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Thermal Vacuum

Encyclopedia
Updated Feb 12, 2024

Contents

Introduction

Thermal Vacuum testing is critical for designing spaceflight hardware to ensure its resilience and functionality in the extreme environment variations encountered in outer space. Johnson Space Center (JSC) Thermal Vacuum Test Facilities provide thermal vacuum chamber test operations for both crewed and uncrewed test environments. The facilities offer a wide range of performance capability, which can be matched to the individual test requirements of smaller test articles or large test article components and subsystems. JSC offers lunar environmental test capabilities for subsystem and system hardware and assemblies. This capability complements existing Agency resources for both ambient dust testing and dirty thermal vacuum capability.  Typical uses of these chambers have included development, engineering evaluation, and qualification testing of spacecraft components, subassemblies, and experiments; and preflight thermal-vacuum conditioning of flight hardware. 

JSC is also home to the Radiant Heat Test Facility, originally constructed to perform development and certification tests for the Space Shuttle thermal protection system (TPS). Two test chambers are equipped with vacuum pumps and heater assemblies to produce a variable pressure profile and heat fluxes for simulating atmospheric re-entry conditions. We invite customers to leverage our diverse range of thermal testing capabilities in order to pursue our collective exploration of the solar system. 

Human-Rated Testing

JSC Chamber B 

Overview | Chamber B is used for human testing in a vacuum environment and for crewed space operations testing. 

Details | NASA JSC Chamber B provides space environmental testing with vacuum thermal conditions. Chamber B is a human-rated chamber equipped with a traversing monorail that provides weight relief to one suited crew member at a time. The chamber also has dual crew airlocks to provide easy access to the test articles as well as a means of transporting test crew members to the test environment and back during tests.  Chamber B has an internal volume of 7.6 m (25 ft) diameter x 7.9 m (26 ft). Its usable test volume and high-fidelity space simulation capabilities are adaptable for thermal vacuum testing of a wide variety of test articles.​ The low temperature range of the chamber is -300° F. The pressure range of the chamber is from 1×10^-6 torr to 760 torr. 

Thermal-Vacuum Human-Rated Testing 

Overview | Johnson Space Center (JSC) is the world leader in human-rated testing in a simulated space environment, offering human testing in vacuum, thermal– vacuum, and vibration environments. JSC offers a collection of unique knowledge and experience as to what works well within the hostile environment of space and what does not. This knowledge is available to support crewed spacecraft and space system hardware design reviews and flight– like simulation of Extravehicular Activity (EVA) operations in pressures ranging from vacuum to one atmosphere. 

Details |

  • Human-rated hardware testing in vacuum and thermal–vacuum environments
  • Space suit development testing
  • Flight crew training 
  • Environmental control and life support system testing 
  • Metabolic loading to life support systems 
  • Parametric testing 
  • Emergency and mobility accommodations of suited crew person 

Human-in-the-loop air revitalization system testing 

  • Carbon dioxide (CO2) removal or reduction testing 
  • Oxygen (O2) generation testing 
  • Trace contaminant control testing 

Human-rated vibration testing 

  • Thermal analysis, including human thermal modeling 

Thermal Vacuum Testing

JSC Chamber A 

Overview | Chamber A is the largest of the thermal-vacuum test facilities at JSC. The chamber’s usable test volume and high-fidelity space simulation capabilities are adaptable for thermal-vacuum testing of a wide variety of test articles, including entire space vehicles. 

Details | NASA JSC Chamber A provides a high vacuum thermal chamber with a usable test volume and space simulation capabilities that are adaptable for testing entire space vehicles. The chamber can simulate low temperatures of deep space (35K) within a 55 feet diameter by 80 feet tall shroud volume.​ The pressure range of the chamber is from 1×10^-6 torr to 760 torr. Additional test support equipment includes mass spectrometers, infrared cameras, and television cameras. The numerous flanges at all levels provide ample pass-throughs for electrical, instrumentation, and gasses to support large systems. 

Specialized Chambers and Environmental Test Complex 

Overview | Contains a collection of chambers of varying thermal & thermal/vacuum environment capabilities configured for testing hardware ranging from flight (qualification) to development hardware in support of JSC Government Furnished Equipment (GFE) activities.​ 

Details |

  • Temperature and humidity cycling
  • Accurate determination of design factors 
  • Operating temperatures 
  • Changes in absorptive or emissive properties of thermal coating 
  • Changes in electrical or mechanical properties of materials
  • Accelerated electrical or electronic components burn-ins and life-cycle testing 
  • Environmental cycling (thermal and humidity) for materials survivability 

Thermal Vacuum Testing 

Overview | Johnson Space Center (JSC) Thermal Vacuum Test Facilities provide thermal vacuum chamber test operations for both manned and unmanned test environments. The facilities offer a wide range of performance capability, which can be matched to the individual test requirements of smaller test articles or large test article components and subsystems. Typical uses of these chambers have included development, engineering evaluation, and qualification testing of spacecraft components, subassemblies, and experiments; preflight thermal– vacuum conditioning of flight hardware; development and calibration of instruments for use in the large chambers or in– flight; spacecraft seal studies; photographic film emulsion studies; and optical surface contamination studies. 

