Raptor Engine

Raptor is SpaceX's reusable rocket engine, the powerplant that lifts Starship, the company's fully reusable Mars-class launch system. It burns liquid methane and liquid oxygen, a mix called methalox, and it is the first engine of its kind ever to fly. This is the engine meant to make reaching orbit cheap enough that a trip to Mars becomes a budget line.

What is Raptor?

Raptor is a methane-and-oxygen rocket engine built to be fired, recovered, and fired again quickly. The Super Heavy booster carries 33 Raptors, and the Starship upper stage carries six: three tuned for sea level and three built for the vacuum of space, known as RVac, with their bell nozzles widened for the thin air up high. Methane was picked over the kerosene that fuels Falcon 9 for a reason that points straight at Mars. It burns cleaner, leaving less of the soot, called coking, that gums up an engine and makes reuse harder, and it can one day be made on the surface of Mars from carbon dioxide and water already there.

Why Raptor Exists

The problem Raptor takes on is that space has always been priced like a national budget. Before rockets could be reused, sending one kilogram to low Earth orbit ran near $10,000, which kept orbit the private club of governments and the occasional billionaire. For a regular engineer or a would-be astronaut, that price shut the door completely, and for society it held back what humanity could even try off the planet. Elon Musk starts from the goal of a self-sustaining city on Mars and works backward, and every part, Raptor most of all, is judged by whether it brings the cost down toward that goal.

How it Works

Full-flow staged combustion sends all of the fuel and all of the oxidizer through two preburners, one heavy on fuel and one heavy on oxidizer, before they reach the main chamber, so nothing gets dumped overboard and the turbines run cooler. Engineers first drew up this kind of engine with the Soviet RD-270 of the 1960s, but it was never flown, and Raptor is the first of its kind to actually reach the sky. Raptor's chamber pressure of about 300 to 350 bar beats the 267 bar of the Russian-built RD-180, and higher pressure means more thrust from the same-sized engine. Across three generations, sea-level thrust climbed by about half, from 185 to 280 metric tons of thrust.

These gains did not come from making the engine bigger. Each generation got lighter even as it got stronger, with dry weight falling from 2,080 kilograms on Raptor 1 to 1,525 on Raptor 3, roughly 27 percent lighter. Raptor 3 tucks the heat shield and the outside plumbing right into the engine, doing away with parts that used to be bolted on, and that pushes its thrust-to-weight ratio above 180 to 1. More push from less weight is the whole game in a stage that has to lift everything stacked on top of it.

The Economics of Raptor

The way the engines are split tells the cost story. A full Starship stack carries 39 Raptors, but not evenly. The Super Heavy booster does the brute work of punching up through the thick lower atmosphere, so it stacks far more engines than the ship it lifts. On the Version 3 booster, 33 Raptor 3 engines fire at once for about 80.8 meganewtons of liftoff thrust by SpaceX's figures, about 18.2 million pounds of force and more than twice what the Saturn V put out to send Apollo to the Moon. Because the booster needs all 33 engines on every flight, each lighter, higher-thrust generation pays off across every stack SpaceX builds, and the cost per engine has fallen from near $1 million on Raptor 1 toward a target around $250,000.

Current Status of Raptor

Total production has passed 600 engines, and Raptor 2 alone has logged more than 226,000 seconds of test runtime, the kind of piled-up burn time that turns a prototype into a real product. The push in late 2021 was a company-wide priority, because Elon Musk made scaling engine output SpaceX's top goal. Output did scale, reaching roughly one engine per day by 2024, and the line is now building Raptor 3, with serial numbers in the hundreds already rolling out of McGregor.

What Comes Next

Raptor 3 is the production version, with an all-in-one design meant to survive reentry and fly again with little work in between. An engine that can fire, come home, and fire again without a rebuild is what would let the cost per kilogram keep dropping as launches get more frequent. Raptor 3 first flew on Starship Flight 12 on May 22, 2026. Flights 12 and 13 put the booster's return relights through their first Version 3 tests, and on Flight 14 the ship reached orbit after one of its vacuum engines shut down early.

The Bottom Line

Raptor is the part where the engineering goal and the money goal meet, because every kilogram shaved off the engine lowers the cost of reaching orbit. Its next test is reuse: catching a Version 3 booster and flying its engines again.