{"id":12974,"date":"2019-08-29T20:29:31","date_gmt":"2019-08-29T12:29:31","guid":{"rendered":"https:\/\/wp-productionenv-bjg9h2g2bgg5b8aa.southeastasia-01.azurewebsites.net\/news\/james-webb-space-telescope-fully-assembled-in-california\/"},"modified":"2019-08-29T20:29:31","modified_gmt":"2019-08-29T12:29:31","slug":"james-webb-space-telescope-fully-assembled-in-california","status":"publish","type":"post","link":"https:\/\/starpath.global\/news\/james-webb-space-telescope-fully-assembled-in-california\/","title":{"rendered":"James Webb Space Telescope fully assembled in California"},"content":{"rendered":"
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Teams have connected James Webb Space Telescope\u2019s science and spacecraft segments for the first time. Credit: NASA\/Chris Gunn<\/figcaption><\/figure>\n

Teams working in Northrop Grumman\u2019s spacecraft factory in Southern California have connected the spacecraft and science modules of the James Webb Space Telescope for the first time, a major milestone as engineers prepare to verify a fix to tears in the observatory\u2019s sunshield, and begin launch vibration and acoustic testing in the coming months.<\/p>\n

Technicians at Northrop Grumman\u2019s facility in Redondo Beach, California, mated JWST\u2019s telescope with its spacecraft bus Aug. 23. Since then, workers have been finalizing mechanical and electrical connections between the two main elements of the observatory, the most capable space telescope ever built.<\/p>\n

\u201cThis is a huge milestone for us,\u201d said Eric Smith, JWST\u2019s program scientist at NASA Headquarters in Washington. \u201cThis is a program that was first kind of in people\u2019s minds about 30 years ago. Some of  the initial contracts went out in 2001 and 2002, and to see it in that clean room now is breathtaking. A lot of people have waited a long time for this. It\u2019s wonderful to see.\u201d<\/p>\n

Set for launch from French Guiana aboard a European Ariane 5 rocket in March 2021, the James Webb Space Telescope will cost more than $10 billion by the time its mission is complete, including contributions from NASA, the European Space Agency and the Canadian Space Agency.<\/p>\n

NASA is bearing the bulk of the cost at around $9.7 billion. ESA is providing instrument hardware and a launch vehicle for Webb, and Canada built the fine guidance sensor and a spectrograph for the observatory.<\/p>\n

\u201cThis is an exciting time to now see all Webb\u2019s parts finally joined together into a single observatory for the very first time,\u201d said Gregory Robinson, the Webb program director at NASA Headquarters. \u201cThe engineering team has accomplished a huge step forward and soon we will be able to see incredible new views of our amazing universe.\u201d<\/p>\n

Webb\u2019s spacecraft and science modules have been individually tested at various steps of assembly over the past decade. Now it\u2019s time to test the entire observatory in one piece.<\/p>\n

A crane lifted Webb\u2019s telescope element over the spacecraft bus and sunshield, and carefully lowered it into place. There are six mechanical attach points between the science module, which includes Webb\u2019s telescope and science instruments, and the spacecraft bus, plus around a dozen wiring harnesses, each routing numerous data and electrical cables, Smith said<\/p>\n

Once teams complete the connections, they will unfurl the observatory\u2019s tennis court-sized sunshield, a thermal barrier designed to keep Webb\u2019s sensitive infrared detectors cold.<\/p>\n

Made of five Kapton membranes, each as thin as a human hair, the sunshield is designed to deploy to its open configuration once Webb is in space. The membranes are coated with aluminum and treated silicon to reflect heat away from the observatory, keeping Webb\u2019s instruments as cold as minus 370 degrees Fahrenheit, or minus 223 degrees Celsius. Internal coolers will chill some of the telescopes\u2019s sensors even colder.<\/p>\n

Engineers found seven tears on the sunshield membranes during a previous deployment test, and a tensioning system used to hold the membrane into its shape developed too much slack during the test, creating a snagging hazard, NASA said.<\/p>\n

Since discovering and repairing the sunshield tears, ground teams put the spacecraft element, which holds the sunshield, through a series of vibration, acoustic and thermal vacuum tests to expose the hardware to the shaky, noisy, cold, airless environments it encounter during launch and in space.<\/p>\n

