Spaceflight Insider

Update: Raptor roars on SpaceX’s Texas test stand

The first firing of a Raptor flight engine. Photo Credit: Elon Musk / SpaceX

The first firing of a Raptor flight engine. Photo Credit: Elon Musk / SpaceX

SpaceX’s next-generation rocket engine, dubbed Raptor, was briefly fired on a test stand. The test comes just days after company CEO and Founder Elon Musk revealed photos of the engine on Twitter.

Raptor is designed to consume liquid methane and liquid oxygen and will be used to power SpaceX’s Starship spacecraft and Super Heavy rocket.

“First firing of Starship Raptor flight engine!” Musk tweeted the evening of Feb. 3, 2019. “So proud of great work by [the SpaceX] team!”

The test, which lasted for only several seconds, took place at the company’s test facility in McGregor, Texas. Musk said the engine is initially being designed to produce 200 metric tons of thrust and will be common across both the 180-foot (55-meter) tall Starship and 207-foot (63-meter) tall Super Heavy rocket, which is expected to have seven and 31 Raptor engines, respectively.

The commonality was done to ensure a faster development time for the vehicles. Once operational, vacuum-optimized and sea-level-optimized versions of Raptor will be made with greater efficiencies, according to Musk.

Update Feb. 4, 2019: According to SpaceX’s Instagram account, the two-second test fire produced about 116 metric tons of force, which the company said was the highest thrust ever from a SpaceX engine—it was only at about 60 percent power.

Raptor is a full-flow staged combustion engine, meaning it uses both oxidizer-rich and fuel-rich preburners and allows a both propellants through the turbines before going through a combustion chamber.

Raptor on the test stand days before being fired. Photo Credit: Elon Musk / SpaceX

Raptor on the test stand days before being fired. Photo Credit: Elon Musk / SpaceX

It allows turbines to run at lower temperatures and is easier on the engine overall, potentially allowing for a longer and more reliable life.

To date, three full-flow staged combustion engines have ever made it to test stands, the Soviet-designed RD-270 in the 1960s, an Aerojet Rocketdyne demonstration project in the 2000s and Raptor. None have seen actual flight, though.

Musk said on Twitter that the engine will be ignited using metholox torch igniters, which he described as “heavy duty spark plugs.” Those ignite dual blow torches that ignite the preburners and main chamber, he said.

A prototype of the upper stage of SpaceX’s Mars rocket, called Starship, is being built in south Texas. This “hopper” will use three Raptor engines to fly to various low altitudes for early tests of the vehicle.

During construction, it was revealed that the ship is now expected to be made out of stainless steel, rather than advanced carbon fiber. Musk said this allows for a simpler and lower-cost design and counter-intuitively, a lower-mass vehicle since stainless steel can withstand much higher temperatures.

Additionally, Musk has been teasing a regeneratively-cooled heat shield that sweats liquid methane through tiny holes in the bottom for added cooling. If done successfully, it would be another words first as all spacecraft heat shields to date have been either ablative, like on SpaceX’s Dragon capsule and NASA’s Orion crew vehicle, or absorptive, like the tiles used on the space shuttles.

The first orbital test flights of Starship could come as soon as 2020, however, even Musk has admitted that is a highly-ambitious schedule. Additionally, a flight around the Moon with Japanese billionaire Yusaku Maezawa and eight artists is planned as early as 2023.

The completed Starship test article at SpaceX's Texas launch site. Photo Credit: Elon Musk / SpaceX

The completed Starship test article at SpaceX’s Texas launch site. Photo Credit: Elon Musk / SpaceX



Derek Richardson has a degree in mass media, with an emphasis in contemporary journalism, from Washburn University in Topeka, Kansas. While at Washburn, he was the managing editor of the student run newspaper, the Washburn Review. He also has a website about human spaceflight called Orbital Velocity. You can find him on twitter @TheSpaceWriter.

Reader Comments

James Lunar Miner

Russia’s Rosatom is reportedly working on a super propellant efficient nuclear powered rocket engine to power high delta-v capable spacecraft that will make obsolete the grossly propellant inefficient fossil fueled Raptor rocket engine powered flights of SpaceX’s low delta-v Starship spacecraft to the Moon and Mars.

Who is Rosatom?

“As of Jan 2017, the total portfolio orders of Rosatom reached $300 billion.[6]”

And, “Rosatom owns 67% of the world nuclear plant construction market and, currently, the orders portfolio exceeded $133 billion. Rosatom has taken the lead in offering nuclear power plants to emerging countries.[34][35] 37% of nuclear reactors under construction worldwide being built by Rosatom itself, usually the OKB Gidropress’ VVER type. Rosatom received $66.5 billion of foreign orders in 2012, including $28.9 billion for nuclear plant construction, $24.7 billion for uranium products and $12.9 billion for nuclear fuel exports and associated activities.”

