1. The short version / what to know first / where this fits in the series

• Where they fit: light structures, insulation, wiring and sliding parts. Carbon-fiber-reinforced PEEK was reported to show no change in its thermal expansion over about four months in an in-orbit experiment on Ten-Koh, a small satellite from the Kyushu Institute of Technology. The NASA database holds records with applications as sensor frames, insulating isolators and cable tubing Sourced[Ref. 3, 14]
• The strength is "little gas"; the weaknesses are "erodes, softens and traps heat". PEEK's outgassing is small in most NASA records, and even 3D-printed PEEK gave an RML of 0.11 % in an ESA test. On the other hand, its atomic-oxygen erosion yield is 2.99 for PEEK and 3.00 for Kapton H (× 10^-24 cm³ per atom), about the same. It loses stiffness above its glass transition (about 143 °C), and because its thermal conductivity is low, an analysis reports local temperatures approaching that point Sourced[Ref. 1, 4]
• 3D printing offers freedom, but we could not confirm a flight record. Printed parts lose density and elongation to pores. The tests outside the ISS were done on printed PEI (Ultem) and PEKK; printed PEEK is at the ground-test stage Sourced[Ref. 4, 5, 6]

2. Background: super engineering plastics and the "five enemies" of space

"Super engineering plastic" is a name for resins with higher heat resistance, strength and chemical resistance than general engineering plastics such as polyamide or polycarbonate. No law or standard defines it. This article centers on PEEK (polyetheretherketone) and covers PEI (polyetherimide, trade name Ultem), PPS (polyphenylene sulfide), PSU and PES (polysulfone types), LCP (liquid crystal polymer) and PAI (polyamide-imide, trade name Torlon), with polyimide and PBI (polybenzimidazole) alongside for comparison.

Here are PEEK's basic numbers, as given in the datasheet values a paper cited: glass transition temperature 143 °C, melting point 343 °C, thermal conductivity 0.25 W/m·K, density 1.30 g/cm³, tensile modulus 4 GPa Sourced[Ref. 4].

This series organizes the space environment as five enemies. A satellite in orbit is in a state of "falling while moving sideways fast enough never to hit the ground", and low orbit near 400 km still holds a thin atmosphere with oxygen atoms. How super engineering plastics fare against the five enemies is shown below (the orbit story is told in more detail in Chapter 2 of our explainer on polyimides for space).

3. Where they are used in space

The uses we could confirm from primary sources are summarized in the figure and table below.

View original SVG, values and sources

Original SVG reference: Concept diagram (vector drawing). Where PEEK-class plastics are used inside a spacecraft, and the evidence we could confirm. The layout is illustrative and does not show any specific satellite. Item 5 (3D printing) is at the ground-test stage.

The "enemy covered" column is this article's organization of what the sources say (commentary). The "application" field in the NASA database is the description written by whoever requested the test, not a guarantee that the material flew or may be used (our reading). We did not check how much is used on spacecraft.

4. As a structural material: the orbital record of carbon fiber and PEEK

Among super engineering plastics, the best-documented space record is the in-orbit measurement of thermal expansion of carbon-fiber-reinforced PEEK (CF/PEEK).

Ten-Koh, a small satellite of the Kyushu Institute of Technology, was launched on 29 October 2018 and orbits in a sun-synchronous orbit at about 600 km. It carried a "material mission" with three CF/PEEK samples (50 mm long, 10 mm wide, 2 mm thick) and measured their coefficient of thermal expansion (CTE) in orbit using strain gauges. The samples were made of plain-woven carbon fabric from Toray and PEEK from Victrex, and two of the three had a protective coating (one for ultraviolet light, one for atomic oxygen) Sourced[Ref. 3].

All Sourced (Abdullah et al., Aerospace 2020 [Ref. 3]). The in-orbit CTE values differ between samples because of strain-gauge misalignment; the authors attribute the differences between orbit and ground data to that misalignment and to different heating and cooling rates.

5. Enemy 1, vacuum: outgassing varies greatly by material

The outgassing test (measuring mass loss and condensation in vacuum) and the meaning of TML, RML, WVR and CVCM are explained in detail in Chapter 4 of our explainer on polyimides for space. A quick recap: TML is the total mass lost, WVR is the water regained, RML = TML − WVR is the loss excluding water, and CVCM is what condensed on a cold plate. ECSS-Q-ST-70-02C runs the test in vacuum (10^-3 Pa or lower) at 125 °C for 24 hours, and sets minimum screening values for material selection of RML < 1.0 % and CVCM < 0.10 % Sourced[Ref. 13].

