Standards

Propulsion

All propulsion figures use the manufacturer's official rating at the time of production. For space vehicles, specifications reference manufacturer-rated thrust (lbs or kN), specific impulse (Isp in seconds), max speed (mph or km/s), and operational altitude (km or miles).

Thrust values are given in both pounds-force (lbf) and kilonewtons (kN) where available. We display the manufacturer's primary figure and note conversions where applicable.

Weight

All weights distinguish between dry mass (unfueled) and gross mass (fully fueled at launch). Where manufacturers provided multiple figures for different configurations, we use the most common operational configuration and note variants.

Performance

Performance metrics include payload capacity to various orbits (LEO, GTO, TLI), delta-v budgets, and mission duration. Where multiple sources conflict, we use the manufacturer's official figure and note discrepancies in the source links.

Propellant

Propellant type and mixture are listed using standard nomenclature (LOX/LH2, LOX/RP-1, N2O4/UDMH, etc.). Solid rocket motor compositions are noted by manufacturer designation where available.

Production Numbers

Production totals include all variants of the listed vehicle unless a specific variant is documented separately. For example, the Soyuz production total includes all crew and cargo variants. Where a specific variant like the Soyuz-MS is listed separately, its production total covers only that variant.

Model vs Variant

We distinguish between models and variants when they represent fundamentally different vehicles. A Falcon 9 v1.0 and a Falcon 9 Block 5 share a lineage but differ in engines, structure, and performance envelope. They are documented separately.

When a variant represents a minor update (avionics upgrade, software change) without changing the vehicle's fundamental nature, we document the most representative version and note the variant range.

Year Ranges

Year ranges reflect the operational period, not the announcement year. The start year is when the vehicle first flew. The end year is when the type was retired from active service or production ended.

Sources

Technical specifications are sourced from manufacturer documentation (SpaceX press kits, NASA fact sheets, ESA technical documents), verified databases (Gunter's Space Page, Astronautix), and official agency records. Every vehicle entry includes source reference links where available. When sources conflict, we note the discrepancy and default to the manufacturer's official figure.

Editorial Independence

Space Heritage is an independent digital archive. No manufacturer, space agency, or commercial entity has editorial influence over vehicle selection, significance assessments, or heritage classifications. Our documentation reflects research and editorial judgment, not commercial relationships.