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, partial gravity, and life support limits. No crewed mission is scheduled, and SpaceX now puts the Moon first.
Orbital Data Centers
Orbital data centers span edge processors and proposed compute constellations; power, heat, links, radiation, launch, and debris set their limits.
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. A Falcon 9 booster has flown 36 times, and China recovered its first orbital booster in July 2026.
Space debris
Space debris includes about 46,000 tracked objects and millions of untracked fragments; collisions and mega-constellations drive 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.