Reaching orbit means going sideways at nearly 8 kilometres every second
Getting to space is mostly about speed, not height. An orbital rocket must climb to roughly 150 kilometres, then push its cargo sideways at no less than 7,814 metres per second so it keeps falling around Earth instead of back onto it. That brutal requirement explains why rockets come in stages.
A launch vehicle is usually a rocket built to carry satellites or a crewed craft from the ground, or the lower atmosphere, up to space. Most look like the classic multistage missile, though the category also covers oddities such as the Space Shuttle. Behind each one stands a pad, a control centre and facilities for assembly and fuelling, and the sophisticated engineering keeps running costs high. Orbital machines burn chemical propellants, including kerosene, liquid hydrogen and liquid oxygen, solid fuel, or hypergolic mixtures.
The physics is unforgiving. In a vacuum the only way to gain speed is to throw mass out the back, which leads to the rocket equation, and in practice that means dropping empty stages on the way up. NASA sorts vehicles by how much they can put into low Earth orbit: under 2,000 kilograms counts as small lift, like Europe's Vega, while more than 50,000 kilograms is super-heavy, the class of the Saturn V. Pads can sit on land, on fixed or floating ocean platforms, or even on a submarine, and some rockets are dropped from aircraft.
For most of history every orbital rocket was thrown away after one flight. The Shuttle and the Soviet Buran broke the pattern partially, gliding their spaceplane portions back to a runway while discarding the big tank. SpaceX then taught the Falcon 9 first stage to land upright, succeeding in December 2015, and since 2017 boosters have routinely touched down on pads or ocean platforms. Blue Origin's suborbital New Shepard, which flies straight up and down, landed in 2015 and had flown the same booster five times by October 2016. Up to 2023, every working reusable system recovered only some of its hardware.
The newest idea is distributed launch, splitting a mission across several flights. The International Space Station was assembled from modules this way, and SpaceX's Starship, begun in 2017, is designed to be refuelled in orbit. Its first attempt in April 2023 lost both stages, but on the fifth the launch tower caught the returning booster, and the ship splashed down in the Indian Ocean.
Source: Launch vehicle
