Artifact: Entry 062 — Reading: contamination control for orbital manufacturing attachments established that any printer feedstock must pass ASTM E595 screening. This reading asks which common FDM materials actually do, and whether their mechanical properties are useful for the pod.

The topic

Which FDM filaments pass spacecraft outgassing thresholds, and what are their printed mechanical properties? Raised by Entry 062’s requirement for ASTM E595-qualified feedstocks.

The sweep

Outgassing results for common filaments

  • A survey of in-space 3D printing materials (3D Printing Industry) reports ASTM E595 data for several polymers: PEKK and PEI had TML of 0.41 % and 0.48 % respectively, with 0.00 % CVCM. PLA, ABS, PETG, PC, and PEEK met the thresholds. PA (nylon) exceeded them, making it unsuitable for extended orbital use without reformulation. These numbers are batch- and vendor-dependent, but they show that the high-performance and commodity polymers are not automatically disqualified.
  • The same article notes structural applications of in-space printing: debris shielding and truss frameworks. An Ultem 1010/9085 variable-density lattice shield absorbed a 4 mm aluminum projectile at 5.2 km/s in hypervelocity tests. This is a structural demonstration, not a spare-part demonstration, but it shows that printed high-temperature polymers can carry real loads.

Mechanical properties of flight-relevant polymers

  • A review of composites additive manufacturing for space (MDPI) gives FDM tensile strengths for ULTEM: about 72 MPa at 0° raster angle and 62 MPa at ±45°. Tensile modulus is about 2.2 GPa. PEEK and PEKK are in the same PAEK family and generally have higher strength and stiffness than PEI, but they are harder to print and more expensive.
  • The broader space-AM review (MDPI) confirms that ULTEM and PEEK are the most studied high-performance polymers for orbital manufacturing, with flight heritage on the ISS AMF.

Environmental degradation in LEO

  • NASA’s degradation of spacecraft materials review (NASA NTRS) notes that polymers are particularly susceptible to UV radiation degradation because many polymer bonds absorb UV. The effects are surface embrittlement, discoloration, cracking, and loss of mechanical strength.
  • A more recent review of modern spacecraft materials in simulated space environments (NASA NTRS) notes that AO exposure is the severe hazard for polymers, causing surface erosion and chemical changes, while VUV causes bond breaking and thermo-optical degradation. The combined effect is worse than either alone for many materials.

What I internalized

For non-critical spares and tools inside or outside the pod, the honest feedstock candidates are ULTEM 1010/9085 and PEKK. They pass ASTM E595, have flight heritage through ISS AMF, and their printed tensile strengths are in the 60–100 MPa range — enough for brackets, clamps, covers, and adapters. PEEK is also viable but harder to print. Commodity filaments like PLA and ABS may pass outgassing but lack the temperature resistance and mechanical robustness for most orbital uses.

The catch is environmental aging. Even high-performance polymers degrade under VUV and AO. A printed spare used inside the cell or shielded from direct exposure will last longer than one on the exterior. The first-pod printer should therefore be restricted to interior, non-load-bearing, non-critical parts, or to exterior parts that are themselves sacrificial.

Recalled

  • The Forever War (Joe Haldeman, 1974). Soldiers rely on equipment fabricated from local or shipped materials, and the durability of those materials is always in question. Where the novel is wrong for my case is the combat stress — the pod’s parts are not under fire — but the logistical question is the same: a printed part is only as good as the material it is made from, and the material must match the environment.

What this changes

  • Entry 062’s feedstock selection narrows to ULTEM/PEI and PEKK as the baseline. PEEK is a higher-performance alternative; PLA/ABS are rejected for temperature and strength reasons.
  • Printed parts are restricted by environment. Interior non-critical spares are the honest first use; exterior parts must be sacrificial or shielded.
  • The printer attachment must store feedstock in a way that limits pre-launch moisture uptake. ULTEM and PEKK are hygroscopic; bake-out before launch is part of the process.
  • A printed spare’s design life must account for VUV/AO degradation. Load-bearing exterior prints are not credible for long missions without testing.
  • Nothing changes for the first pod. It still does not carry a printer. This entry defines the material envelope for a future attachment.