{"id":16864,"date":"2014-11-05T22:51:33","date_gmt":"2014-11-05T14:51:33","guid":{"rendered":"https:\/\/wp-productionenv-bjg9h2g2bgg5b8aa.southeastasia-01.azurewebsites.net\/news\/engineers-recommend-changes-to-orion-heat-shield\/"},"modified":"2014-11-05T22:51:33","modified_gmt":"2014-11-05T14:51:33","slug":"engineers-recommend-changes-to-orion-heat-shield","status":"publish","type":"post","link":"https:\/\/starpath.global\/news\/engineers-recommend-changes-to-orion-heat-shield\/","title":{"rendered":"Engineers recommend changes to Orion heat shield"},"content":{"rendered":"
\"The
The Orion crew module for Exploration Flight Test 1 \u2014 set for launch Dec. 4 \u2014 is seen before attachment to its service module. The heat shield is covered in a reflective silver tape that protects it from the extreme cold temperatures of space. Credit: NASA<\/figcaption><\/figure>\n

Lessons learned during preparations leading up to the first orbital test flight of NASA\u2019s Orion spacecraft in December have prompted engineers to recommend changing the design of the crew capsule\u2019s heat shield for future missions to the moon, Mars, or an asteroid, according to Lockheed Martin officials.<\/p>\n

The change centers on how technicians put together the Orion crew module\u2019s heat shield, which protects the capsule during its descent through the atmosphere. The heat shield can endure temperatures of up to 4,000 degrees Fahrenheit, conditions the Orion capsule would see when returning from deep space missions to the moon, asteroids or Mars.<\/p>\n

The heat shield is one of the key components of the crew capsule to be demonstrated on Exploration Flight Test 1, a four-hour orbital mission set for launch Dec. 4 aboard a Delta 4-Heavy rocket.<\/p>\n

Engineers are gearing up to move the Orion spacecraft next week from an assembly building at Kennedy Space Center to the Delta 4 launch pad at Cape Canaveral Air Force Station.<\/p>\n

The Orion heat shield\u2019s titanium skeleton and carbon fiber skin was fabricated by Lockheed Martin \u2014 the craft\u2019s prime contractor \u2014 in Colorado. The skeleton was shipped to Textron Defense Systems in Massachusetts for installation of a fiberglass-phenolic honeycomb structure.<\/p>\n

More than 330,000 individual cells make up the honeycomb, and Textron technicians \u2014 using a special dispensing gun \u2014 filled the cells by hand with a material called Avcoat.<\/p>\n

The Avcoat insulation is supposed to ablate away during the Orion spacecraft\u2019s re-entry, protecting the underlying structure from searing temperatures. The Apollo moon capsule used the same type of manually-applied material for its heat shield, and it worked so well Lockheed Martin and NASA decided to dust off the design.<\/p>\n

Engineers scaled up the heat shield for the Orion crew capsule, which is about four feet wider at its base than the Apollo command module.<\/p>\n

\u201cThat\u2019s what worked for Apollo, and that\u2019s what we\u2019ll work with for this mission,\u201d Bray said, referring to the EFT-1 launch in December.<\/p>\n

But a review of the heat shield on the Orion spacecraft set for launch Dec. 4 revealed the Avcoat was slightly more uneven than expected, according to Jim Bray, crew module director at Lockheed Martin, Orion\u2019s prime contractor.<\/p>\n

\"Textron
Textron technicians apply the Avcoat material by \u201cgunning\u201d the material into each of the 330,000 individual cells of the honeycomb structure. Credit: NASA<\/figcaption><\/figure>\n

A statement from a Lockheed Martin spokesperson said the company is recommending changes to the heat shield\u2019s design that allows for different contraction rates between the Avcoat and the composite heat shield substrate.<\/p>\n

\u201cThis wouldn\u2019t change the heat shield material, but it would change the manufacturing approach, which will resolve thermal contraction\/expansion differences,\u201d the statement said.<\/p>\n

The spokesperson said a final decision on the recommended design change was expected soon. The heat shield modification will not be implemented on the December flight.<\/p>\n

\u201cWhen we fabricated the entire heat shield, we didn\u2019t get the full-up properties that we expected to get with individual gunner variability,\u201d Bray said in a presentation last month at the International Astronautical Congress in Toronto. \u201cBy going to a block architecture, we will be able to get the properties in advance before we adhere it to the substrate of the heat shield.\u201d<\/p>\n

For Orion\u2019s next unmanned test flight set for launch in 2017 \u2014 known as Exploration Mission 1 \u2014 engineers plan to switch from a honeycomb design to a monolithic heat shield, Bray said.<\/p>\n

\u201cOn the heat shield that we\u2019ve got right now, we have a composite substrate, and we attach a honeycomb structure to that,\u201d Bray said. \u201cIt takes us about six months to fill 330,000 holes with individual gunners.\u201d<\/p>\n

It turns out the Avcoat applied by hand did not meet expectations, Bray said.<\/p>\n

\u201cThere was variability between gunners, and we haven\u2019t determined the root cause of that yet,\u201d Bray said. \u201cThe heat shield is good for this mission. There\u2019s no question about that. It has credentials to fly, but we really need it to better for the missions farther out for the higher-speed returns, so the question that we had to deal with was how can we prove the material to make sure we know what we\u2019re getting before you finish the heat shield.<\/p>\n

