the telescope can withstand a rocket launch,” said Bill Ochs, James Webb Space Telescope project manager. “This is a great way to start 2016!”
The mirrors were built by Ball Aerospace & Technologies Corp., in Boulder, Colorado. Ball is the principal subcontractor to Northrop Grumman for the optical technology and optical system design. The installation of the mirrors onto the telescope structure is performed by Harris Corporation, a subcontractor to Northrop Grumman. Harris Corporation leads integration and testing for the telescope.
“The Harris team will be installing the aft optics assembly and the secondary mirror in order to finish the actual telescope,” said Gary Matthews, director of Universe Exploration at Harris Corporation. “The heart of the telescope, the Integrated Science Instrument Module, will then be integrated into the telescope. After acoustic, vibration, and other tests at Goddard, we will ship the system down to Johnson Space Center in Houston for an intensive cryogenic optical test to ensure everything is working properly.”
It will be the most powerful space telescope ever built. Webb will study many phases in the history of our universe, including the formation of solar systems capable of supporting life on planets similar to Earth, as well as the evolution of our own solar system. It’s targeted to launch from French Guiana aboard an Ariane 5 rocket in 2018. Webb is an international project led by NASA with its partners,ESA (European Space Agency) and the Canadian Space Agency.
To watch the Webb telescope being built at Goddard, visit the “Webb-cam” page at:
President Dwight D. Eisenhower established the National Aeronautics and Space Administration (NASA) in 1958 with a distinctly civilian (rather than military) orientation encouraging peaceful applications in space science. The National Aeronautics and Space Act was passed on July 29, 1958, disestablishing NASA’s predecessor, the National Advisory Committee for Aeronautics (NACA). The new agency became operational on October 1, 1958.
Since that time, most U.S. space exploration efforts have been led by NASA, including the Apollo moon-landing missions, the Skylab space station, and later the Space Shuttle. Currently, NASA is supporting the International Space Station and is overseeing the development of the Orion Multi-Purpose Crew Vehicle and Commercial Crew vehicles. The agency is also responsible for the Launch Services Program (LSP) which provides oversight of launch operations and countdown management for unmanned NASA launches. Most recently, NASA announced a new Space Launch System that it said would take the agency’s astronauts farther into space than ever before and lay the cornerstone for future human space exploration efforts by the U.S.
October 31st, 1995: The “Next Generation Space Telescope” (NGST) project, now known as “James Webb Space Telescope” (JWST) starts to become a reality. Twenty years later we’re sitting together with Dr. John Mather, Senior Project Scientist at Goddard and one of the Founders of JWST. Working at NASA for over 40 years provides a lot of experiences and stories.
NASA/Webb
Daniela and Verena: How would you describe your areas of activity to a layperson?
John Mather: Oh, to a layman it would look like I just sit and talk and write e-mails. But I guess, the more interesting thing is what the conversation is about. So the conversation is about ‘What do we need to do?’ so that the telescope will work. And so some days it’s about the engineers and technicians that found something that isn’t quite right, so ‘What are we going to do about it?’. Some days it is just making sure that the scientific world is ready. So we talk to our scientists around the world to say ‘This is how we’re going to operate the telescope. This is what you have to do to prepare a proposal.’ If you’re a scientist then you find your friends and you say ‘This is the topic I think we really should examine and then this is how much time we need from the telescope to answer our questions. This is why we’re the best team in the entire world to do this work.’ Afterwards, a committee will consider the proposals. We receive thousands of proposals – it’s a very popular telescope. So that’s what our conversations are about these days. A time ago, it was more about how could you possibly come up with a technology that would enable such a telescope. Because at the beginning none of this was possible – it was only an idea. So we needed mirrors and detectors and we needed to make an agreement amongst various space agencies about who was going to do what. All of those things were very tricky and they showed us what things to do.
Credit: NASA/Chris Gunn
Daniela and Verena: What was your favorite moment at the JWST project so far?
John Mather: It’s hard to say. I think my favorite moment will be when it goes up and successfully reaches orbit, unfolds in space and functions properly. That’s the thing everyone thinks about.
