The Space Environments Complex (SEC), formerly known as the Space Power Facility (SPF), houses the world’s largest and most powerful space environment simulation facilities. The Space Simulation Vacuum Chamber is the world’s largest, measuring 30.5 m (100 ft) in diameter by 37.2 m (122 ft) high. The Reverberant Acoustic Test Facility (RATF) is the world’s most powerful spacecraft acoustic test chamber, and the Mechanical Vibration Facility (MVF) is the world’s highest capacity and most powerful spacecraft shaker system. The SEC is located at the NASA’s Plum Brook Station in Sandusky, Ohio. This website provides information on the capabilities of this facility and the supporting infrastructure. The facility is available on a full-cost reimbursable basis to government, universities and the private sector.
Space Simulation Vacuum Chamber
The vacuum chamber was designed and constructed to test both nuclear and nonnuclear space hardware in a simulated low-Earth-orbiting environment. Although the facility was designed for testing nuclear hardware, only non-nuclear tests have been performed throughout its history. Some of the test programs that have been performed at the facility include high-energy experiments, full-scale rocket-fairing separation tests, Mars Lander system tests, deployable solar sail tests and International Space Station (ISS) hardware tests.
The chamber can sustain a high vacuum (10 to 6 torr) and provide an optically tight, high-emissivity, thermal background environment of –160°C to 60°C (–250°F to +140°F) within the 12-m- (40-ft-) diameter by 12-m- (40 ft-) high variable-geometry cryogenic shroud. The facility can also provide power systems and thermal controllers for customer-provided thermal heaters or solar simulators.
The vacuum chamber has a volume of 22,653 m³ (800,000 ft³) and measures 30.5 m (100 ft) in diameter and 37.2 m (122 ft) high with 15.24-m (50-ft) by 15.24-m (50-ft) loading doors on each side leading to high bays. The chamber features all-aluminum construction, including a removable polar crane with an 18.1 t (20 ton) critical lift trolley and a 9.1 t (10 ton) auxiliary hook, and a removable, reconfigurable, cryoshroud system. The chamber cryoshroud system can provide both warm and cold thermal background environment, data acquisition and test monitoring capabilities.
The vacuum chamber is surrounded by an equal-volume concrete enclosure which is typically reduced in pressure to 20 torr during chamber operations.The vacuum chamber incorporates several electrical and instrumentation penetrations, and several blank penetrations at various locations around the chamber perimeter. Removable rail tracks in the chamber can be used in conjunction with rail dollies or the cryoshroud floor(s) to transport hardware or test articles through the facility and chamber. The facility provides a visually-clean environment. The chamber provides an empty-chamber vacuum capability of 2×10–6 torr using a combination of roughing pumps and high-vacuum equipment. The roughing system consists of two identical 5-stage, parallel trains of rotary-lobe blowers and rotary-piston mechanical pumps, which pump the chamber and annulus simultaneously to 20 torr, and subsequently the chamber only to 30 mtorr. High-vacuum is achieved using 5 turbomolecular pumps and 10 cryogenic pumps. The chamber can reach a vacuum level of 2×10–6 torr in less than 8 hr.
The facility uses a removable, reconfigurable, cryoshroud for background heating and cooling. The cryoshroud is warmed and cooled using a recirculating gaseous nitrogen (GN2) system. The system utilizes compressor heat-of-compression to provide up to 60°C (140°F) wall temperatures, and a heat exchanger/liquid-nitrogen (LN2) desuperheater to provide temperatures down to –160°C (–250°F). The facility is in the process of installing the ‘baseline’ cryoshroud configuration, a 12 m (40 ft) diameter by 12 m (40 ft) high cylinder centered in the chamber. The chamber provides in-chamber “low-power” connections and closed-loop controls for up to 33 channels of 1,200 W heater power, and is in the process of installing additional “high-power” connections and closed-loop controls for up to 10 channels of 50,000 W heater power.