Three points in reading the figure.

• PEEK, PPS and LCP often show little gas. The PEEK molding compound has a TML of 0.26 % (RML 0.14 % without water), PPS 0.05 % and LCP 0.03 %. Rinaldi and colleagues say the high crystallinity of PEEK is what to expect behind its low outgassing Sourced[Ref. 14, 4].
• PAI, polyimide, PBI and PES have records with large TML. ECSS says the TML of water-absorbing materials (polyamides, polyimides, polyurethanes and so on) is often above 1.0 % Sourced[Ref. 13]. In the figure, Vespel SP-1 (polyimide) has a TML of 1.04 % but an RML of 0.85 %, while Torlon 4203 (PAI) has a TML of 1.68 % and, even without water, an RML of 1.36 %, over the limit. Yet another Torlon, 5030 (a different grade), has a TML of 0.42 % and an RML of 0.20 %, so values differ greatly by grade Sourced[Ref. 14].
• Even the same product gives different values in different records. Miniflex PEEK tubing has two records. One has a TML of 0.71 % and a CVCM of 0.12 % (above the 0.10 % limit). The other shows "24 h, 140 °C, air" in the database's treatment column, with a TML of 0.23 % and a CVCM of 0.01 %. We did not confirm what that column means from the database's own description, but Inference: a heating pre-treatment (bake-out) may have cut the outgassing sharply Sourced[Ref. 14].

Outgassing of 3D-printed PEEK

Rinaldi and colleagues (University of Rome Tor Vergata, Thales Alenia Space Italia and ESA/ESTEC) tested three PEEK specimens printed by FDM (a process that pushes heat-softened plastic through a nozzle and stacks it) in ESA/ESTEC's µVCM apparatus according to ECSS-Q-ST-70-02C. On average the TML was 0.19 %, the CVCM 0.01 % and the RML 0.11 %: the RML was far below the 1.0 % limit and the CVCM one tenth of its limit. The printed parts were not fully dense (1.221 to 1.244 g/cm³, about 94 to 96 % of the datasheet's 1.300), and the authors had worried that the pores would raise outgassing. Comparing with the NASA database's PEEK 450 pellets (TML 0.3 %, CVCM 0.02 %, RML 0.12 %), they concluded that printing did not affect PEEK's outgassing behavior Sourced[Ref. 4].

6. Enemy 4, atomic oxygen: PEEK erodes about as fast as Kapton

Atomic oxygen (AO) and erosion yield (the volume lost per oxygen atom) are explained in Chapter 5 of our explainer on polyimides for space. In short, oxygen atoms float in low orbit near 400 km and hit the front of a satellite flying at about 7.7 km per second, slowly turning the surface of a polymer into gas. The smaller the erosion yield, the harder the material is to erode, and Kapton H's 3.0 × 10^-24 cm³ per atom is also used as a ruler for the oxygen-atom dose in orbit Sourced[Ref. 1].

NASA measured PEEK's erosion yield in an experiment that put 41 polymers outside the ISS for 3.95 years (the PEACE Polymers of MISSE 2).

The result is strikingly simple. PEEK's erosion yield of 2.99 × 10^-24 cm³ per atom is about 1.00 times that of Kapton H (3.00). PSU (polysulfone) is 2.94, and PEI was reported only as "greater than 3.31" because the sample was partly or fully eroded. The fluoropolymers FEP (0.200) and PTFE (0.142), by contrast, are about 15 times and about 21 times lower than Kapton H (3.00 ÷ 0.200 = 15, 3.00 ÷ 0.142 = about 21) Sourced[Ref. 1]Our calculation.

7. Enemy 2, UV and radiation: molecular structure and test atmosphere decide

PEEK's molecular structure and its resistance to radiation

In a 1988 presentation to an IEEJ (Institute of Electrical Engineers of Japan) research group on insulating materials, Sasuga T. (affiliation not checked here; taken from the INIS record) examined the radiation resistance of "fully aromatic" engineering plastics whose main chains consist entirely of aromatic rings. According to the abstract, radiation resistance depends strongly on chemical structure, and the order of stability of the aromatic units was "imide ring > diphenyl ether-diphenyl ketone > aromatic amide >> bisphenol A > diphenyl sulfone". PEEK's repeat unit corresponds to the "diphenyl ether-diphenyl ketone" one. Under conditions involving oxygen (gamma rays in pressurized oxygen), the polymers deteriorated at doses 1/5 to 1/10 of those without oxygen. In electron-beam irradiation without oxygen, PEEK and polyimide mainly cross-linked, while irradiation with oxygen cut the main chains Sourced[Ref. 7].