Daniela and Verena: The JWST is a very complex construction project. In your eyes, what is its biggest challenge?
John Mather: I think everyone believes that the biggest challenge is to make sure that it unfolds properly in space. Because this is new – that is not something we’ve done many times. Many observatories have things that unfold in space but ours is much more precise for the unfolding. So it’s complicated and has this big sunshield design – nobody ever needed a piece of plastic as big as a tennis court in space. It all has to be carefully designed, managed and tested. We also have to imagine every possible way to go wrong and then make sure that this does not happen. So it’s either by thinking about it or by designing something or by testing something that you have to succeed in making a good design. Then, at the very end, of course it’s the technicians, the people who actually touch the equipment, that have to do their job exactly right.
Daniela and Verena: Winning the Nobel Prize is for sure an experience with far-reaching effects. Can you tell us if it resulted in any professional or private changes?
John Mather: I think the main changes were getting far more invitations for traveling and speaking. I tried to make no other changes – I have the same job that I had beforehand. The prize came in 2006 and the telescope project was already eleven years old by then. So I’m still doing the same job and I just get more chances to talk to people.
Daniela and Verena: We know that you’re a passionate traveler. What was your most impressive destination or trip?
John Mather: I guess there are several. The most spectacular one was traveling to see the giant animals in Southern Africa – we went to Namibia and Botswana and we saw the lions and the elephants. Just thinking about the history where human beings come from and how we must have lived with lions everywhere back then – it sort of makes you think a lot. Because our history here on earth is so short as human beings, we’ve only been here for a very short time and those big animals also haven’t been here that long. Lions and elephants are also just a few million years old. Earth is like 4.6 billion years old – so what was going on between the beginning and now? That’s one of the things I love to think about. Another one is our cultural history. The first time I saw Italy and just see things written on the monuments in Latin and I thought ‘I really should have studied Latin in school so I would be able to read what they said.’ That only reaches back a few thousand years of history. So that seems to be the attraction that I feel. When traveling I’m thinking of history.
Daniela and Verena: There are a lot of young people with brilliant ideas out there. Often they are not taken seriously and have struggles realizing their visions. Which advice would you give them?
John Mather: Well, I don’t know if there’s any general advice but everything is about communication. And so sharing the ideas with other people, talking with your friends ‘I’ve got this idea, would you like to help me? Or can you make a better idea?’ – all of these things are part of the process that successful ideas have. I guess it’s always an interesting question because maybe the idea is bad. But how will you find out if you don’t try to push it forward? And maybe if you start pushing it then somebody will say ‘Oh, I have a better idea, let’s do that one instead.’ So I think it’s more like choosing the direction to go in than rather saying which exact tree you’re going to reach – it’s more direction-orientated than goal-orientated. People often talk about how goals are important to us. I think it’s less important than the direction along which the goals might be. Let’s say our direction is that we want to have civilization last for a billion years – what are the things that we have to do between now and a billion years?
Blueshift is produced by a team of contributors in the Astrophysics Science Division at Goddard. Started in 2007, Blueshift came from our desire to make the fascinating stuff going on here every day accessible to the outside world.
Jan. 6, 2016
Laura Betz
NASA’s Goddard Space Flight Center
The instruments that will fly aboard NASA’s James Webb Space Telescope not only have to be tough enough to survive in the cold of space, but they also have to work properly in the electromagnetic environment on the spacecraft, so they’re tested for both. Recently, they passed a test for the latter in a very unique room.
A team of engineers in special clean room suits at NASA Goddard. Seen from left to right: Andy Mentges, Nathan Block, Vaughn Nelson, Rob Houle, John McCloskey, Mark Branch, Rick Jones, Greg Jamroz. Credits: NASA/Chris Gunn
Stepping inside NASA’s Electromagnetic Interference or EMI laboratory at NASA’s Goddard Space Flight Center in Greenbelt, Maryland feels like stepping inside a Lady Gaga music video. Inside this white room where conical structures jut out from the walls, a team of engineers clad in “bunny suits” or white suits recently and successfully completed one of the key environmental tests for the Integrated Science Instrument Module (ISIM), the science payload of the James Webb Space Telescope.
