Webb Telescope Passes Mission Design Review Milestone

NASA's Northrop Grumman-built James Webb Space Telescope has passed its most significant mission milestone to date, the Mission Critical Design Review, or MCDR. This signifies the integrated observatory will meet all science and engineering requirements for its mission.

"I'm delighted by this news and proud of the Webb program's great technical achievements," said Eric Smith, Webb telescope program scientist at NASA Headquarters in Washington.

"The independent team conducting the review confirmed the designs, hardware and test plans for Webb will deliver the fantastic capabilities always envisioned for NASA's next major space observatory. The scientific successor to Hubble is making great progress."

NASA's Goddard Space Flight Center, in Greenbelt, Md., manages the mission. Northrop Grumman, Redondo Beach, Calif., is leading the design and development effort.

"This program landmark is the capstone of seven years of intense, focused effort on the part of NASA, Northrop Grumman and our program team members," said David DiCarlo, sector vice president and general manager of Northrop Grumman Space Systems.

"We have always had high confidence that our observatory design would meet the goals of this pioneering science mission. This achievement testifies to that, as well as to our close working partnership with NASA."

The MCDR encompassed all previous design reviews including the Integrated Science Instrument Module review in March 2009; the Optical Telescope Element review completed in October 2009; and the Sunshield review completed in January 2010. The project schedule will undergo a review during the next few months.

The spacecraft design, which passed a preliminary review in 2009, will continue toward final approval next year.

The review also brought together multiple modeling and analysis tools. Because the observatory is too large for validation by actual testing, complex models of how it will behave during launch and in space environments are being integrated. The models are compared with prior test and review results from the observatory's components.

Although the MCDR approved the telescope design and gave the official go-ahead for manufacturing, hardware development on the mirror segments has been in progress for several years.

Eighteen primary mirror segments are in the process of cryo-polishing and testing at Ball Aerospace in Huntsville, Ala. Manufacturing on the backplane, the structure that supports the mirror segments, is well underway at Alliant Techsystems, or ATK, in Magna, Utah.

This month ITT Corp. in Rochester, N.Y., demonstrated robotic mirror installation equipment designed to position segments on the backplane. The segments' position will be fine-tuned to tolerances of a fraction of the width of a human hair. The telescope's sunshield moved into its fabrication and testing phase earlier this year.

The three major elements of Webb - the Integrated Science Instrument Module, Optical Telescope Element and the spacecraft itself - will proceed through hardware production, assembly and testing prior to delivery for observatory integration and testing scheduled to begin in 2012.

The Webb is the premier next-generation space observatory for exploring deep space phenomena from distant galaxies to nearby planets and stars.

The telescope will provide clues about the formation of the universe and the evolution of our own solar system, from the first light after the Big Bang to the formation of star systems capable of supporting life on planets like Earth. The telescope is a joint project of NASA, the European Space Agency and the Canadian Space Agency.

NASA Administrator Visits Marshall's X-Ray and Cryogenic Facility

NASA Administrator Charles Bolden, second from right, listens as Dave Chaney, right, a principle optical engineer for Ball Aerospace Technologies Corp. in Boulder, Colo., explains how the James Webb Space Telescope mirror segments are tested in the Marshall Space Flight Center's X-ray and Cryogenic Facility, or XRCF, in Building 4718. From front are Helen Cole, Webb telescope activities project manager at Marshall; Charles Scales, NASA associate deputy administrator; and Robert Lightfoot, Marshall center director.

The XRCF at the Marshall Center is the world's largest X-ray telescope test facility and a unique, cryogenic, clean room optical test facility. Cryogenic testing will take place in a 7,600 cubic foot helium cooled vacuum chamber, chilling the Webb flight mirror from room temperature down to frigid -414 degrees Fahrenheit. While the mirrors change temperature, test engineers will precisely measure their structural stability to ensure they will perform as designed once they are operating in the extreme temperatures of space.

NASA's James Webb Space Telescope is a large, infrared-optimized space telescope that will be the premier observatory of the next decade. 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. Its instruments will be designed to work primarily in the infrared range of the electromagnetic spectrum, with some capability in the visible range.

Northrop Grumman is the prime contractor for the Webb telescope, leading a design and development team under contract to the Goddard Center.

The James Webb Space Telescope is expected to launch in 2013. NASA's Goddard Space Flight Center in Greenbelt, Md. is managing the overall development effort for the Webb telescope. The telescope is a joint project of NASA and many U.S. partners, the European Space Agency and the Canadian Space Agency. (NASA/MSFC/David Higginbotham)

Viewpoint: The Two Pillars of NASA

We are at a pivotal period in defining NASA’s future. In the current debate about redirecting U.S. civil space activities, it is important to keep this in mind: Both human space exploration and space science are fundamental to that future. The partnership between human spaceflight and space science programs flourishes when their mutual interests are not just simply aligned, but when they find ways together to build on their respective strengths.

The most prominent recent example was the return of seven astronauts to the Hubble Space Telescope to install new scientific instruments and repair failed components, making it more powerful than at any time since its launch nearly two decades ago. This partnership is core to NASA’s mission and is an essential element to achieving the next great leaps in space science.

The proposed “flexible path,” in which NASA would not focus on returning astronauts to the Moon but send humans and robots to a variety of points far from Earth, provides the opportunities to reach the next exciting frontiers in space science. As scientists, we seek to see farther and with greater clarity in order to reveal nature’s unseen phenomena. This will require increasingly large and complex structures well beyond low Earth orbit. Some of these scientific facilities will require assembly in orbit and launch vehicles capable of delivering massive payloads to high Earth orbits, Sun-Earth Lagrange points, and beyond. NASA’s current plan recognizes and enables this by laying out a sequence of realistic and frequent steps to extend our ability to build, deploy and operate advanced spacecraft at ever-increasing distances from Earth.