Details | Human-rated space environmental testing 

  • 12.5-foot internal diameter spherical chamber with ~78-inch diameter clear entry for easy access
  • Materials outgassing evaluations 
  • Accelerated electrical and electronic component burn-ins and life-cycle testing 
  • Environmental cycling (thermal and humidity) for materials survivability 
  • Materials and hardware testing in extreme environments (manned and unmanned) 
  • Determination of design factors
  • Operating temperatures 
  • Combined thermal and pressure-load distortions of dimensionally critical structural elements 
  • Fluid and gas leak rates 
  • Changes in absorptive or emissive properties of thermal coating 
  • Evolution of harmful or undesirable offgassing products
  • Presence of conditions conducive to electrical arc or corona discharge 
  • Thermal analysis, including human thermal modeling 

RITF Thermal Vacuum Chambers 

Overview | Thermal Vacuum chambers are used to test or prove out a design prior to flight to ensure its reliability. The Receiving, Inspection and Test Facility (RITF) team operates two TVAC chambers capable of housing units approximately 24” X 24”.

Details | The purpose of the RITF TVAC chambers are to expose payloads, mechanisms, or components to representative space environment conditions – a vacuum state combined with repeated cycling between high and low thermal extremes to assess their likely flight performance. Heating and cooling of components and devices can be investigated using the chamber.

  • Vacuum Range:  Up to 5×10-6 torr 
  • Temperature range: -100°C to + 250°C
  • 24″ x 24″ internal space

Dust Chambers

15-foot Dirty Thermal Vacuum Chamber 

Overview | NASA JSC 15-foot dirty thermal vacuum chamber (TVAC) provides unique testing capabilities for dust and planetary surface environments. The 15-foot chamber is a spherical chamber designed to test advanced concepts, especially for battery power systems, space vehicle actuators and auxiliary power units. 

Details |

  • 12.5-foot internal diameter spherical chamber with ~78-inch diameter clear entry for easy access
  • Vacuum conditions: 1×10^-6 torr to 760 torr 
  • Thermal conditions: -186°C to +120°C 
  • Air, GN2 pressurization
  • Feed-throughs for high-power electrical connections and high-channel count data 
  • Control automation enabling low-cost operations 
  • Ambient dust containment room for regolith control and testing 
  • Hardware exposure testing to dust / regolith 
  • Regolith bin for design and test of excavation, processing, or construction technology

3-foot Dirty Thermal Vacuum Chamber 

Overview |  NASA JSC’s 3-foot dirty thermal vacuum chamber (TVAC) provides unique testing capabilities for dust and planetary surface environments. The 3-foot chamber is a 3ft x 3ft x 3ft cube designed to test component level concepts in a lunar simulated environment.

Details |

  • Thermal Vacuum capability with dust mitigation for pumping system
  • 36”x36”x36” (0.9m x 0.9m x 0.9m) cube shape
  • Rough or High vacuum (10^-5 torr range quickly, 10^-7 torr demonstrated)
  • Shroud temperature range of -300°F to +300°F (-185°C to +148°C)
  • Shroud walls independently controlled for zone temperature conditioning if needed

Regolith Simulant Component Test Lab 

Overview | The Component Test Lab offers multiple small vacuum environments for testing in simulant and a simulant dispersal test box with ambient dispersal capabilities. 

Details |

  • Multiple 1’-3’ thermal vacuum bell jars for testing with simulant
  • Ambient 2’ x 2’ x 3’ dust box for quick and easy functional testing with fan-blown simulant 
  • Vacuum box with glove ports and airlock chamber
    • Capable of reaching 0.05 torr (ultimate)
    • Air or GN2 repress
    • Dimensions:
    • Chamber: 1.1m x 0.74m x 0.9m (44” x 29” x 35”)
    • Airlock: ⌀0.36m x 0.41m (⌀14” x 16”)
  • Settling Dust Chamber
    • Meets the following industry standards for dust exposure
      • SAE J575 Section 4.5
      • DIN 40050, Part 9, IP Codes 5K and 6K
      • ISO 20653, Section 8.3.1
      • IEC 529, IP Codes 5 & 6
    • 72”x36”x30” (1.8m x 0.9m x 0.76m) interior
    • Max test article weight: 50 lbs (22.7 kg)
    • Timed dusting allows for repeated application of dust to moving test articles
    • Validated for use with lunar simulants

Thermal Testing

Thermal Testing 

Overview | Johnson Space Center (JSC) thermal test facilities offer a wide range of performance capability, which can be matched to the individual test requirements of smaller test articles or large test article components and subsystems. Typical uses of these chambers have included development, engineering evaluation, and qualification testing of spacecraft components, subassemblies and experiments, and preflight thermal conditioning of flight hardware. 

