Concepts & Technology
The ideas behind spaceflight: orbital mechanics, reusable rockets, space debris, and more.
How rockets work
How rockets work: Newton's third law, the Tsiolkovsky rocket equation, staging, propellant types, engine cycles, and why orbit is about sideways speed.
Mars colonization
Mars colonization faces radiation, toxic dust, low gravity, and cost hurdles; SpaceX targets Starship landings and NASA pursues a Moon-first path.
Orbital mechanics
Orbital mechanics explains how spacecraft move: Kepler's laws, delta-v budgets, Hohmann transfers, gravity assists, Lagrange points, and rendezvous.
Reusable rockets
Reusable launch vehicles recover and refly rocket stages: one Falcon 9 booster has flown 35 missions; New Glenn, Starship, and Zhuque-3 follow.
Space debris
Space debris includes over 40,000 tracked objects and millions of fragments; collisions and mega-constellations drive mitigation rules and cleanup missions.
Space tourism
Space tourism began with Dennis Tito's 2001 ISS visit and now spans suborbital hops and private orbital missions, with prices from $750,000 to $70 million.
The Space Race
The Space Race was the 1955-1975 US-Soviet competition that produced Sputnik, Gagarin's flight, and the Apollo Moon landings before ending in detente.