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\u201cWe\u2019re trying to correlate the models of the hardware thermally and also thermally stress the vehicle in both the cold and the hot cases, within the limits of what a facility can do. With the EMI\/EMC testing, we\u2019re going to provide an RF (Radio Frequency)-quiet environment so that we can test the intra-system compatibility and then we\u2019ll also provide an RF environment and a reverberant environment to be able to test external sources, RF sources.\u201d<\/p>\n
The spacecraft will be oriented vertically in the large vacuum chamber on a stand, surrounded by thermal conditioning equipment. \u201cThe chamber itself is about a hundred and twenty feet tall and a hundred feet in diameter,\u201d Smith noted. \u201cInside of that chamber we have a cryo (cryogenic) shroud that provides the cold background of space. We can take that down to about minus two-hundred fifty [degrees] Fahrenheit but for this test I think we\u2019ll be at about minus a hundred Fahrenheit, so we\u2019ll just maintain that constant background.\u201d<\/p>\n
![\"\"](\"https:\/\/www.nasaspaceflight.com\/wp-content\/uploads\/2019\/05\/vlcsnap-2019-05-19-1401-04-16-11h04m48s863.png\")
<\/p>\nCredit: NASA\/Glenn Research Center.<\/p>\n
(Photo Caption: Animation showing the EM-1 Orion spacecraft moving into the vacuum chamber at Plum Brook. To the right, the cryo shroud is shown open to move Orion inside. The shroud helps simulate in-space thermal conditions within the vacuum chamber.)<\/em><\/p>\n
\u201cThe cryo shroud kind of looks like a canister, forty feet in diameter and forty feet tall and then it also has a ceiling and a floor and both the ceiling and the floor are also cold walls,\u201d she explained. \u201cSo when you see the animation or pictures you\u2019ll see the spacecraft looks like it\u2019s sitting on a big floor which is the cryo floor and there\u2019s a number of different things that are kind of stacked up on it, various types of GSE (Ground Support Equipment) like the cone spacer stand that it sits on.\u201d<\/p>\n
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\u201cAlso on that floor but directly around the vehicle is the heat flux system, so that\u2019s what gives us the ability to provide the heating of being in the Sun,\u201d she added. \u201cWe can turn the heat flux system on or off depending on what part of the thermal cycle that we\u2019re in, that we\u2019re trying to simulate.\u201d<\/p>\n
\u201cWe also have a lot of other heaters, we have aft heater plates that are underneath the vehicle,\u201d Smith noted. \u201cOn that heat flux system that is all around really the Crew Module and then underneath of that are the baffle plates. On the underside of the baffles is where we have the baffle heaters.\u201d<\/p>\n
\u201cAnd then we have a lot of others in the chamber which are really support stuff, because we\u2019re trying to prevent large thermal masses from altering what the vehicle is seeing and making it a test condition versus a flight, more-realistic condition,\u201d she said. \u201cSo we have all of these cables that go to the vehicle for EGSE (Electrical Ground Support Equipment), like at the T-0 panel; we don\u2019t want those cables to get super cold and create a thermal sink basically, so we do put heaters on those to kind of bring them up to a temperature that is not going to cause a test-specific effect to what the spacecraft is seeing.\u201d<\/p>\n
![\"\"](\"https:\/\/www.nasaspaceflight.com\/wp-content\/uploads\/2019\/05\/Installation-nozzle-ESM.jpg\")
<\/p>\nCredit: NASA.<\/p>\n
(Photo Caption: Orion team members at Kennedy Space Center in front of the EM-1 Service Module in April after installation of the nozzle on the OMS-E main engine. Additional hardware is currently installed for testing at KSC, but this is closer to the configuration of the Service Module for the testing that will be performed at Plum Brook later this year.)<\/em><\/p>\n