As successful as NASA has been over its 50-plus years, NASA’s new plan can enable both revolutionary new scientific capabilities from space and, at the same time, propel our human exploration of space forward. Here are two prime examples:

A little over two decades ago, the first planet was found orbiting a distant star. Now, more than 400 such planets are known, and NASA’s Kepler mission will reveal how common are Earth-size planets located in the temperate zones around their host stars where liquid water can exist on a planet’s surface. The James Webb Space Telescope may be able to study the atmospheres of a handful of Earth-like planets, but only if a separate “star shade” spacecraft is flown alongside.

To definitively address the question of whether life exists elsewhere in the universe, however, requires a space telescope that is at least four times larger than the Hubble and at least four times more precise in its imaging capabilities than the Webb telescope. With such an observatory, we will be able to directly search for the faint signatures of life in the atmospheres of more than 100 planets around stars as far away as 60 light years, allowing us, for the first time in history, to systematically address the question: “Are we alone?” A still larger telescope would enable even more—the ability to detect oceans and track changes in weather and seasons on potentially habitable worlds.

One of the other major frontiers of astrophysics is to “see the beginning.” The quest to see back to the time when the very first stars formed will tell us much about how the universe came to be filled with all the chemical elements we see today and which enable life. But detecting these first stars is a terrific challenge. The Webb telescope will detect the first galaxies these massive stars formed, but will not be able to see the X-ray-emitting remnants of each of those first stars—the black holes they leave behind. We can fill that gap with a next-generation large X-ray telescope that is 1,000 times more sensitive than any X-ray observatory ever built.

Both of these remarkable next-generation telescopes are tantalizingly within reach but will require new heavy-lift launchers or assembly in space. They will also likely be designed to be serviceable (either by humans or robotic spacecraft) to allow them to pursue scientific investigations for decades beyond their commissioning. These capabilities are precisely the same ones our human space exploration program will require to make the next major foray into our Solar System. The two pillars of NASA—exploration and science—have made it synonymous with inspiration, vision and discovery. Both are intrinsically outward-looking endeavors. The next steps can be revolutionary, if we think boldly.

Marc Postman is an astronomer at the Space Telescope Science Institute in Baltimore and works on future mission concepts. Kathryn Flanagan is a senior scientist at the institute and heads its mission office for the James Webb Space Telescope.

Source:- AviationWeek.com

Students Bring Fresh Perspective and New Technology to Webb Telescope

Engineers at Ball Aerospace test the Wavefront Sensing and Control testbed to ensure that the 18 primary mirror segments and one secondary mirror on JWST work as one. The test is performed on a 1/6 scale model of the JWST mirrors. Credit: NASA/Northrop Grumman/Ball Aerospace

Deep inside Building 5 at NASA's Goddard Space Flight Center in Greenbelt, Md., graduate students are on the front lines of technology development adjusting lasers and mirrors and spending long hours at a computer terminals. University partnerships are playing key roles in developing new and innovative technologies for NASA missions while creating a pathway for future NASA scientists and engineers.

"Investments in students today help us build what comes after the Webb telescope," said Lee Feinberg, Webb telescope Optical Telescope Element Manager at NASA Goddard. "University professors serve on our advisory boards. It allows us to tap the brightest minds in the country."

Past experience bears out Feinberg's observations.

Six years ago, Matthew Bolcar was a graduate student from the University of Rochester, N.Y. when he started working at NASA Goddard. He has been exploring interesting problems and developing risk-reduction techniques related to aligning segmented mirrors on the Webb telescope.

The Webb telescope primary mirror is composed of 18 segments that will unfold to create a single 6.5-meter (21-foot) mirror system once the observatory reaches orbit and begins operations. To work properly, the mirrors must be perfectly aligned. "If there were a problem, the telescope's operators could adjust the mirrors from the ground to correct for any possible misalignments," said Bruce Dean, group leader of the Wavefront Sensing and Control (WFSC) group at NASA Goddard.

Dean's group was charged with developing the software to compute the optimum position of each of the 18 mirrors, and then adjusting and aligning them, if necessary. The work was funded by the Webb telescope technology development program and was patented by Goddard in 2009. Goddard worked together with Ball Aerospace & Technologies Corp. in 2005, to develop this flight software for the Webb Space Telescope.

In 2006-2007, a team of engineers from both Goddard and Ball Aerospace & Technologies Corp., successfully tested the WFSC algorithms on a laboratory model of the Webb Telescope, proving they are ready to work in space.

Today, Bolcar is a full-time optical engineer for the Goddard WFSC group. Currently, he is working on the Thermal InfraRed Sensor (TIRS) instrument that will fly on the Landsat Data Continuity Mission (LDCM), the next in a series of satellites that have remotely sensed Earth’s continental surfaces for more than 30 years. He's also working on an experimental instrument, called the Visible Nulling Coronagraph (VNC) that would be used for exoplanet detection.

The graduate fellowship and co-op programs give NASA time to train students for optical engineering. "It takes four to five years to really train someone in wavefront-sensing technology," Dean added.

University partnerships are a great way to get young engineers and scientists interested in NASA, Bolcar agreed. "When you're a graduate student, wherever the funding is, you are going to develop partnerships and relationships," he added. "There is a potential to go beyond graduate school. It's good for the university and its good for attracting young talent to NASA."

Alex Maldonado, a University of Arizona graduate student in optical engineering, is following in Bolcar's footsteps. He spends half his time working at Goddard as a co-op student and the other half taking classes at the university in Tucson, Ariz. When at Goddard, he researches new techniques for polishing optical lenses to prevent light scattering.

