🚀 Space Glossary

Manoeuvres & Propulsion

The physics and operations of changing orbits — from collision avoidance and orbit raising to interplanetary transfers. Every manoeuvre costs delta-v, the fundamental currency of spaceflight. 14 terms, each explained in plain language with key data and links to live trackers.

CP Chemical Propulsion Thrust generated by combusting chemical propellants 250–450 s~2.5–4.5 km/s COLA COLA Thruster firing to dodge a predicted close approach 3–5 per year45,000+ in 2023 Δv Delta-V Velocity change — the currency of spaceflight ~9.4 km/s~2.4 km/s D Deorbit Lowering orbit to cause atmospheric re-entry 5 yr after mission end25-year guideline EP Electric Propulsion Spacecraft thrust systems powered by electricity rather than combustion 1,500–5,000 smN to 1 N EV Escape Velocity The minimum speed needed to permanently leave a gravitational field 11.2 km/s2.4 km/s GA Gravity Assist Using a planet's gravity to change speed and direction Zero (trajectory only)Voyager 2 Grand Tour HET Hall-Effect Thruster The electric engine that flies most mega-constellations 1,500–3,000 s20–600 mN HT Hohmann Transfer Fuel-efficient two-burn orbit change 23.9 km/s OR Orbit Raising Boosting a satellite to a higher orbit Prograde (+velocity)300 km → 550 km OP Orbital Phasing Moving along an orbit by briefly changing its size Go lower (faster)Go higher (slower) PC Plane Change The most expensive manoeuvre in orbital mechanics Δv = 2·v·sin(θ/2)10° ≈ 1.4 km/s Isp Specific Impulse Engine fuel efficiency — seconds of thrust per kg ~230 s~310 s SK Station-Keeping Maintaining precise orbital position over time ~50 m/s/yr~90–95%

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All terms 🌐 Orbit Types 📐 Orbital Elements 📡 Tracking & Space Surveillance 🛡️ Debris & Space Safety 🛰️ Spacecraft Systems 🏗️ Launch & Ascent ☀️ Space Environment ⚖️ Policy & Regulation 📍 Navigation & Timing 🔭 Earth Observation 📡 Amateur Radio & Satellites 🔭 Deep Space & Astrophysics 👨‍🚀 Human Spaceflight 🌐 Satellite Internet & Mega-Constellations 🪐 Planetary Science & Exploration