\u201cWe have decided to move to a block architecture where we can gun the blocks in advance,\u201d Bray said.<\/p>\n

After adding the Avcoat ablator, Textron engineers examined each cell under X-ray and a robot sanded off fractions of an inch of the material to meet specifications, according to a NASA website describing the heat shield.<\/p>\n

\u201cBy going to a block architecture, we will be able to get the properties (of the Avcoat) in advance before we adhere it to the substrate of the heat shield,\u201d Bray said.<\/p>\n

Textron will remain Lockheed Martin\u2019s heat shield subcontractor for the Orion program, according to Bray. Data collected on the thermal insulator\u2019s performance on the EFT-1 mission Dec. 4 will still be useful even though future Orion missions will fly with a modified heat shield, he said.<\/p>\n

\u201cIt\u2019s still Avcoat, so what we will test on the first mission and with the second mission is the difference in the rescission rate,\u201d Bray said. \u201cIt\u2019s an ablative material. We expect it to ablate. Whether it ablates the same as a block or a little bit different than the honeycomb \u2014 you might expect minor variations, but you wouldn\u2019t expect major variations.\u201d<\/p>\n

The sides of the Orion crew module are covered with black tiles borrowed from the space shuttle. They are rated to withstand temperatures greater than 3,000 degrees Fahrenheit, but the Avcoat will take the brunt of the heat during the capsule\u2019s fall back to Earth.<\/p>\n

Lockheed Martin proposed the EFT-1 mission to NASA as a risk reduction flight for the agency\u2019s next-generation crew vehicle, which is designed to fly to destinations in deep space.<\/p>\n

Piloted missions \u2014 and the next unmanned flight in 2017 \u2014 will blast off on the Space Launch System, an enormous rocket NASA is developing to launch crews and massive cargo loads farther than low Earth orbit, where space shuttle missions went and the International Space Station flies today.<\/p>\n

Orion\u2019s first space mission \u2014 riding a Delta 4 rocket\u2019s upper stage \u2014 will reach a peak altitude of 3,600 miles and dive back into Earth\u2019s atmosphere at about 20,000 mph, just shy of the speed the capsule would reach when returning from the moon.<\/p>\n

Officials bill the mission as an opportunity to test the performance of the heat shield during the high-speed re-entry, which will be faster than space shuttles encountered at the end of their missions.<\/p>\n

\u201cWe\u2019re interested in seeing the performance of the heat shield,\u201d Bray said. \u201cWe have arc jet test facilities where we test the heat shield for the thermal environments, but we can\u2019t do it at the same time as we do thermal and pressure, and it\u2019s really one of the most critical systems that we\u2019ve got.<\/p>\n

\u201cIt\u2019s about 80 percent the velocity of what we\u2019ll have on the other missions, but we\u2019ll get a pretty good test of its maximum capability with temperature and pressure,\u201d Bray said. \u201cWe can\u2019t quite get that using modeling on the ground.\u201d<\/p>\n

Computers, guidance systems, software, and the Orion spacecraft\u2019s launcher adapter and separation systems will also be put to the test on the Dec. 4 mission.<\/p>\n

\u201cThis mission is a compelling mission in that we have 16 events you can\u2019t fully test as an integrated system on the ground,\u201d Bray said. \u201cWe\u2019ll use this test flight to verify 10 of those system major events.\u201d<\/p>\n

NASA and Lockheed Martin will incorporate results from the EFT-1 mission into a critical design review planned next year, when officials will decide whether the program is ready to proceed into the final stage of development.<\/p>\n

\u201cEFT-1\u2019s purpose was to leverage the lessons learned from actually building the spacecraft, and we are implementing that already into the design for the EM-1 spacecraft (set to fly in 2017),\u201d Bray said.<\/p>\n

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

The Orion crew module for Exploration Flight Test 1 \u2014 set for launch Dec. 4 \u2014 is seen before attachment to its service module. The heat shield is covered in a reflective silver tape that protects it from the extreme cold temperatures of space. Credit: NASA Lessons learned during preparations leading up to the first […]<\/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":[3688,640],"class_list":["post-16864","post","type-post","status-publish","format-standard","hentry","category-news","tag-eft-1","tag-orion"],"acf":[],"_links":{"self":[{"href":"https:\/\/starpath.global\/blog\/wp-json\/wp\/v2\/posts\/16864"}],"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=16864"}],"version-history":[{"count":0,"href":"https:\/\/starpath.global\/blog\/wp-json\/wp\/v2\/posts\/16864\/revisions"}],"wp:attachment":[{"href":"https:\/\/starpath.global\/blog\/wp-json\/wp\/v2\/media?parent=16864"}],"wp:term":[{"taxonomy":"category","embeddable":true,"href":"https:\/\/starpath.global\/blog\/wp-json\/wp\/v2\/categories?post=16864"},{"taxonomy":"post_tag","embeddable":true,"href":"https:\/\/starpath.global\/blog\/wp-json\/wp\/v2\/tags?post=16864"}],"curies":[{"name":"wp","href":"https:\/\/api.w.org\/{rel}","templated":true}]}}