Data are acquired at the vacuum chamber via the Mobile Data Acquisition System (MDAS), a 256-channel high-speed digital system.
Space Simulation Vacuum Chamber Data
|Test pressure||<2×10–6 torr|
|Cryoshroud temperature||–160 °C to 60 °C (–250 °F to 140 °F)|
|Chamber pumping speed||500,000 L/s at 1×10–6 torr|
|Instrument penetrations (varies by test)|
|Type T thermocouple||540|
|BNC coaxial connector||126|
|Chamber diameter||30.48 m (100 ft)|
|Chamber height||37.18 m (122 ft)|
|Chamber volume||22,653 m3 (800,000 ft3)|
|Blank ports||Three each, 0.5 m diam.|
|Blank ports||Ten each, 0.68 m diam. (alternately used for high-power feed-through)|
|Blank ports||One each, 0.68 m diam.|
Reverberant Acoustic Test Facility (RATF)
The Reverberant Acoustic Test Facility (RATF) chamber is located within the Vibroacoustic High Bay, taking advantage of the 1.8-m- (6-ft-) thick surrounding concrete walls to help attenuate sound migration through the SEC. The high bay also serves as redundant protection from the RATF nitrogen atmosphere during operation. The RATF is a 2,860-m³ (101,189-ft³) reverberant acoustic chamber capable of achieving an empty-chamber acoustic overall sound pressure level (OASPL) of 163 dB. The facility structure is designed for a future upgrade to 166-dB OASPL, including areas in the horn room wall which have been left blank for future installation of additional modulators/horns. The RATF includes various supporting subsystems including a GN2 generation system, horn room with acoustic modulators and horns, acoustic control system and hydraulic supply system. Test articles are mounted onto elevated customer-provided mounting fixtures for testing. The chamber has been constructed with load-bearing wall attachments for future installation of a 5-ton interior bridge crane. The chamber can be operated as a Class 100,000 clean room once the access doors are closed and the facility is cleaned. The combinations of servohydraulic and electropneumatic noise modulators utilize GN2 capable of producing a tailored wide range of acoustic spectra in the frequency range from 25 to 10,000 Hz. The RATF chamber internal dimensions are 11.4 m wide by 14.5 m deep by 17.4 m high (37.5 by 47.5 by 57 ft).
A maximum of 19 control microphones can be placed around the test article for closed-loop control using the acoustic control system (ACS). The ACS, control microphone or other response instrumentation (accelerometers, microphones) may be input into the analog abort system (AAS) to provide automatic shutdown capability. Each of 23 servohydraulic acoustic modulators is coupled with individual horns of six different cut-off frequencies. Each of 13 electro-pneumatic acoustic modulators is coupled with individual horns of one cut-off frequency. This combination of modulators and horns provides for an extremely variable and tailored acoustic spectrum. Threaded inserts are located in the floor for attachment of test article mounting fixtures.
The east side of the chamber has a large rolling door and hinged door to provide access to the chamber up to 10.5 m (34.5 ft) in width. A 5.5-m-wide by 4.2-m-high (18- by 14-ft) door is located on the west side of the chamber for loading equipment when the vacuum chamber is occupied.
The Vibroacoustic High Bay is secured, and support systems (hydraulics, compressed air, LN2, GN2, HVAC (heating, ventilation and cooling), and video) are set up and energized. A watchdog facility control system (FCS) monitors these subsystems and ensures that all permissives and interlocks are verified. The acoustic chamber is filled with a predetermined level of GN2. The FCS verifies that a matching modulator selection file agrees with the ACS and subsequently provides a run permit to the ACS. The ACS performs a self-check, and the operator initiates testing using the tailored choice of modulators/horns. The nitrogen generation system automatically vaporizes LN2 into GN2 as required up to 1,981 standard cubic meters per minute (70,000 scfm). At the conclusion of testing, fresh air is force ventilated into the chamber via the HVAC system to purge the chamber of nitrogen for safe entry. Temperature, humidity and oxygen monitors are located in the chamber and high bay.
