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  • richardmitnick 8:23 am on July 24, 2015 Permalink | Reply
    Tags: , , , NASA Webb, SPACE DAILY   

    From SPACE DAILY: “New Method Finds Best Candidates for Telescope Time” 

    Temp 1

    SPACE DAILY

    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 Telescope
    NASA/Webb

    ESO E-ELT
    ESO E-ELT Interior
    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.

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    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.

    See the full article here.

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  • richardmitnick 10:54 am on June 2, 2015 Permalink | Reply
    Tags: , , , NASA Webb   

    From NASA: “Engineers Conduct “Heart Surgery” on the Webb Telescope” 

    NASA Goddard Banner
    Goddard Space Flight Center

    May 29, 2015

    Laura Betz
    NASA’s Goddard Space Flight Center

    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.

    NASA Webb Telescope
    Webb

    Airbus DS is associated with the European Space Agency, one of NASA’s two partners on the Webb. The other is the Canadian Space Agency.

    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.

    For more information about the ISIM, visit: http://www.jwst.nasa.gov/isim.html

    For more information about the Webb telescope, visit: http://www.jwst.nasa.gov or http://www.nasa.gov/webb

    See the full article here.

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    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.

    NASA Goddard Campus
    NASA/Goddard Campus
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  • richardmitnick 3:11 pm on May 28, 2015 Permalink | Reply
    Tags: , , NASA Webb,   

    From CBS: “After 25 years of Hubble, NASA plans ambitious follow-up” 

    CBS News

    CBS News

    April 24, 2015
    William Harwood

    NASA Webb Telescope
    James Webb Space Telescope

    NASA WFIRST telescope
    WFIRST

    NASA plans to follow up the enormous success of the Hubble Space Telescope with two major space-based observatories, the James Webb Space Telescope, scheduled for launch in late 2018, and the Wide Field Infrared Survey Telescope, or WFIRST, in the mid 2020s.

    NASA Hubble Telescope
    NASA/ESA Hubble

    The James Webb is a $6.5 billion flagship mission featuring a huge, 21-foot-wide segmented mirror three times larger than Hubble’s and a suite of instruments optimized for infrared observations. If all goes well, the James Webb will detect light from the first generations of stars and galaxies to form after the big bang birth of the universe.

    WFIRST features a mirror donated to NASA by the National Reconnaissance Office, the super-secret agency that operates the nation’s spy satellites. The donated mirror, one of two given to NASA, is the same size as Hubble’s, but features a much wider field of view.

    The James Webb Space Telescope will be roughly 100 times more powerful than Hubble. Among its key science goals are studies of star formation and the evolution of galaxies, studying the atmospheres of planets orbiting other stars and looking for clues about habitability to get a better sense of how common life might, or might not be, across the cosmos.

    Like the James Webb, WFIRST will be optimized for infrared observations and will focus on the nature of dark energy and pioneering studies of planets orbiting other stars. The WFIRST observatory will have roughly the same optical power and resolution as Hubble, but it’s field of view will be twice as large.

    In now-famous “deep field images” taken by Hubble, astronomers focused the telescope on patches of sky that were 50 times smaller than the full moon. In those images, astronomers can make out some 10,000 galaxies.

    “In a typical WFIRST deep field, we’ll have a million galaxies,” said Jason Kalirai, an astronomer at the Space Telescope Science Institute. “Our statistical sense of what’s happening in the universe and our interpretation of what those sources mean, will expand exponentially with these tools.”

    Hubble is still going strong after a quarter century in orbit because spacewalking shuttle astronauts were able to fix its initially blurry vision, replace older instruments with newer, more powerful versions and repair or replace aging components when they broke down.

    None of that will be possible for Hubble’s successors.

    Unlike Hubble, which was placed in a low-Earth orbit reachable by astronaut repair crews, the James Webb Space Telescope will be boosted to Lagrange Point 2, about one million miles from Earth, where the gravity of the sun, Earth and moon roughly balance to allow the observatory to maintain its position with minimal use of rocket fuel.

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    Lagrange points in the Sun–Earth system (not to scale)

    Equally important, Lagrange Point 2 will allow JWST’s sun shade, a complex five-layer parasol the size of a tennis court, to block out the light of the sun, Earth and moon to keep the telescope at the ultra-low temperatures needed for its instruments to capture the faint infrared light of the very first stars and galaxies.

    After release from a European Ariane 5 rocket, the JWST will unfold like a robotic origami. First, telescoping rods will extend, pulling the sunshade open and separating its layers. Then the segments making up Webb’s primary mirror will unfold, along with the support beams for the telescope’s secondary mirror.

    Unlike Hubble, the Webb was not designed to be serviced by astronauts. NASA’s Orion spacecraft, the only piloted vehicle under development that could even reach JWST, is not equipped with any sort of robot arm or any analogue of the shuttle’s payload bay where servicing could be attempted. JWST has to work right out of the box.

    And also unlike Hubble, NASA does not expect to still be receiving images from Webb when its 25th anniversary rolls around. Or even its 20th. While only a small amount of fuel is needed to maintain the observatory’s place at Lagrange Point 2, what propellant there is will run out after about 10 years.

    Hubble is “an experiment in extreme serviceability,” said John Grunsfeld, veteran of three shuttle servicing missions and NASA’s current director of space science. “On the other extreme is James Webb, with no serviceability whatsoever. And so, as a society, we do these experiments. I’m hoping the James Webb experiment works out well.”