The ISIM can be considered the eyes and ears of Webb telescope and the purpose of the test was to verify that these eyes and ears will be compatible with the electromagnetic environment on the spacecraft.
Once inside the clean room, the team set up antennae for different tests. Their first task was to measure the electromagnetic emissions from the ISIM in order to assess the likelihood of interference to the rest of the spacecraft. They also illuminated the ISIM with electromagnetic waves in order to assess the likelihood of interference from the rest of the spacecraft.
These tests must be performed in an anechoic (Latin for “no echo”) chamber. The conical structures jutting out from the walls absorb the electromagnetic energy in order to minimize reflections. As much as a sound booth works to minimize the reflection of sound waves, the anechoic material minimizes reflections of electromagnetic waves so that they don’t bounce back and combine with the original waves, which would disturb the integrity of the test.
“The anechoic material minimizes reflections in order to give maximum control of the test,” said Goddard Chief EMC Engineer John McCloskey. “A metal wall is like a mirror for electromagnetic waves. These walls are designed to absorb the radiated energy and minimize reflections so that we know what we are actually measuring. We need to know that what we are measuring is actually coming directly from ISIM and not from multiple reflected paths in the room.”
The project schedule allotted 10 days for the test. The team met all the test objectives in 8.5 days. ISIM passed with flying colors.
“Despite a few setbacks, our team finished the test ahead of schedule and beat the deadline,” said John McCloskey. “This test is important because when the James Webb Space Telescope is operating in space and identifying distant galaxies and other astronomical objects, we will have confidence that these are indeed real objects and not blips caused by electromagnetic interference.”
Now, the ISIM is inside the thermal vacuum chamber at NASA Goddard, undergoing its third and final cryogenic test. This test will ensure that Webb telescope’s eyes and ears will work properly in the frigid temperatures of space.
The images from the Webb telescope will reveal the first galaxies forming approximately 13.5 billion years ago. The telescope will also see through interstellar dust clouds to capture stars and planets forming in our own galaxy. At the telescope’s final destination in space, one million miles away from Earth, it will operate at incredibly cold temperatures of minus 387 degrees Fahrenheit, or 40 degrees Kelvin. This is 260 degrees Fahrenheit colder than any place on the Earth’s surface has ever been.
It will be the most powerful space telescope ever built. Webb is an international project led by NASA with its partners, the European Space Agency and the Canadian Space Agency.
The James Webb Space Telescope will be a large infrared telescope with a 6.5-meter primary mirror. Launch is planned for later in the decade.
Webb telescope will be the premier observatory of the next decade, serving thousands of astronomers worldwide. It will study every phase in the history of our Universe, ranging from the first luminous glows after the Big Bang, to the formation of solar systems capable of supporting life on planets like Earth, to the evolution of our own Solar System.
Webb telescope was formerly known as the “Next Generation Space Telescope” (NGST); it was renamed in Sept. 2002 after a former NASA administrator, James Webb.
Webb is an international collaboration between NASA, the European Space Agency (ESA), and the Canadian Space Agency (CSA). The NASA Goddard Space Flight Center is managing the development effort. The main industrial partner is Northrop Grumman; the Space Telescope Science Institute will operate Webb after launch.
Several innovative technologies have been developed for Webb. These include a folding, segmented primary mirror, adjusted to shape after launch; ultra-lightweight beryllium optics; detectors able to record extremely weak signals, microshutters that enable programmable object selection for the spectrograph; and a cryocooler for cooling the mid-IR detectors to 7K.
Launch is scheduled for later in the decade on an Ariane 5 rocket. The launch will be from Arianespace’s ELA-3 launch complex at European Spaceport located near Kourou, French Guiana. Webb will be located at the second Lagrange point, about a million miles from the Earth.
17 December 2015
Markus Bauer
ESA Science and Robotic Exploration Communication Officer
Tel: +31 71 565 6799
Mob: +31 61 594 3 954
Email: markus.bauer@esa.int
Peter Jensen
ESA’s JWST project manager
Email: peter.jensen@esa.int
Two polished test mirror segments for the James Webb Space Telescope being inspected by an optical engineer: one segment with the gold coating already applied, the other without.