Funk and Sykes of NASA Langley (1988) say in their abstract that they evaluated PEEK thin films and carbon-fiber composites, including how film crystallinity affects stability under electron radiation and the mechanical properties of the composites after electron radiation followed by thermal cycling simulating 30 years in geosynchronous orbit (we could not confirm the numbers) Sourced[Ref. 8].

Printed PEI and PEKK outside the ISS

For PEEK itself, we could not confirm numbers from in-orbit ultraviolet and radiation data within the sources we checked (we have only the abstract saying that PEEK resin samples flew on LDEF and were evaluated after 5.8 years of exposure [Ref. 9]). In its place there is a NASA report on 3D-printed samples of PEI and PEKK, from the same family of super engineering plastics, that were put outside the ISS.

All Sourced (NASA/TM–20230008474 [Ref. 6]). The percentages are our calculation from the ksi values in the table (Our calculation). The samples are not PEEK but PEI and PEKK printed by Stratasys, Made In Space (now Redwire) and MSFC. In the same report NASA states that ABS was not chosen because of its low glass transition temperature.

From these results NASA concludes that the optical and mechanical properties of the printed parts show consistency that implies durability for about a year in low Earth orbit if they are not exposed to AO Sourced[Ref. 6]. Beyond one year, in other orbits, on forward-facing surfaces (with AO) and for PEEK itself, this report cannot tell us.

8. Enemy 3, temperature: the glass-transition wall and heat paths

PEEK is said to have high heat resistance. What really matters on a spacecraft, though, is not "the highest temperature it survives" but "what temperature each part of the component reaches".

The temperature of the Ten-Koh samples was -40 to 20 °C each orbit Sourced[Ref. 3]. Over this range, the storage modulus E′ of printed PEEK in the dynamic mechanical analysis (DMTA) by Rinaldi and colleagues is relatively stable: 3.9 GPa at -70 °C and 2.3 GPa at 125 °C. E′ begins to fall at about 125 °C and stayed above 1 GPa up to 140 °C. The Tg read from the tan-delta peak is 153 °C Sourced[Ref. 4]. In other words, between -70 and 125 °C PEEK's stiffness does not collapse.

The story changes, though, when heat cannot escape.

Rinaldi and colleagues analyzed the temperature distribution when the structure of a 2U CubeSat (10 × 10 × 21 cm) is made of PEEK. The heat from the internal equipment enters the structure at four joints, and the surroundings are assumed to be at 4 K with a surface emissivity of 0.8. The results follow.

Because PEEK's thermal conductivity, 0.25 W/m·K, is three orders of magnitude lower than aluminum's 170 W/m·K, the heat-generating spots come close to Tg locally, and there the stiffness drops and thermal deformation may appear, the authors write. When they worked out the conductivity needed to keep the inner-outer temperature difference within 40 °C, a figure of about 5 W/m·K came out. That is far above a neat (unfilled) resin, so they say it must be made up with high-conductivity composites or with heat sinks, protective layers and coatings (MLI, white and black paint) Sourced[Ref. 4].

The cold side: down to liquid-nitrogen temperature

On the cold side, a 1991 NASA abstract reports that when PEEK film was cooled from 23 °C to -196 °C (liquid nitrogen), the free volume seen by positron lifetime spectroscopy fell by about 46 % in amorphous samples and about 36 % in semicrystalline samples. If the trend continues, the authors "surmise" that liquid-hydrogen temperature would not harm the film's diffusivity for liquid hydrogen Sourced[Ref. 10]. This is a surmise confirmed in an abstract, not a result of strength or cracking tests on hardware at low temperature.

9. 3D-printed (additively manufactured) PEEK

Printing PEEK in a 3D printer (by FDM or FFF, which push softened plastic through a nozzle and stack it) allows complex lightweight shapes and may reduce the number of parts. How far has it been checked against space criteria?

The CubeSat structure of Rinaldi and colleagues

The printing conditions were a nozzle temperature of 410 °C, a bed temperature of 120 °C, a layer height of 0.2 mm, 100 % infill and a raster angle of ±45°. The specimens were printed flat (in the XY plane). The results are in the figure: as a ratio to the datasheet (injection molding), tensile strength was about 80 %, tensile modulus about 73 %, elongation at break about 15 % (6.9 % ÷ 45 %) and density about 94 to 96 %. Flexural strength, though, was 173 MPa, above the datasheet's 165 MPa Sourced[Ref. 4]Our calculation.

