{"id":14641,"date":"2017-05-10T00:49:10","date_gmt":"2017-05-09T16:49:10","guid":{"rendered":"https:\/\/wp-productionenv-bjg9h2g2bgg5b8aa.southeastasia-01.azurewebsites.net\/news\/james-webb-space-telescope-shipped-to-texas-for-its-biggest-test-yet\/"},"modified":"2017-05-10T00:49:10","modified_gmt":"2017-05-09T16:49:10","slug":"james-webb-space-telescope-shipped-to-texas-for-its-biggest-test-yet","status":"publish","type":"post","link":"https:\/\/starpath.global\/news\/james-webb-space-telescope-shipped-to-texas-for-its-biggest-test-yet\/","title":{"rendered":"James Webb Space Telescope shipped to Texas for its biggest test yet"},"content":{"rendered":"
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The primary mirror of the James Webb Space Telescope pictured at NASA\u2019s Goddard Space Flight Center in Greenbelt, Maryland. Credit: NASA\/Chris Gunn<\/figcaption><\/figure>\n

The centerpiece of the James Webb Space Telescope has arrived at NASA\u2019s Johnson Space Center in Houston for a three-month test to ensure the observatory\u2019s sensors and gold-coated mirrors work in the frigid temperatures of deep space.<\/p>\n

While the assembly and initial checks of the telescope\u2019s durability have uncovered no major problems, NASA officials caution that the $10 billion, multi-national project is on the cusp of some of its most critical tests leading up to a planned launch in October 2018.<\/p>\n

Over the next few months, technicians will unpack the telescope and install it inside a thermal vacuum chamber at the space center, then pump air out of the test facility as helium and liquid nitrogen chills the hardware to a temperature colder than minus 370 degrees Fahrenheit, or about 50 Kelvin, a measure above absolute zero.<\/p>\n

Parts of the telescope, the largest ever built to fly in space, will be even colder during the 93-day freeze to verify the sensitivity of JWST\u2019s infrared detectors, part of an end-to-end test of the observatory\u2019s optics to ensure they will function in space.<\/p>\n

The mission\u2019s four science instruments already went through three cryogenic tests at NASA\u2019s Goddard Space Flight Center in Greenbelt, Maryland, but officials had to ship the fully-assembled telescope to Houston to subject the complete structure to the conditions it will encounter in space.<\/p>\n

\u201cThe Webb telescope is about to embark on its next step in reaching the stars as it has successfully completed its integration and testing at Goddard. It has taken a tremendous team of talented individuals to get to this point from all across NASA, our industry and international partners, and academia,\u201d said Bill Ochs, NASA\u2019s Webb telescope project manager, in a press release. \u201cIt is also a sad time as we say goodbye to the Webb Telescope at Goddard, but are excited to begin cryogenic testing at Johnson.\u201d<\/p>\n

JWST\u2019s suite of instrumentation peer back in time, resolving the first stars and galaxies that formed in the dark early universe around 13.5 billion years ago, a few hundred million years after the Big Bang.<\/p>\n

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JWST will peer back in time to the earliest epoch of the universe. Credit: Space Telescope Science Institute<\/figcaption><\/figure>\n

In the Milky Way Galaxy, the observatory will see into clouds of gas and dust where stars and planets are forming. JWST will determine that chemical make-up of atmospheres of planets around other stars, producing data on which worlds might be habitable.<\/p>\n

Some of the observatory\u2019s scientific targets are among the coldest spots in the known universe, requiring the telescope\u2019s sensors to be even colder to register infrared light coming from faraway stars and galaxies.<\/p>\n

The cryogenic test at Johnson Space Center will occur inside \u201cChamber A,\u201d the largest facility in the world designed to mimic the cold, airless conditions of deep space.<\/p>\n

NASA tested Apollo spacecraft inside Chamber A, a National Historic Landmark, before sending astronauts to the moon.<\/p>\n

Eric Smith, director of the JWST program at NASA Headquarters, said last month that the coming months include \u201ca lot of very challenging activities that are new, and they carry a lot of risk with them.\u201d<\/p>\n

