Methodology

NASA NSSDCA (National Space Science Data Center), JPL mission pages, ESA Science, JAXA, ISRO, CNSA official publications. These are the gold standard — official mission data backed by the originating agency.

Journal of Geophysical Research: Planets, Icarus, Nature Astronomy, Space Science Reviews. Used when agency primaries lack specific figures or for scientific interpretations of mission data.

NASA Office of Inspector General audits, Government Accountability Office reports, Congressional budget testimony. Critical for budget figures and program cost estimates.

Official statements from mission operators. Used with caution for current-status figures, cross-checked against agency primaries.

SpaceNews, Aviation Week, Spaceflight Now. Used only when Tier 1–4 sources are unavailable, and clearly labelled. Never used for budget figures.

Historical Soviet Missions

Soviet Mars programme data (Mars 1–7, Zond) is sourced primarily from NASA NSSDCA, which holds the most complete open records for Soviet planetary missions. Some figures remain uncertain due to incomplete Soviet-era documentation. These are labelled 'medium' confidence.

Budget Figures

All NASA budget figures are from official NASA budget requests or OIG audit reports. The Mars Sample Return campaign cost range reflects the September 2023 IRB-2 findings, not NASA's original (now superseded) $4.4B baseline. We never use the original baseline without flagging it as superseded.

Operational Status

Mission status is updated when NASA, ESA, or other agencies publish formal status updates. We do not infer status from secondary sources. For active missions, status was last verified against agency publications.

ISRU Resource Estimates

All resource quantity estimates are based on orbital remote sensing data (MRO SHARAD, Mars Odyssey GRS, MAVEN). Subsurface estimates carry inherent uncertainty. Utilization status reflects demonstrated technology readiness, not commercial viability.