Falcon 9 is a two-stage rocket built by SpaceX, and its defining feature is a first stage that lands after launch and flies again. The rocket carries a payload to orbit using two stacked sections, and the lower one returns to Earth to be reused. That reuse is why Falcon 9 became the most frequently flown rocket in the world and reset expectations for launch cost.
SpaceX built Falcon 9 to prove a plain point about economics. The first stage holds the engines and most of the structure, so it is the most expensive part of the rocket. Recovering and reflying it, rather than dropping it in the ocean, spreads that cost across many launches. The Falcon 9 has now flown boosters many times each, and that cadence is the core of the story.
How Falcon 9 Is Built
Falcon 9 has two stages that separate during flight. The first stage lifts the rocket off the pad and through the thickest part of the atmosphere, then falls away so the lighter second stage can finish the trip to orbit. Dropping the empty first stage lets the rest of the vehicle keep accelerating without hauling dead weight.
Both stages run on Merlin engines, which burn refined kerosene, known as RP-1, together with liquid oxygen. Nine Merlin engines cluster at the base of the first stage, which gives the rocket its name. A single vacuum-optimized Merlin powers the second stage, using a larger nozzle tuned for the near-vacuum above the atmosphere. For a plain-language look at how these engines produce thrust, see how rocket engines work.
How the First Stage Lands
The first stage lands by flying itself back down and touching down upright on its engines. After it separates from the second stage, it flips around and relights some of its Merlins for a boostback burn that steers it toward a landing zone. This is the step that makes Falcon 9 reusable rather than expendable.
On the way down, four grid fins near the top swivel to steer the booster through the air like the fins of a dart. A landing burn slows it in the final seconds, four legs fold out, and the stage settles onto its target. That target is one of two places:
- A droneship at sea. For launches that use most of the rocket’s energy, the booster lands on an autonomous droneship stationed downrange in the ocean, because it lacks the propellant to fly all the way back to shore.
- A pad back on land. For lighter missions, the booster has enough propellant left to fly back and land near the launch site, a profile called return to launch site, or RTLS.
Once recovered, the stage is inspected and refurbished, then stacked for another flight. The reusable-rocket guide covers that refurbishment process and the cost math behind it in more detail.
What Falcon 9 Launches
Falcon 9 flies a wide mix of payloads, which is why it earns the workhorse label. The same rocket handles internet satellites, government missions, and human spaceflight, and it does so on a steady schedule rather than a handful of times a year.
- Starlink satellites. SpaceX launches batches of its own Starlink internet satellites on Falcon 9, and those flights make up a large share of its launches.
- Crew and cargo to the space station. Falcon 9 carries the Dragon spacecraft, which delivers astronauts and supplies to the International Space Station for NASA. Crew Dragon flies people, and Cargo Dragon flies supplies and experiments.
- Commercial and national-security payloads. Falcon 9 launches communications satellites, Earth-observation spacecraft, and defense payloads for a range of customers.
For heavier payloads, SpaceX also flies Falcon Heavy, which straps three Falcon 9 first-stage cores together to roughly triple the lifting power. It uses the same Merlin engines and the same landing approach as Falcon 9.
How Often Falcon 9 Flies
Falcon 9 flies far more often than any other rocket, and that cadence makes its reuse pay off. A booster that sits in a hangar earns nothing, so flying the same stages again and again, on a schedule measured in days between launches, is how SpaceX spreads each booster’s build cost across many missions. The high flight rate also builds a long track record, which is part of why customers trust it with expensive payloads and with crew.
That track record matters most for human spaceflight. To fly astronauts for NASA, Falcon 9 and the Dragon capsule had to pass a certification process that checks the rocket’s reliability across many flights. A rocket that launches often accumulates the flight history that certification depends on, so cadence and trust reinforce each other. A booster is also flown a set number of times before it is retired or inspected more deeply, and SpaceX has raised that limit as it learned how the hardware holds up.
Why Falcon 9 Matters
Falcon 9 matters because it made frequent, lower-cost launch routine rather than rare. Before it, first stages were thrown away on every flight, so each launch paid the full price of a new rocket. By landing and reflying the most expensive section, SpaceX turned launch into something closer to airline operations, where the same hardware earns its cost back over many trips.
That model set the pace the rest of the industry now measures itself against. It also fed directly into Starship, which extends the same reuse idea to both stages instead of one. The Starship explainer covers how that next step builds on what Falcon 9 proved. As of 2026, though, Falcon 9 remains the vehicle doing the everyday work of getting satellites and people to orbit.
There is a limit to Falcon 9’s reuse worth keeping in mind. Only the first stage comes back. The second stage, which carries its own Merlin engine, is expended on every flight, so each launch still builds and discards one stage. That partial reuse is exactly what Starship aims to close by recovering the upper stage too. It is also why the second stage is now the most expensive part of the rocket to build for each flight. For how the landing and refurbishment side of reuse works across the industry, the reusable-rocket guide lays out the mechanics and the cost math.
| Feature | Falcon 9 |
|---|---|
| Stages | Two |
| Reusable part | First stage |
| First-stage engines | Nine Merlin |
| Propellant | Kerosene and liquid oxygen |
| Payload to low Earth orbit | Roughly 22 metric tons, expended |
To check a specific Falcon 9 mission or its current payload figures, look at SpaceX’s own Falcon 9 page, since capabilities and reuse records change as the program adds flights.