The \u201cserialized\u201d test and assembly steps planned over the next year mean each milestone is vital for JWST to remain on schedule for its October 2018 launch on an Ariane 5 rocket from Kourou, French Guiana.<\/p>\n

Instead of accomplishing parallel work on JWST\u2019s instruments, mirrors, thermal sunshield and spacecraft components, big pieces of the observatory are coming together. Smith told NASA\u2019s Astrophysics Advisory Committee on April 24 that the program is down to two hardware flows now.<\/p>\n

\u201cIf something gets delayed, you don\u2019t have progress you can make with another piece of the schedule,\u201d Smith said. \u201cIt\u2019s all kind of lining up in a row.\u201d<\/p>\n

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A webcam view of the James Webb Space Telescope on Tuesday inside the clean room adjacent to Chamber A at the Johnson Space Center in Houston. The door to the test chamber is seen on the right. The cryogenic test volume measures 55 feet (16.8 meters) in diameter by 90 feet (27.4 meters) tall. Credit: NASA<\/figcaption><\/figure>\n

Since December, technicians at Goddard put the telescope and instrument segment of JWST through vibration and acoustic testing to ensure its sensitive components, such as internal camera micro-shutters, will survive the rough conditions of launch. Engineers halted vibration testing more than a month after ground crews heard an unexpected noise during shake testing on the telescope.<\/p>\n

Smith said the problem was traced to a latching mechanism that did not seat properly before the test. The latch holds one of the telescope\u2019s wings folded up for launch to fit inside the Ariane 5\u2019s payload fairing, then releases once JWST is in space to fully unfurl its 21.3-foot-diameter (6.5-meter) primary mirror.<\/p>\n

Two plates in the latching mechanism clapped together to generate the noise, but Smith said technicians found no sign of damage to the telescope. The problematic latch was a test unit, and was already due to be replaced with a space-qualified latch before the mission\u2019s launch.<\/p>\n

Engineers wrapped up vibration and acoustic tests in March, then spent several weeks re-checking the telescope\u2019s alignment and curvature to make sure it withstood the testing unscathed.<\/p>\n

\u201cBefore and after these environmental tests took place, optical engineers set up an interferometer, the main device used to measure the shape of the Webb telescope\u2019s mirror,\u201d NASA said in a statement. \u201cAn interferometer gets its name from the process of recording and measuring the ripple patterns that result when different beams of light mix and their waves combine or \u2018interfere.’\u201d<\/p>\n

The primary mirror is made of 18 gold-coated beryllium hexagonal mirror segments made by Ball Aerospace. Each segment more than half the size of the mirror on the Hubble Space Telescope.<\/p>\n

The primary mirror segments and JWST\u2019s secondary mirror will adjust their focus with the help of tiny mechanical motors once the telescope is in space.<\/p>\n

\u201cSome people thought it would not be possible to measure beryllium mirrors of this size and complexity in a clean room to these levels but the team was incredibly ingenious in how they performed these measurements and the results give us great confidence we have a fantastic primary mirror,\u201d said Lee Feinberg, Webb\u2019s telescope optical element manager.<\/p>\n

\u201cThe measurements are very stringent for us,\u201d Smith said. \u201cWe have to measure our surface figure within a fraction of (the width of) a bacterium, and keep it clean \u2026 We have to keep the optics clean, which is especially challenging for a telescope that has naked optics.\u201d<\/p>\n

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The James Webb Space Telescope is seen during a \u201clights out\u201d inspection on March 5. The clean room lights were turned off to inspect the telescope after it experienced vibration and acoustic testing. The contamination control engineer used a bright flashlight and special ultraviolet flashlights to inspect for contamination because it\u2019s easier to find in the dark. Credit: NASA\/Chris Gunn<\/figcaption><\/figure>\n

\u201cIt\u2019s pretty exciting to see $4 billion worth of hardware being shaken like that, but it passed the vibration testing,\u201d Smith said.<\/p>\n