An electrostatic analyzer printed in CNT-filled PEEK

Larrick and colleagues (printing at the University of Alaska Fairbanks Geophysical Institute, residual-gas analysis at NASA Goddard) printed an electrostatic analyzer (ESA) for measuring space plasma (electrons) in PEEK with carbon nanotubes (CNT) and in plain PEEK. The nozzle was at about 420 °C, the chamber at 90 °C and the bed at 140 to 160 °C; the three electrodes that need conductivity are CNT-filled and the insulating support is PEEK. The ground-test results were as follows Sourced[Ref. 5].

• Vibration: no damage under a simulated launch (20 G GEVS profile, 20 minutes in each of two orientations). With about three times its own mass (30 g) of aluminum attached, it survived 20 minutes at 14.1 G RMS
• Outgassing: residual-gas analysis (NASA Goddard) showed no difference from the empty chamber and no problem was found. The authors say a full analysis of condensable material remains to be done
• Electron beam, UV and temperature: the pass band stayed stable when electron beams were applied at different temperatures. Under ultraviolet light (simulating Lyman-alpha) it rejected out-of-band electrons and UV photons better than a machined aluminum analyzer
• Remaining worries: charging at low energy (test results were inconsistent), the dark CNT-PEEK surface expected to reach about 100 °C in sunlight, and thermal expansion and warping

This work is at the ground-test stage and is not a report of a flight. The authors note possible large mass savings, shapes that cannot be made otherwise and simpler manufacturing and assembly. Inference: charging is a challenge common to insulating materials made conductive rather than something particular to super engineering plastics, and assessing spacecraft charging is the territory of standards such as ECSS-E-ST-20-06C [Ref. 26].

Connection to standards

NASA-STD-6030 sets requirements for additive manufacturing (AM) processes used for NASA spaceflight hardware. All crewed spaceflight hardware is covered, tailoring guidance is given for uncrewed missions, and in-space AM is also meant to be covered, though significant tailoring is expected (baseline of 21 April 2021; not a NASA mandatory standard) Sourced[Ref. 21]. ECSS has an additive manufacturing standard, ECSS-Q-ST-70-80C, but it is for metallic powder bed fusion, and we could not find an ECSS or ISO standard for plastic FDM Sourced[Ref. 25].

10. Limits, and what could not be confirmed

• PEEK's in-orbit ultraviolet and radiation numbers: we could confirm only the abstracts of the LDEF evaluation of PEEK resin and of NASA Langley's electron-beam evaluation. We give no numbers from them
• Quantity and locations of use on spacecraft: we could not confirm statistics on how much PEEK is used where on which spacecraft. The "application" field of the NASA database is the description of the party that requested the test
• Requirements for cable insulation: we confirmed that PEEK tubing has records with a cable-insulation application, but not spacecraft wiring standards or statistics on the record of PEEK-insulated wire
• An in-orbit record for 3D-printed PEEK: we could not confirm one. The CubeSat of Rinaldi and colleagues is a "proof-of-concept model" and the analyzer of Larrick and colleagues was tested on the ground
• The scope of the Ten-Koh data: the observations cover about four months (101 measurements), and there are no data after contact was lost on 19 March 2019. Long-term change cannot be inferred from these data
• The text of standards: we did not confirm the test conditions of the ISO standards (paywalled) or the text of ECSS-Q-ST-70-04C and 70-06C. For ECSS-Q-ST-70-02C we checked the relevant passages of the publicly available PDF
• ASTM: we did not open ASTM's site. ASTM E 595 is only the number and title written on NASA's page, and ASTM D 638 only the number and title written in the references of the paper by Rinaldi and colleagues

11. How to read the yardsticks and standards

Space evaluation of super engineering plastics goes beyond a table of properties: it checks one environmental factor at a time with tests reproduced on the ground. The yardsticks fall into five groups: (1) what comes out in vacuum (outgassing: TML, RML, CVCM); (2) what erodes in low orbit (erosion yield); (3) how the material changes under ultraviolet light and particles (changes in optical properties and strength); (4) temperature swings and temperature distribution (relation to the glass transition, thermal-vacuum cycling); and (5) for crewed craft, flammability and odor and toxic gas (flammability and offgassing). Each measures only one factor, whereas in space they act together. A yardstick is a tool for screening and comparing materials; it does not directly predict lifetime in orbit.

