What Is Thermal Vacuum?
The thermal vacuum test is a space qualification test in which the specimen is subjected to temperature cycles under high vacuum, evaluating its function and thermal behaviour.
Purpose of Thermal Vacuum
The purpose is to verify that the spacecraft component operates within its expected temperature range under the convection-free heat-transfer conditions of vacuum.
Which Products Is Thermal Vacuum Applied To?
- Satellite subsystems
- Space electronics
- Thermal-control equipment
- Mechanisms and actuators
In Which Sectors Is Thermal Vacuum Used?
Standards Related to Thermal Vacuum
- ECSS-E-ST-10-03
- MIL-STD-1540
- NASA-STD-7002
Thermal Vacuum Conditions
- Vacuum
- High vacuum defined in the standard
- Temperature range
- Hot and cold extremes defined according to the mission profile
- Number of cycles
- Different according to qualification and acceptance levels
- Dwell
- Until thermal equilibrium is reached at each extreme
Equipment for Thermal Vacuum
- Thermal vacuum chamber
- Cold-shock-cooled thermal shrouds
- Multi-channel temperature recording
- Function monitoring and telemetry
Sample Requirements for Thermal Vacuum
- The specimen must represent the flight configuration
- Thermocouple locations must be determined
- Function monitoring must be set up via telemetry
- Cleanliness class must be maintained
Duration of Thermal Vacuum
It depends on the number of cycles; qualification programmes can take weeks.
Thermal Vacuum Procedure
- 1The specimen is set up in the chamber and instrumented.
- 2The system is pumped down to vacuum.
- 3Hot and cold extreme cycles are applied.
- 4Thermal equilibrium is awaited at each extreme and function is checked.
- 5The defined number of cycles is completed.
- 6A final function check and visual inspection are performed.
Thermal Vacuum Acceptance Criteria
The acceptance criterion is defined in the programme: continuity of function throughout all cycles and temperatures staying within design limits.
Evaluation of Results
Since there is no convection in vacuum, conduction and radiation dominate; temperatures therefore come out differently than in atmospheric tests.
Thermal Vacuum Report
- Standard applied
- Vacuum level and temperature profile
- Number of cycles
- Measured temperatures
- Function results and telemetry records
Accreditation
EUROLAB holds internationally recognised accreditation obtained from accreditation bodies party to the IAF and ILAC multilateral recognition arrangements, under ISO/IEC 17025 for laboratory testing, ISO/IEC 17020 for inspection and surveillance, and ISO/IEC 17021-1 and ISO/IEC 17065 for system and product certification. This chain ensures the reports and certificates issued are accepted worldwide.
Whether this test can be offered within accredited scope depends on your product and the standard applied; since accreditation is method-based, the scope is confirmed in writing at the quotation stage.
Scope and authorisationsRelated Regulations
- Space qualification specifications
Aerospace Testing — What Does This Testing Field Cover?
The section below describes the field that the Thermal Vacuum test belongs to; the conditions and acceptance criteria of this particular test are given in the sections above. The scope specific to your product is confirmed in writing at the quotation stage.
Aerospace testing shows that equipment keeps working in the flight environment and provides evidence for the airworthiness file. In this family the acceptable probability of failure is several orders of magnitude lower than in other sectors; this directly determines the scope of testing and the certification burden.
The most distinctive feature of the field is TRACEABILITY. Which melt an aircraft part came from, in which heat treatment furnace and with which cycle it was processed, which operator made the weld and which inspector approved it are all recorded. The test report is one link in this chain; if the chain is broken, the report carries no value on its own.
Environmental qualification runs through RTCA DO-160, with categories selected according to the equipment's MOUNTING LOCATION in the aircraft. A device mounted on the cockpit panel and one mounted inside the wing pass the same section under different categories. When reading a DO-160 report it is therefore essential to know which sections were applied at which categories.
On the software and complex hardware side the approach changes entirely: the evidence is not testing but PROCESS ASSURANCE. DO-178C for software and DO-254 for complex electronic hardware define how the development process is to be run and which evidence is to be produced. Every step, from requirement to code, from testing of the code to coverage analysis, must be traceable. Testing software does not make it certifiable; the process record does.