    When he came on board as NASA’s associate administrator for space science, Grunsfeld argued, unsuccessfully, to add a small grapple fixture to the James Webb so “if something goes wrong, we could send a little, teeny spacecraft out and just shake it gently, to unfurl something,” he said.

    “But it was too late in the design cycle to do anything like that,” he said. “So it is a grand experiment.”

    See the full article here.

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  • richardmitnick 6:40 am on March 28, 2015 Permalink | Reply
    Tags: , , , NASA Webb,   

    From Hubble: “Hubblecast 83″ 

    NASA Hubble Telescope

    Hubble

    March 19, 2015

    As Hubble enters its 25th year in orbit, with celebrations planned around the world for its anniversary on 24 April 2015, this Hubblecast celebrates the relationship that the telescope will have with its future colleague, the James Webb Space Telescope.

    See the full article here.

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    The Hubble Space Telescope is a project of international cooperation between NASA and the European Space Agency. NASA’s Goddard Space Flight Center manages the telescope. The Space Telescope Science Institute (STScI), is a free-standing science center, located on the campus of The Johns Hopkins University and operated by the Association of Universities for Research in Astronomy (AURA) for NASA, conducts Hubble science operations.

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  • richardmitnick 6:36 am on March 24, 2015 Permalink | Reply
    Tags: , , , NASA Webb   

    From Cosmos via James Webb: “Pulling back the curtain on the Universe” Well Worth Your Time 

    NASA James Webb Header

    NASA James Webb Telescope

    James Webb Space Telescope

    Cosmos
    1

    23 Mar 2015
    Dan Falk

    When it is launched in 2018, the James Webb Space Telescope will be able to look further back in time than we have ever seen. Dan Falk reports.

    I’m standing in the second-floor viewing gallery in Building 29 at NASA’s Goddard Space Flight Centre, just outside Washington DC. On the other side of the enormous plate-glass window is the facility’s giant “clean room”, one of the largest in the world.

    On the floor below, a couple dozen scientists and engineers are buzzing about, weaving around cranes, ladders, miles of cables and one very large robotic arm. With their all-white protective suits and face masks, the workers look like little snowmen. The suits aren’t for their protection, but for the protection of the delicate equipment they’re handling – because the machine they’re assembling is one of the most ambitious and expensive telescopes ever conceived. If all goes well, it will be launched into space on top of an Ariane 5 rocket a little more than four years from now. Eventually, from its desolate home 1.5 million kilometres from Earth, it will send back images and data that will revolutionise our picture of the cosmos.

    It’s been nearly 25 years since the launch of the Hubble Space Telescope, and the hardy instrument is still going strong.

    NASA Hubble Telescope
    NASA/ESA Hubble

    But Hubble won’t last forever. Astronomers have been planning a larger, more ambitious telescope since the mid-1990s. That telescope is finally beginning to take shape in Building 29. Originally dubbed the Next Generation Space Telescope, it was later renamed in honour of James E. Webb, the man who served as NASA administrator back in the days of the Apollo Moon missions. Not that this is a solely American project: the Webb telescope is too big, too complex and too costly for any one country to go it alone, and the European Space Agency and the Canadian Space Agency are both playing a significant role. In all, more than 1,000 scientists and engineers, from at least 17 countries, are working on the project.

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    A bird’s eye view of NASA’s Goddard clean room where the Webb telescope will be assembled, including its honeycomb mirror (bottom right). Credit: NASA / Chris Gunn

    The biggest difference between the Webb and Hubble is sheer size: Hubble has a single mirror a bit less than 2.5 metres across, while Webb will use an array of 18 hexagonal mirrors. Arranged honeycomb-style, they’ll function as a single mirror 6.5 metres across (that’s a bit wider than the cabin of a jumbo jet). True, the largest ground-based telescopes in use today are bigger, with mirrors about 10 metres across – but 6.5 metres is still enough to make Webb by far the largest telescope ever planned for space.

    The other crucial difference between Webb and Hubble is that, while Hubble works primarily in visible light, Webb is designed to work in the infrared. This long wavelength light passes right through the dust and gas clouds that can obscure Hubble’s view – one of the reasons infrared is the best way to study phenomena from ancient galaxies at the edge of the visible universe to stellar nurseries where new solar systems are taking shape. “Hubble is wonderful, but not quite wonderful enough,” John Mather, senior project scientist for Webb, put it recently. “There’s stuff just beyond what Hubble can see, that we really want to be able to pursue.”

    Webb is often described as a successor to Hubble – but since it’s designed to probe the infrared, it might more accurately be thought of as a successor to the Spitzer Space Telescope, an infrared space observatory launched in 2003.

    NASA Spitzer Telescope
    NASA/Spitzer

    But again, size is of the essence. Spitzer’s main mirror, at 85 centimetres across, will be dwarfed by Webb’s 6.5-metre reflector. On the day of my visit, engineers were using the clean room’s robotic arm to manipulate Webb’s secondary mirror – or rather, the “flight-spare” secondary, an exact duplicate of the telescope’s secondary mirror – designed to collect light from the massive primary and direct it back toward the telescope’s detectors. My guide for the day was Mark Clampin, observatory project scientist for Webb, and a veteran of several previous projects including Hubble. We watched as the robotic arm slowly lifted the flight-spare secondary mirror for a series of tests.

