In 1961, when President John F. Kennedy issued his challenge for the United States to send humans to the Moon and back by the end of that decade, a site was needed to test the powerful rocket engines and stages that would propel them on the historic journey. For NASA officials, the rough terrain of Hancock County, Mississippi provided five essentials for testing the large Apollo Program engines and stages: isolation from large population centers, water and road access for transportation, available public utilities, supporting local communities, and a climate conducive to year-round testing.

Crews at Stennis lift and install the first core stage of NASA’s new Space Launch System (SLS) rocket onto the B-2 Test Stand. A top-to-bottom, integrated series of Green Run tests is being conducted on the stage and its sophisticated systems.

The site was selected and in May 1963, workers began the building project. On April 23, 1966, a Saturn V second-stage prototype was test-fired on the newly completed A-2 Test Stand on the site. Astronauts Neil Armstrong and Buzz Aldrin walked on the lunar surface in 1969, safely transported thousands of miles by a space vehicle whose boosters were tested and proven flight-worthy at Stennis Space Center (SSC).

Until 1972, Stennis test-fired first and second stages of the Saturn V rockets used in the Apollo Program. All the engines used to boost the space shuttle into low-Earth orbit were flight-certified at SSC beginning in 1975 and the same stands were used to test-fire all first and second stages of the Saturn V in the Apollo and Skylab programs. Space shuttle main engine testing continued at Stennis for 34 years, from 1975 to 2009.

Stennis now is testing RS-25 rocket engines for the Space Launch System (SLS) that will carry humans back to the Moon as part of NASA’s Artemis Program and, ultimately, to Mars. Stennis also will test the SLS core stage that will fly on the maiden Artemis I mission next year. Testing will involve installing the stage on the B-2 Test Stand and firing its four RS-25 engines simultaneously. At the same time, the center is partnering with commercial companies to test engines and components for various commercial and military missions.

Over the years, Stennis has evolved into a multidisciplinary facility comprised of NASA and more than 40 other resident agencies engaged in space and environmental programs and the national defense, including the U.S. Navy’s world-class oceanographic research community.

The center has undergone a number of name changes from its original name, Mississippi Test Operations. In May 1988, it was given its current name honoring Senator John C. Stennis for his support of the nation’s space program.

Back to the Moon — Through Stennis

The Cryogenic Cam Butterfly Valve is designed so that the disc rides on a cam shaft and is held rigid by a torsion spring, which provides both axial movement of the disc in addition to the standard 90-degree rotation of a standard butterfly valve. It enables low leakage at both ambient and cryogenic temperatures.

With the Artemis program, NASA will land the first woman and next man on the Moon by 2024, using innovative technologies to explore more of the lunar surface than ever before. NASA’s powerful new rocket will send humans and cargo to the Moon and beyond. The Space Launch System is designed to be flexible and evolvable and is the agency’s first deep space rocket since Saturn V. Every SLS configuration uses the core stage with four RS-25 engines.

For the first Artemis unmanned mission, Artemis I, the engines have been built and tested, and are ready for attachment to the core stage. After the engines were installed and the core stage was fully assembled, the entire stage was sent to Stennis for Green Run testing.

Green Run testing is the first top-to-bottom integrated testing of the stage’s systems prior to its maiden flight. The testing is conducted on the B-2 Test Stand at Stennis and takes place over several months, culminating with an eight-minute, full-duration, hot fire of the stage’s four RS-25 engines to generate 2 million pounds of thrust — what the system will incur during an actual launch.

The energy harvesting smart sensor is a highly power-conservative monitoring system consisting of a base station and wireless sensor units. The sensors lay fully unpowered within a dormant state until they receive a trigger energy, so they consume no stored power.

NASA completed extensive modifications at Stennis to prepare the B-2 stand for the test series. This required upgrades of every major system on the stand as well as the high-pressure system that provides hundreds of thousands of gallons of water needed during a test. It also involved adding 1 million pounds of fabricated steel to the Main Propulsion Test Article framework that will hold the mounted core stage and extending the large derrick crane atop the stand that is used to lift the SLS stage into place.

Once installed on the stand, operators begin testing each of the stage’s sophisticated systems. Among other things, they will power up avionics, conduct main propulsion system and engine leak checks, and check out the hydraulics system and the thrust vector control unit that allows for rotating the engines to direct thrust and “steer” the rocket’s trajectory.

