By Jen KramerMars. The Red Planet. 142 million miles away from our sun. Visiting such a place – let alone colonizing it – was long thought to be in the realm of science fiction. But now, thanks to the National Aeronautics and Space Administration’s (NASA) Space Launch System (SLS) and spray polyurethane foam (SPF), fiction is quickly becoming fact. Spray Foam Magazine was invited behind the scenes at NASA’s Marshall Space Flight Center (MSFC) in Huntsville, Alabama to see the vital role
spray foam is playing in mankind’s journey into deep space.
Preparing for Launch
The voyage to Mars begins on 18 hundred acres of gently rolling hills in Alabama. Located on the Redstone Arsenal Army base, founded by the “Father of Rocket Science,” Wernher von Braun, and named for General George Marshall, the Marshall Space Flight Center (MSFC) is the largest of NASA’s facilities.
Once the primary site of research, development, and testing, the rocket engines themselves are no longer fired up at Marshall. “Huntsville grew too big and windows would shatter in the surrounding neighborhoods,” explains our guide, Tracy McMahan, Public Affairs Specialist, Marshall Space Flight Center. However, they are still researched, designed, and built at Marshall.
Spray Foam Magazine’s Creative Director, Heather Westrol, McMahan, and I are standing in the anteroom of von Braun’s office. Huge banks of windows look out over the Marshall campus – including the series of test stands where conditions are replicated to test the rocket engines under a variety of stresses, such as forces experienced on take off and re-entry.
“Over there,” McMahan points out a non-descript building in the distance, “Is the International Space Station (ISS)’s Payload Operations building. It’s the only point of contact with the astronauts on the ISS.”
“And over there,” she says pointing to a building in the opposite direction, “is the TPS (Thermal Protection Systems) facility where the spray foam-related activities occur.”
The Moment Sinks In.
Here at Marshall, they are talking to space and spraying foam. We happen to be standing right outside Werhner von Braun’s office. When von Braun and his coworkers first sent rockets into space, they did so using technology that wasn’t even as advanced as the cell phone that I’m using to record this moment. In fact, it probably wasn’t as advanced as the spray equipment that they are using to apply the foam. But they created a successful space program through determination and an uncompromising insistence on finding and using the right tools for the job. That same drive is alive today. No wonder everyone on this campus says, “When we get to Mars.” No one says “if.” We will be getting there courtesy of some very skilled people, some very advanced rocket science, and spray foam.
The Space Launch System
The SLS – the most advanced rocket system to-date – is the next step in NASA’s space program. It provides more payload mass, volume capability, and energy than any previous launch vehicle. And foam plays a very important part in the system.
A combined effort between multiple NASA facilities, as well as private industry (including Boeing of Chicago, Aerojet Rocketdyne of Sacramento, and Teledyne Brown Engineering of Huntsville), the SLS is designed to be flexible enough to increase capacity and adapt to new payloads, opening exploration to other deep-space destinations in addition to Mars, including Saturn and Jupiter.
The first phase of SLS is known as Block 1. According to NASA, the Block 1 vehicle will have a minimum lift capability of 70 metric tons and will be powered by two five-segment rocket boosters and four RS-25 liquid propellant engines, as well as a modified version of the upper stage. The upper stage is the section of the system that is designed to support robotic, and eventually, human missions. This SLS will be 322 feet tall and weigh 5.75 million pounds when fueled. Thrust produced at liftoff will be 8.8 million pounds – more than 160,000 Corvette engines. The first planned SLS Block 1 mission is set to launch an unmanned Orion spacecraft to orbit the moon. The second planned SLS Block 1 mission will launch a crew of four to the vicinity of the moon.
SLS Block 1B phase will use a more powerful exploration upper stage and will deliver a 105-metric ton lift capacity. It is 364 feet taller than Saturn V and will be used to launch humans into near moon orbit.
SLS Block 2 will replace the current five-segment boosters with a pair of advanced solid or liquid propellant boosters to provide 130-metric ton lift capacity. It will be the “workhorse” of SLS, weighing 6.5 million pounds and providing 9.2 million pounds of thrust at liftoff. Block 2 will be the phase capable of supporting human deep space exploration – the Mission to Mars.
However, whether it is Block 1, 1B, or 2, the SLS will continue to use the same core with four RS-25 engines. Designed by Aerojet Rocketdyne, these engines are upgrades from a NASA inventory of 16 leftover shuttle RS-25 engines. Performance enhancements to the engines include new engine controllers, nozzle insulation, and require operation at 418,000 pounds of thrust, instead of the 395,000 pounds required for shuttles. The four engines propel a core in which the avionics that will control the SLS are stored.
The core, 200 feet tall with a diameter of 27.6 feet, stores 730,000 gallons of super-cooled liquid hydrogen and liquid oxygen that fuel the SLS engines. Constructed of aluminum, the core itself is being built at NASA’s Michoud Assembly Facility in New Orleans, using state-of-the-art equipment, including the largest friction-stir-welding tool in the world. The avionics computer software is being developed at Marshall Space Flight Center.
Also at Marshall are 30- and 150-foot diameter tanks that are part of the SLS program. The tanks are there to be insulated with spray polyurethane foam.
SLS and SPF
McMahan escorts us into the long-awaited TPS facility, introducing us to Amy Buck, Materials and Processes Engineer; Michael Frazier, the head of Materials, Processes, and Manufacturing Department – Chief, Nonmetallic Materials Branch; and Michael Alldredge, Materials and Processes Engineer – the trio responsible for the spray foam testing and application procedures at Marshall.