    “Just to give you some idea of the scale, the secondary mirror up there is about 10 centimetres smaller than the Spitzer Space Telescope’s primary mirror,” Clampin says. “So that gives you an idea of how big this telescope is.” Below the secondary mirror, and partially hidden by the clean room’s massive steel scaffolding, I can see the flight-spare “backplane” – the carbon-composite structure that will hold the mirrors in place. The robotic arm, Clampin explains, will be used to put each of the mirrors into place on the backplane, one at a time. The flight-spares – exact copies of the components that will travel into space – are essential as back-ups, in case anything happens to the actual flight hardware; plus, there’s always a risk of parts being damaged during testing. The actual primary mirror segments are kept under wraps. They were manufactured at Ball Aerospace in Colorado and were shipped to Goddard more than a year ago – they’re kept in sealed, nitrogen-filled steel chambers (which look rather like giant pots for cooking spaghetti). Still, one only needs to click on the Webb telescope’s website to see what the fully assembled mirror will look like. Cast from lightweight beryllium and coated with a microscopically thin layer of gold, the hexagonal mirror segments will look spectacular when they’re eventually deployed in space – if anyone were around to see them.

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    The Hubble’s best known image, the Pillars of Creation, and right as the star nursery would look with the Webb’s infrared vision.Credit: NASA / ESA / Hubble Heritage Team (STScI/AURA)

    While Hubble circles the Earth some 500 kilometres up, the James Webb Space Telescope is heading for the “L2 Lagrange point”, located 1.5 million kilometres out in space. Back in the 18th century – long before anyone had imagined sending a telescope into space – the French mathematician Joseph-Louis Lagrange was working on what physicists call the “three-body problem”: If you have a pair of massive bodies like the Earth and the Sun, with each body’s motion dictated solely by the force of gravity, would there be any stable locations where you could place a third body and have it stay there, without drifting away? Lagrange found that, yes, there are five such points, and L2 is one of them.

    “If you think of the Sun, and draw a line from the Sun to the Earth, and keep going for a million miles – that’s basically where it’s located,” Clampin explains. “We picked that because it’s a point that has a quasi-stable gravitational field. It’s a great place to be, for doing astronomy.” Great, but lonely: L2 is about four times more distant than the Moon. Hubble was serviced by astronauts four times once in orbit, but Webb will not feel human hands after launch. Everything has to work perfectly the first time.

    5
    The five Lagrange points, where objects in space can be held in place by gravity. Credit: Cosmos Magazine

    But working so far from home has its advantages: L2 is so far from Earth that our planet never blocks the Sun’s light. That means the telescope will effectively be in “daytime” 24/7, with no troublesome day-night fluctuations in temperature. Even so, Webb’s infrared detectors need to be protected from the Sun’s heat – a dazzling stream of infrared radiation that would swamp the faint signals the telescope is designed to detect. Even the telescope’s own heat needs to be carefully managed. The telescope will have, in effect, a “hot side” that faces the Sun, and a “cold side” that faces deep space. The hot side will house the telescope’s communications equipment and electronics, while the mirrors and delicate infrared detectors will be on the cold side.

    Separating the two halves of the telescope will be another unique feature – a giant, diamond-shaped sunshield. Dwarfing even the giant primary mirror, the sunshield is the telescope’s largest component, spanning an area about the size of a tennis court. It’s composed of five parallel layers of ultra-thin plastic film with a reflective metallic coating (which goes by the trade name of Kapton). Once deployed, it will block the Sun’s heat while also radiating the telescope’s own heat out into space. This way the cold side of the telescope will be kept down to 40 Kelvin – about 230 degrees below zero on the Celsius scale.

    A cold telescope makes for great infrared observing – but also for staggering engineering hurdles. “This is one of the challenges … that the telescope has to work at 40K, but we polish the mirrors at room temperature,” Clampin says. The fine-polishing of the mirrors has to be carried out in stages: at Goddard, engineers will work on the mirror surfaces until a precision of 100 nanometres is reached – that’s about one-thousandth of the thickness of a human hair. Then the mirrors will be sent to the Marshall Space Flight Centre in Alabama, where they’ll be cooled in a cryogenic chamber that mimics the conditions the telescope will experience in space – with engineers noting exactly how the mirror’s shape changes as the temperature drops. Then the mirrors return to Goddard for a final tweak. “That way, the next time we cool it down to 40K, we’ll have the right prescription,” Clampin says. When the mirror is finally sent into space, the largest irregularities on its surface will be no more than 20 nanometres in size. If the mirror were scaled up to be the width of the continental United States, those defects would be less than two centimetres high.

    And cryogenic testing is only a part of the challenge. At Goddard, I gawked at the machines that have been pushing and pulling on the telescope’s various components, to ensure that each piece of equipment can survive the launch. After all, being launched into space inside an Ariane 5 rocket is a bit like being strapped to a giant firecracker. There’s a lot of shaking and rattling. Goddard also has a massive centrifuge that can whirl objects around until they feel a pull equivalent to 15 times that of gravity – more than enough to simulate the g-forces experienced at launch. But the launch also produces a lot of sound – which is why there’s also an acoustics chamber, to blast the telescope’s parts with high-intensity sound waves. Ray Lundquist, one of the lead engineers for Webb, explained the chamber can produce sounds up to about 150 decibels, though 100 to 115 decibels are typical. What if I were unlucky enough to be in the chamber when it was cranked up to that level? “You’d pass out,” Lundquist assures me.

    The real excitement will begin in 2018, when the James Webb Space Telescope unfolds, origami-like, from its launch vehicle, and makes its way to the L2 Lagrange point. And then when it starts recording data and sending it back to planet Earth. Some of the data will be coming from the most distant matter in the visible Universe – structures that formed perhaps a few million years after the Big Bang. In this quest, Webb’s use of infrared wavelengths is key: because the Universe is expanding, the light from these distant objects has been stretched – in astronomical jargon, the light has been “redshifted”. (Think of an ambulance driving past you – as it speeds away, its siren seems to emit a lower pitch sound.) Because of this redshift, light that would have been emitted at visible wavelengths is now shifted well into the infrared – and is ripe for detection by Webb.