Data are acquired at the RATF via the facility data acquisition system (FDAS), a 1,024-channel high-speed digital system.
The RATF has been tested up to a maximum OASPL of 161 dB and is currently undergoing characterization checkout testing in preparation for customer testing in early 2013. The following are various characteristics of the acoustic facility.
Reverberant Acoustic Test Facility (RATF) Data
|Team Mk VI modulators||12|
|Team Mk VII modulators||11|
|Wyle WAS5000 modulators||13|
|Max. Empty-chamber SPLa||163 dB OASPLb|
|Frequency Range||25 Hz to 10 KHz|
|Chamber dimensions||14.5 by 11.4 by 17.4 m (47.5 by 37.5 by 57 ft)|
|Chamber volume||2,860 m3 (101,189 ft3)|
|Crane capacity||18,143 kg (40,000 lb)|
|Floor loading||54,422 kg (120,000 lb)|
|Blank penetrations||25 at 0.15 m (6 in.) diam., 2 at 0.20 m (8 in.) diam.|
aSound pressure level.
bAcoustic overall sound pressure level.
Mechanical Vibration Facility (MVF)
The Mechanical Vibration Facility (MVF is a three-axis, 6-degree-of-freedom, servohydraulic, sinusoidal base-shake vibration system located within the same Vibroacoustic High Bay as the RATF on the west side of the vacuum chamber. The proximity to the RATF allows shared use of the hydraulic system, safety systems, high-speed data acquisition system and surveillance system. The MVF system consists of reaction mass, 4 horizontal servohydraulic actuators, 16 vertical servohydraulic actuators mounted on double-spherical couplings, an aluminum table, a hydraulic supply system, table control system (TCON), vibration control system (VCON) and the same FCS used by the RATF.
The MVF reaction mass includes an embedded steel plate for modal testing. The 2,100,000-kg (4,650,000-lb) reaction mass is used to resist the vibratory energy from the hydraulic actuators, table and test article, transferring the energy into the shale bedrock foundation. The reaction mass has been sized such that it has sufficient inertia mass and stiffness to react against the forces applied by the actuator/couplings during sine vibration testing. The reaction mass has been designed to accommodate future growth in vibration system and test article mass. The existing actuator and table design is for sine sweep capability of 0 to 1.25g (peak), from 5 to 150 Hz in the vertical axis and 0 to 1.0g from 5 to 150 Hz in each of the horizontal axes for a test article mass of 34,000 kg (75,000 lb) with a center of gravity elevation of 7 m (23 ft). Currently, the MVF controller is capable of sinusoidal control in three independent axes.
The MVF system design uses a large aluminum table approximately 6.7 m (22 ft) in diameter with a 0.61-m (2-ft) wide annular mounting surface centered about a 5.5-m (18-ft) nominal diameter. Table weight is partially off-loaded from the system via four inflatable airbags.
The table vertical actuation is provided by 16 hydraulic cylinder actuators attached to the reaction mass onto which 16 double-spherical couplings are attached. The vertical actuator assemblies provide the controlled vertical sine vibration, enable horizontal vibration and provide overturning constraints during horizontal vibration. The table rests on the double-spherical couplings. The double-spherical couplings couple each vertical actuator to the table and provide high-axial stiffness to deliver the vertical vibratory force during vertical excitation. Each double-spherical coupling has internal pressure sensors to enable the vibration controller to limit forces. Four horizontal actuators provide the controlled horizontal sine vibration and comprise two single-ended pistons, which maintain outward force through hydrostatic pad-bearings to the table. The horizontal actuator assemblies provide vertical alignment during vertical actuation. The system is designed to permit testing in three independent axes without removing or lifting the test article from the table.