The arrangement of this table is Our calculation (our own reordering). Standard numbers, titles and status were checked on the official pages of ECSS, ISO and NASA (checked 17 October 2026). For ASTM we give only the numbers and titles written in NASA reports or papers; we did not open ASTM's site. ISO texts are paywalled, so we limited ourselves to titles and scope.

Cautions in reading (for materials engineers)

• Ground tests and flight results are different things: Ten-Koh's four months and MISSE-9 and 10's 198 to 250 days are valuable in-orbit data, but they are limited in time and orbit. AO changes by orders of magnitude with orientation
• A database "record" is not a "product guarantee": a NASA record is a test result for one lot at one time, and products with the same name change with pre-treatment (Chapter 5)
• Check whether a standard is a recommendation or a requirement: ISO 15856 is recommended guidance. NASA-STD-6016 and 6030 are shown as not NASA mandatory standards. An ECSS standard becomes a requirement when a contract applies it, and it can be tailored
• A proof of concept and a qualified flight part are different: the CubeSat structure of Rinaldi and colleagues is a "proof-of-concept model" and the analyzer of Larrick and colleagues was ground-tested; neither is reported as having passed qualification testing as a flight part

12. Glossary

13. References

1. de Groh K. K. et al. (NASA Glenn) "MISSE PEACE Polymers Atomic Oxygen Erosion Results", NASA/TM—2006-214482 (November 2006) — ntrs.nasa.gov/citations/20070002707
2. Stambler A. H. et al. (NASA Glenn) "Ground-Laboratory to In-Space Atomic Oxygen Correlation for the Polymer Erosion and Contamination Experiment (PEACE) Polymers", NASA/TM—2011-216904 (January 2011) — ntrs.nasa.gov/citations/20110006367
3. Abdullah F., Okuyama K., Fajardo I., Urakami N. (Kyushu Institute of Technology) "In Situ Measurement of Carbon Fibre/Polyether Ether Ketone Thermal Expansion in Low Earth Orbit", Aerospace 7(4), 35 (2020), DOI 10.3390/aerospace7040035 — doi.org/10.3390/aerospace7040035
4. Rinaldi M. et al. (University of Rome Tor Vergata, Thales Alenia Space Italia, ESA/ESTEC) "Additive Manufacturing of Polyether Ether Ketone (PEEK) for Space Applications: A Nanosat Polymeric Structure", Polymers 13(1), 11 (2021), DOI 10.3390/polym13010011 (open access) — doi.org/10.3390/polym13010011
5. Larrick Q. et al. "Additively Manufactured Plastic Plasma Spectrometer" (electrostatic analyzer printed in CNT-filled PEEK; NASA Technical Reports Server, 2024) — ntrs.nasa.gov/citations/20240014082
6. Finckenor M. M., McElderry J. R. (NASA Marshall) "Space Environmental Effects on Additively Manufactured Materials – Results from MISSE-9 and MISSE-10", NASA/TM–20230008474 (July 2023) — ntrs.nasa.gov/citations/20230008474
7. Sasuga T. "High temperature irradiation effect on fully aromatic polymers" (abstract on radiation resistance of aromatic polymers; 1988, IEEJ insulating materials research group; checked in the INIS record; in Japanese) — inis.iaea.org/records/za72j-pp962
8. Funk J. G., Sykes G. F. Jr. "Space radiation effects on poly(aryl-ether-ketone) thin films and composites" (1988; abstract only) — ntrs.nasa.gov/citations/19880054320
9. Whitaker A. F., Finckenor M. M., Kamenetzky R. R. "Property changes induced by the space environment in polymeric materials on LDEF" (1992; abstract only) — ntrs.nasa.gov/citations/19920045605
10. NASA "Investigation of microstructural changes in polyetherether-ketone films at cryogenic temperatures by positron lifetime spectroscopy" (1991; abstract only) — ntrs.nasa.gov/citations/19910008903
11. Theiler G., Gradt T. (BAM) "MoS2-Filled PEEK Composite as a Self-Lubricating Material for Aerospace Applications", 40th Aerospace Mechanisms Symposium (2010; abstract only) — ntrs.nasa.gov/citations/20100021916
12. Delzeit L. D., Vance J. R., Shaw A. "Engineering Polymers as Structural Materials in Spacecraft Water Systems" (2021; abstract only) — ntrs.nasa.gov/citations/20210024171