JWST has a foldable mirror composed of 18 hexagonal-shaped segments mounted onto a framework that forms the spine of the observatory. This structure has two wings that can be folded to fit inside the launcher. Once in space, JWST will unfold and spread its wings. It will then be the largest astronomical telescope in space.
The next great space observatory took a step closer this week when ESA signed the contract with Arianespace that will see the James Webb Space Telescope launched on an Ariane 5 rocket from Europe’s Spaceport in Kourou in October 2018.
Ariane is part of the European contribution to the cooperative mission with NASA and the Canadian Space Agency, along with two of the four state-of-the-art science instruments for infrared observations of the Universe.
The telescope’s wide range of targets includes detecting the first galaxies in the Universe and following their evolution over cosmic time, witnessing the birth of new stars and their planetary systems, and studying planets in our Solar System and around other stars.
With a 6.5 m-diameter telescope, the observatory must be launched folded up inside Ariane’s fairing. The 6.6 tonne craft will begin unfolding shortly after launch, once en route to its operating position some 1.5 million km from Earth on the anti-sunward side.
The contract includes a cleaner fairing and integration facility to avoid contaminating the sensitive telescope optics.
“With this key contract now in place with our long-standing partners, we are closer than ever to seeing the scientific goals of this next-generation space observatory realised,” says Jan Woerner, ESA’s Director General.
“This agreement is a significant milestone,” says Eric Smith, NASA’s JWST programme director. “The years of hard work and excellent collaboration between the NASA, ESA and Arianespace teams that have made this possible are testimony to their dedication to the world’s next great space telescope.”
“It is a great honour for Arianespace to be entrusted with the launch of JWST, a major space observatory which will enable science to make a leap forward in its quest of understanding our Universe,” said Stéphane Israël, Chairman and CEO of Arianespace.
“It is also an immense privilege to be part of such an international endeavour gathering the best of US, European and Canadian space technology and industry.”
JWST’s science module, with all four flight instruments, is undergoing final tests at cryogenic temperatures at NASA’s Goddard Space Flight Center. Assembly of the 18 mirror segments, which will unfold after launch, is also now underway.
“With the launch service agreement formally agreed, and with NASA’s continuing solid progress of integrating and testing JWST, we keep the steady pace towards the launch in October 2018,” says Peter Jensen, ESA’s project manager.
The European Space Agency (ESA), established in 1975, is an intergovernmental organization dedicated to the exploration of space, currently with 19 member states. Headquartered in Paris, ESA has a staff of more than 2,000. ESA’s space flight program includes human spaceflight, mainly through the participation in the International Space Station program, the launch and operations of unmanned exploration missions to other planets and the Moon, Earth observation, science, telecommunication as well as maintaining a major spaceport, the Guiana Space Centre at Kourou, French Guiana, and designing launch vehicles. ESA science missions are based at ESTEC in Noordwijk, Netherlands, Earth Observation missions at ESRIN in Frascati, Italy, ESA Mission Control (ESOC) is in Darmstadt, Germany, the European Astronaut Centre (EAC) that trains astronauts for future missions is situated in Cologne, Germany, and the European Space Astronomy Centre is located in Villanueva de la Cañada, Spain.
Nov. 30, 2015
Rob Gutro
NASA’s Goddard Space Flight Center
Recently, the James Webb Space Telescope’s “pathfinder telescope,” or “Pathfinder” completed its second super-cold optical test that resulted in the first checkout of specialized optical test equipment designed to illuminate the telescope’s optics through to the instrument focal planes, and the procedures used to operate this test equipment.
Engineers inspect the James Webb Space Telescope’s “pathfinder telescope,” after its second super-cold optical test in Chamber A at NASA’s Johnson Space Center. Credits: NASA/ Chris Gunn
While the actual flight elements of NASA’s Webb telescope are assembled, engineers are testing the non-flight equipment installed in the test chamber to ensure that tests on the real Webb telescope later go safely and according to plan.