\u201cThey will now deploy the sunshield to make sure that it behaves as expected after going through the launch (environments),\u201d Smith said Wednesday. \u201cThey\u2019ll release all the membrane devices and push out the booms for the sunshield, and tension up the membranes.<\/p>\n

\u201cThat\u2019s one of the things they certainly will be looking for, is having gone through the environments, what\u2019s the shape of the sunshield coming out of those?\u201d Smith said. \u201cWere the procedures that they put in place to correct some of the things that caused some tears last time, did they work as planned? That\u2019s very much a part of this deployment test.<\/p>\n

\u201cThey also needed to make some adjustments to the so-called membrane tensioning system, the system of pulleys that actually tighten up the sunshield,\u201d Smith said in an interview with Spaceflight Now. \u201cSo they made those adjustments, and we\u2019ll be seeing did that do what we needed it to do as well.\u201d<\/p>\n

The test crew at Northrop Grumman will also deploy other structures on the telescope, then put the entire observatory through electrical, vibration and acoustic tests. After those checks are complete, technicians will unfurl the full observatory once more to make sure all the mechanisms survived the launch environment testing.<\/p>\n

Then technicians will stow the observatory into launch configuration.<\/p>\n

The observatory folds up origami-style to fit under the Ariane 5 rocket\u2019s payload shroud. Depending on how you count, Webb 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 NASA.<\/p>\n

Named for James Webb, the NASA administrator from 1961 through 1968, the new observatory will be stationed nearly a million miles (1.5 million kilometers) from Earth, using a 21.3-foot (6.5-meter) mirror and four science instruments to peer into the distant universe, studying the turbulent aftermath of the Big Bang, the formation of galaxies and the environments of planets around other stars.<\/p>\n

\"\"
Teams have connected James Webb Space Telescope\u2019s science and spacecraft segments for the first time. Credit: NASA\/Chris Gunn<\/figcaption><\/figure>\n

Smith said NASA has around three months of margin in Webb\u2019s schedule before the mission\u2019s target launch date of March 30, 2021. That extra time could be used to resolve issues that crop up during the remaining ground tests.<\/p>\n

\u201cYou test this hardware on the ground because if there are issues, you want to find them so you can correct them before you send it up to orbit,\u201d Smith said. \u201cA program as large as Webb has a very extensive testing program, and it\u2019s something we have to go through.<\/p>\n

\u201cThe number of first-time activities \u2014 those things that we\u2019ve never done before, and hence maybe we don\u2019t understand as (fully) as something we\u2019ve already done before \u2014 those numbers are getting small now,\u201d he said. \u201cMost of this hardware has been exercised. The vibe (vibration) and acoustics test as one unit, yeah, that\u2019s a first-time activity because we\u2019ve never had it together before. But it\u2019s something we\u2019ll have to do, and that\u2019s why we have schedule margin built in to fix things that go awry, if they do, during testing.\u201d<\/p>\n

NASA last year acknowledged Webb would not be ready for its previous target launch date in 2019. That launch delay came after an announcement in 2017 that the mission would not launch in 2018, as previously scheduled.<\/p>\n

The launch delay to 2021 came with an extra cost of nearly $1 billion. It was just the latest in a series of budget-busting schedule slips in the program\u2019s tortured history.<\/p>\n

An independent review board blamed the the most recent delay and cost growth primarily on mistakes by Webb\u2019s manufacturing and test team at Northrop Grumman. The panel also said NASA was being too optimistic in its schedule predictions.<\/p>\n

NASA says engineers have replaced a catalyst bed heater and valves in Webb\u2019s propulsion system damaged by human error.<\/p>\n

Workers improperly installed fasteners on Webb\u2019s sunshield before an acoustic test, and a number of screws, washers and nuts came loose during the spacecraft\u2019s acoustic test. After initially failing to account for all of the fasteners \u2014 raising concerns some of it fell into the spacecraft \u2014 teams have now found all of the hardware, Smith said.<\/p>\n

Read more details on the issues that caused Webb\u2019s launch delay to 2021.<\/p>\n

Engineers have identified a couple of other problems on the spacecraft bus that require attention, Smith said.<\/p>\n

\u201cWhen we came out of environmental testing on the spacecraft, there were two electronic components that did not work as planned,\u201d he said. \u201cOne was a component of a communications system. It\u2019s an amplifier. We have redundant amplifiers, but one of them didn\u2019t work as planned.<\/p>\n

