spacemat

Python tools for spaceflight materials selection.

The package bundles a snapshot of the NASA GSFC outgassing database (all 13,582 ASTM E595 test entries as of the retrieval date, fetched from outgassing.nasa.gov) so it can be queried offline, plus cryogenic property curves for the alloys and insulators commonly used in cryo tank and instrument work.

pip install -e .
spacemat summary "scotchweld 2216"

64 test(s) matching 'scotchweld 2216': 18 pass, 46 fail, 0 incomplete
TML  min 0.10  median 1.10  max 2.85
CVCM min 0.00  median 0.03  max 1.50

Keeping the per-test history matters: EC-2216 is usually quoted as passing E595, but across 64 tests it failed 46 times depending on lot and cure schedule. Single quoted values hide this spread.

Outgassing database

Each entry has material, manufacturer, TML, CVCM, WVR, application, cure schedule, data reference, and year. NASA data is a US Government work and may be redistributed. python scripts/fetch_nasa_outgassing.py rebuilds the snapshot from the live site.

from spacemat import outgassing

outgassing.search("RTV 566")
outgassing.screen(tml_max=1.0, cvcm_max=0.1, contains="epoxy")
outgassing.summarize("braycote")
outgassing.snapshot_info()

The same things from the shell:

spacemat search "rtv 566"
spacemat screen --tml 1.0 --cvcm 0.1 --application adhesive --csv passing.csv
spacemat info

Numeric screens drop entries with missing values, so a screen result means tested and passed, not no data found.

Cryogenic property curves

Thermal conductivity, specific heat, thermal contraction, and Young's modulus are evaluated from the curve-fit equations NIST publishes for cryogenic materials, using NIST's own coefficients (scripts/fetch_nist_fits.py parses them off the NIST pages). Materials covered this way: 304L, 316, 6061-T6, Inconel 718, Ti-6Al-4V, Invar 36, PTFE, polyimide, and G-10, most over 4 to 300 K.

NIST does not publish strength fits, so the yield and ultimate curves are typical values from the open literature, with a source string on each entry. They are suitable for trade studies, not design allowables. The same applies to 301 cold rolled and Al-Li 2195 in general, which NIST does not cover.

Queries outside a curve's measured range return None; the thermal tools raise. Cryogenic data is never extrapolated.

from spacemat import screen, TML, CVCM, YIELD_STRENGTH, CONTRACTION, K

screen(TML < 1.0, CVCM < 0.1, YIELD_STRENGTH > 1000, T_service=90*K)
screen(CONTRACTION < 0.3, T_service=77*K)

Thermal tools

Heat leak through a support depends on the integral of k dT across the temperature span. The integral is computed exactly for point curves and numerically for the NIST fits:

from spacemat import K
from spacemat.thermal import heat_leak, contraction_mismatch

heat_leak("G-10", area_m2=1.1e-4, length_m=0.3, T_cold=90*K, T_hot=295*K)
contraction_mismatch("PTFE", "304L", 77*K)   # differential strain, percent

examples/strut_heat_leak.py contains a worked strut-sizing example.

Compliance reports

spacemat report 304L "RTV 566" "Vespel SP-1" --temp 90 -o compliance.md

Generates a Markdown report with E595 pass/fail, flammability flags, and properties at the service temperature. Non-metals are also checked against the bundled NASA database, reporting the number of upstream tests and their TML/CVCM spread. Materials that exceed the TML limit only because of absorbed water (TML minus WVR under the limit) are marked CONDITIONAL, since these are normally accepted after bakeout.

examples/vet_bom.py runs the same check over a bill of materials.

Other utilities

• compare(["304L", "Al-Li 2195"], T_service=90*K) prints a trade table
• ashby_plot(DENSITY, YIELD_STRENGTH, T_service=90*K) scatter plots, requires pip install spacemat[plot]
• spacemat.export flattens materials and database entries to CSV or dict records for pandas
• The test suite enforces that every data value carries a source string

Development

pip install -e .[dev]
pytest

MIT licensed. Data contributions must include a source.