After the first Pathfinder test was completed in June 2015, the Aft Optics System or AOS, which includes the Tertiary Mirror and Fine Steering Mirror, was installed on the Pathfinder to prepare for a second test.
The Pathfinder is a non-flight replica of the Webb telescope’s center section backplane, or “backbone,” that includes flight spare mirrors. The full Pathfinder was then outfitted with special fiber-fed infrared optical sources that simulate star images. Those star images, or infrared sources, along with a specially instrumented infrared detector were used during the second test to perform end-to-end testing of the full Pathfinder telescope system. The AOS and the source system was built by Ball Aerospace and Technologies Corp’s facilities in Boulder, Colorado.
“Practice makes perfect. Since we will be testing the world’s largest ever cryogenic telescope for the first time in the world’s largest cryogenic test chamber, we need to be experienced in using our test equipment so we can focus on the performance of the telescope,” said Mark Clampin, Webb telescope Observatory Project Scientist at NASA’s Goddard Space Flight Center in Greenbelt, Maryland.
The flight backplane comes in three segments, a center section and two wing-like parts, all of which will support large hexagonal mirrors on the Webb telescope. The pathfinder only consists of the center part of the backplane. However, during the test, it held two full size spare primary mirror segments and a full size spare secondary mirror to demonstrate the ability to optically test and align the telescope at the planned operating temperatures of -400 degrees Fahrenheit (-240 Celsius). The test equipment used to test the telescope primary mirror and used to hold the entire pathfinder telescope were built by Harris Corporation of Rochester, New York.
The first and second cryogenic optical testing of the Pathfinder were conducted in Chamber A at NASA’s Johnson Space Center in Houston, Texas, where the testing of the flight hardware will occur in 2017. The extremely cold conditions inside the chamber are created by running liquid nitrogen and extremely cold helium gas through plumbing criss-crossing the surface of two big metal shells or “shrouds” nested inside the chamber walls.
“Now that the second test is done, it means that all optical test systems have been checked out,” said Lee Feinberg, Webb telescope Optical Telescope Element Manager at NASA Goddard.
A third and final precursor test called “Thermal Pathfinder” will follow in 2016 that will fully test all the test equipment needed to simulate the temperature environment of space. Once this is complete, all test equipment and procedures needed to test the actual full flight telescope in early 2017 will be checked-out and ready.
The James Webb Space Telescope will be a large infrared telescope with a 6.5-meter primary mirror. Launch is planned for later in the decade.
Webb telescope will be the premier observatory of the next decade, serving thousands of astronomers worldwide. It will study every phase in the history of our Universe, ranging from the first luminous glows after the Big Bang, to the formation of solar systems capable of supporting life on planets like Earth, to the evolution of our own Solar System.
Webb telescope was formerly known as the “Next Generation Space Telescope” (NGST); it was renamed in Sept. 2002 after a former NASA administrator, James Webb.
Webb is an international collaboration between NASA, the European Space Agency (ESA), and the Canadian Space Agency (CSA). The NASA Goddard Space Flight Center is managing the development effort. The main industrial partner is Northrop Grumman; the Space Telescope Science Institute will operate Webb after launch.
Several innovative technologies have been developed for Webb. These include a folding, segmented primary mirror, adjusted to shape after launch; ultra-lightweight beryllium optics; detectors able to record extremely weak signals, microshutters that enable programmable object selection for the spectrograph; and a cryocooler for cooling the mid-IR detectors to 7K.
Launch is scheduled for later in the decade on an Ariane 5 rocket. The launch will be from Arianespace’s ELA-3 launch complex at European Spaceport located near Kourou, French Guiana. Webb will be located at the second Lagrange point, about a million miles from the Earth.
“Up to this point, for as long as we’ve been working on Webb, you’ve only ever really seen a cartoon of the telescope. Towards the end of this year, you will actually be able to see the James Webb Space Telescope realised in hardware.”
It’s been a long time coming but we are now at the business end of building Hubble’s successor.
NASA/ESA Hubble
The spectacular new observatory that has been designed to find the “first light” to shine in the Universe is getting real.
And Eric Smith, the programme director and programme scientist on this $10bn venture, is understandably quite excited by what is about to unfold in the next few months.