    For astronomers such as Marcia Rieke, that ancient light holds the promise of new insight into the Universe’s turbulent early years. Rieke, based at the University of Arizona, grew up reading science fiction and pondering the possibility of visiting distant stars and planets. “I was good at science, so I sort of gravitated toward physics and astronomy,” she says. She’s now the principal investigator for Webb’s Near Infrared Camera, known as NIRCam.

    NASA Webb NIRcam
    NIRCam

    It’s one of Webb’s four main detectors, and has been carefully designed to snare the light from those ancient structures. Exactly how far we can push back the clock, so to speak, is hard to say; it depends on how rapidly matter in the early Universe condensed into the first stars and galaxies. “We may get as close as a few million years after the Big Bang,” Rieke says.

    Our models of the early Universe – specifically, those first few million years – are a bit sketchy. We know that gravity was the great choreographer; under its pull, and in spite of the Big Bang’s initial outward push, matter attracted matter; clouds of gas and dust spawned the first stars; those stars came together to form primordial galaxies. “I’m hoping that when it comes to things like looking at how galaxies assemble, that we really will be able to see the full sweep of cosmic history,” Rieke says. “We’d like to see the very first galaxies.”

    Distant galaxies make appealing targets, but there are equally enticing objects to focus on closer to home. Webb will also be looking at the birth of planetary systems around stars in our own galactic neighbourhood.

    Local Grp II
    The Local Group of galaxies. The Milky Way and Andromeda are the most massive galaxies by far.

    These days, of course “exoplanets” are a booming business; the Kepler observatory, a space telescope launched in 2009, has already found more than 1,000 planets orbiting stars beyond our solar system.

    NASA Kepler Telescope
    NASA/Kepler

    Webb won’t compete with Kepler; rather, the two will function as a team. While Webb may well discover some new planets, “its bigger strength is as a planet characterisation machine,” says Ray Jayawardhana, an astronomer at York University in Toronto, and the author of a popular book on the search for exoplanets, Strange New Worlds. Webb will be able to tell us more about some of the exoplanets Kepler has discovered.

    Thanks to its exquisite resolution, Webb will be able to discern some exoplanets as distinct objects, separated from their parent stars – what astronomers aptly call “direct imaging”. (Most exoplanets found to date were discovered using indirect methods. Kepler, for example, infers the existence of exoplanets by watching as the light of the parent star is periodically dimmed, as a planet passes in front.)

    Giant planets, roughly the size of Jupiter or Saturn, will be easier for Webb to pick out, because of their girth. Such planets emit a fair bit of heat, meaning they radiate strongly in the infrared – which is what the telescope is designed to detect. A handful of exoplanets have already been directly imaged using ground-based instruments but Webb, with its greater resolution, will be much better at spotting an exoplanet in spite of the overwhelming glare of the parent star. But that’s not all: by monitoring a planet carefully for many hours, the telescope should reveal any regular changes in brightness – the sort of pattern one might expect if some irregularity in a planet’s atmosphere were periodically coming into view. (We know that the giant planets in our own Solar System have such features – think of the Great Red Spot on Jupiter.) “You might actually learn something about the storms in the atmospheres of these directly-imaged Jovian planets – that would be very cool,” says Jayawardhana.

    Any information about the atmospheres of these distant worlds would be a goldmine for astronomers – especially for those pondering the question of life beyond our own blue-white orb. Webb’s spectrograph will split an exoplanet’s light into its component colours, allowing scientists to look for the chemical signatures of water vapour or carbon compounds in its atmosphere, explains Jayawardhana. Again, these planets are most likely to be larger than Earth; the smaller the planet, the closer it has to be for Webb to detect it, and so the smaller the area of space in which to hunt for them. But slightly larger planets may well turn up in abundance, their atmospheres prime targets for study. “And that’s a very exciting prospect, because some of these ‘super Earths’ may well be rocky planets, with atmospheres that at least in principle allow for habitability,” says Jayawardhana. “That’s probably the most exciting thing that we’re planning for.” He emphasised the element of surprise. “In the exoplanet business, we’ve learnt time and again to expect the unexpected.”

    Webb is, first and foremost, a scientific instrument – but like Hubble it holds the promise of producing images that resonate far beyond the scientific community. They won’t have the same flavour as Hubble’s images, though; in infrared light, everything looks different. In fact, by collecting these longer wavelengths of light, the telescope will be able to look through the clouds of dust and gas that, in visible light, would obscure whatever might lie behind them. The telescope will, in effect, be “pulling back the curtain” to reveal new celestial vistas. Consider Hubble’s best-known image – the Eagle Nebula, known as the “Pillars of Creation”. Deep in the interior of the nebula, new stars – and perhaps new planets – are being born. “Webb will allow you to peer into these objects in much more detail,” says Mark Clampin, my guide at Goddard. “So if you think of the Eagle Nebula, Webb will be able to … look inside the nursery, if you like.”

    The James Webb Space Telescope is big science, and it inevitably comes with a big price tag – which has gotten even bigger over the years. Initially estimated to cost between $US1-2 billion, the latest estimates put the figure at around $9 billion. There are, of course, some equally expensive science projects out there – the Large Hadron Collider comes to mind – but it’s still a lot of cash. And it’s been a bumpy ride: in the spring of 2011, Congress moved to pull funding from the project, but NASA fought back, and by autumn of that year, the funding was restored. The project has also taken longer than planners had originally thought. The launch had first been planned for 2011; the new date is 2018.

