To see the first stars and galaxies in the early universe, the James Webb Space Telescope will need to look more than 13 billion light years into space.
Set for launch in 2018, the project was nearly scrubbed in 2011 before being revived by funding from Congress. Recently, Ball Aerospace completed fabrication of the mirrors, a major milestone in the complex telescope's development. Named for former NASA administrator James Webb, the telescope's primary flower-like folding mirror is made up of 18 individual, highly polished, hexagonal gold coated beryllium segments that will capture the faintest traces of infrared light from distant galaxies.
Because warm objects give off infrared light, or heat, if the telescope's mirror was the same temperature as the Hubble Space Telescope's, the faint infrared light from distant galaxies would be lost in the infrared glow of the mirror. Instead, the Webb telescope requires extremely cold temperatures, with its mirrors at around -220 degrees C.
To keep Webb cold, it will be sent into deep space, far from the Earth. Sun shields will shade the mirrors and instruments from the sun's heat, keeping the telescope as cold as possible for maximum clarity.
The Optical Telescope Element (OTE) is the eye of the James Webb Space Telescope. The OTE gathers as much light as possible coming from space and provides it to the science instruments, labeled in this diagram.
NASA engineer Ernie Wright prepares the first six flight-ready James Webb Space Telescope's primary mirror segments at NASA's Marshall Space Flight Center before cryogenic testing begins to confirm that the mirrors will respond as expected to the extreme temperatures of space prior to integration into the telescope's permanent housing structure.
This comparison of the Hubble and Webb primary mirrors shows the scale relative to a human. Webb's primary mirror array will have a 21-foot diameter, about 7 times the collecting area of Hubble's 8-foot mirror. This larger light collecting area means that Webb can peer farther back into time than Hubble is capable of doing. Scientists hope the James Webb Space Telescope will be capable looking at galaxies first created after the Big Bang, hopefully answering fundamental questions about how the universe was created.
Inspecting the first gold coated primary mirror segment
Ball Aerospace optical technician Scott Murray inspects the first gold coated primary mirror segment on September 1, 2010, prior to cryogenic testing in the X-ray & Cryogenic Facility at NASA's Marshall Space Flight Center in Huntsville, Ala. The mirror was coated in gold by by Quantum Coating Incorporated.
A thin coating of gold, just about 3 grams for each of the 18 hexagons, is vaporized into a cloud and applied to the beryllium mirrors in a layer just 120 nanometers thick to improve the reflection of infrared light.
During cryogenic testing, the mirrors will be subjected to temperatures dropping down to -415 degrees Fahrenheit, permitting engineers to measure in extreme detail how the shape of each mirror changes as it cools.
Updated:Caption:James MartinPhoto:NASA/MSFC/David Higginbotham/Emmett Given
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Primary mirror segment cryogenic testing
Project scientist Mark Clampin is reflected in the flight mirrors at Marshall Space Flight Center on April 15, 2011.
A full-scale sun-shield membrane has been deployed on the membrane test fixture at Mantech in Hunstville, Ala., on September 14, 2011, where it is ready for a precise measurement of its three dimensional shape.
Updated:Caption:James MartinPhoto:Northrop Grumman Aerospace Systems
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The telescope's sunshield
The five-layer sun shield, which will protect the James Webb telescope, consists of thin membranes made from a polymer-based film and an internal support framework made of spreader bars, booms, cabling, and containment shells.
Designed to block solar light and keep the observatory operating at cryogenic temperatures, the sun shield will help enable the Webb telescope's infrared sensors to see distant galaxies, early stars and planetary systems, and help astronomers better understand dark matter.
The Integrated Science Instrument Module (ISIM) forms the scientific heart of the James Webb Space Telescope, providing the structure, environment, control electronic, and data handling for the science instruments and the telescope's fine-guidance sensor including Fine Guidance Sensor , Mid-Infrared Instrument, Near Infrared Camera, Near-InfraRed Imager and Slitless Spectrograph, Near Infrared Spectrometer.
Here, Goddard technicians lifting the ISIM framework onto the test structure. The ISIM will sit atop this platform during space environmental testing.
The James Webb Space Telescope Backplane Pathfinder, seen here on April 30, 2012, is a flight-like model of the center section of the Webb telescope back plane used to practice assembly and integration before the final flight hardware is done.
This photo, taken on August 7, 2012, shows a group of technicians watching carefully as the Fine Guidance Sensor/Near InfraRed Imager and Slitless Spectrograph (FGS/NIRISS) are moved into position.
During Wavefront Sensing and Control, or WFSC, software aboard the James Webb Space Telescope will compute the best position for each of 18 mirrors and one secondary mirror, and then adjust the positions. Here, engineers used a one-sixth scale model to test the WFSC software.
The James Webb Space Telescope secondary mirror just after gold coating at Quantum Coating Incorporated on July 19, 2011. Unlike the array of hexagon primary mirrors, the singular secondary mirror is rounded and convex.
The secondary mirror is of critical importance because it captures light from the 18 primary mirror segments and relays those distant images of the cosmos to the telescope's science cameras.
Dan Patriarca, president of Quantum Coating, inspects Webb's gold coated tertiary mirror on June 22, 2010.
Updated:Caption:James MartinPhoto:Ben Gallagher (Ball Aerospace) and Quantum Coating
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Inside the MIRI cleanroom
Contamination control engineers conducted a "receiving inspection" of the James Webb Space Telescope's Mid-Infrared Instrument (or MIRI) on May 29, 2012 in the giant clean room at NASA's Goddard Space Flight Center in Greenbelt, Md., and gave it a clean bill of health after its transatlantic journey from the U.K. The Mid-Infrared Instrument has both a camera and a spectrograph that sees light in the mid-infrared region of the electromagnetic spectrum, with wavelengths that are longer than our eyes see.
Jose Lorenzo, MIRI Instrument Manager/onsite European Space Agency representative (in the blue hood), is shown holding a flashlight. Standing beside him, wearing a white hood, is Eve Wooldridge, NASA Goddard engineer.
NIRSpec Microshutters for James Webb Space Telescope
Microshutters, seen here being inspected on June 23, 2012, are a new piece of technology being used on the Near Infrared Spectrograph (NIRSpec) instrument on Webb. NIRSpec is an instrument that will allow scientists to capture the spectra of more than 100 objects at once. 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.
The Near-Infrared multi-object Spectrograph 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, the microshutter system, to control how light enters the NIRSpec.
One unique technology in the NIRSpec is a micro-electromechanical system called a "microshutter array." NIRSpec's microshutter cells, seen here up close, are each approximately as wide as a human hair, and 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.
This image taken on April 30, 2012 shows several critical items related to NASA's next-generation James Webb Space Telescope being tested in the thermal vacuum test chamber at NASA's Goddard Space Flight Center in Greenbelt, Md.
