What are falcon 9 rockets?

Falcon 9 is a medium-to-heavy orbital launch vehicle built and operated by SpaceX. It stands about 70 m tall, has a diameter of 3.7 m and weighs roughly 549 t at lift-off. The first stage carries nine Merlin engines burning kerosene and liquid oxygen, producing about 7,600 kN of thrust at sea level; the second stage uses a single vacuum-optimised Merlin. The name refers to those nine engines and to the Millennium Falcon of the Star Wars films. SpaceX quotes a capacity of up to 22,800 kg to low Earth orbit when the booster is expended, and less when it is recovered.

What sets Falcon 9 apart is that its first stage flies back. After separation, the booster uses cold-gas thrusters and grid fins to steer, relights a subset of its engines to slow down, and lands on deployable legs either on a concrete pad near the launch site or on an autonomous drone ship at sea. The first successful landing took place in December 2015, and the first reflight of a used booster in March 2017. Since then individual boosters have flown more than twenty times, and the payload fairing halves are also recovered and reused.

The current version, Block 5, debuted in 2018 and carries most of SpaceX's manifest: Starlink batches, commercial and government satellites, cargo and crew missions to the International Space Station in the Dragon capsule, and rideshare flights with dozens of small spacecraft. It launches from Cape Canaveral and the Kennedy Space Center in Florida and from Vandenberg in California. Three cores strapped together form Falcon Heavy, but the single-core Falcon 9 is by far the most flown orbital rocket in the world today.