    Will the Webb be the last of the big-budget space observatories? Perhaps. The project is so large and complex, that it’s “right at the limit of what people can do,” says Rieke. “And obviously from a cost perspective, it really is right at the limit.” And yet, as Jayawardhana points out, it’s all relative. Should we choose to one day send astronauts to Mars, the expense would almost certainly be tallied in hundreds of billions of dollars. One often hears how much good could come from that sort of money if it were spent here on Earth. There are various responses to such objections, but an internet video-blogger named Hank Green has as pithy a reply as any: “There are two ways to make the world a better place,” he says. “You can decrease the suck, and you can increase the awesome.” The Webb is a perfect example of increasing the awesome, he argues – and many astronomers (although not all) would agree.

    Back at the Goddard Space Flight Centre, there is still plenty of nuts-and-bolts work to be done. The assembly and testing of the components will continue for another four years. Eventually, the mirror and the main instrument package will be shipped to Northrop Grumman’s “Space Park” complex in Los Angeles, where the giant sunshield will be integrated with the rest of the telescope. Eventually the whole shebang will be folded up and packed on to a barge bound for French Guiana and the European Spaceport on its coast. Then its million-mile odyssey will begin.

    See the full article here.

    Please help promote STEM in your local schools.

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    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.

    There will be four science instruments on Webb: the Near InfraRed Camera (NIRCam), the Near InfraRed Spectrograph (NIRspec), the Mid-InfraRed Instrument (MIRI), and the Fine Guidance Sensor/ Near InfraRed Imager and Slitless Spectrograph (FGS-NIRISS). Webb’s instruments will be designed to work primarily in the infrared range of the electromagnetic spectrum, with some capability in the visible range. It will be sensitive to light from 0.6 to 28 micrometers in wavelength.

    Webb has four main science themes: The End of the Dark Ages: First Light and Reionization, The Assembly of Galaxies, The Birth of Stars and Protoplanetary Systems, and Planetary Systems and the Origins of Life.

    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.

    NASA

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    Canadian Space Agency

     
  • richardmitnick 8:38 pm on July 30, 2014 Permalink | Reply
    Tags: , , , , NASA Webb, ,   

    From NASA/Webb: “Revolutionary Microshutter Technology Hurdles Significant Challenges” 

    NASA James Webb Header

    NASA James Webb Telescope

    James Webb Space Telescope
    July 29, 2014
    Lori Keesey
    NASA Goddard Space Flight Center, Greenbelt, Maryland

    NASA technologists have hurdled a number of significant technological challenges in their quest to improve an already revolutionary observing technology originally created for the James Webb Space Telescope.

    The team, led by Principal Investigator Harvey Moseley, a scientist at NASA’s Goddard Space Flight Center in Greenbelt, Maryland, has demonstrated that electrostatically actuated microshutter arrays — that is, those activated by applying an specific voltage — are as functional as the current technology’s magnetically activated arrays. This advance makes them a highly attractive capability for potential Explorer-class missions designed to perform multi-object observations.

    “We have identified real applications — three scientists want to use our microshutter arrays and the commercial sector has expressed interest,” said Mary Li, a Goddard engineer who is working with Moseley and other team members to fully develop this already groundbreaking observing technology. “The electrostatic concept has been fully demonstrated and our focus now is on making these devices highly reliable.”

    Progress, she said, is in large part due to the fact that the team successfully eliminated all macro-moving parts — in particular, a large magnet — and dramatically lowered the voltage needed to actuate the microshutter array. In addition, the team applied advanced electronic circuitry and manufacturing techniques to assure the microshutter arrays’ dependable operation in orbit, Li added.

    The Microshutter Breakthrough

    Considered among the most innovative technologies to fly on the Webb telescope, the microshutter assembly is created from micro-electro-mechanical technologies and comprises thousands of tiny shutters, each about the width of a human hair.

    Assembled on four postage-size grids or arrays, the 250,000 shutters open or close individually to allow only the light from targeted objects to enter Webb’s Near Infrared Spectrograph (NIRSpec), which will help identify types of stars and gases and measure their distances and motions. Because Webb will observe faint, far-away objects, it will take as long as a week for NIRSpec to gather enough light to obtain good spectra.

    NASA Webb NIRspec
    NASA/Webb NIRSpec

    NIRSpec’s microshutter array, however, enhances the instrument’s observing efficiencies. It will allow scientists to gather spectral data on 100 objects at a time, vastly increasing the observatory’s productivity. When NASA launches the Webb telescope in 2018, it will represent a first for multi-object spectroscopy.

    close
    This image shows a close-up view of the next-generation microshutter arrays during the fabrication process. The technology advances an already groundbreaking multi-object observing technique.
    Image Credit: NASA/Bill Hrybyk

    Quest to Improve Design

    Determined to make the microshutter technology more broadly available, Goddard technologists have spent the past four years experimenting with techniques to advance this capability.

    One of the first things the team did was eliminate the magnet that sweeps over the shutter arrays to activate them. As with all mechanical parts, the magnet takes up space, adds weight, and is prone to mechanical failure. Perhaps more important, the magnet cannot be easily scaled up in size without creating significant fabrication challenges. As a result, the instrument’s field of view — that is, the area that is observable through an instrument — is limited in size. This greatly impedes next-generation space observatories that will require larger fields of view.

    Magnetic activation also takes longer. With the Webb telescope, the magnet must first sweep over the array to open all the shutters before voltages are selectively applied to open or close specific shutters.