To better simulate the space environment where most of Orion\u2019s mission will occur, the pressure in the chamber will be reduced to almost zero. \u201c[For] the inner chamber we pump down to about three times ten to the minus six (3 \u00d7 10-6) Torr for that,\u201d Smith explained. \u201cIt\u2019s 5.8 times ten to the minus 8 (5.8 \u00d7 10-8) psi, so it\u2019s a lot of zeros. Usually when I talk to kids I count on my fingers all the zeros that has.\u201d<\/p>\n
After reconfiguring the chamber, it will also be used for EMI\/EMC testing. \u201cThe spacecraft will actually be in the thermal vac chamber but the chamber is configured a little differently,\u201d Smith noted. \u201cThat heat flux system cage goes away, we\u2019ll take that off and we\u2019ll have the cryo shroud open and we\u2019ll put the spacecraft actually on the cryo floor but without the cryo floor being active, back in the chamber.\u201d<\/p>\n
Long thermal vacuum test<\/p>\n
The spacecraft will be run through different thermal profiles while the chamber remains at vacuum. \u201cIt\u2019s going to be one continuous pump down, so we\u2019re looking at the chamber pumped down for about sixty-five days, so it will be one, continuous test,\u201d Smith said.<\/p>\n
The vehicle will be in an in-space configuration; the mated Crew and Service Modules won\u2019t have any of the launch system fairings or adapters attached. The nozzle for the main OMS-E engine will be attached, but the Orion will be missing its solar array wings.<\/p>\n
\u201cThere\u2019s an emulator for it, [the acronym] stands for \u2018front-end emulator,’\u201d Smith noted. \u201cIt emulates what the solar array wing would actually do. \u201cWhile it\u2019s in the chamber as part of the testing I do know that they\u2019re going to actually rotate the solar array drive mechanisms, so I know they\u2019re going to do that kind of what I call first motion because that usually refers to unfurling a solar array but actually it checks out that it\u2019ll work in the environment.\u201d<\/p>\n
![\"\"](\"https:\/\/www.nasaspaceflight.com\/wp-content\/uploads\/2019\/05\/vlcsnap-2019-05-19-2368-11-10-02h59m24s354.png\")
<\/p>\nAnimation depicting the tail-to-Sun attitude that Orion will be in during most of its mission. Credit: NASA.<\/p>\n
Smith provided an overview of the thermal vacuum testing timeline. \u201cThe first thing that we\u2019ll do is the thermal balance, so we will do a couple of different points in the thermal balance \u2014 that\u2019s really the part that correlates the model,\u201d she said. \u201cSo we\u2019re going to anchor the thermal model by doing that and that\u2019s really the nominal tail-to-Sun condition.\u201d<\/p>\n
While flying on its own, Orion will spend most of its time in a tail-to-Sun attitude, such as during transit to and from the Moon and in different lunar or cislunar orbits.<\/p>\n
\u201cSo we have the thermal balance, we do a first, short cold stress from there which is really in an eclipse case, and then we do a hot stress and then we go back down to a cold [test case], and then a hot, and then we come back to ambient and end the test,\u201d she explained. \u201cDuring that time that we are providing that sort of an environment to the vehicle, the vehicle is going to be doing a number of different things functionally.\u201d<\/p>\n
![\"\"](\"https:\/\/www.nasaspaceflight.com\/wp-content\/uploads\/2018\/10\/L2-banner@2x.jpg\")
\u201cIt\u2019ll be powered up, they\u2019ll be powering on and off some of the hardware, they\u2019ll be checking out things like prop valves, the avionics are going to be on, they\u2019re going to be turning heaters on and off,\u201d she added. \u201cDuring the thermal balance, they\u2019ll actually depress the crew cabin and it\u2019ll stay depressed all the way until the second cold cycle and then we\u2019ll repress the cabin.\u201d<\/p>\n\u201cWe\u2019re going to do that so we can see the cabin depress during the extreme [thermal] stress conditions so they can check that out.\u201d<\/p>\n
