Orion service module passes major shake test at NASA’s Plum Brook Station
SANDUSKY, Ohio — Testing on the European-built Orion service module is continuing at NASA’s Plum Brook Station facility in Sandusky, Ohio. The service module test article, provided by the European Space Agency (ESA) and built by Airbus Defence and Space, arrived at Plum Brook Station late last fall (2015) and began its battery of tests in the spring.
The first round of evaluations was conducted at Plum Brook’s acoustic test chamber, which subjected the test article to a tremendous bombardment of sound pressure, simulating the deafening acoustics of its planned launch atop the Space Launch System (SLS) super-heavy-lift rocket.
At the beginning of summer, the test article was moved out of the acoustic chamber and bolted atop the Mechanical Vibration Facility (MVF), a table operated by a series of hydraulic actuators. It has been dubbed the most powerful machine of its kind in the world. It simulates the violent vibrations the spacecraft will experience during SLS’s launch and ascent.
Engineers and technicians at Plum Brook conducted a long campaign of MVF tests on the service module throughout the summer, shaking it in the horizontal and vertical axes, with the service module’s tanks both fully and partially loaded.
“We look at how the structure is holding up to the vibe test with the liquid sloshing around in there,” Plum Brook Station’s Orion Testing Project Manager, Nicole Smith, told SpaceFlight Insider, “and the answer to that is that it is holding up great.”
For safety purposes, the testing engineers do not use real fuel in the tanks for the trial runs.
“We are using deionized water as one simulant, and an organic fluid called HFE-7100, which is non-toxic and non-flammable,” Smith said. “To be able to run hydrazine during a test you have to have serious flammability protection in the facility and it’s very dangerous. So we pick fluids that are organic and safe and have a pretty good density and viscosity simulation with the real fuel that would be in there.”
The tests on the Orion service module are the first done by the newly-installed MVF, which was part of a $130 million upgrade to the Space Power Facility at Plum Brook. The upgrades also included enhancements to the Reverberant Acoustic Test Facility (RATF).
The RATF and the MVF added to the Space Power Facility’s central structure, the 100-foot (30-meter) wide by 122-foot (37-meter) tall giant Thermal Vacuum Chamber, make the facility a trifecta of launch stress and space environment simulations. This is something that NASA will utilize to test Orion and other flight systems as the agency pursues its Journey to Mars.
“Everything from the facility side to the test hardware side has really been working well,” Space Power Facility Manager, Jerry Carek, told SpaceFlight Insider. “So we are very pleased with the type of data that we’ve been pulling in. And we have great information to do that analysis and evaluation of the structure.”
The MVF subjects the spacecraft to a simulation of the vibrations it could possibly experience during the launch and ascent stages of the mission. However, the tests themselves may not look exactly how the general public imagines them to be.
“You can feel it,” Carek said, “and at the lower frequencies, you can see it. It will move about an inch up and down or side to side. You might imagine something being violently whipped around left and right and up and down, but it doesn’t look like that.”
With the vibration evaluations now completed, engineers will unbolt the service module from the MVF and move it into the facility’s Assembly High Bay for a set of pyroshock tests. Pyroshocks are explosive bolts that function as a release mechanism.
“We have two different pyroshock tests that will happen the first week of November,” Smith said. “We fire the pyros for the fairing-separation mechanism, and then we fire the pyros on the spacecraft adapter separation mechanism. Those are two separate tests about a week apart.”
Sometime around Nov. 30, engineers will conduct a second solar array deployment test on the service module. An initial solar array deployment was performed in the spring. This second test will demonstrate if it will deploy after going through the simulated effects of launch and ascent.
“The idea is that now that we’ve beaten the heck out of this thing, so to speak, by shaking it and hitting it with sound pressure,” Carek said, “we want to make sure the solar arrays still deploy. That’s one of the primary verifications.”
So far the testing has all gone according to schedule and there have been no surprises. Following its testing at Plum Brook, the service module article will be transported to Kennedy Space Center (KSC) to be integrated with a test version of the Orion crew capsule. The capsule and service module will then go to the Lockheed Martin facility in Denver for further evaluation.
Exploration Mission 1 (EM-1) flight hardware will arrive at Plum Brook late next year. The service module and the crew capsule will arrive fully integrated. Evaluation of hardware will continue into 2018 and will include testing in the giant thermal vacuum chamber.
Smith said flight hardware testing should take about five months. Following those tests, the spacecraft will be flown down to KSC for integration and assembly with the launch vehicle in preparation for EM-1.
Michael Cole is a life-long space flight enthusiast and author of some 36 educational books on space flight and astronomy for Enslow Publishers. He lives in Findlay, Ohio, not far from Neil Armstrong’s birthplace of Wapakoneta. His interest in space, and his background in journalism and public relations suit him for his focus on research and development activities at NASA Glenn Research Center, and its Plum Brook Station testing facility, both in northeastern Ohio. Cole reached out to SpaceFlight Insider and asked to join SFI as the first member of the organization’s “Team Glenn.”