    Achieving the Voltage Sweet Spot and Other Milestones

    To accommodate the needs of future observatories, the team replaced the magnet with electrostatic actuation. By applying an alternating-current voltage to electrodes placed on the frontside of the microshutters, the shutters swing open. To latch the desired shutters, a direct current voltage is applied to electrodes on the backside. In other words, only the needed shutters are opened; the rest remain closed. “This reduction in cycles should allow us to extend the lifetime of the microshutter arrays 100 times or more,” Li explained.

    And because the magnet no longer dictates the size of the array, its elimination will allow scientists to assemble much larger arrays for instruments whose fields of view are 50 times larger than Webb’s NIRSpec, she said.

    Just as significant is the voltage needed to actuate the arrays. When the effort first began four years ago, the team only could open and close the shutters with 1,000 volts. By 2011, the team had slashed that number to 80 volts — a level that still could exceed instrument voltage specifications. By last year, the team had achieved a major milestone by activating the shutters with just 30 volts — a voltage sweet spot, Li said.

    “But we also did something else,” she added.

    Through experimentation, the team used atomic layer deposition, a state-of-the-art fabrication technology, to fully insulate the tiny space between the electrodes to eliminate potential electrical crosstalk that could interfere with the arrays’ operation.

    The team also applied a very thin anti-stiction coating to prevent the shutters from sticking when opened. Before applying the coating, a 3,000-cycle laboratory test indicated that a third of the shutters stuck. After coating them, the team ran a 27,000-cycle test and not a single shutter adhered to the sides, Li said.

    Success Breeds Success; More Work Ahead

    men
    Goddard engineers Devin Burns and Lance Oh are pictured here with the next-generation microshutter arrays.
    Image Credit:
    NASA/Bill Hrybyk

    oh
    Goddard engineer Lance Oh is one of several technologists developing a next-generation microshutter array technology originally developed for the James Webb Space Telescope.
    Image Credit: NASA/Bill Hrybyk

    As a result of the progress, Li said three astrophysicists now are interested in applying the technology to their own mission concepts, which include observing nearby star-forming regions in the ultraviolet, studying the origins of astronomical objects to better understand the cosmic order, and understanding how galaxies, stars, and black holes evolve. In fact, one of those scientists is so committed to advancing the microshutter array that he plans to demonstrate it during a sounding-rocket mission next year, Li said.

    Although spectroscopy — the study of the absorption and emission of light by matter — is the obvious beneficiary of the technology’s advance, Li said it also is applicable to lidar instruments that measure distance by illuminating a target with a laser and analyzing the reflected light. A major automotive company also has expressed interested in the technology, she added.

    However, before others can use the new and improved microshutter technology, Li said the team must develop an assembly and packaging to house multiple arrays. “If you want to use the microshutter array on a large telescope, we need to make a larger field of view. To make this happen, we need to take multiple arrays and stitch them together,” Li said.

    Currently, the technology relies on a large computerized switch box — a heavy device unsuitable for spaceflight missions. The team plans to incorporate an integrated circuit, or silicon chip, that drives the switching functions. Placed next to the shutters, the circuit would take up only a fraction of the space. The team currently is identifying circuits from different vendors and plans to begin testing shortly.

    “In just four years, we have made great progress. A major private company has expressed interest in our technology, to say nothing of the three potential astrophysics missions,” Li said. “Given our progress, I am confident that we can make this technology more readily accessible to the optics community.”

    See the full article here.

    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.

    There will be four science instruments on Webb: the Near InfraRed Camera (NIRCam), the Near InfraRed Spectrograph (NIRSpec), the Mid-InfraRed Instrument (MIRI), and the Fine Guidance Sensor/ Near InfraRed Imager and Slitless Spectrograph (FGS-NIRISS). Webb’s instruments will be designed to work primarily in the infrared range of the electromagnetic spectrum, with some capability in the visible range. It will be sensitive to light from 0.6 to 28 micrometers in wavelength.

    Webb has four main science themes: The End of the Dark Ages: First Light and Reionization, The Assembly of Galaxies, The Birth of Stars and Protoplanetary Systems, and Planetary Systems and the Origins of Life.

    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.

    NASA

    ESA Icon Large

    Canadian Space Agency


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  • richardmitnick 8:12 pm on April 18, 2014 Permalink | Reply
    Tags: , , , , , NASA Webb   

    From NASA/Blueshift: “[Maggie’s Blog] A Secondary Space Mirror” 

    NASA Blueshift

    April 18, 2014
    Maggie Masetti

    One of the cool things about the James Webb Space Telescope’s design is the giant boom that sticks out in front of the telescope. This structure is what holds the telescope’s secondary mirror. It’s the “small” round gold thing, visible in this artist’s conception.

    boom
    Credit: NASA

    Here’s what it looks like for real. This is the flight mirror, the one that is going into space! It’s coated in gold like JWST’s other mirrors to optimize it for reflecting infrared light.

    men
    Credit: NASA/Chris Gunn

    It’s actually pretty big – in fact it’s not much smaller than the Spitzer Space Telescope’s primary mirror! (Spitzer’s primary mirror is 0.85 meters in diameter, JWST’s secondary mirror is 0.74 meters.) It just looks small next to JWST’s 21 foot diameter primary mirror!

    stacks
    Credit: NASA

    Northrop Grumman has the pathfinder, or test version of this boom structure that will hold the secondary mirror.

    ng
    Credit: Paul Geithner

    I found out a little more about it from Deputy Project Manager for JWST, Paul Geithner, and Optical Telescope Element Manager, Lee Feinberg. Here’s their caption for the above photo.