\u201cWe\u2019ve got a little initial functional tests that we\u2019ll do and then we\u2019ll drop the temperature and then through the thermal balance that\u2019s about roughly the first twenty days or so,\u201d Smith said. \u201cThen the cold soak is going to be another five days and then while we raise the temperature to the hot stress and you\u2019re probably looking at another five to seven days for just raising the temperature.\u201d<\/p>\n
![\"\"](\"https:\/\/www.nasaspaceflight.com\/wp-content\/uploads\/2019\/05\/47023545684_965e519e2d_k.jpg\")
<\/p>\nCredit: NASA\/Rad Sinyak.<\/p>\n
(Photo Caption: Lines running to the Orion Service Module Umbilical are carried along with the EM-1 Service Module as it was moved down the aisle in the O&C Building at KSC in late April. EGSE will also be hooked to the Orion during testing at Plum Brook, in part substituting for the solar array wings that won\u2019t be installed.)<\/em><\/p>\n
\u201cAnd then we\u2019ll sit at the hot stress temperature for probably five to six days, drop the temperature again and sit at the second cold stress for another five to six days. Usually for the stress periods we usually hang out there for five days-ish, somewhere in that time-frame.\u201d<\/p>\n
A lot of other EGSE is also connected for the tests at Plum Brook. \u201cThere\u2019s quite a bit of EGSE that comes along with the spacecraft that we have a whole room dedicated to,\u201d Smith said. \u201cWe do have test specific lines that go to the vehicle, one of them is R134a coolant, ground cooling that goes to the vehicle that we use for the beginning part of the test and then we turn it off, and then we have the CM (Crew Module) depress lines that I was telling you about, and there is a lot of EGSE that is supporting the vehicle that is test-specific that does go through the chamber to the vehicle that you wouldn\u2019t necessarily see during [flight].\u201d<\/p>\n
The cryo shroud and heat flux system produce the desired test conditions during each phase of the vacuum testing. \u201cSo for example the tail to Sun, we have aft heater plates and then we have heaters that are on what are called baffle plates that are up around the Crew Module Adapter and so during the tail to Sun we\u2019ll have the cold background with the cryo shroud but we\u2019ll have those two sets of heaters on, so basically heating the aft side of all that\u2019s going to be exposed to the vehicle,\u201d Smith explained.<\/p>\n
\u201cWith the hot stress that I was talking about we have [the] heat flux system which are basically calrods or wall rods that go all the way around the Crew Module, so all that will be on. We\u2019re really testing for the stress situations, cold shock and hot stress.\u201d<\/p>\n
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NASA\u2019s Plum Brook Station in Sandusky, Ohio, is finishing preparations for pre-flight testing of the Orion spacecraft assigned to Exploration Mission-1 (EM-1). The Space Environments Complex of the Glenn Research Center test facility will be used to put the in-space configuration of Orion through thermal vacuum and electromagnetic testing that should take a few months. […]<\/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":[3718,640,8923],"class_list":["post-38031","post","type-post","status-publish","format-standard","hentry","category-news","tag-em-1","tag-orion","tag-plum-brook"],"acf":[],"_links":{"self":[{"href":"https:\/\/starpath.global\/blog\/wp-json\/wp\/v2\/posts\/38031"}],"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=38031"}],"version-history":[{"count":0,"href":"https:\/\/starpath.global\/blog\/wp-json\/wp\/v2\/posts\/38031\/revisions"}],"wp:attachment":[{"href":"https:\/\/starpath.global\/blog\/wp-json\/wp\/v2\/media?parent=38031"}],"wp:term":[{"taxonomy":"category","embeddable":true,"href":"https:\/\/starpath.global\/blog\/wp-json\/wp\/v2\/categories?post=38031"},{"taxonomy":"post_tag","embeddable":true,"href":"https:\/\/starpath.global\/blog\/wp-json\/wp\/v2\/tags?post=38031"}],"curies":[{"name":"wp","href":"https:\/\/api.w.org\/{rel}","templated":true}]}}