Details | Temperature and humidity cycling 

  • Accurate determination of design factors 
  • Operating temperatures 
  • Changes in absorptive or emissive properties of thermal coating 
  • Changes in electrical or mechanical properties of materials 
  • Accelerated electrical or electronic components burn-ins and life-cycle testing
  • Environmental cycling (thermal and humidity) for materials survivability 
  • Battery performance and abuse testing 
  • Thermal analysis, including human thermal modeling 
  • Subscale evaluation of thermal components 

Radiant Heating Test Facility (RHTF) 

Overview | The Radiant Heat Test Facility (RHTF) provides for simulation of the heating experienced by spacecraft as they enter planetary atmospheres. The facility provides the capability to perform multi-zone, high-temperature, radiant heat testing of large spacecraft thermal protection systems and associated structures in a controlled pressure environment to simulate entry thermal profiles, thermal gradients, and pressures. 

Details |

  • Basic material testing and screening
  • Development testing – gaps, seals, and attachments 
  • Clipped hardware 
  • RCS nozzles, antennas, instrument penetration, windows, and hatches
  • Sustaining Engineering 
  • Orbital debris 
  • Design changes 
  • Recertification of materials 
  • Simulation
  • Ascent heating and pressure decay 
  • On-orbit cold soak 
  • Reentry heating and pressure 
  • Uniquely shaped large scale system tests 
  • Nose cap
  • Wing leading edge 
  • Small scale tests 
  • Materials screening 
  • Conductivity testing 
  • Advanced materials

Thermal Conditioning (Burn-in)

Overview | The Receiving, Inspection and Test Facility (RITF) team maintains multiple temperature and humidity chambers to provide testing support of electronics, composites, and other materials that a customer may need screened. Burn-in is the process by which components of a system are exercised prior to being placed in service (and often, prior to the system being completely assembled from those components). 

Details | Burn-in is a test performed for the purpose of screening or eliminating marginal devices, those with inherent defects or defects resulting from manufacturing aberrations which cause time and stress dependent failures. The combination of variable humidity and temperature are a particular concern for the design of electronics, where moisture build up may lead to short circuiting and product failure. Similarly, high, and low humidity can affect electrical characteristics such as increased conductivity at higher humidity or electrostatic discharges at lower humidity. This screening capability can be used to identify design faults/problems that if corrected in the early stages of the design phase will save rework later.

  • Thermal Conditioning (Burn -In) Temperature Range:  -100 degC to +300 degC
  • Thermal Cycling Range from -100 degC to +125 degC
  • Humidity Cycling Range from +250 degC to +850 degC @ 20% RH to 85% RH (Relative Humidity)
Inside NASA’s giant thermal vacuum chamber, called Chamber A, at NASA’s Johnson Space Center in Houston, the James Webb Space Telescope’s Pathfinder backplane test model, is being prepared for its cryogenic test. Previously used for manned spaceflight missions, this historic chamber is now filled with engineers and technicians preparing for a crucial test. Exelis developed and installed the optical test equipment in the chamber. The optical test equipment was developed and installed in the chamber by Exelis, said Thomas Scorse, Exelis JWST Program Manager. The Pathfinder telescope gives us our first opportunity for an end-to-end checkout of our equipment.
Engineers and technicians at NASA’s Johnson Space Center in Houston are testing the spacesuit astronauts will wear in the agency’s Orion spacecraft on trips to deep space. On June 22, 2017, members of the Johnson team participated in a Vacuum Pressure Integrated Suit Test to verify enhancements to the suit will meet test and design standards for the Orion spacecraft. During this test, the suit is connected to life support systems and then air is removed from Johnson’s 11-foot thermal vacuum chamber to evaluate the performance of the suits in conditions similar to a spacecraft. The suit will contain all the necessary functions to support life and is being designed to enable spacewalks and sustain the crew in the unlikely event the spacecraft loses pressure. Part of Batch images transfer from Flickr.
Space Shuttle Discovery’s underside nosecone thermal protection tiles are featured in this image photographed by astronaut Stephen K. Robinson, STS-114 mission specialist, during the mission’s third session of extravehicular activities (EVA). Part of the P1 truss and a solar array are visible in the background. The blackness of space and a blue and white Earth form the backdrop for the image.

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