And, “Nuclear power plants in China, India, and Iran, were either designed and built by Rosatom or with the corporation’s participation. Rosatom is involved with the construction of the Tianwan Nuclear Power Plant in China, the construction of Unit № 2 of Kudankulam Nuclear Power Plant in India, and the construction of Unit № 1 of the Belarusian Nuclear Power Plant in Belarus.[36][37][38][39][40]”

From: “Rosatom” Wikipedia

James Lunar Miner

Yikes! TEM powered spaceships are going to do Space Dominance missions while flying circles around the slow fossil fueled Star Wars II/BFR/Starship!

“TEM (Russian: Транспортно-энергетический модуль, ‘transport and energy unit’, NPPS in English) is a nuclear propulsion spacecraft project between the Russian Keldysh Research Center,[1] NIKIET (Research and Design Institute of Power Engineering) institute[2][3] and Rosatom.”

From: “TEM (nuclear propulsion)” Wikipedia

James Lunar Miner

“The cooling system of a Russia-developed nuclear-powered spacecraft has passed ground tests, according to materials published on the government procurement website on Monday.”

And, “The tests of the most important element of the megawatt-class have been conducted successfully under conditions as close as possible to outer space, with results meeting the requirements of the technical specifications, the website said.”

From: “Russia successfully tests key element of nuclear propulsion spacecraft”
Source: Xinhua| 10/29/2018

Double Yikes!

Isn’t it a Raptor/BFR/Star Wars II/Starship cult belief that highly propellant efficient and super high Isp and fast spaceships powered by nukes are not a good idea?

Why would Russia and China want to join our slow and low Isp and grossly propellant inefficient and fossil fueled Raptor/Starship American government promoted and supported cult?

That is probably not going to happen, is it?

Maybe winning our Cold War II with lots of Space Dominance and Star Wars II and Prompt Global Strike stuff is going to be quite a bit harder than most folks understand, right?

Maybe in 23 years, but until then Raptor and BE4 will dominate.
“NASA has contemplated similar engines for Mars missions. The biggest obstacle facing Russia is not the science of the engine, but the cost of developing it on Russia’s shoestring space budget. And then there’s also the small matter that if it doesn’t quite escape Earth’s gravitational pull, we’ll get a nuclear reactor crashing from space to Earth.”

James Lunar Miner

“Maybe in 23 years, but until then Raptor and BE4 will dominate. – JBURN

Nope. You remain confused. Space engineers, Russia, China, Congress, and our President have all decided that highly propellant efficient nuclear thermal rocket engines will soon cost-effectively “dominate” on the Moon and in Cislunar Space.


“Of that total, $180 million will go to Restore-L, a satellite servicing mission also previously threatened with cancellation, and $100 million to nuclear thermal propulsion research, including planning for a flight demonstration mission by 2024.”

From: Final fiscal year 2019 budget bill secures $21.5 billion for NASA
By Jeff Foust 2/17/2019

James Lunar Miner

Blue Origin has recently switched their second stage from using a propellant inefficient fossil fueled BE4 rocket engines to using two higher Isp and more propellant efficient hydrogen powered BE-3U rocket engines.


“New Glenn is a 7-meter-diameter (23 ft) two-stage orbital launch vehicle with a reusable first stage[10] and an expendable second stage.”

And, “The second stage will be powered by two BE-3U engines, also designed and manufactured by Blue. BE-3Us are an expander cycle variant of the BE-3 engine are explicitly designed for use in upper stages.”

From: “New Glenn” Wikipedia,

Hydolox gives a second, or third, stage a higher delta-v and/or payload capability than would be the case with a methane powered upper stage.

Having the second stage be expendable probably boosts the New Glenn’s payload capacity to LEO by about 20%.

The “expander cycle” hydrogen rocket engines are relatively simple, super reliable and robust, may have a 450 Isp to 465 Isp when used in upper stages or Lunar Landers, and they are inherently easy to start and restart.

“$100 million to nuclear thermal propulsion research” chump change. At that rate it will be 20+ years…

James Lunar Miner

The overly complex and grossly propellant inefficient 380 Isp Raptor powered stainless steel Mars colonies soon chump or sucker Starship spacecraft is a slow, risky, and radiation rich way to go anywhere beyond LEO when compared to the faster, higher delta-v capabilities, and much higher propellant efficient 900+ Isp nuclear thermal rocket powered spaceships that both NASA and Russian space experts have wanted (and have been capable of building) for over forty-five years.


“NERVA demonstrated that nuclear thermal rocket engines were a feasible and reliable tool for space exploration, and at the end of 1968 SNPO certified that the latest NERVA engine, the NRX/XE, met the requirements for a human mission to Mars. Although NERVA engines were built and tested as much as possible with flight-certified components and the engine was deemed ready for integration into a spacecraft, much of the U.S. space program was cancelled by Congress before a manned mission to Mars could take place.”

From: “NERVA” Wikipedia

Both Russia and China want and need commercial and military Space Dominance and they need nuclear thermal rocket engine spacecraft and nuclear powered electric propulsion system spacecraft to gain that dominance.

We may not lead in developing highly propellant high delta-v capable nuclear thermal rocket engine powered spacecraft, but if we want to be able to defend our military and commercial assets and investments in space we had better hustle hard in building such highly mission capable spacecraft.

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