Methodology: how the data is made and checked

Every number on Space Mushroom is traceable to a named source. This page explains how a value gets from a source into a profile, what we check automatically and what we leave out.

1. Sources

We use manufacturer datasheets, standards bodies, NASA and ESA reports, NIST, USGS, university and open-access papers, and handbooks. Reseller and aggregator pages are used only when nothing better is available and are labelled as such.

2. Drafting

Profiles are drafted with the help of AI assistants that read the cited pages. The assistants copy values as printed, with their unit, the test conditions and the place in the source (table or row). They are not allowed to estimate, convert silently or fill a gap from memory.

3. Automated checks

• Schema check: every property needs a unit, conditions, method, status and a source that exists in the profile.
• Source check: each value is searched for in the text of its cited source. A value that is not found is removed.
• Designation check: every UNS, EN, AISI or trade designation must be printed in its cited source.
• Story check: numbers in the written summary must also exist as recorded values.
• Full-grade bar: a profile appears in search only if it has at least 12 properties, 8 sources, 2 uses, a hazards entry, a supply section and corrosion or failure information.

4. Articles

Data articles are built from the profile records at publication time. Their numbers are computed from the records, and the build stops if a quoted fact is no longer in its profile. Each article lists what the data does not cover.

5. What we leave out

Values at unstated conditions are labelled "not stated", not assumed. Where two sources disagree we show both. Where no source has a value we say "not found in any source we hold".

6. Corrections and updates

Each page shows the date it was published and last updated. See the editorial policy for how corrections are handled.