Astronomers need bigger and smoother mirrors that will collect more light to allow scientists to see faint objects farther into the distant universe. A common and effective technique for shaping optical lenses is called diamond-turning, where a diamond tip cuts away the lens material. However, this technique also introduces flaws that can deflect light. Maldonado spends much of his time designing and executing testing procedures to see if new polishing techniques reduce this effect -- efforts that will be applied to the Near Infrared Camera (NIRCam), a Webb telescope imager.

The University of Arizona is providing the Near Infrared Camera (NIRCam) to the Webb Space Telescope, an imager with a large field of view and high angular resolution. Prof. Marcia Rieke at the University is the lead for that instrument.

The James Webb Space Telescope is the next-generation premier space observatory, exploring deep space phenomena from distant galaxies to nearby planets and stars. The Webb Telescope will give scientists clues about the formation of the universe and the evolution of our own solar system, from the first light after the Big Bang to the formation of star systems capable of supporting life on planets like Earth.

"In addition to the students, we work with the professors," according to Dean. Bolcar's graduate professor, James R. Fienup, is a world-renowned expert in optics. "We asked him to help us cover high-risk areas on the Webb telescope," said Dean.

"This is a win-win for the schools and NASA," said Feinberg. "We fund their graduate students, and in return, we get really bright, fresh minds working on NASA's most challenging missions.

Expected to launch in 2014, the telescope is a joint project of NASA, the European Space Agency and the Canadian Space Agency.

A View of the JWST NIRSpec Instrument

The Universe has always set the standard for colors. It produces all possible combinations of colors, granted not always in the visible light spectrum. But figuring out how these nuances intertwine is absolutely essential to, for example, determining the distance a certain object is from Earth, what chemicals it contains and so on. This is why the most impressive space observatory ever built, the James Webb Space Telescope (JWST), will feature an instrument perfectly capable of extracting this sort of data from whatever wavelengths of light enter its detectors.

The Near-Infrared Spectrograph (NIRSpec) device will be one of the most advanced spectrographs ever developed, and undoubtedly the most complex to ever fly to space. EADS/Astrium is the European Space Agency's (ESA) prime contractor for the overall NIRSpec instrument, but some of the components were constructed at the NASA Goddard Space Flight Center (GSFC), in Greenbelt, Maryland. The prototype for the actual NIRSpec instrument that will fly on the JWST recently arrived at the GSFC for preliminary testing, from its construction site in Germany.

“A spectrograph is an instrument that separates light into a spectrum. One example of a spectrograph that most folks know about is a chandelier (or diamond ring). When sunlight shines through it, it breaks it up into colors. NIRSpec analyzes those colors from deep space to help us solve mysteries,” explains GSFC expert Bernie Rauscher. He is the deputy project scientist of the telescope's Integrated Science Instrument Module (ISIM) and also the principal investigator of the NIRSpec Detector Subsystem.

This particular spectrograph will have the ability to analyze more than 100 cosmic objects at the same time, as its components were especially designed for this task. The instrument will collect readings in the infrared portion of the electromagnetic spectrum, which will enable researchers analyzing data from the instrument to determine the age, chemical composition and distances of faint galaxies. One of the primary mission goals for the James Webb Space Telescope will be to determine how galaxies began to form in the early Universe, and so this ability that the NIRSpec has will be absolutely fundamental to completing its mission.

Hubble's successor one step closer to completion

A working replica of MIRI - the pioneering camera and spectrometer for the James Webb Space Telescope - has just been shipped (16th March) from the Science and Technology Facilities Council’s Rutherford Appleton Laboratory to NASA’s Goddard Space Flight Centre, bringing the Webb Telescope one small step closer to embarking on its journey into space where it will produce the sharpest images yet of the farthest depths of the cosmos.

The Webb telescope, a joint collaboration between NASA, the European Space Agency (ESA) and the Canadian Space Agency (CSA), is a large, cold orbiting infrared observatory that will succeed the currently operating Hubble Space Telescope. With the help of MIRI and its three other sophisticated instruments, it will be able to examine the first light in the universe and investigate the evolution of galaxies and the process of star and planet formation - helping to answer some of the fundamental questions about the origin of our Universe.

MIRI (Mid InfraRed Instrument) is an infrared camera and spectrometer that will operate as part of the Webb telescope to observe the Universe at wavelengths that are difficult or impossible to observe from the ground. It is an international project combining the talents of a consortium of European partners, the European Space Agency, and an international science team with those of scientists and engineers at NASA’s Jet Propulsion Laboratory.

The MIRI Structural Thermal Model realistically replicates the thermal, mechanical and optical alignment characteristics of the real flight model MIRI. It was assembled at the Science and Technology Facilities Council’s Rutherford Appleton Laboratory (RAL) from modules built by the University of Leicester, CEA in France, CSL in Belgium, JPL in the USA, Nova-Astron in the Netherlands, STFC’s UK ATC, & the Danish Space Research Centre, with system engineering, product assurance and management provided by Astrium Ltd. It has already been subjected to an extensive series of tests at RAL, and later this year it will be used at NASA’s Goddard Space Flight Centre for pre-integration testing with the Integrated Science Instrument Model (ISIM) - the key element of JWST that holds all four instruments in the correct positions. Meanwhile engineers across Europe and the USA are pressing ahead at full speed to build the flight instrument, which is due for delivery next year.

“The MIRI team is delighted to have reached this important technical milestone after many years of design and development work for the instrument” said the European PI, Gillian Wright of STFC’s UK Astronomy Technology Centre.

George Rieke, MIRI Science Team Lead at University of Arizona, Tucson added, "It is inspirational to see how well the team has worked to make this happen." "It is another big step toward making MIRI a reality."

