March 17, 2015 – The heat shield for NASA’s Orion spacecraft that successfully survived a high-velocity re-entry during its December 2014 flight test, has completed another overland trek from NASA’s Kennedy Space Center in Florida to the agency’s Marshall Space Flight Center in Huntsville, Alabama. The heat shield arrived March 9 at Marshall, where engineers from the center and the agency’s Ames Research Center in California will extract samples of the ablative material on the heat shield, called Avcoat.
The samples will be used to help measure the char layers and degree of erosion or ablation. Engineers will also extract the various instruments in the heat shield to assess their performance. The collected data will be analyzed to determine whether any improvements need to be made to the heat shield before Orion begins carrying astronauts to deep space destinations.
The heat shield was sent to Marshall because it has machinery and fixtures that can accommodate the heat shield. NASA’s Space Launch System (SLS) rocket is managed at Marshall, so the North Alabama team is accustomed to working with large structures.
“Marshall was asked to aid in this effort because of our experience in dealing with large structures and fixtures that can accommodate a 13-foot in diameter heat shield,” said Larry Gagliano, Marshall’s deputy project manager for the Orion Launch Abort System. “The support fixture can rotate in a vertical or horizontal position to allow for core sample removal and close up imaging of the heat shield.”
After the analysis is complete, the heat shield will be loaded into the 7-axis milling and machining center, for removal of the remaining Avcoat material and then will be shipped to NASA’s Langley Research Center in Hampton, Virginia, for water impact testing.
Heat Shield Technology
The heat shield consist of a fiberglass-phenolic honeycomb structure that fits over Orion’s titanium skeleton and carbon-fiber skin. Each of the 320,000 cells is filled with an ablative material that provides some insulation and consumes heat energy by chemical decomposition and gas release.
“Our team put a lot of hard work into Orion’s first test flight and it’s exciting to see how well the heat shield performed,” said Terry Abel, project manager at Lockheed Martin in Huntsville. “We look at this task as a large part of Orion’s success – the heat shield has to perform well and it’s our job to see if we can improve upon Orion’s first flight.”
Orion’s heat shield experienced much higher heating levels and temperatures than that of the space shuttle tile systems. The heating was higher because Orion returned from a farther distance than the space shuttle ever experienced, resulting in a faster and hotter re-entry.
For the first test flight of Orion, the Avcoat surface reached temperatures of about 4,000 degrees Fahrenheit. Instrumentation in the Avcoat and back shell tiles measured the rise of the surface and internal temperatures during re-entry as well as heating levels and pressures. Additional instrumentation in the Avcoat recorded how the surface recedes as it consumes heat energy.
Avcoat is designed to burn away, or ablate, as the material heats up, rather than transfer the heat back into the crew module. At its thickest, the heat shield is 1.6 inches thick. Roughly 20 percent of the Avcoat eroded as Orion traveled through Earth’s atmosphere.
In the future, Orion will launch on NASA’s new heavy-lift rocket, the Space Launch System. More powerful than any rocket ever built, SLS will be capable of sending humans to deep space destinations such as an asteroid and eventually Mars.
Meanwhile, Orion program managers from both NASA and Lockheed Martin continued their visits to American companies which contributed elements to Orion.
Several members of the Orion leadership team visited Orbital ATK’s test facilities in Promontory, Utah, last week where the company performed a major qualification test for the booster that will propel NASA’s Space Launch System, with Orion atop it, to space. The company also built Orion’s Launch Abort System.
During the week of March 16, managers will continue their visits to major Orion contributors, visiting NASA’s Michoud Assembly Facility in New Orleans, Marshall, United Launch Alliance in Decatur, Alabama and NASA’s Langley Research Center in Hampton, Virginia.