Whereas in the past, the talk has all been about the development and manufacture of individual components, such as Webb’s instruments or its beryllium and gold mirrors – these have all now been produced (bar one or two items).
For years, the James Webb Space Telescope has been just an artist’s impression. The coming year will see it really take shape
The time has come to put everything together in preparation for the big launch into orbit on an Ariane rocket in 2018.
The US aerospace giant Northrop Grumman is the industrial prime contractor and it has just completed the main telescope structure at its facility in Los Angeles.
This includes the “backplane” – the part of Webb that will hold the 18 mirror segments in its primary reflecting surface.
Shortly, the telescope structure will ship to Nasa’s Goddard centre outside Washington DC for this integration task to begin.
It will be an iconic milestone because, as Eric Smith says, it’s the moment when everyone will go: “So, this is JWST!” At last, we will have something that starts to resemble all those artist impressions.
And while this is happening, the telescope’s instruments reach a critical juncture of their own at Goddard.
Slowly but surely
James Webb has four sophisticated tools to study the sky – the American NIRCam, NIRSpec and Miri from Europe, and the Canadian FGS/NIRISS.
NIRCam
NIRSpec
MIRI
FGS/NIRISS
This quartet has now been mounted inside a composite support frame, known as the Integrated Scientific Instrument Module or ISIM.
In the next few weeks, this entire edifice will be checked for any electronic interference issues, and also shaken and blasted with sound to simulate the thunderous environment of flying on an Ariane.
All four of James Webb’s instruments are in the ISIM and ready for their third and final test in the Goddard cryo-chamber
The ISIM structure will then go inside a vast chamber at Goddard for three months to experience the deep cold and vacuum of space.
“Because James Webb is such a large and complex observatory, and also because it’s a cryogenic one – you can’t just put everything together at once and then test it,” explains project scientist Mark Clampin, as we stand next to the big cryo-vac facility.
“As you put stuff together, it gets sealed in thermally isolated packages. So you have to start by testing the smallest piece first, adding it to the next item and then testing them, and so on.
“And as you get to the largest items, it’s then very difficult to go back if you have a problem with, say, a detector. As a consequence James Webb has been a long and deliberate process.”
This autumn’s cryo campaign will be the third and final one for ISIM and its passengers at Goddard.
When the instruments are inside, they will be exposed to a light source – a fake star, if you will. It will give the instrument teams an opportunity to gather the calibration data they will need to fine-tune Webb when it goes into orbit.
Replacing components
“We have another complex piece called the Optical Telescope Simulator, and it takes the place of the telescope, producing a light that simulates a star for each of the instruments,” explains Begoña Vila, an engineer with particular responsibility for the Fine Guidance Sensor.
“We can then all check things related to that star, like its brightness or the dispersion the instruments get with either a slit or a prism. It confirms that everything works as if there is a real star.”
Europe will be heavily involved in the cryo campaign, confirms Marco Sirianni from the European Space Agency.
“We are putting together a large team that will come to Goddard and work 24/7 to support the test.
“We already have seven people here, but more are coming from the NIRSpec and Miri groups. And this test is very important because it will be a final verification of the modifications that were made at the component level.”
Those modifications refer to the underperforming parts of NIRSpec and Miri that were present in the European instruments when they were delivered to Goddard from Germany and the UK.
These included degraded detectors and electronics, and, in the case of NIRSpec, a troublesome micro-shutter array intended to tease apart the colours of stars.
Some of its shutters had the annoying habit of sticking open or closed. All this suspect componentry has now been exchanged.
When ISIM and the instruments emerge from the cryo-vac, they will be joined to the finished telescope structure complete with mirrors.
Months in reserve
By then, there really will be no mistaking James Webb. But yes, you’ve guessed it, these joined items then have to be tested again as a single unit. And for that task, they will be shipped in 2016 to Nasa’s Johnson centre. It has a giant vacuum chamber that was built originally to run the rule over the Apollo spaceships before they launched.
Of course, the fear is always that some big problem emerges – that perhaps something breaks or simply does not meet the specifications demanded of it.