When launched in 2014, the Webb telescope will have a set of four instruments, including MIRI. MIRI will provide enormous increases in sensitivity, spatial and spectral resolution for three key reasons: Firstly, its location in space will remove the blocking and large background noise effects of the atmosphere which limit ground-based telescopes. Secondly, the telescope is cooled to a very low temperature, reducing its emission and greatly improving its performance. Thirdly, the telescope’s mirror is larger then any other infrared space observatory, giving improved angular resolution and collecting area. This combination makes the Webb telescope a very powerful space observatory which promises to revolutionise our view of the cosmos yet again - just as Hubble did.

The UK is playing a key role in the Webb telescope with the Science and Technology Facilities Council (STFC) leading the European development of the MIRI Optical System. This UK contribution includes leadership by the European PI based at STFC’s UK ATC; Astrium Ltd providing the project management, PA, and system design/engineering; STFC’s Rutherford Appleton Laboratory (RAL) responsible for the Assembly, Verification and Test and the thermal systems work; STFC’s UK ATC designing and building the spectrometer pre-optics module; and the University of Leicester leading the structure and mechanical systems work for MIRI.

Dr David Parker, Director of Space Science and Exploration at the British National Space Centre (BNSC), said, “With the delivery of this sophisticated replica of MIRI, we’ve reached another important milestone in the build of this new window on the ancient Universe. Right now, the UK is involved in many exciting, new space projects. With the upcoming creation of a UK executive space agency we will ensure that the UK continues to play key roles in amazing discovery machines like James Webb Space Telescope.”

Professor Richard Holdaway, Director of Space Science and Technology at the Science and Technology Facilities Council’s Rutherford Appleton Laboratory, added, “The shipping of the MIRI replica to NASA’s Goddard Space Flight Centre, highlights again, the effectiveness of international collaboration on a mission of this size. Each organisation, including Rutherford Appleton Laboratory’s Space Science and Technology Department, contributes their own set of skills and expertise to the project, gradually steering us towards its completion”.

Matt Greenhouse, Project Scientist for the Webb telescope Science Instrument Payload at NASA's Goddard Space Flight Center, Greenbelt, Md. said, "Receipt of the MIRI structural thermal (STM) model represents a major milestone in 8 years of development work by the joint ESA and JPL instrument team. Tests with this prototype model of the MIRI, conducted at Rutherford Appleton Laboratories in the UK, have shown that this science instrument is on track to meet all of its performance requirements. Upon receipt of the STM, GSFC engineers will begin testing it with supporting systems in the Webb telescope Integrated Science Instrument Module to facilitate smooth integration of the flight model."

Color It Ready - Webb Telescope Instrument Now at Goddard

The cosmos is filled with color, and color is a key in determining age, chemical composition and how far objects are from Earth. To help identify these colors and objects the James Webb Space Telescope will be using a spectrograph called NIRSpec. Recently, the engineering test unit for the Webb telescope's Near-Infrared Spectrograph (NIRSpec) instrument arrived at NASA's Goddard Space Flight Center, Greenbelt, Md. from its manufacturer in Germany for preliminary testing.

"A spectrograph is an instrument that separates light into a spectrum," said Bernie Rauscher of NASA Goddard. "One example of a spectrograph that most folks know about is a chandelier (or diamond ring). When sunlight shines through it, it breaks it up into colors. NIRSpec analyzes those colors from deep space to help us solve mysteries." Rauscher is the Principal Investigator for the NIRSpec Detector Subsystem and the Deputy Project Scientist of the Webb's Integrated Science Instrument Module (ISIM).

The NIRSpec instrument will be the principal spectrographic instrument on-board the Webb telescope.

The components that make up NIRSpec will be sensitive to infrared wavelengths from the most distant galaxies and will be capable of obtaining spectra of more than 100 objects in the cosmos simultaneously. Determining an object's spectra is important, because it will help scientists determine the age, chemical composition and distances of faint galaxies. These measurements are key to unraveling the history of galaxy formation in the early Universe - one of the primary science goals of the Webb mission.

One unique technology in the NIRSpec that enables it to obtain those 100 simultaneous spectra is a micro-electromechanical system called a "microshutter array." NIRSpec's microshutter cells, each approximately as wide as a human hair, have lids that open and close when a magnetic field is applied. Each cell can be controlled individually, allowing it to be opened or closed to view or block a portion of the sky. It is this adjustability that allows the instrument to do spectroscopy on so many objects simultaneously. Because the objects NIRSpec will be looking at are so far away and so faint, the instrument needs a way to block out the light of nearer bright objects. Microshutters operate similarly to people squinting to focus on an object by blocking out interfering light.

NASA Goddard has a lot invested in the NIRSpec. Goddard built NIRSpec's detector and microshutter systems. EADS/Astrium is the European Space Agency's (ESA) prime contractor for the overall NIRSpec instrument. The prototype instrument was integrated and tested at Astrium's facility in Munich, Germany, before being shipped to Goddard.

Now that it has arrived at Goddard, the NIRSpec engineering test unit will go through pre-integration testing with the ISIM, which acts as a "chassis" to the Webb telescope observatory. Along with the other instruments, NIRSpec will be fitted into the ISIM, which is also currently at Goddard. The engineering test unit reproduces the physical, thermal, electrical and optical (up to the Micro-Shutter Array unit) properties of the flight model.

The James Webb Space Telescope is the next-generation premier space observatory, exploring deep space phenomena from distant galaxies to nearby planets and stars. The Webb Telescope will give scientists clues about the formation of the universe and the evolution of our own solar system, from the first light after the Big Bang to the formation of star systems capable of supporting life on planets like Earth.

The Webb Telescope project is managed at NASA's Goddard Space Flight Center in Greenbelt, Md. The telescope is a joint project of NASA, the European Space Agency and the Canadian Space Agency, and will launch in 2014.