13. ECSS ECSS-Q-ST-70-02C "Thermal vacuum outgassing test for the screening of space materials" (15 November 2008; checked on the ECSS page and PDF) — ecss.nl/standard/ecss-q-st-70-02c-thermal-vacuum-outgassing-test-for-the-screening-of-space-materials/
14. NASA Goddard Outgassing Database (searchable test results; checked 17 October 2026) — outgassing.nasa.gov/
15. ISO ISO 15856:2010 "Space systems — Space environment — Simulation guidelines for radiation exposure of non-metallic materials" (edition 1, August 2010; reconfirmed in 2026; checked on the ISO page) — iso.org/standard/45843.html
16. ISO ISO 15104:2025 "Space systems — Environmental testing for spacecraft thermal control materials" (edition 1, January 2025; checked on the ISO page) — iso.org/standard/84447.html
17. ECSS ECSS-Q-ST-70-06C "Particle and UV radiation testing for space materials" (31 July 2008) — ecss.nl/standard/ecss-q-st-70-06c-particle-and-uv-radiation-testing-for-space-materials/
18. ECSS ECSS-Q-ST-70-04C "Thermal testing for the evaluation of space materials, processes, mechanical parts and assemblies" (15 November 2008) — ecss.nl/standard/ecss-q-st-70-04c-thermal-testing-for-the-evaluation-of-space-materials-processes-mechanical-parts-and-assemblies/
19. ECSS ECSS-Q-ST-70-71C Rev.1 "Materials, processes and their data selection" (15 October 2019) — ecss.nl/standard/ecss-q-st-70-71c-rev-1-materials-processes-and-their-data-selection-15-october-2019/
20. NASA NASA-STD-6016 "Standard Materials and Processes Requirements for Spacecraft" (Version C with Change 1; dated 30 September 2021, changed 15 November 2023; checked on the NASA Standards page) — standards.nasa.gov/standard/NASA/NASA-STD-6016
21. NASA NASA-STD-6030 "Additive Manufacturing Requirements for Spaceflight Systems" (baseline, 21 April 2021; checked on the NASA Standards page) — standards.nasa.gov/standard/NASA/NASA-STD-6030
22. NASA NASA-STD-6001 "Flammability, Offgassing, and Compatibility Requirements and Test Procedures" (Version B with Change 3; dated 26 August 2011, changed 9 June 2025; checked on the NASA Standards page) — standards.nasa.gov/standard/NASA/NASA-STD-6001
23. ECSS ECSS-Q-ST-70-21C "Flammability testing for the screening of space materials" (5 February 2010) — ecss.nl/standard/ecss-q-st-70-21c-flammability-testing-for-the-screening-of-space-materials-5-february-2010/
24. ECSS ECSS-Q-ST-70-29C "Determination of offgassing products from materials and assembled articles to be used in a manned space vehicle crew compartment" — ecss.nl/standard/ecss-q-st-70-29c-determination-of-offgassing-products-from-materials-and-assembled-articles-to-be-used-in-a-manned-space-vehicle-crew-compartment/
25. ECSS ECSS-Q-ST-70-80C "Processing and quality assurance requirements for metallic powder bed fusion technologies for space applications" (30 July 2021; covers metallic powder bed fusion) — ecss.nl/standard/ecss-q-st-70-80c-processing-and-quality-assurance-requirements-for-metallic-powder-bed-fusion-technologies-for-space-applications-30-july-2021/
26. ECSS ECSS-E-ST-20-06C Rev.1 "Spacecraft charging" (15 May 2019) — ecss.nl/standard/ecss-e-st-20-06c-rev-1-spacecraft-charging-15-may-2019/
27. ECSS ECSS-E-ST-32-08C Rev.1 "Space engineering - Materials" (15 October 2014) — ecss.nl/standard/ecss-e-st-32-08c-rev-1-space-engineering-materials-15-october-2014/

14. Claim-to-source audit

Last updated: 17 October 2026 / Sources are limited to primary materials (NASA technical reports, the NASA Goddard database, peer-reviewed papers, the official pages of ECSS, ISO and NASA, and an INIS record). In-orbit measurements are values under the conditions reported and do not carry over to other orbits or periods. Calculated and analyzed values rest on the assumptions of this article or of the papers cited, are illustrative, and do not predict the lifetime or temperature of real hardware. We could not confirm PEEK's in-orbit ultraviolet and radiation numbers, the quantity of use on spacecraft, an in-orbit record for printed PEEK, or the test conditions in the standards' texts, so we do not state them.