A customer-supplied adapter ring is necessary to attach the test article to the vibration table mounting holes. The Vibroacoustic High Bay is secured, the support systems (hydraulics, compressed air, life safety, video and table mode) are setup and energized and interlocks are verified (including vibratory mode-choice setup) using the FCS. The TCON and FCS communicate with the table actuator servovalve drivers; position the table to a lifted, centered, ready position; and verify all servodrivers are started and ready. Operators then initiate the VCON to generate the sine wave inputs to the servovalve controllers, establishing vibration. The VCON controller generates drive voltage waveforms for each servovalve driver to satisfy the control and limit channel constraints from the test article (outer-loop control), and each servovalve driver maintains a closed-loop control to each actuator (inner-loop control). The VCON has 64 analog input channels, which can be assigned to control channels, limit channels or response channels, where the control and limit channels can be set to alarm and/or abort a test. Up to 44 of the analog input channels can be available for test article limit channels. Data are acquired at the MVF via the FDAS, a 1,024-channel high-speed digital system.
Mechanical Vibration Facility
|Max. test article mass||34,000 kg (75,000 lb)|
|Max. Cg above table||7.2 m (23.6 ft)|
|Seismic mass||2,100,000 kg (4,650,000 lb)|
|Max. vertical static force||3,203 kN (720,000 lb)|
|Max. vertical dynamic displacement (peak-to-peak)||3.18 cm (1.25 in.)|
|Max. vertical velocity||41.7 cm/s (16.4 in./s)|
|Max. lateral static sorce||1,139 kN (256,200 lb)|
|Max. lateral dynamic displacement (peak-to-peak)||3.048 cm (1.2 in.)|
|Max. lateral velocity||33.8 cm/s (13.3 in./s)|
|Frequency range||5 to 150 Hz|
|Sine sweep rate||Dwell to 4 oct/min|
|Table mounting bolt-circle diam.||518.16, 538.48, 558.8, and 579.12 cm (204, 212, 220, and 228 in.)|
|Max. test article height||23.5 m (77 ft)|
|Max. test article height below crane bridge||20.4 m (67 ft)|
|Sine sweep rate||Dwell to 4 oct/min|
Data Acquisition Systems
The SEC commissioned a new 1,024-channel high-speed FDAS which serves the RATF facility. The architecture was leveraged to provide a separate, smaller-scale (256-channel) mobile data acquisition system (MDAS) for use with the thermal vacuum chamber. The FDAS system includes test article sensor interface cabling, signal conditioners, data recording, data storage, display and archive systems.
The FDAS system can provide a minimum of 20 kHz analog bandwidth per channel, for all 1,024 channels. Data are synchronized by an external facility Inter-Range Instrumentation Group (IRIG)-B signal. Data are stored within four, 3-TB redundant arrays of independent disks (RAIDs). The FDAS currently has 800 signal conditioners of the integrated electronic piezoelectric (IEPE) type for accelerometers or microphone conditioning.
After commissioning the FDAS system, the SEC constructed a close-coupled, 256-channel MDAS to measure the high-bandwidth thermal vacuum instrumentation signals using similar architecture to the FDAS. In addition, the thermal vacuum facility has a 512-channel digital temperature scanner system for any thermocouple type, which includes isothermal blocks, analog-to-digital conversion (ADC) and a microprocessor, which outputs temperature data to the MDAS system. The MDAS and FDAS systems have successfully been used as the primary data systems for recent fairing deployment and acoustic tests.
Overall Facility Layout/Configuration
The SEC was originally constructed in 1969 to perform nuclear and nonnuclear testing of large space systems needed for advanced missions beyond low-Earth orbit. The facility was designed with excess capacity such as extremely large high bays, doors, power systems and supporting infrastructure to accommodate expanding test requirements well into the future of the space program.