A separate body of work applies on the material and special process side. AWS D17.1 is used for welding, SAE AMS 2750 for pyrometry in heat treatment and NAS 410 for non-destructive testing personnel. For special processes (heat treatment, coating, welding, NDT, bonding) NADCAP accreditation is effectively mandatory in the supply chain; without NADCAP it is not possible to sell parts to many OEMs.
On the quality system side the AS/EN 9100 series is used: 9100 for manufacturers, 9110 for maintenance organisations and 9120 for distributors. Without these certificates it is practically impossible to enter the aerospace supply chain, and audits are markedly more detailed than in other sectors.
Counterfeit part risk is a subject peculiar to the field. Separate standards and verification methods (visual inspection, X-ray, decapsulation and internal structure examination, XRF) are used to detect counterfeit or reworked parts in the electronic component supply chain.
Space applications add further layers: outgassing in vacuum, radiation tolerance, long-duration thermal vacuum cycling and assessment of single event effects.
Method groups in this field
Environmental qualification
RTCA DO-160 sections: temperature and altitude, vibration, shock, humidity, sand and dust, fungus, salt fog, fluid susceptibility, icing, lightning.
Electromagnetic
The EMC sections of DO-160; MIL-STD-461 and MIL-STD-704 power characteristics on military platforms.
Software and hardware assurance
DO-178C software life cycle and DO-254 hardware design assurance evidence; requirement traceability and coverage analysis.
Materials and welding
Welding qualification under AWS D17.1, mechanical testing of materials, metallography and non-destructive examination.
Special process control
SAE AMS 2750 pyrometry, coating and heat treatment process verification, preparation for NADCAP audits.
Space environment
Thermal vacuum cycling, outgassing, radiation tolerance and acoustic/vibration qualification.
Commonly confused in this field
- There is no such document as a "DO-160 certificate"; DO-160 is a test specification and its output is a qualification report.
- The selection of sections and categories comes from the customer's equipment specification; the laboratory cannot make that selection on its own.
- DO-178C and DO-254 cannot be satisfied by testing; the evidence is the traceability of the development process.
- An AS9100 certificate is not a product approval; it is a quality system certificate and part approval runs separately.
- For special processes, work carried out without NADCAP is not accepted in the supply chain even when it is technically correct.
- MIL-STD-810 and DO-160 are often confused: one is a military and the other a civil aviation specification, and their profiles differ.
Which decisions these results support
- Airworthiness and TSO/ETSO files
- Entry into the aerospace supply chain and supplier approval
- Special process approval and NADCAP preparation
- Determining the impact of a design change on qualification
- Managing counterfeit part risk and component verification
Related Tests
Frequently Asked Questions About Thermal Vacuum
According to which standard is Thermal Vacuum made?
Thermal Vacuum is executed in scope ECSS-E-ST-10-03, MIL-STD-1540 and NASA-STD-7002. The limit values and acceptance criteria to be applied are defined in the product standard; The version valid for your product is confirmed in writing at the offer stage.
Which products does Thermal Vacuum apply to?
Mainly applied to Satellite subsystems, Space electronics, Thermal-control equipment and Mechanisms and actuators. Whether your product is included in the scope is determined by examining its technical specifications and intended use.
Under what conditions is Thermal Vacuum done?
The determining parameters are: Vacuum — High vacuum defined in the standard, Temperature range — Hot and cold extremes defined according to the mission profile and Number of cycles — Different according to qualification and acceptance levels. The full terms are in the "Test Conditions" section on the page and vary depending on the product standard.
What kind of sample is needed for Thermal Vacuum?
The specimen must represent the flight configuration, Thermocouple locations must be determined and Function monitoring must be set up via telemetry. The number of samples is determined according to the product standard and the scope to be reported.
How long does Thermal Vacuum take?
It depends on the number of cycles; qualification programmes can take weeks. This duration belongs to the experiment itself; sample preparation, queuing and reporting are also evaluated. A realistic schedule for your product is given in the offer.
What is the Thermal Vacuum result called "appropriate"?
The acceptance criterion is defined in the programme: continuity of function throughout all cycles and temperatures staying within design limits.