    This is the secondary mirror structure (SMSS) for the Pathfinder telescope structure. The flight one will be virtually identical. This image is from a ‘walkout’ of the structure from its stowed to its deployed condition. The scale is evident in the photo, comparing the people and the structure. This walkout involved careful offloading of weight in the 1g environment on Earth; this deployment will take place in space where there is the inertia of the mass but not the weight, and ground deployments require offloading. The flight SMSS is in strength testing, and it will be integrated with the backplane before it is sent to NASA Goddard for telescope assembly.

    Before this, the Pathfinder telescope backplane and SMSS will come to Goddard for ‘pathfinding’ operations as practice for the integration we will do on the flight in 2015. Once at Goddard, two spare primary mirror segments and a spare secondary will be installed to make up the Pathfinder telescope.

    This is the first time a deployable secondary mirror structure for a space telescope has ever been tested. The SMSS is over 8 meters (26.2 feet) tall.

    Here is the Northrop Grumman Integration and Test team after successfully transferring the pathfinder SMSS from the floor assembly jig (that tall, black, latticed structure you see in the other photo) to the backplane pathfinder.

    team
    Credit: Northrop Grumman

    We’ll be sure to give a report when this huge structure shows up at NASA Goddard – we’ll be excited to see it for ourselves!

    See the full article here.

    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.

    NASANASA Goddard Banner


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  • richardmitnick 11:54 am on March 9, 2014 Permalink | Reply
    Tags: , , , , NASA Webb   

    From NASA/Webb: “About Webb’s Orbit” 

    NASA James Webb Header

    NASA James Webb Telescope

    James Webb Space Telescope

    The James Webb Space Telescope will observe primarily the infrared light from faint and very distant objects. But all objects, including telescopes, also emit infrared light. To avoid swamping the very faint astronomical signals with radiation from the telescope, the telescope and its instruments must be very cold. Therefore, Webb has a large shield that blocks the light from the Sun, Earth, and Moon, which otherwise would heat up the telescope, and interfere with the observations. To have this work, Webb must be in an orbit where all three of these objects are in about the same direction. The answer is to put Webb in an orbit around the L2 point.

    The L2 orbit is an elliptical orbit about the semi-stable second Lagrange point . It is one of the five solutions by the mathematician Joseph-Louis Lagrange in the 18th century to the three-body problem. Lagrange was searching for a stable configuration in which three bodies could orbit each other yet stay in the same position relative to each other. He found five such solutions, and they are called the five Lagrange points in honor of their discoverer.

    lp
    A contour plot of the effective potential due to gravity and the centrifugal force of a two-body system in a rotating frame of reference. The arrows indicate the gradients of the potential around the five Lagrange points—downhill toward them (red) or away from them (blue). Counterintuitively, the L4 and L5 points are the high points of the potential. At the points themselves these forces are balanced.

    lp2
    Visualisation of the relationship between the Lagrangian points (red) of a planet (blue) orbiting a star (yellow) anticlockwise, and the effective potential in the plane containing the orbit (grey rubber-sheet model with purple contours of equal potential).

    In three of the solutions found by Lagrange, the bodies are in line (L1, L2, and L3); in the other two, the bodies are at the points of equilateral triangles (L4 and L5). The five Lagrangian points for the Sun-Earth system are shown in the diagram below. An object placed at any one of these 5 points will stay in place relative to the other two.

    In the case of Webb, the 3 bodies involved are the Sun, the Earth and the Webb. Normally, an object circling the Sun further out than the Earth would take more than one year to complete its orbit. However, the balance of gravitational pull at the L2 point means that Webb will keep up with the Earth as it goes around the Sun. The gravitational forces of the Sun and the Earth can nearly hold a spacecraft at this point, so that it takes relatively little rocket thrust to keep the spacecraft in orbit around L2.

    lp3
    Other infrared missions have selected an L2 orbit, like WMAP and H2L2. For a more detailed explanation of the Lagrangian points, please see the WMAP discussion of this orbit.

    Here are a few graphics that illustrate how far away Webb will be. It will take Webb rough 30 days to reach the start of its orbit of L2.
    ref

    lp4
    (Note that these graphics are not to scale.)

    Astronomy Cast has a podcast on Lagrange points that you may find interesting.

    See the full article here.

    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.

    There will be four science instruments on Webb: the Near InfraRed Camera (NIRCam), the Near InfraRed Spectrograph (NIRSpec), the Mid-InfraRed Instrument (MIRI), and the Fine Guidance Sensor/ Near InfraRed Imager and Slitless Spectrograph (FGS-NIRISS). Webb’s instruments will be designed to work primarily in the infrared range of the electromagnetic spectrum, with some capability in the visible range. It will be sensitive to light from 0.6 to 28 micrometers in wavelength.

    Webb has four main science themes: The End of the Dark Ages: First Light and Reionization, The Assembly of Galaxies, The Birth of Stars and Protoplanetary Systems, and Planetary Systems and the Origins of Life.

    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.

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    Canadian Space Agency


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  • richardmitnick 10:34 pm on March 8, 2014 Permalink | Reply
    Tags: , , , , NASA Webb   

    From NASA/Webb: “JWST Deployment Sequence” Video 

    NASA James Webb Header

    NASA James Webb Telescope

    James Webb Space Telescope

    NASA/Webb has just put out this short video about Webb’s deployment.

    Really cool. I hope that you enjoy it.

    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.