The SEC aluminum vacuum chamber surrounded by the concrete vacuum enclosure is central to the facility. The large east and west chamber doors (15 by 15 m) lead directly into large high bays. The high bay on the east side of the facility, the Assembly High Bay, is primarily used for receiving, assembling and preparing test hardware. The high bay on the West side of the facility, the Disassembly High Bay, was originally constructed to safely disassemble nuclear components. The recent construction project converted this area into the Vibroacoustic High Bay, housing the MVF and the RATF. North and south of the chamber and high bays are various supporting areas. North of the chamber are the facility control rooms, signal conditioning and instrumentation areas, machine shop and two-story office building. The office building contains 41 offices and 4 conference rooms. South of the chamber are the electric substations, cryogenics room, vacuum room and mechanical rooms. The south outdoor courtyard areas behind the SEC support the LN2 and GN2 storage bottles, vaporizers and cooling tower.
Assembly High Bay
Adjacent and east of the vacuum chamber is the Assembly High Bay, primarily used for setup and assembly of test hardware and ground-support equipment. The high bay is approximately 22.86 m (75 ft) wide by 45.72 m (150 ft) long with a clear height under the 22.68 t (25-ton) bridge crane of 22.86 (75 ft). Doors leading outdoors and into the vacuum chamber measure 15.24 by 15.24 m (50 by 50 ft). The high bay contains three sets of parallel, standard-gauge rail tracks to permit rolling stock and dolly transport from outdoors, into the assembly high bay, the vacuum chamber, and into the vibroacoustic high bay.
Vibroacoustic High Bay
Adjacent and west of the vacuum chamber is the Vibroacoustic High Bay, which houses the MVF, a modal floor and the RATF facility. The high bay has a clear height under the (18.14 t) (20-ton) bridge crane of 62 feet. Doors into the vacuum chamber measure 15.24 by 15.24 m (50 ft by 50 ft).
The SEC houses the world’s largest space environment simulation chamber, measuring 30.48 m in diameter by 37.19 m high (100 by 122 ft). In this chamber, large space-bound hardware can be tested in a severe environment similar to that encountered in space. The facility can sustain a high vacuum and simulate solar radiation via a 4-MW quartz heat lamp array, solar spectrum by a 400-kW arc lamp and cold environments with a variable-geometry cryogenic cold shroud.
|Name:||Space Environments Complex (SEC)|
|Test area space simulation vacuum chamber|
|Key features:||Low-earth-orbit plasma simulation
Cryogenic shrouds (cold walls)
Large clean high bays
Accessibility by air, ground, or water transportation
Class 100,000 clean room
|Reverberant acoustic test facility (RATF)|
|Key features:||Reverberant acoustic chamber
GN2 generation system
Horn room with acoustic modulators and horns
Acoustic control system
Hydraulic supply system
|Mechanical vibration facility (MVF)
|Key features:||Embedded steel plate for modal testing (2,100,000 kg/4,650,000 lb reaction mass)
Large aluminum table – 6.7 m (22 ft) in diam.
Wide annular mounting surface – 0.61 m (2 ft) wide
16 hydraulic cylinder actuators
- Recent hardware additions to the SEC include the RATF, a 2,860 m³ (101,189 ft³) reverberant acoustic chamber capable of achieving an empty-chamber OASPL of 163 dB.
- A further addition is the MVF, a three-axis, 6 degree-of-freedom, servohydraulic, sinusoidal base-shake vibration system located within the same Vibroacoustic High Bay as the RATF on the west side of the vacuum chamber.
- The SEC was designed to test nuclear and nonnuclear space hardware in a simulated low-Earth-orbit environment.
- Ithas supported Mars lander system tests, ISS hardware tests and rocket-fairing separation tests.
- Itsustains high vacuum, simulates solar radiation and produces cold environments via a cryogenic cold wall.
- The SEC has two 15.24 by 15.24 m (50 by 50 ft) entrances and a 18.14 t (20-ton) vacuum compatible polar crane on top of the chamber.