For information about NASA's James Webb Space Telescope, visit:

http://www.jwst.nasa.gov/

For more information about the NIRSpec, visit:

http://www.jwst.nasa.gov/nirspec.html

For more information, visit the NIRSpec website at the Space Telescope Science Institute:

http://www.stsci.edu/ngst/instruments/nirspec/

Extracting Information From Starlight

The cosmos is filled with stars. However, the closest star beyond the Sun is so far away, that it would take the fastest spacecraft 75,000 years to reach it. Astronomers can't study the cosmos by sending probes to gather information about other stars, as we do with our own Sun and its planets. Fortunately they don't have to. The information comes to us at the speed of light!

The light of stars is produced by atoms and molecules that encode, in the starlight itself, key science information about their chemical composition, temperature, pressure, and velocity. To receive and extract this information, astronomers will use the James Webb Space Telescope and a first-of-its kind science instrument whose prototype has just arrived at NASA's Goddard Space Flight Center, Greenbelt, Md. from its manufacturer in Germany.

The Webb telescope contains a giant 25 square meter (~30 square yard) mirror that will collect the faint light from distant stars and feed it to one of four science instruments that are each designed to extract a specific type of information contained in the light itself.

One of the most scientifically powerful instruments is a Near-Infrared multi-object Spectrograph (NIRSpec) that disperses the white star light into a spectrum so that the contribution of individual atoms and molecules in the star can be seen.

The atoms and molecules in the star imprint lines on this spectrum that uniquely fingerprint each chemical element and reveal a wealth of information about physical conditions in the star. Spectroscopy (the science of interpreting these lines), is among the sharpest tools in the shed for exploring the cosmos.

Many of the objects that the Webb will study, such as the first galaxies to form after the Big Bang, are so faint, that the Webb's giant mirror must stare at them for hundreds of hours in order to collect enough light to form a spectrum. In order to study thousands of galaxies during its 5 year mission, the NIRSpec is designed to observe 100 objects simultaneously.

The NIRSpec will be the first spectrograph in space that has this remarkable multi-object capability. To make it possible, Goddard scientists and engineers had to invent a new technology micro-shutter system to control how light enters the NIRSpec.

Although the night sky appears black, it's not really dark. If your eyes could see in the infrared, the night sky would appear to glow just as the daytime sky glows at visible wavelengths. The infrared glow of the night sky, known as the Zodiacal light, is produced by a cloud of dust that surrounds the Earth and Mars that the Webb must look through. Observing the first galaxies through this Zodiacal light, is analogous to observing stars during the daytime with your eye.

To prevent the NIRSpec from being blinded by the Zodiacal light, the Webb telescope forms a magnified image of the sky onto a programmable array of 250,000 shutters that are each the diameter of a human hair. Shutters under objects in this image for which a spectrum is desired, are commanded open allowing their light to enter the NIRSpec. The remaining shutters are held closed to minimize the Zodiacal light that can enter NIRSpec and reduce its sensitivity.

The NIRSpec micro-shutter system is one of 10 technologies that had to be invented to make the Webb mission possible. During the Webb mission, each shutter must withstand approximately 100,000 open/close cycles while operating at 40 K (-230 oC).

In order to make the large NIRSpec instrument light enough to fly on the Webb, its structure and optics are made of an advanced ceramic material called silicon carbide. The NIRSpec is among the most advanced astronomy instruments ever built.

NASA Goddard has a lot invested in the NIRSpec. Goddard built NIRSpec's detector and microshutter systems. EADS/Astrium is the European Space Agency's (ESA) prime contractor for the overall NIRSpec instrument. The prototype instrument was integrated and tested at Astrium's facility in Munich, Germany, before being shipped to Goddard.

Now that it has arrived at Goddard, the NIRSpec prototype will go through pre-integration testing with electronic and mechanical systems of the Webb's Integrated Science Instrument Module (ISIM). Along with the other prototype instruments, the NIRSpec will be fitted into the ISIM flight structure, which is also currently at Goddard.

These prototype instrument models are flight-like in form, fit, and function. They enable engineers to develop and practice integration and test procedures before handling the actual flight units.

The James Webb Space Telescope is the next-generation premier space observatory, exploring deep space phenomena from distant galaxies to nearby planets and stars. The Webb Telescope will give scientists clues about the formation of the universe and the evolution of our own solar system, from the first light after the Big Bang to the formation of star systems capable of supporting life on planets like Earth.

The Webb Telescope project is managed at NASA's Goddard Space Flight Center in Greenbelt, Md. The telescope is a joint project of NASA, the European Space Agency and the Canadian Space Agency, and will launch in 2014.

Turning up the heat: Finding out how well the Webb telescope's sunshield will perform

Keeping an infrared telescope at very cold operating temperatures isn't an option, it's an absolute necessity. For the James Webb Space Telescope to see the traces of infrared light generated by stars and galaxies billions of light years away, it must be kept at cryogenic temperatures of under 50 Kelvin (-370 F). Otherwise, sunlight would warm the telescope and this heat from the telescope itself will swamp the very faint astronomical signals, effectively blinding the telescope's eye. The job of the huge, five-layer sunshield is to keep that from happening.

Serving as a radiation blocker, the sunshield is subjected to nearly 100,000 thermal watts of solar heat, and reduces that to one tenth of a watt on the cold side, a million to one reduction.

But how do you test a complicated structure the size of a tennis court? There isn't a cryogenic chamber on the planet big enough and building one doesn't make sense from a budget and practical standpoint. So Webb engineers have constructed a 1/3-scale model and a test facility to perform the critical thermal test of the sunshield system.