The methodical checks of JWST\u2019s optics after vibration testing, and in cryogenic conditions, are aimed at avoiding a repeat of the mirror deformity that plagued the Hubble Space Telescope after its launch in 1990. Space shuttle astronauts had to add corrective vision aids to the orbiting observatory in 1993 to fix the problem.<\/p>\n

No such astronauts visits are planned to JWST, which is not designed to be serviced in space.<\/p>\n

Smith said the observatory program, a partnership between NASA, the European Space Agency and the Canadian Space Agency, has around four-and-three-quarters months of slack in the schedule leading up to the October 2018 launch window.<\/p>\n

The vibration test glitch in December consumed more than a month of schedule margin.<\/p>\n

The super-cold test in Houston will be the last time the telescope experience something like its operating environment until launch. The entire observatory cannot be tested in such a way once the telescope element is connected to the mission\u2019s spacecraft module at Northrop Grumman Corp. in Southern California.<\/p>\n

\u201cWhy do we do these tests? There\u2019s a lot of verification that has to go on, and unlike most NASA missions, we can\u2019t test like we fly,\u201d Smith said. \u201cWe\u2019re just too big. There\u2019s no vacuum chamber big enough in the world.\u201d<\/p>\n

\u201cWe have to do our testing piecemeal, and then use analysis to make sure that it all comes together in the end,\u201d Smith said.<\/p>\n

During the cryogenic test in Houston, which should begin in July, engineers will trace the path light from cosmic targets will take from JWST\u2019s primary mirror, through secondary and tertiary mirrors, and finally to the instrument\u2019s detectors.<\/p>\n

Engineers put models of the telescope into the cryogenic vacuum chamber in Houston over the last few years to practice for the upcoming test.<\/p>\n

The telescope flew from Andrews Air Force Base, Maryland, to Ellington Field near the Johnson Space Center over the weekend aboard a U.S. Air Force C-5 cargo plane.<\/p>\n

During the next few weeks, workers will unpack the telescope from its shipping container and roll it into the cavernous vacuum chamber. It will take around 30 days to chill the chamber to JWST\u2019s operating temperature.<\/p>\n

In the meantime, engineers at Northrop Grumman\u2019s satellite factory in Redondo Beach, California, are putting together the spacecraft that will host the telescope. The platform will provide propulsion, electricity, cooling and pointing for JWST at its operating post at the L2 Lagrange point, a gravitational balance point located around 930,000 miles (1.5 million kilometers) from Earth in the direction opposite the sun.<\/p>\n

JWST\u2019s sunshield, comprising five membrane layers of kapton each as thin as a human hair, is also being attached to the spacecraft in Southern California.<\/p>\n

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JWST\u2019s five-layer thermal sunshield, about the size of a tennis court, will keep the observatory cold enough to detect infrared light. The final kapton layer was delivered to Northrop Grumman from a factory in Huntsville, Alabama, last year. Credit: Northrop Grumman<\/figcaption><\/figure>\n

Spacecraft assembly tasks have also been delayed a few months recently for technicians to re-weld transducers into the propulsion system to replace units damaged during testing.<\/p>\n

Workers will install deployable radiators on the spacecraft and put the platform through an acoustic test in July. The spacecraft\u2019s own cryogenic thermal vacuum test is scheduled for September in Redondo Beach, around the same time the telescope is undergoing its freeze test in Houston.<\/p>\n

The telescope join the other half of JWST in California around November for a final sequence of combined vibration and acoustic tests, making it perhaps the most tested vehicle ever sent into space, according to Smith.<\/p>\n

Another crucial milestone scheduled for early 2018 will be the full deployment of the observatory into its flight configuration. Because of the dimensions of the Ariane 5\u2019s nose cone \u2014 the largest payload shroud currently available \u2014 JWST will launch with its mirrors, sunshield and solar panels folded up origami-style.<\/p>\n