Recently, the part of James Webb that has been in the “dog house” is the so-called cryo-cooler for Miri. The UK-led instrument will work at just a few degrees above absolute zero and must be actively chilled even in space to get down to the right temperature.
The cooler unit is late but it has now been delivered from the American manufacturer to begin its testing programme. Assuming the cryo-cooler passes, Webb stays on track.
Eric Smith told me: “Right now, we are carrying nine months of funded, scheduled reserve. So, we have nine months of slack in our schedule that can be consumed, or used, before we would think of changing the launch date.
“This nine months is about what we had planned five years ago when we re-structured the programme.”
Jul 22, 2015
Amanda Doyle for Astrobiology Magazine
If life exists on planets beyond our Solar System, its presence could be obscured by the haze and clouds in the planet’s atmosphere. Even next generation telescopes – such as the James Webb Space Telescope (JWST) as well as ground-based telescopes like the European Extremely Large Telescope (E-ELT) – will have a hard time penetrating such hazy worlds in search of biomarkers.
NASA/Webb
ESO/E-ELT
Astronomers Amit Misra and Victoria Meadows of the University of Washington have developed a new technique to check if a planet has clear skies, which will make it easier for astrobiologists to target the most promising exoplanet candidates for life. Their research has been published in the Astrophysical Journal Letters and was funded by the NASA Astrobiology Institute element of the Astrobiology Program at NASA.
Light being refracted in the atmosphere of the Earth can sometimes create a halo around the Sun or Moon. Similarly, light from another star being refracted in an exoplanet atmosphere can cause an increase in the amount of light detected from the star just before the planet transits. Image courtesy Doug Wilson.
Hazy worlds
As a planet transits a star, light from that star passes through the planet’s atmosphere and certain molecules in the planet’s atmosphere absorb the light, enabling astronomers to measure the composition of the atmosphere. This technique is known as transit transmission spectroscopy, and extending this to Earth-like planets is quite a challenge.
The height of the atmosphere of a potentially habitable planet is minuscule compared to that of a gas giant or icy planet close to its host star, so catching the light of the star as it passes through the atmosphere of an Earth-like planet will require extremely lengthy observations. For example, JWST would require around 200 hours to detect the spectrum, while the E-ELT would need at least 20 hours. Even with extensive observations, it is possible that the spectrum would reveal nothing if all the atmospheric features were masked by clouds or haze.
“We’ve seen a couple of cases already in which observers have spent substantial telescope time on a single target only to get a flat, featureless spectrum,” says Misra. “Telescope time is valuable, so it would be useful to know which exoplanets to spend hundreds of hours on beforehand.”
Planets with halos
Misra and Meadows have thought of a solution to this problem. On Earth, light can be refracted by ice crystals in the atmosphere resulting in a halo around the Sun or Moon. The same principle can be applied to exoplanets, as the starlight being refracted in the planet’s atmosphere can create a halo around the planet.
Transiting exoplanets are revealed through a regular dip in light from the star. The refraction halo amplifies the light a little so that it can be seen as a bump in the light curve.
“We can see the effect in the light curve prior to and after the transit itself, and you don’t need transit transmission spectroscopy, you could just measure brightness,” explains Meadows.
A planet covered in clouds or haze would not refract light easily, as the atmospheric layer where the refraction occurs would be murky and block the light. Therefore, if refraction was detected, it would imply that the planet has a clear atmosphere and is an excellent target for follow up spectroscopy.
The scientists used computer models to predict the strength of the refractive signal that would be detected for different types of planetary atmospheres. They simulated Solar System planet atmospheres, as well as super-Earths and mini-Neptunes, while also taking into account the distance of the planet from the star, as this will affect the angle of deflection of the light.
Their results showed that planets akin to Saturn would have the highest signal, as they are large in size. They also have the advantage of having a lower surface gravity than the higher mass Jupiter planets, meaning that the atmosphere is quite extended. For both Jupiter and Saturn analogue planets, JWST could detect a refracted light signal in less than ten hours. E-ELT could detect signals from super-Earths and mini-Neptunes in the same amount of time. In contrast, a hazy planet would need more than 100 hours of E-ELT time before the refraction signal could be distinguished.