The thermal test had two main goals: 1- to verify that the sunshield design can actually block and redirect the sun's energy before it reaches the telescope; and 2- to verify the accuracy of computer thermal models used to predict how the full-size sunshield will perform. 'The flight sunshield will be deployed and visually inspected prior to flight, but only a computer simulation of its thermal performance will be used to determine if it's ready to launch,' explains Keith Parrish, Webb telescope Sunshield Manager at NASA's Goddard Space Flight Centre, Greenbelt, Md.

'This is very similar to wind tunnel testing of large aircraft,' he notes. 'Most aircraft, especially large commercial airliners, are simply too large to undergo full-size testing. Computer models, which extrapolate the test data from smaller scale model wind tunnel tests, are used to verify final design and predict the full size aircraft's performance. Our Webb sunshield 1/3-scale model test is a very similar approach.'

In space, the sunshield will be heated by the sun. For ground testing, the 1/3-scale model was placed in a thermal vacuum test chamber at lead contractor Northrop Grumman's manufacturing facilities in Redondo Beach, Calif. The sun's heat was simulated by electrical heater plates placed very close to, but not touching layer 1, the warm sun- facing layer. Power to the heaters was steadily increased until layer 1 reached similar temperatures as those expected in flight, well over 100 degrees C (212 F, the boiling point of water at sea level).

Approximately 400 temperature sensors were placed all over the sunshield. 'We also keep an eye on the chamber's gaseous helium-refrigerated shroud temperatures and liquid helium cooling plates,' adds Parrish. 'These cooling plates simulate the cold background temperature of space at the orbit of Webb, which is around 7 Kelvin (-446.8 F). We can't get these plates all the way down to 7 K, which is pretty close to absolute zero. The plates typically get down to the 15 to 25 K (-434.4 F. to -414.4 F) temperature range, so exact knowledge of their temperature is critical to understanding the sunshield's performance.'

The engineering team used the 1/3-scale tests for a trial run of a device called a radiometer. Hung or mounted around the sunshield, these devices measure the heat radiation that is bouncing around and between the sunshield, the cold plates and the chamber walls. Since this kind of effect doesn't occur in space, it's important to understand how this heat bouncing impacts the test results. When the flight instruments and observatory are tested at Goddard and Johnson Space Centre, these devices need to be working well.

Seven different testing conditions were used to gather temperature data, and these test conditions were tailored so that engineers can study how the sunshield performs in space under a variety of conditions. Some test conditions exaggerated or increased temperatures and heat flows in specific areas of the sunshield. Even though these test conditions do not simulate flight conditions, they're designed to isolate and better define particular variables used in computer thermal simulations. 'One specific test condition used a mechanism in the chamber to change or warp the sunshield's shape,' Parrish explained. 'Since proper shape is critical to the sunshield's performance, this test condition gave engineers important data so they could see if computer models can actually predict the thermal impact of shape changes.'

After the temperature data was gathered, engineers ran computer models over and over again with small changes to mimic the actual test conditions. The goal is to better match the temperature data from the sensors on the sunshield to the computer models. 'This is really the critical part in the whole testing process,' says Parrish. 'Gathering the test data was just the beginning. Understanding that data and how it applies to the flight sunshield's predicted thermal performance is the critical step.'

To understand how the membrane shape affects thermal performance, a Light Detection And Ranging (LIDAR) laser device took highly accurate shape measurements on each of the five layers of the sunshield at room temperature. These measurements were used to validate the computer model predictions of each membrane under ambient conditions. The computer models were then used to predict the membrane shapes over the various test conditions.

Later this spring, the thermal chamber will be modified with a window so that the LIDAR device can see into the chamber and measure the shape of layer 5, the coldest layer, near its cryogenic operating temperature, approximately 77 K (-320.8 F). This test will allow the engineers to confirm if the computer model's prediction of shape at temperature is correct.

Careful planning and following rigourous procedures paid off - the test was very successful because all test objectives were met and engineers were able to collect the data they needed. That data is being carefully analysed to see if the test temperatures accurately reflect the thermal performance of the flight sunshield. Data analysis is a lengthy process scheduled to be complete by the end of March 2010.

The 1/3-scale tests go a long way in establishing model verification well in advance of the flight test. As a result, the fidelity of the master model is improved, which adds flight confidence and reduces technical risk.

The thermal testing took place over four weeks, from Nov. 23 to Dec. 19, 2009 in Northrop Grumman's largest thermal vacuum chamber at the company's Aerospace Systems manufacturing facilities in Redondo Beach, Calif.

Source: NASA/Goddard Space Flight Centre

NASA's James Webb Space Telescope Unfolds by Animation

> View streaming Windows Media Viewer animation
Credit: Northrop Grumman Aerospace Systems


> View streaming Windows Media Viewer animation
Credit: Northrop Grumman Aerospace Systems


>View larger image
Credit: NASA

Although engineers, scientists and manufacturers are still in the process of building all of the instruments that will fly aboard NASA's James Webb Space Telescope, they had to figure out long ago, how it was going to "unfold" in space. That's because the Webb Telescope is so big that it has to be folded up for launch. Now, animators have made that "unfolding" come to life in two new videos.

A brand new animation of how NASA's massive next-generation space telescope will open up in space once it achieves orbit, was created by the Image center at Northrop Grumman Aerospace Systems, Redondo Beach, Calif. The Webb Telescope is roughly 65 feet (21 meters) from end to end and about 3 stories high.

"Animation helps designers and their colleagues to fully visualize and explain the complex motions required to deploy this observatory," said Mike Herriage, Webb Telescope Deputy Program Manager at Northrop Grumman. "And while it’s a visual tool, producing accurate animation is a technical challenge as well."

The James Webb Space Telescope is a large, infrared space telescope. It will find the first galaxies that formed in the early Universe, connecting the Big Bang to our own Milky Way Galaxy. It will peer through dusty clouds to see stars forming planetary systems, connecting the Milky Way to our own Solar System.

