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Space Test Branch helps change the world with decades of testing

  • Published
  • By Deidre Moon

With the first ballistic missile being introduced in 1944 during World War II, the newest threat to the nations of the world was realized.

At this time, the V-2 rockets, the world’s first long-range, guided, ballistic missiles, were not very accurate, but this new capability created new urgency for the U.S. and its allies.

When the war ended and American scientists had discovered Germany’s sophisticated flight simulation test facilities, Henry “Hap” Arnold, the general of the Air Force, made it his mission to never let the U.S. fall behind in warfighting technology. Thus, Arnold Engineering Development Center (AEDC), named after Arnold at a ceremony June 25, 1951, was established to provide much-needed test capabilities.

The Space Test Branch for AEDC, now known as the Arnold Engineering Development Complex, headquartered at Arnold Air Force Base, Tenn., has contributed greatly to national defense and technology development over the last several decades by providing capabilities to ground test missiles, space vehicles and associated components.

Rocket motor test facilities

The Rocket Propulsion Ground test and evaluation (T&E) capability has been a component of AEDC since its founding. The upper-stage motors powering Peacekeeper, Minuteman, Trident and Titan are just a few of the motors that have been tested in the facilities. From ballistic missiles to the lunar lander to rockets for positioning commercial satellites into orbit, AEDC has played a role in their development and ensuring they work as designed.

The earliest documented solid-fueled rocket motor testing took place in 1958 in the T-3 test cell in the AEDC Engine Test Facility. Before it was converted in 1989 to conduct small turbine engine testing, T-3 was a rocket workhorse, conducting 2,423 firings.

In 1961, AEDC’s first vertically-oriented Rocket Motor Test Facility J-3 came into service, fulfilling the need to provide the capability to test liquid-powered rocket motors.

AEDC Rocket Development Test Cell J-4, also a vertical test cell designed for testing large rocket engines, came into service in 1964 to support the Apollo program, which put man on the moon. This facility provided unmatched testing of liquid propellant rocket engines and solid-propellant rocket motors. J-4 was used to test a variety of engines over the years, including the test firings conducted on the RL-10B-2 between Sept. 8 and Oct. 3, 2001, in support of the Evolved Expendable Launch Vehicle (EELV). The EELV, in turn, led to the development of the Delta IV and Atlas V, the two primary launch systems for U.S. military satellites.

After it became operational in 1963, the Rocket Development Test Cell J-5 was used to test more than 500 motors for such systems as Minuteman and Peacekeeper, both Intercontinental Ballistic Missiles; and Poseidon and Trident, both submarine-launched ballistic missiles. The facility was used until 1994.

AEDC’s J-6 facility went into service in 1994 to provide expanded ground test capabilities for solid-propellant rocket motors from ignition through steady state thrust production to thrust termination at simulated altitude conditions up to 100,000 feet above sea level. These tests support development efforts by the DOD and commercial aerospace industry.

For the last several years, the focus of AEDC Rocket Propulsion Ground T&E has been on the aging and surveillance of the Minuteman III Intercontinental Ballistic Missile rocket motors. That role is expanding with the development of the Ground-Based Strategic Deterrent program and the growth of hypersonics.

“AEDC’s contribution to closing the missile gap, the space race and nuclear surety are unmatched,” said Randy Quinn, Rocket Propulsion Ground T&E capability manager.

Multi-Spectral Signature Measurement and Analysis

The Space Test Branch has also contributed to the study of missiles through multi-spectral signature measurement and analysis carried out by the AEDC Advanced Missile Signature Center.

Multi-spectral signature measurement and analysis is carried out by the AEDC Advanced Missile Signature Center (AMSC) to support the development and evaluation of missile defense systems, aircraft warning systems, surrogate threat simulators and countermeasures.

The AMSC Field Measurement Team, which can deploy worldwide, collects optical, infrared and ultraviolet signatures from missile launches, impact engagements and threat systems, including air-to-air missiles, anti-tank guided missiles, man-portable air defenses and rocket-propelled grenades, and small arms fire.

The AMSC Modeling and Simulation takes the data collected by the Field Measurement Team and creates modeling tools that replicate the threat system signatures for the development of detection, identification and self-protection systems.

Space environmental chambers

The first space chamber went into operation in 1961 when 7V was accepted for service. The 7-foot diameter, 30-foot long space chamber has been reconfigured over its lifetime to support a variety of test programs, with support in recent years to Missile Defense Agency and Air Force Space and Missile Systems Center.

7V is part of the Space Systems Test Facility, or SSTF, at Arnold and is one of the thermal-vacuum chambers for electro-optical/infrared (EO/IR) sensors and satellite component testing. The three large chambers in the SSTF are 7V, 10V and 12V.

Additionally, an assortment of smaller chambers of varying sizes are available for internal and external use. These include the Characterization of Combined Orbital Surface Effects, chamber, the 7A Chamber, the Ultra-High Vacuum Chamber and the Component Checkout Chamber.

The 10V Chamber at Arnold provides mission simulation capability for the Ground-Based Interceptor, specifically its kill vehicle sensor. The chamber is able to stimulate the EO/IR sensor in a hardware-in-the-loop/software-in-the-loop configuration to characterize sensor performance in a space environment against simulated operational scenarios.

The 12V Chamber, a vertical chamber, is a thermal vacuum test facility originally designed and constructed for thermal balance testing of small vehicles and components and with solar simulation capability. In the early 2000s, the chamber was configured for electric propulsion thruster plume analysis and integration effects testing.

