From its opening in September 1963 until its closing earlier this year, Johnson Space Center’s “Arc Jet” facilities were intended to be hands-on, enclosed fire-breathing labs where engineers gathered to recreate the extreme high-temperature air flows that spacecraft as different as Apollo and the space shuttle confronted to deliver their passengers safely back to Earth.
“We simply could not have carried out human spaceflight without the capability of the Arc Jet and the expertise of the people who have staffed it over the years,” said JSC Director Ellen Ochoa. “Regardless of where the hardware is, we’ll continue to need that expertise to address the safety of crews returning from space and other exploration activities.”
As the labs evolved, the primary requirement for the facilities clustered in the center’s northeast quadrant was always the same: to demonstrate the ruggedness of heat shielding and help to "human rate" a succession of NASA spacecraft, from Apollo and shuttle to the emerging Orion and Commercial Crew Program vehicles.
Buildings 262, 222 and the professionals who staffed the 1.0 megawatt (MW) Arc Jet Facility, a 1.5 MW upgrade and the more recent 10 MW Atmospheric Reentry Materials and Structures Evaluation Facility (ARMSEF) and its upgrades, lowered the mission-ending risks of returning the first lunar explorers to Earth and addressed the challenges of flying the first reusable orbital spacecraft. They helped colleagues, some at other NASA centers or designers from outside the agency, with efforts to develop the National Aero-Space Plane, the X-33 technology demonstrator and X-38 crew return vehicle and more.
Finally, they contributed to future human missions to Mars with Orion and breakthrough commercial crew transportation to the International Space Station.
“The people were dedicated and original pioneers at JSC, like Dr. Robert Gilruth, the first center director, and my first division chief, Joe Kotanchik ,” said Don Tillian, whose association with arc jet operations stretched from 1964 until his 2011 retirement. “These people were part of the Space Task Group and had the first patents on arc jets. They understood the need to simulate the entry heating conditions. It was a very exciting era, of course.”
Tillian’s long-running ties as an arc jet test engineer, section head and test branch chief, produced a detailed history of the first staffed test facility at JSC.
In late March, arc jet operations were closed out in response to a January 2011 directive from NASA Headquarters to eliminate a duplication of infrastructure across the agency. Major components, including the unique water-cooled copper heater and spare components, were transferred to NASA's Ames Research Center for future head shield test activities.
A final JSC test run on March 21 was in support of a Safety & Mission Assurance internal research and development risk reduction project.
“It’s fun,” said Steven Del Papa, who was among the last of those staffing the Arc Jet Facility as a test director and lab manager. “It appealed to me as an engineer working out of a place like that. A lot of the work is really hands on. Every test is similar, but different. You execute each test the same way, but each program has a uniqueness you have to account for to make sure it’s done right.”
Del Papa came to the Arc Jet shortly after the 2003 Space Shuttle Columbia
tragedy, which marked the start of an especially important chapter for the ARMSEF, which opened in 1967. The 10 MW facility underwent a significant upgrade five years later to advance the development of the shuttle’s underside acreage tile and carbon-carbon wing lead edge and nose-cap components. Multiple shift operations were the norm.
In addition to serving as a resource to the Columbia
Accident Investigation Board, the Arc Jet played a critical role in supporting post-Columbia
missions by enabling engineers to assess thermal protection repair strategies and inflight damage.
So critical was the Arc Jet’s role that plans to close the facility initiated shortly before the Columbia
loss were abandoned.
“We had to staff back up,” recalled Chris Madden, chief of JSC’s Thermal Design Branch, which supervised Arc Jet activities. “It was a little clunky in the beginning. The skills were not fine-tuned.”
One challenging task unrelated to the thermal protection system was modeling a complex flow field between the shuttle’s cargo bay with its changing payloads and the orbiter’s exterior. It took eight months and readings from 200 sensors to document the circulation.
As the shuttle program entered retirement in 2011, Arc Jet staffers turned their efforts to heat shield development for Orion and Boeing’s CST-100 commercial crew vehicles, both capsules and larger than Apollo.
“They came to us with conditions outside our experience with the shuttle,” Del Papa said. “Meeting their conditions was always fun—basically doing things that had not been done before.”
The Arc Jet staff also found time in a busy close-out period for a new challenge—recreating the entry conditions for the carbon-dioxide-rich atmospheres of Mars and Venus. Had the lab not faced closeout, it would have ventured deeper into that new realm by helping NASA’s Jet Propulsion Laboratory prepare the Curiosity Mars rover and future landers for their missions.
“Unfortunately, because of the workload we had for Orion and what we had for the shutdown, we just were not able to get to them,” Del Papa said.
Arc Jet, however, demonstrated that future labs of its type will be able to simulate the flow conditions for Mars missions by substituting carbon dioxide for the high-speed rush of nitrogen and oxygen gases that accelerate through the electric heaters to simulate terrestrial atmospheric conditions.
“We were laying the groundwork,” Del Papa said. “The biggest hurdle was making sure we would not create cyanide and drop like flies. We demonstrated you could do it safely.”
As the Arc Jet closed, Del Papa moved his office to the nearby Radiant Heat Facility, Building 260, where he is a test director. There, he re-joined Jim Milhoan, who came to Arc Jet operations in February 1967 as one of only a handful of JSC personnel involved in thermal protection system testing.
Now a senior engineer with Barrios Technology, Milhoan has fond memories of the Arc Jet’s early and sometimes rustic period.
The challenges included testing in the 1.5 and 10 MW labs simultaneously. As a young test director, a slight Milhoan would sprint the 150 yards between Buildings 222 and 262, crossing a drainage ditch on a low-hanging wooden board stretched across the waterway to supervise the two arc jets.
“You would run and hit the board with the middle of your foot,” Milhoan recalled. “It would flex into the water, then you would spring to the other side. At the same time, you could see the water moccasins in the water, moving everywhere. You did not want to fall.”
NASA Johnson Space Center
The Arc Jet team poses for a photo at the last test run of the ARMSEF in Building 222 on March 21. Image credit: NASA/James Blair
David Williamson works in the Arc Jet Facility. Image credit: NASA/James Blair
Reinforced Carbon Carbon is tested with the fire-breathing properties of the Arc Jet Facility, exposing the material to extreme heating conditions. Image credit: NASA
Image of the exterior of ARMSEF, also known as JSC's Arc Jet Facility. Image credit: NASA/Bill Stafford