Earth-like atmospheres
E-ELT has the potential to detect habitable exoplanets with clear skies. Of course this does not mean that no clouds are present at all, as clouds on Earth are essential for the water cycle.
“Earth’s water clouds are typically close to the surface, and while they can reduce the detectability of molecular absorption features in transit transmission, work that I and others have done has shown that it should still be possible to detect features from gases like carbon dioxide, water, and possibly even oxygen for a cloudy, Earth-like planet,” says Misra.
This new work is an important step forward towards characterizing atmospheres of Earth-like planets. By only needing a few hours of E-ELT time to see if a planet has an atmosphere worthy of follow up, the longer observations can then be used to acquire the spectra that are vital in the search for life.
In this new NASA video, engineers from Airbus Defense and Space (DS), Ottobrunn, Germany, dressed in white protective suits and special white gloves, recently completed a delicate surgical procedure to exchange two key components from the “heart” of an instrument on the James Webb Space Telescope at NASA’s Goddard Space Flight Center in Greenbelt, Maryland.
Webb has four main instruments that will detect light from distant stars and galaxies, and planets orbiting other stars. The operation required the team to open one of those four instruments, the Near Infrared Spectrograph or NIRspec, which is a highly sensitive instrument. This was the last chance to provide upgrades before it flies on the Webb telescope in 2018.
Once in space, NIRSpec will be capable of measuring the spectrum of up to one hundred objects simultaneously. With this tool, scientists will be capable of observing large samples of galaxies and stars at unprecedented depths across large swaths of the Universe and far back in time.
To make this remarkable achievement possible, Goddard scientists and engineers had to invent a new device. This so-called Micro Shutter Array (MSA) controls whether light from an astronomical object in the telescope field of view enters the NIRSpec. The MSA consists of just under a quarter of a million individually controlled microshutters. Each shutter is approximately as wide as a human hair.
“We exchanged two very crucial subsystems, NIRSpec’s Focal Plane Array and the Micro Shutter. We were working deep in the heart of the instrument,” said Maurice te Plate, European Space Agency’s Webb system integration and test manager working at NASA Goddard. “We used laser trackers and special camera systems to make sure that everything was accurately aligned. We’ve had very good support from NASA and we’ve had a great team from Airbus DS Germany that was super professional and dedicated.”
Each morning after dressing in special garments that do not generate dust, the team began work with the lights in the big clean room switched off. They turned their specialized flashlights on and begin pouring over this vital piece looking for fibers. Any presence of fibers could weave through the micro shutters and prevent them from properly closing.
“To prepare for this operation we planned for a year,” said Ralf Ehrenwinkler Airbus DS NIRSpec Post Delivery Support Manager. “We performed everything in a different environment so it’s an added challenge. We needed to copy the same clean room environment as the instrument was integrated in Germany, so we needed to establish special clothes and requirements. There was a lot of coordination. The recorded data showed that the required cleanliness levels were well achieved.”
Once NIRSpec received its last chance updates, it joined the three other Webb science instruments that were mounted on the ISIM.
NIRSpec weighs about 430 pounds (195 kg), about as much as an upright piano. It is one of four instruments that will fly aboard the Webb telescope. The other instruments include the Near-Infrared Camera (NIRCam), the Mid-Infrared Instrument (MIRI) and the Fine Guidance Sensor/ Near InfraRed Imager and Slitless Spectrograph (FGS/NIRISS).
NIRSpec was provided by the European Space Agency and built by Airbus Defense and Space in Germany.
The James Webb Space Telescope is the successor to NASA’s Hubble Space Telescope. It will be the most powerful space telescope ever built.
NASA’s Goddard Space Flight Center is home to the nation’s largest organization of combined scientists, engineers and technologists that build spacecraft, instruments and new technology to study the Earth, the sun, our solar system, and the universe.
Named for American rocketry pioneer Dr. Robert H. Goddard, the center was established in 1959 as NASA’s first space flight complex. Goddard and its several facilities are critical in carrying out NASA’s missions of space exploration and scientific discovery.
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