Space Technology
The engineering of the impossible - systems that must work perfectly in the most hostile environment imaginable.
Rocket Propulsion
Rockets work by Newton's third law: expelling mass backward propels the vehicle forward. Chemical rockets burn propellant (liquid hydrogen/oxygen, kerosene/oxygen, or solid fuels) to produce hot exhaust. The Tsiolkovsky rocket equation shows that propellant must make up most of a rocket's mass. SpaceX's Merlin engine burns RP-1 (refined kerosene) and LOX, generating 845 kN of thrust. Raptor, SpaceX's newest engine, burns methane and is the highest-thrust-to-weight rocket engine ever built.
Reusable Rockets
For decades, rockets were thrown away after one use. SpaceX changed this with the Falcon 9, which lands its first stage booster vertically after launch. A single Falcon 9 booster has been reused 20+ times. Reusability reduced launch costs from $10,000-$50,000 per kg to roughly $2,700 per kg, transforming the economics of space access. Starship aims to be fully and rapidly reusable, targeting costs below $100 per kg.
Satellites and GPS
There are over 8,000 active satellites in orbit. GPS uses a constellation of 31 satellites; your phone calculates its position by measuring the time delay from at least 4 satellites. GPS is accurate to 3-5 meters for civilians, centimeters with corrections. Satellite internet (Starlink: 6,000+ satellites) provides broadband anywhere on Earth. Earth observation satellites monitor deforestation, agriculture, disasters, and military activity in near real-time.
The Challenges of Space
Space is extraordinarily hostile: vacuum, extreme temperature swings (-150C to +120C), radiation, micrometeorites, and no ability to repair hardware after launch. Electronics must be radiation-hardened. Materials must not outgas (release vapors that condense on optics). Thermal management is complex with no convection in vacuum. Everything must be tested exhaustively because there is rarely a second chance.
Nuclear Power in Space
Solar panels lose efficiency far from the Sun. Plutonium-238 radioisotope thermoelectric generators (RTGs) power deep space probes by converting heat from radioactive decay directly to electricity with no moving parts. NASA has used RTGs in Voyager, Cassini, New Horizons, and the Mars Curiosity and Perseverance rovers. Nuclear fission reactors in space are also being actively developed for future crewed missions to Mars.
James Webb Space Telescope
JWST, launched Christmas Day 2021, is the most powerful space telescope ever built. Its 6.5-meter gold-coated mirror (18 hexagonal segments) unfurled in space over two weeks. It observes in infrared, seeing through dust clouds invisible to Hubble. It can detect the atmospheric composition of exoplanets, observe the first galaxies formed after the Big Bang, and image objects Hubble could not. It is located 1.5 million km from Earth at the L2 Lagrange point, far beyond repair.