🛡️ Space Glossary

Debris & Space Safety

The growing challenge of orbital debris — how collisions are predicted, how satellites dodge threats, and the rules and technologies being developed to keep space sustainable. 19 terms, each explained in plain language with key data and links to live trackers.

2YR 25-Year Rule Guideline for post-mission deorbit timeline 25 years5 years ADR ADR Missions to capture and deorbit defunct objects ADRAS-J (2024)ClearSpace-1 (2026) ASAT ASAT A weapon designed to destroy or disable satellites in orbit Debris & Space Safety CE Casualty Expectation The 1-in-10,000 rule that governs re-entry risk Ec < 1 in 10,000Design for demise CDM CDM The standard warning message for a predicted close approach CCSDS formatSeries per event CA Conjunction Assessment Screening for potential collisions in orbit 29,474 live18th SDS (USSF) CRE Controlled Re-entry A guided return to Earth targeting an uninhabited ocean area SPOUA (Point Nemo)48°52'S, 123°23'W DC Debris Cloud What one breakup becomes: a shell of shrapnel in orbit Swarm → ring → shellGabbard diagram FE Fragmentation Event Breakup of a space object into debris 650+ HBR Hard-Body Radius How big two objects are, as far as a collision is concerned ~1–20 m combinedConservative (~20 m) KS Kessler Syndrome Self-sustaining cascade of orbital collisions 29,474 live1978 (Donald Kessler) OD Orbital Decay Gradual altitude loss due to atmospheric drag Days to weeks1–2 years P Passivation Depleting stored energy to prevent explosions 650+ (all time)IADC / UN COPUOS PC Pc The number that decides whether a satellite dodges ~10⁻⁴ (1-in-10,000)Trend across CDMs PR Protected Regions The two orbital zones the world agreed to keep clean GEO ±200 km, ±15° lat SV Screening Volume The alarm perimeter drawn around a protected satellite Ellipsoid / box~5–7 days ahead SD Space Debris Defunct satellites, rocket bodies, and fragments orbiting Earth 36,500+1,000,000 TCA TCA The instant two orbits nearly touch 7–15 km/sHours-to-TCA WS Whipple Shield The thin wall that sacrifices itself to stop hypervelocity debris ~mm–cm debris

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