As we walk through corridors – some leading to projects in development, and some with firmly closed doors – Frazier explains NASA’s history of foam and the transition from the space shuttle program to the SLS.
“In 2005, NASA thought that new launch vehicles would be allowed to use the same cryoinsulation materials previously used on the Space Shuttle external tank (ET). Unfortunately, all of the ET material systems contained the HCFC-141b blowing agent, which was an ozone-depleting substance that was phased out of industry use effective January 1, 2003. ET usage of HCFC-141b-based materials was only allowed via a yearly renewable Environmental Protection Agency (EPA) exemption allowance. This exemption specifically authorized suppliers to produce HCFC-141b for the ET project only and expired when the Shuttle flew its last flight in 2011. Afterwards, NASA decided to pursue environmentally compliant replacement materials that could be used for future vehicles.”
We have walked through the facility, outside, and are now standing in front of the spray room – a soaring building with hangar doors pulled tightly shut.
Frazier continues, “Marshall Space Flight Center’s Materials and Process Laboratory Thermal Protection System (TPS) team was established and assigned to conduct the necessary development activities for the replacement materials. After development efforts were successfully completed, SLS funded Boeing to qualify the pour and automatic spray foam materials, and the MSFC Thermal Protection Team continued to qualify the manual spray foam material. NASA anticipates qualification of all the foam systems for SLS to be successfully completed in 2016. This means that the cryoinsulations will be ready for use on the first SLS launch vehicle for Exploration Mission-1 scheduled for launch in 2018.”
And with that, Frazier leads us into the spray room, which features “automatically applied polyisocyanurate spray foam, manually applied polyurethane spray foam, and manually applied polyurethane pour foam,” as described by Buck. “All are closed-cell foam materials and all foams are HFC 245a-based blowing agent materials.”
Before we enter the 30-foot x 30-foot x 85-foot spray area, we pause first in the pump room. Alldredge notes that the magnetic pumps have the capacity to handle 5:1 foam, 1:1 pour, 2:1 spray – this is state-of-the-art equipment. A video camera allows the crew to monitor the pumps from their office steps away.
The office features a wall of windows banked by a row of computers. The team is not only able to visually monitor the spray room, but also they can electronically monitor the calibration of all the equipment, as well as the conditions.
The spray room itself is Class 1, Division 1 rated so the team has the ability to spray flammable materials if necessary. And the hangar doors allow for large objects to be moved in and out. “Objects such as rocket tanks?” I ask. Frazier smiles. “Absolutely.”
“We have the capacity to spray vertically or horizontally using the robot,” says Frazier. “Historical is to do a vertical spray.”
And thickness? “It depends on the location,” says Buck, “but thickness typically runs between ½-inch and two-inches, with the majority of the foam applied at about one-inch-thick.”
The massive spray robot is the centerpiece of the room. To provide scope, the robot is approximately 25-feet by 10-feet by six-feet, including the tower. But it is the height and the “nine axes of freedom it provides” that are more important.
“We don’t want to stop the spray once we start,” says Alldredge. In fact, the machine holds three GX-7 guns that are used as a redundancy to prevent this very problem. The spray robot is hooked to a Binks pressure pot and a Gusmer PNDS hydraulic proportioning unit. And, in spite of all the high-tech buzz, the NASA engineers are just like SPF technicians when it comes to designing inspired fixes on the fly.
“If necessary, we use weed eater line to unclog the guns,” says Alldredge.
There are also five strategically placed cameras in the booth allowing the team to monitor the spraying operation from the office right outside. Whether they are running the robot or employing a crew of spray foam technicians, the spray room features top-of-the-line HVAC capabilities. “The booth has a state-of-the-art cross-flow ventilation system,” explains Frazier. “The filter bank sucks up any overspray as well as any off-gassing from the hex chrome primer.”
In space travel, weight matters. Spray foam provides a durable, lightweight, insulative material that will withstand the rigors of deep space travel and the stresses of re-entry – protecting the vehicle and its occupants. As Alldredge says, explaining the genius protective properties of the lightweight insulation that can protect against the deep freeze of deep space and then, upon re-entry, “the rind on the foam will char and protect the foam. It insulates itself.”
The TPS program is in the process of qualifying SPF for use on the SLS.
Buck explains, “The cryoinsulation development effort began in 2007 and Qualification for the Space Launch System (SLS) applications should be completed in 2016 (not counting long-term aging studies).”
In the spray room, hundreds of 24-inch-by-24-inch test panels for three foam system houses have been sprayed and/or poured and tested throughout an extensive development and qualification cycle. The three foam houses involved in the tests are NCFI, J6 Polymers, and Utah Foam Products, Inc.
In order to recreate the conditions to which the foam will be exposed as closely as possible, the TPS team subjects the SPF panels to a wide-ranging variety of tests. Just a few of these tests include:
- Wind tunnel testing
- Cryoflex tests run at -425°F
- ASTM governed bond tension tests at various temperature conditions
- Hot Gas testing that exposes the SPF to heating environments similar to those the flight will see during ascent
- “Pull Plug” dolly bondline adhesion checks
- Density measurements
- Wet chemistry “fingerprint” testing
Whether robot- or manual-spray, or poured, and no matter which systems house, whatever SPF is ultimately chosen by whichever application method, it will have been thoroughly vetted by the TPS team.
Spray foam will be going to Mars. Having seen “behind the scenes,” I now have no doubt. The SLS program will be a success, thanks in no small part to SPF. And when we get to Mars, and establish our colony, the infrastructure will need good insulation. It is absolutely a job for spray polyurethane foam. •
Artist concept images courtesy of NASA/MSFC; Site Visit Photos: Spray Foam Magazine