The Webb Telescope is extremely large and cannot fit in a rocket unless it is folded. It has a sunshield the size of a tennis court and an 18-segment mirror that looks like a honeycomb. Because of its large size, the telescope needs to be folded up to fit in the rocket. The sunshield will be compactly folded, much like a parachute, around the front and back of the telescope. The mirror segments are mounted on the "spine" or backplane of the telescope and the segments on the left and right sides of the honeycomb shape are folded in the rocket.

Once the Webb telescope is on its way to its final orbit, approximately 1 million miles from the Earth, engineers at Northrop Grumman will issue commands to the Webb Telescope to unfold it. "Think of the sunshield as five candy wrappers the size of a tennis court," said Mark Clampin, Webb Telescope Observatory Project Scientist at NASA’s Goddard Space Flight Center, Greenbelt, Md.

The animation shows the first part of the telescope to unfold is the solar panel, followed by the communications antenna. Next, the five layers of sunshield will drop into place from the front and back, spread out into a kite shape. The "secondary mirror support structure," an arm-like feature holding the secondary mirror assembly will then drop down from its folded center perch, and finally, the side mirror segments will be moved forward to form the complete "honeycomb."

"There are videos showing a simple deployment and a version that includes detailed views of key points in the sequence," Clampin said. "There are 2 and 4 megabyte versions of each video and they are high definition."

James Webb Space Telescope is a joint project of NASA, the European Space Agency and the Canadian Space Agency.

A Model Home For NASA's New Space Telescope

NASA commissioned construction of an environmental simulation test chamber which was completed in 1964 at Johnson Space Center (JSC) in Houston, Texas. The facility, Chamber A, was invaluable for testing spacecraft and satellites before deployment to space. By testing spacecraft in an environment similar to the one they would be functioning in, potential problems could be addressed before launch.

A new addition to NASA's observatory inventory is called the James Webb Space Telescope (JWST), after a former Administrator of NASA. The new telescope will have seven times the mirror area of the Hubble, with a target destination approximately one million miles from earth. Scheduled for launch in 2013, the JWST will allow scientists the ability to see, for the first time, the first galaxies that formed in the early Universe. Pre-launch testing of JWST must be performed in environments that approximate its final target space environment as closely as possible.

The Commission
JSC's Chamber A will require modifications to accommodate testing of the JWST. Some of these changes involve upgrades to cryogenic, vacuum pumping, and structural elements. To accomplish this, JSC presented a need for a 3-D model of the chamber and the surrounding area in its current state. This effort will provide engineers an accurate facility representation to be used in identifying and correcting any conflicts in upgrade design and installation.

To accomplish such a feat, NASA looked to Houston engineering firm, Taylor and Hill, Inc., who has been providing engineering services to the oil, gas, chemicals and power industries since 1974. The firm qualified as a category finalist in the Houston Business Roundtable award for "Outstanding Safety Performance" for 2003 and 2004 and received previous awards for outstanding safety leadership from BP South Houston in 1996, 1997, and 1999.

The project scope entailed scanning and modeling all eight levels, two large staging areas, two mechanical rooms and liquid nitrogen piping and storage tanks comprising the chamber and the area surrounding it.

"We were hired to identify the major obstructions, clearances and open areas surrounding the test chamber," noted Glen Kearns, Taylor & Hill's Laser Scanning Department Manager and Project Manager over this job.

The information would be used to facilitate the planning of new piping, electrical conduit runs, cable trays and equipment upgrades for the 118ft. tall chamber.

Obstacles
The project was marked high priority status by NASA, and therefore the measurements had to be completed in a timely manner. Construction and maintenance had already begun, which meant Taylor & Hill would be operating within a confined workspace.

Conventionally, engineers would gather the necessary data by using tape measures, photographs, and written notes to generate 2-D drawings. This would have been quite time consuming, obtrusive and open to error. "There would have always been the risk of overlooking something," Kearns stated.

Technology Suited for the Job
Taylor & Hill employed a method known as Laser Scanning Metrology (LSM) to gather all the necessary measurements. LSM involves using high-speed computer-aided laser scanners to generate high-accuracy measurements that are digitally recorded for 2-D and 3-D modeling, inspection, visualization or reverse engineering. The practice has been useful for a variety of applications, ranging from documenting as-is conditions for accident reconstruction or building renovations to reverse engineering boat hulls to virtual asset management of power facilities.

Using the Laser Scanner LS from FARO Technologies, and a combination of modeling and CAD softwares, Rito Morales and Don Meyer of Taylor & Hill produced the requested deliverables ahead of schedule.

FARO's Laser Scanner LS operates via phase shift technology by emitting a beam from the instrument's laser sensor to a vertical mirror. The beam is then deflected onto the object or environment being scanned. This includes full horizontal 360 degree coverage and vertical 320 degree coverage within a distance of 76m (249ft.). Finally, the beam is diverted back to the laser scanner and the distance coordinates are digitally recorded via angular encoders that measure the rotation of the vertical mirror and horizontal axis of the laser scanner. These X, Y Z coordinates are computed at a rate of nearly 120,000 points per second. A scan at minimal resolution can be completed in less than a minute.

"The speed at which the data was collected with FARO's phase-based scanner is a major consideration," Kearns observed. "Traditional methods would have taken several weeks or months to collect the data we gathered in about ten days of scanning."

The resulting points produce a high resolution picture-quality image with a major advantage­the data is represented in 3-D. The image, also known as a point cloud, contains all the scanned coordinates. This allows operators not only to have an accurate representation of the physical appearances of the scanned items, but also to obtain useful measurements for inspection, analysis and modeling.