Depending on how you count, Smith said JWST will have more than 300 deployments after it separates from from the upper stage of the Ariane 5 launcher. Counting steps in a similar way, the Curiosity Mars rover had around 70 deployments, according to Smith.<\/p>\n

A complicated apparatus of hoists, cranes and lift fixtures will counteract the effect of gravity during the deployment testing. JWST\u2019s mechanisms are designed to function in microgravity, not the 1g environment on Earth.<\/p>\n

The spacecraft will travel by boat from Southern California through the Panama Canal to the Ariane 5 launch base in Kourou, French Guiana, in mid-2018 for fueling and final launch preparations.<\/p>\n

\u201cWe are still on track budget- and schedule-wise, but we are moving into a very challenging period with enormous tests of very complex hardware,\u201d Smith said.<\/p>\n

The JWST program escaped the danger of being canceled in 2011 as delays mounted and costs skyrocketed. NASA officials re-planned the program\u2019s budget and schedule at that time, committing to launching the mission by October 2018 at a cost of $8.84 billion to the U.S. space agency.<\/p>\n

Adding the contributions of European and Canadian partners, including the Ariane 5 launcher, pushes the mission\u2019s total cost to around $10 billion.<\/p>\n

But any significant problems during the rapid-fire test campaign over the next year could delay the launch date.<\/p>\n

\u201cPeople are naturally going to be very cautious if they see any anomalies,\u201d Smith said.<\/p>\n

Email the author.<\/i><\/b><\/p>\n

Follow Stephen Clark on Twitter: @StephenClark1.<\/strong><\/em><\/p>\n","protected":false},"excerpt":{"rendered":"

The primary mirror of the James Webb Space Telescope pictured at NASA\u2019s Goddard Space Flight Center in Greenbelt, Maryland. Credit: NASA\/Chris Gunn The centerpiece of the James Webb Space Telescope has arrived at NASA\u2019s Johnson Space Center in Houston for a three-month test to ensure the observatory\u2019s sensors and gold-coated mirrors work in the frigid […]<\/p>\n","protected":false},"author":1,"featured_media":0,"comment_status":"","ping_status":"","sticky":false,"template":"","format":"standard","meta":{"_acf_changed":false,"inline_featured_image":false,"footnotes":"","_links_to":"","_links_to_target":""},"categories":[2],"tags":[1540,498,1690,2715,559,1790,1560,302],"class_list":["post-14641","post","type-post","status-publish","format-standard","hentry","category-news","tag-ariane-5","tag-arianespace","tag-astrophysics","tag-big-bang","tag-exoplanets","tag-goddard-space-flight-center","tag-james-webb-space-telescope","tag-johnson-space-center"],"acf":[],"_links":{"self":[{"href":"https:\/\/starpath.global\/blog\/wp-json\/wp\/v2\/posts\/14641"}],"collection":[{"href":"https:\/\/starpath.global\/blog\/wp-json\/wp\/v2\/posts"}],"about":[{"href":"https:\/\/starpath.global\/blog\/wp-json\/wp\/v2\/types\/post"}],"author":[{"embeddable":true,"href":"https:\/\/starpath.global\/blog\/wp-json\/wp\/v2\/users\/1"}],"replies":[{"embeddable":true,"href":"https:\/\/starpath.global\/blog\/wp-json\/wp\/v2\/comments?post=14641"}],"version-history":[{"count":0,"href":"https:\/\/starpath.global\/blog\/wp-json\/wp\/v2\/posts\/14641\/revisions"}],"wp:attachment":[{"href":"https:\/\/starpath.global\/blog\/wp-json\/wp\/v2\/media?parent=14641"}],"wp:term":[{"taxonomy":"category","embeddable":true,"href":"https:\/\/starpath.global\/blog\/wp-json\/wp\/v2\/categories?post=14641"},{"taxonomy":"post_tag","embeddable":true,"href":"https:\/\/starpath.global\/blog\/wp-json\/wp\/v2\/tags?post=14641"}],"curies":[{"name":"wp","href":"https:\/\/api.w.org\/{rel}","templated":true}]}}