- Sustains high vacuum
- Simulates solar radiation (400-kW arc lamp)
- Simulates solar radiation (4-MW quartz heat lamp array)
- Produces cold environments via cryogenic cold shroud (–160°C, –320°F)
- Provides a high degree of vibration isolation
- 30.48-m- (100-ft-) diameter by 37.19-m- (122-ft-) tall test area
- Designed for external pressure of 1.19 bar (2.5 psig)
- Designed for internal pressure of 1.36 bar (5.0 psig)
- Chamber floor designed for a load of 272.16 t (300 tons)
- Two 15.24 by 15.24 m (50 by 50 ft) entrances, 180° apart
- Personnel entry door measuring 2.44 by 2.44 m (8 by 8 ft)
- 18.14 t (20-ton) vacuum compatible polar crane at top of chamber
- Chamber penetrations for power, data acquisition and high-pressure liquids and gases
- Concrete chamber enclosure, 1.83 to 2.44 m (6 to 8 ft) thick
Vacuum Pumping System
- Five 2,200 L/s (581.18 gal/s) turbopumps
- Sixteen 1.22-m- (48-in.-) diameter LN2-baffled electrically heated, oil diffusion pumps (pumping speed—700,000 L/s (184,920 gal/s))
- Ten 1.22-m- (48–in.-) diameter cryopumps with vacuum isolation gate valves (pumping speed—600,000 L/s/158,500 gal/s)
- Pumpdown times:
- Atmospheric pressure to 20 torr (0.79 inHg)—2 hr
- 20 to 1×10–3 torr (0.79 to 1.18´10–4 inHg)—4 hr
- 1×10–3to 1×10–6torr (1.18´10–4 to 1.18´10–7 inHg)—2 to 6 hr
- Cooling tower water to dissipate waste heat produced by such devices as GN2 compressors and vacuum pumps
- Domestic and fire water: 567,810 L (150,000 gal) water tower
- Demineralized water system
- GN2: 3,822,800 L (135,000 ft³) at 166.49 bar (2,400 psig)
- GN2 (trailer): 1,982,200 L (70,000 ft³) at 166.49 bar (2,400 psig)
- Helium: 6,229,700 L (220,000 ft³) at 194.07 bar (2,800 psig)
- Variable geometry
- Can be configured inside the test chamber
- Cryoshroud is 12.80 m wide by 24.38 m long (42 by 80 ft) with a 6.71-m (22-ft) height
- Alternate configuration—12.19-m- (40-ft)-diameter cylinder by 12.19 m (40 ft) tall
- Ten individual zones with separate temperature control
- Temperatures from ambient to –156.67°C (–250°F)
- Temperature transition of 0.56°C (1°F) per min
- Capable of removing 14 MW of heat from cryoshroud
- 7 MW of power available for infrared heat lamps
- 400 kW solar simulator
Reverberant Acoustic Test Facility
- Reverberant acoustic chamber
- 14.5 by 11.4 by 17.4 m (47.5 by 37.5 by 57 ft)
- Chamber volume: 2,860 m³ (101,189 ft³)
- GN2 generation system
- Horn room with acoustic modulators and horns
- Acoustic control system
- Hydraulic supply system
Mechanical Vibration Facility
- Three-axis, 6-degree-of-freedom, servohydraulic, sinusoidal base-shake vibration system
- Embedded steel plate for modal testing (2,100,000 kg/4,650,000 lb reaction mass)
- Large aluminum table—6.7 m (22 ft) in diameter
- Wide annular mounting surface—0.61 m (2 ft) wide
- 16 hydraulic cylinder actuators
- Facility data system
- Slow speed test data acquisition system (1 Hz continuous)
- High-speed test data acquisition system (100 kHz sampling rate using ΣΔ sampling)
Space Environments Complex Facility
Facility Manager—David Taylor
21000 Brookpark Rd., MS 6-8
Cleveland, Ohio 44135
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