Taylor & Hill produced more than 170 point clouds from the data collected throughout the 10 days on the job site. Off-site, all laser scans were registered using FARO Scene point cloud software to a building coordinate system established through dimensional control.

From the registered point clouds, 3-D solid models were developed through INOVx 3-D PlantLINx® showing objects outside of the chamber: floors, columns, major equipment and large diameter piping. They also furnished a detailed model of the steel that makes up the roof structure. The 3-D model was then exported into AutoCAD where final presentation visuals were added. Surface finishes were applied and rendered images were generated complete with lights and shadows.

"Contractors responsible for the upgrades are now aware of the obstacles that may impede their plans," stated Kearns.

Software Focus
FARO Scene is a high-performance and practical 3-D point cloud software tool designed for viewing, administrating and working on 3-D scan points from high-resolution 3-D laser scanners. This tool allows the user to manipulate raw 3-D scan points and acquire with analysis functions initial point-cloud data comprehension. Through data analysis and manipulation, scan points may be prepared for export into the user's operating platform as targets (.cor), scan points (.dxf, VRML, .igs, .pts, .ptx, .ptc), CAD objects (.igs, .dxf) or scan pictures (.jpg).

FARO Scene features:
• Measures distances between objects
• Completes point cloud filtering, compression, noise reduction and registration
• Analyzes CAD models against point clouds to recognize collisions and deviations
• Models basic graphical objects such as planes, spheres, and cylinders from point clouds

3-D PlantLINx converts the output of laser scanning and survey data into accurate 3-D models of existing plants. This is achieved through the creation of physical databases consisting of analysis of laser scans, stereo photos and survey points captured during field data collection utilizing automated surface modeling or assisted primitive modeling. Based on the level of detail required for a specific project, 3-D PlantLINx databases can be composed of conceptual, single revamp, major revamp or intelligent models.

3-D PlantLINx features:
• Processes laser images from most major laser scanning systems
• Rapid access to logical and complete regions of points
• Ability to customize or use industry standardized specifications for selected piping, structural steel and electrical elements
• User Defined customizable catalogs for complex assemblies, such as pumps, vessels, platforms, portable equipment, etc.
• Assisted 3-D modeling enables rapid creation of complete and accurate CAD geometry, including entire piping systems
• Structures 3-D models into userdefined conventions such as P&ID
• Roll based with optional concurrent user database access for increased modeling and QA/QC efficiency

Rito Morales is the CAD Support and Laser Scanning Specialist for Taylor & Hill, Inc. based in Houston, Texas. He has seven years of field experience with laser data collection in the petrochemical industry. A 1.956Mb PDF of this article as it appeared in the magazine—complete with images—is available by clicking HERE

James Webb Space Telescope First Flight Mirror Completes Cryogenic Testing

The first mirror segment that will fly on the James Webb Space Telescope, built by Northrop Grumman Corporation, has completed its first series of cryogenic temperature tests in the X-ray and Cryogenic Facility at the Marshall Space Flight Center in Huntsville, Ala.

"We’re excited that we can support the James Webb Space Telescope with our world class cryogenic and x-ray telescope test facility," said Helen Cole, project manager for the Webb Telescope activities at NASA's Marshall Space Flight Center, Huntsville, Ala. "The test performed here are crucial to the success of the program since they’ll ensure the mirrors and components will be able to withstand the extreme cold temperatures of space."

The mirror segment is the first of 18 flight mirror segments that will be joined to make a giant, 6.5-meter diameter (21.3 ft.) hexagonal mirror. The segments will be subject to temperatures of -414 degrees Fahrenheit in a 7,600 cubic-foot helium-cooled vacuum chamber at NASA Marshall.

Engineers will measure how the mirror changes shape going from room temperature to cryogenic (frigid) temperatures, as the metal expands and contracts. They can model these changes to some extent, but not perfectly. The mirrors will be polished to about 100 nanometers (a human hair is approximately 60,000 to 120,000 nanometers) accuracy at room temperature, based on the expected changes. Then it will be cooled down to cryogenic temperatures and engineers will measure the mirror's surface, creating a "hit map" of unexpected changes.

"This is what we have done so far with the first flight mirror segment," said Jonathan Gardner, Webb Telescope Deputy Project Scientist at NASA Goddard Space Flight Center, Greenbelt, Md. "Now, engineers will warm it up and polish out the "hit map" areas to get the mirror to 20 nanometer accuracy - a process which will take months. The mirrors will then be brought back down to cryogenic temperatures to verify the increased accuracy." In addition to this testing, engineers also did some "cryo cycling." That means going up and down in temperature (without polishing in between) to test the repeatability of the changes.

Since there are 18 mirror segments, each measuring about 1.5 meters (4.9 ft.) in diameter, they will be tested in batches of six and chilled to cryogenic temperatures four times in a six-week time span. It takes approximately five days to cool a mirror segment to cryogenic temperatures. All flight mirror tests are expected to be completed in June 2011. The Webb telescope is scheduled for launch in 2013.

Northrop Grumman is the prime contractor for the Webb telescope, leading a design and development team under contract to NASA’s Goddard Space Flight Center.

"It has taken years of intense effort for the Webb Telescope team to begin flight mirror cryotesting and we’re gratified that testing was successful," said Martin Mohan, Webb telescope program manager for Northrop Grumman’s Aerospace Systems sector, Redondo Beach, Calif. "Along the way, we’ve had to invent entire manufacturing and measurement processes because no one has ever built a telescope this large that has to operate at temperatures this extreme."

The James Webb Space Telescope is the next-generation premier space observatory, exploring deep space phenomena from distant galaxies to nearby planets and stars. The Webb Telescope will give scientists clues about the formation of the universe and the evolution of our own solar system, from the first light after the Big Bang to the formation of star systems capable of supporting life on planets like Earth.