Technologies

SSC engineers invent, design, and test innovative software tools, algorithms, and systems that help enable the next generation of space exploration.

The PiezoElectric Gravimeter (PEG) is a lightweight, cost-effective solution for structural measurements that features three piezoelectric shear elements weighed for gravitational measurement with an embedded charge amplifier.

High-Speed, High-Dynamic-Range Video Recording System – The HiDyRS-X imaging system combines computational photography and HDR (High Dynamic Range) imaging to increase a camera’s dynamic range and eliminate saturation. “Extreme HDR” was enabled by creating a software algorithm for an extreme dynamic range scene that reads, processes, decomposes, and reconstructs the video data from the different cameras to develop the extreme HDR video for events like a rocket engine test.

Analytical Process for Measurement of O-Phthaladehyde (OPA) – On the International Space Station (ISS), waste heat loads are removed by an Internal Active Thermal Control System (IATCS) that is water-based. OPA is used in the IATCS as a biocide to prevent negative impacts to coolant flow, heat transfer, and corrosion, all of which could result in damage to the IATCS and adversely affect crew health and safety. A simple process to analyze OPA that neither required highly hazardous chemicals nor involved a hazardous waste stream was developed.

Floating Piston Valve – This low-maintenance valve consists of a solid piston floating in a medium to control the flow stream. The piston is designed to be axially and radially balanced within the flow stream whether the valve is in the open or closed position. The only force imparted onto the piston is what the operator chooses to input. This eliminates a conventional actuator, valve stem, and stem seals as well as most flow-induced thrust forces. Additionally, the valve consists of only five parts with a few simple seals. It’s used in nominal or extremely high pressures and for the use of soft or hard metal seats in the chemical industry, in storage tanks, and in pharmaceutical manufacturing facilities.

Cryogenic Cam Butterfly Valve – Typical butterfly valves can’t seal at both ambient and cryogenic temperatures. The inability to do this triggered the design of the Cryogenic Cam Butterfly Valve (CCBV) in which the disc rides on a cam shaft and is held rigid by a torsion spring, which provides both axial movement of the disc in addition to the standard 90-degree rotation of a standard butterfly valve. Because the valve’s disc can rotate and translate, it can hold a tighter seal, preventing leakage despite dimensional changes caused by changing operating temperatures.

Advanced Wireless Sensor – This power-conservative monitoring system stays fully unpowered in a dormant state until it receives a trigger energy that consumes no stored power. Once activated, the sensor takes a measurement, transmits the data with a synchronized time stamp, and then returns to its dormant state. The system can be utilized in commercial applications that require long-term monitoring of events associated with strain, cryogenic temperatures, ambient temperatures, limit switches, milliamp signals, volt signals, and magnetic fields.

Field-Deployable PiezoElectric Gravimeter (PEG) – Sensors and sensing systems are typically designed for specific functions. This can result in a time-consuming and costly cycle of design, test, and build, since there is no real standard-sensor building block that can be adapted and used to sense a variety of attributes and physical states. The PEG provides a sensing system and method that can serve as the foundation for a wide variety of sensing applications. Commercial applications include automotive, aviation, satellites, seismology monitors, security monitoring, motion detectors, and altitude detectors.

In-Situ Monitoring of Piezoelectric Sensors and Accelerometers – An in-situ measurement system monitors performance of piezoelectric sensors including characteristics such as resonant frequency, response, cable status, connectivity, bonding, and linear range. Sensors can be tested in a wide frequency range with out removing them from their mounted locations. Assessments can be performed in-situ with handheld test equipment or integrated into instrumentation systems. Applications include accelerometers, automotive sensors, structural sensors, and any application where vibration is monitored.

Technology Transfer

SSC technologies are licensed to private industry to stimulate the U.S. economy. For more information on commercializing SSC technologies, contact Duane Armstrong at This email address is being protected from spambots. You need JavaScript enabled to view it. or This email address is being protected from spambots. You need JavaScript enabled to view it., phone 228-688-2180, or visit here .


Tech Briefs Magazine

This article first appeared in the September, 2020 issue of Tech Briefs Magazine.

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