    There will be four science instruments on Webb: the Near InfraRed Camera (NIRCam), the Near InfraRed Spectrograph (NIRSpec), the Mid-InfraRed Instrument (MIRI), and the Fine Guidance Sensor/ Near InfraRed Imager and Slitless Spectrograph (FGS-NIRISS). Webb’s instruments will be designed to work primarily in the infrared range of the electromagnetic spectrum, with some capability in the visible range. It will be sensitive to light from 0.6 to 28 micrometers in wavelength.

    Webb has four main science themes: The End of the Dark Ages: First Light and Reionization, The Assembly of Galaxies, The Birth of Stars and Protoplanetary Systems, and Planetary Systems and the Origins of Life.

    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.

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    Canadian Space Agency


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  • richardmitnick 3:01 pm on February 19, 2014 Permalink | Reply
    Tags: , , , , , , NASA Webb   

    From ESA: ” MIRI keeps cool under low pressure” 

    ESASpaceForEuropeBanner
    European Space Agency

    19-Feb-2014
    No Writer Credit

    The Mid-Infrared Instrument (MIRI) on JWST has performed beautifully during its first cryo-vacuum test campaign carried out at NASA’s Goddard Space Flight Center towards the end of last year. An examination of data recorded during those tests confirms that the instrument is in good health and performing well.

    In August last year preparations began for the first ISIM (Integrated Science Instrument Module) test campaign to be performed in a vacuum and at cryogenic temperatures. Fitted with two instruments – MIRI and FGS/NIRISS (the Fine Guidance Sensor / Near-InfraRed Imager and Slitless Spectrograph) – ISIM was installed in the Space Environment Simulator (SES), a large cryogenic test chamber at Goddard. The doors to the chamber were closed on 29 August and after about 5 days the vacuum (approximately 10-6 mbar) was achieved, ISIM and the instruments were checked to be functioning and in good shape, and the cool-down then began.

    NASA Webb MIRI
    MIRI

    NASA Webb Fine Guidance
    FGS/NIRISS

    isim
    ISIM with MIRI and FGS/NIRISS, mounted on a test rig Credit: NASA / Chris Gunn

    ses
    ISIM inside the SES chamber at Goddard. Credit: NASA / Chris Gunn

    cryo
    The cryocooler under development for MIRI.
    Credit: Northrop Grumman

    Nearly twenty days later, the ISIM reached a temperature of -233 °C (40.15 K) – the same temperature it will experience in space. However, this temperature is not low enough for the advanced detectors on MIRI. To ensure that the detectors are not blinded by temperature-driven parasitic light and currents, astronomers require the instrument to be cooled down to around -266 °C. This is barely seven degrees above absolute zero – the latter being the lowest temperature possible, as defined by the laws of physics. To achieve this level of cooling, a dedicated cooling system, called the MIRI cryocooler is being developed by NASA JPL.

    During the almost three-week cool down of MIRI, team members on-site at Goddard, across Europe and elsewhere in the US monitored the health of the instrument, 24 hours a day, seven days a week.

    Once the Optical Telescope Simulator (OSIM), ISIM, MIRI and FGS/NIRISS all reached their operating temperatures, the scientists and engineers resumed their tests, constantly monitoring the state of the instruments, as well as conducting their experiments and analysing the data.
    Left: Thermal and vacuum test rig for ISIM. Credit: NASA / Chris Gunn.

    osim
    Erin Wilson is seen here preparing the JWST OSIM for environmental testing. Image credits: NASA / Chris Gunn

    Every indication showed that MIRI performed well, however, not even scientific experiments deep in the Goddard cryogenic test chamber are immune from external perturbations and on 1 October all testing was put on hold as the American government shut down.

    Once the furlough ended, testing started again on 17 October. To reduce the impact of the unscheduled ‘break’, the sequence of tests was revised and heavily streamlined. The most critical activities were given the highest priorities and tested accordingly.

    Despite this interruption, and due to the great efforts from all of the teams, the tests at operating temperature were successfully completed on 29 October and all of the primary goals of the first ISIM test campaign were reached. Warm-up then started and was finished in the week of 11 November, after which this first ISIM cryo-vacuum test campaign was officially declared complete.

    This was the first time MIRI could be tested at its operating temperature since the instrument-level testing at RAL in Europe in 2011. The data gathered by the MIRI team have shown that the instrument performed beautifully and is in good health.

    About JWST

    The James Webb Space Telescope (JWST) will be a general-purpose observatory with a 6.5-m telescope optimised for infrared observations and a suite of four astronomical instruments capable of addressing many of the outstanding issues in astronomy. The primary aim is to examine the first light in the Universe – those objects which formed shortly after the Big Bang. Further aims include: looking at how galaxies form; the birth of stars; and the search for protoplanetary systems and the origin of life, including the study of exoplanets. JWST is a joint project of NASA, ESA and the Canadian Space Agency. It is scheduled for launch in 2018 by an Ariane 5 and will operate approximately 1.5 million kilometres from the Earth in an orbit around the second Lagrange point of the Sun-Earth system, L2.

    About MIRI

    The Mid-Infrared Instrument (MIRI) is one of four instruments on JWST. MIRI will provide direct imaging, medium- and low-resolution spectroscopy, and coronagraphic imaging. It is expected to make important contributions in all of the primary science aims of JWST. MIRI was developed as a partnership between Europe and the USA – the main partners are a consortium of nationally funded European institutes (the MIRI European Consortium), the Jet Propulsion Laboratory (JPL), ESA, and NASA’s Goddard Space Flight Center (GSFC).

    See the full article here.

    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.


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