\u201cAnd some boards on one of the command and telemetry processors that (were also behaving in a way that wasn\u2019t expected,\u201d he said. \u201cSo we\u2019re buying new amplifiers \u2026 and we are taking engineering units of the command and telemetry processors that we already have and sort of upgrading those for flight.\u201d<\/p>\n

Workers will replace the amplifier and command and telemetry processor after the sunshield deployment test.<\/p>\n

\u201cAt the same time we\u2019re replacing this amplifier, we will replace one of these command and telemetry processors,\u201d Smith said. \u201cThis is a redundant system, so we\u2019re just replacing one of them.\u201d<\/p>\n

\u201cThe spacecraft has all of its electronics and avionics on the side panels of it, so there is a period now where we have to basically (lay) one of those panels flat to replace these two things,\u201d Smith said. \u201cSo we had to use up some schedule margin to accommodate that change, but that\u2019s factored in, and we still have margin to launch.\u201d<\/p>\n

Officials from ESA and Arianespace have also agreed to modify the design of vents on the Ariane 5 rocket\u2019s payload shroud to address a concern that a depressurization event could damage the Webb observatory when the fairing jettisons after liftoff.<\/p>\n

The clamshell-like fairing will protect Webb as the Ariane 5 rockets through the dense lower layers of the atmosphere. Once above the discernible atmosphere, the fairing will release to shed weight as the Ariane 5 climbs into space.<\/p>\n

Engineers were concerned residual air trapped in Webb\u2019s folded sunshield membranes could cause an \u201cover-stress condition\u201d at the time of fairing separation.<\/p>\n

Smith said NASA provide Arianespace, the Ariane 5\u2019s launch operator, with high-fidelity sensors to fly on two Ariane 5 missions and measure the pressure inside the fairing during the shroud separation sequence.<\/p>\n

\u201cThey show that there is an issue with depressurization, meaning that there would be enough residual pressure that it could threaten some of our hardware,\u201d Smith said. \u201cSo they have agreed that to resolve this, what they\u2019re going to do is install some additional hardware on their vents. These shrouds have vents around the base of them, and we believe the issue was that while they open on the way up, just because they\u2019re vibrating around, they may not stay full open the whole way.<\/p>\n

\u201cSo ESA and Ariane are working on a design that will essentially keep these vents open once they open up, and all the calculations show that that should make the pressure fall below where we need it to for our payload,\u201d Smith said. \u201cSo that story is coming to a good resolution.\u201d<\/p>\n

The new hardware to keep the fairing vents latched open will fly on an Ariane 5 mission before Webb to verify the change works.<\/p>\n

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

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

Teams have connected James Webb Space Telescope\u2019s science and spacecraft segments for the first time. Credit: NASA\/Chris Gunn Teams working in Northrop Grumman\u2019s spacecraft factory in Southern California have connected the spacecraft and science modules of the James Webb Space Telescope for the first time, a major milestone as engineers prepare to verify a fix […]<\/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":[1540,498,1690,880,2540,831,1560,190],"class_list":["post-12974","post","type-post","status-publish","format-standard","hentry","category-news","tag-ariane-5","tag-arianespace","tag-astrophysics","tag-canadian-space-agency","tag-eric-smith","tag-european-space-agency","tag-james-webb-space-telescope","tag-nasa"],"acf":[],"_links":{"self":[{"href":"https:\/\/starpath.global\/blog\/wp-json\/wp\/v2\/posts\/12974"}],"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=12974"}],"version-history":[{"count":0,"href":"https:\/\/starpath.global\/blog\/wp-json\/wp\/v2\/posts\/12974\/revisions"}],"wp:attachment":[{"href":"https:\/\/starpath.global\/blog\/wp-json\/wp\/v2\/media?parent=12974"}],"wp:term":[{"taxonomy":"category","embeddable":true,"href":"https:\/\/starpath.global\/blog\/wp-json\/wp\/v2\/categories?post=12974"},{"taxonomy":"post_tag","embeddable":true,"href":"https:\/\/starpath.global\/blog\/wp-json\/wp\/v2\/tags?post=12974"}],"curies":[{"name":"wp","href":"https:\/\/api.w.org\/{rel}","templated":true}]}}