12V supported the development of the International Space Station (ISS) by testing a hatch for the station in 1992. The 200-pound, 53-inch-square hatch, which will close the passageway between compartments in the station, underwent the thermal/vacuum testing in the chamber.

Testing in the 7A Chamber helped prepare the Roll-Out Solar Array (ROSA), for its successful experimental deployment in June 2017 at the ISS in June 2017. ROSA is an innovative type of a solar panel that rolls open in space like a tape measure and is more compact than current rigid panel designs.

The AEDC Mark 1 Test Facility was constructed starting in February 1965. This facility is a space environment simulation test chamber for full-scale space systems testing. At 42-feet-diameter by 82-feet-high, the facility exposes test articles to conditions that replicate the extreme vacuum and temperatures of space. Mark 1 was essential for testing the Global Positioning Satellite in 1977. In late-1999 to early-2000, the Solar Arrays for the Wilkinson Microwave Anisotropy Probe (WMAP) were tested in Mark I. The WMAP imaged some of the first light in the universe – the Cosmic Microwave Background – created in the Big Bang some 13 billion years ago. In 2000, The GOES-M Weather Satellite underwent pre-launch qualification testing in the facility. GOES stands for Geostationary Operational Environmental Satellite that provide weather predictions and hurricane warnings. Mark 1 has also been used to conduct faring separation testing.

“So many of the everyday things we take for granted, from the GPS on our cell phone to whether to grab an umbrella or sunscreen on our way out the door, to cutting edge knowledge of the universe and more, came through AEDC along the way,” said Jim Burns, deputy, Space Test Branch.

Another unique facility within the Space Test Branch is the Space Threat Assessment Testbed, known as STAT. STAT is a combination of two 7-foot diameter chambers that enables research, development, test and evaluation (RDT&E) of materials, components, subsystems, and small satellites in environments that may threaten performance to reduce the risk of failure of mission-critical assets. In the STAT, test engineers can simulate a mission environment for evaluating space systems-of-systems and subsystems as if in orbit.

Arc jet heater facilities

The arc jet heater facilities, H1, H2 and H3, at Arnold AFB reproduce thermal environments simulating flight from Mach 8 to Mach 20 for the long exposure periods required to validate thermostructural performance and survivability of materials and components. In the arc heater facilities, high-speed vehicles, such as hypersonic missiles, re-entry vehicles and high speed transports, ordinances and munition systems are tested.

The arc heaters use an arc discharge to conduct ablation testing, which is the burning away of a material from an object. This kind of testing shows engineers how the high-speed vehicles will perform and survive under simulated conditions. The goal is to maintain the structural integrity of the test material.

Testing in the arcs have supported programs such as the Intercontinental Ballistic Missile, Navy Submarine-Launched Ballistic Missile, Defense Advanced Research Projects Agency (DARPA) Hypersonic Technology Vehicle 2 and HTV-3, DARPA Materials Development for Platforms, the Air Force Hypersonic Technology Scramjet, Army missile programs and Missile Defense Agency hypersonic interceptor programs, among others. Civil and NASA programs supported include the Crew Exploration Vehicle, Mars Science Lab, Heat Shield for Extreme Entry Environments and the Orion/Multi-Purpose Crew Vehicle.

Hypervelocity ballistic ranges

The Hypervelocity Flyout, Impact and Lethality Ground T&E capability is conducted in the ballistic ranges at Arnold to collect data about flight characteristics of projectiles in re-entry, hypersonic and orbital flight environments, and the result of their impact.

Projectiles are launched with a two-stage, light-gas gun into a simulated altitude chamber, up to speeds nearing 7 kilometers per second, or Mach 20. Re-entry vehicles, interceptors, and simulated space debris are some of the projectiles tested.

“Currently, we're working with the Hypersonic Test and Evaluation Investment Program to reinvigorate our weather encounter test capability,” said Jonathan Carroll, Hypervelocity Flyout, Impact and Lethality Ground T&E capability manager. “The range is configured with a track to ensure the projectile encounters the generated rain, snow, ice or dust fields that simulate real world flight conditions. This allows programs to evaluate the survivability of hypersonic and re-entry systems.”

Range G, the workhorse of the facilities, propels a sub-scale model of projectiles down a 1,000-foot long track at speeds up to 23,000 feet per second. Testers are also able to recover model fragments after impact. Specialized photography using laser illumination provides still and video imagery of the projectile models in flight.

The hyperballistic ranges also include Range I, S-1 and S-3 facilities. Range S-3, a 7-inch, single stage gun, was originally used for bird-strike impact testing of aircraft canopies. It was also used to conduct impact testing of space shuttle block foam in support of the Return to Flight mission following the Columbia disaster.

In 1977, a track was installed inside the Range G, allowing models to be guided through erosive environments, not just experience ablation. Testing in the range has also included work done on the gun barrels and ammunition of the Air Force’s A-10 Warthog and testing in support of NASA’s Apollo capsule. In 2001, a scale model of a conceptual missile powered by a scramjet was launched down the facility’s two-stage light gas gun through its 130-foot long gun barrel. This was the first-ever successful free-flight demonstration that AEDC performed of a hypersonic projectile powered by a scramjet engine burning hydrocarbon fuel.

While relishing in the success of the last 70 years, the Space Test Branch team members are also looking forward to what the future holds for ground test in their facilities.