Relativity Space’s Terran R, while similar in performance to the Falcon 9, looks more like SpaceX’s Starship vehicle, from its metallic finish to the aerodynamic design of the upper stage. And, like Starship, both stages of Terran R are intended to be reusable. Credit: Relativity Space

WASHINGTON — For years after Boeing and Lockheed Martin combined their launch vehicle businesses into a joint venture, United Launch Alliance had a lock on the medium- to heavy-lift launch market in the United States. SpaceX would eventually challenge that, but it would take years of effort, including a lawsuit, for that company to win national security launch business. That created a SpaceX/ULA duopoly that survived competition from Blue Origin and Northrop Grumman to win National Security Space Launch Phase 2 contracts last year.

The next time around, SpaceX and ULA may face even more competition. Besides the prospect of Blue Origin and perhaps Northrop Grumman bidding on future contracts, startups that originally focused on small launch vehicles are looking to move into larger markets. In recent months, both Relativity Space and Rocket Lab have unveiled plans for rockets that can serve medium-class payloads for commercial and government customers. The two companies, while sharing similar ambitions, are taking different approaches to developing larger vehicles.


For most of the company’s history, Rocket Lab and its founder, Peter Beck, showed no interest in rockets larger than its Electron, which can place up to 300 kilograms into low Earth orbit. The closest Beck came to discussing a larger rocket was when he tweeted a photo of himself standing next to a version of Electron with three first stages: Electron Heavy, analogous to the Delta 4 Heavy and Falcon Heavy. It was an April Fool’s joke.

That changed in March. At the same time Rocket Lab announced it was going public through a merger with a special-purpose acquisition corporation (SPAC), it also unveiled Neutron. That rocket will be far more powerful than Electron, capable of placing up to 8,000 kilograms into orbit.

Illustrations of Neutron show a relatively nondescript vehicle with a conical payload fairing 4.5 meters in diameter. The only features that stand out are what appear to be landing legs folded up at the base of the first stage, like those on the Falcon 9 (Rocket Lab plans to land the first stage on a ship and reuse it.)

Relativity Space and Rocket Lab are both developing larger rockets that could vie with Falcon 9 and Vulcan Centaur for some classes of payloads. Credit: SpaceNews graphic by Robin McDowal

However, those public images don’t represent the true shape of Neutron. “The image you see of Neutron there is a bit of a ruse. Neutron looks nothing like that,” Beck said in a webinar by the Space Generation Advisory Council in early August. “Basically, we’re sick of people copying us all the time.” He said the company would reveal the actual design of Neutron “in time.”

With that unwillingness to show what Neutron looks like, it’s not surprising that Rocket Lab has shared few technical details about the rocket, including its engines. The company says that Neutron will use the same propellant combination as Electron, liquid oxygen and kerosene, but hasn’t discussed the performance or even the number of engines on each stage of the rocket.

In an interview shortly after the announcement of Neutron, Beck said the company would leverage the technology it developed for the Rutherford engines on Electron. Those engines make extensive use of 3D printing as well as battery-powered pumps, and produce up to 56,000 pounds-force of thrust.

“Engines are always the long pole” in launch vehicle development, he said, but emphasized the experience the company has from flying more than 200 Rutherford engines. “We know how to build engines. We know how to scale up manufacturing.”

Rocket Lab CEO Peter Beck standing inside a Neutron payload fairing. Credit: Rocket Lab

Beck said he expects Rocket Lab to incorporate at least some aspects of the Rutherford engine design for the engine that will power Neutron. “We did a lot of work around combustion stability and injectors, so a lot of that will scale nicely,” he said. That new engine will also likely make use of 3D printing.

One challenge, he acknowledged, may be the turbomachinery of the larger engine. Rocket Lab, though, isn’t seeking to optimize the performance of the engine but instead build a “workhorse” for frequent launches. “For us, extracting the last second of specific impulse out of an engine is probably not the right way to go,” he said. “What we’re looking for is maximum reusability and maximum reliability.”

Work on Neutron will likely shift into high gear once Rocket Lab’s SPAC merger is completed, which is scheduled for late August. Beck said the company wanted to wait until it secured financing before starting Neutron, with a goal of a first launch as soon as 2024.

Rocket Lab believes that, with Electron and Neutron, it can launch as much as 98% of commercial and government satellites forecast to launch through the end of the decade, with Neutron focused on deploying constellations. The U.S. government is already a major customer of Electron, with NASA, the Space Force, NRO and DARPA all launching payloads on it.

The company will also human-rate Neutron, even though it has no current plans to launch people on it. “I’m covering our bases,” Beck said. “There’s no point building a launch vehicle of that class that isn’t rated for human spaceflight.”


Relativity Space also started small, with its Terran 1 rocket designed to place up to 1,250 kilograms into orbit for $12 million. Although the company has yet to fly Terran 1 — the first launch is scheduled for late this year — Relativity has won contracts from satellite operators like Iridium and Telesat, who plan to use the rocket to replenish their LEO constellations.

In June, Relativity announced its largest funding round to date, $650 million, a little more than six months after raising $500 million. That funding will go toward development of a much larger rocket, the Terran R. That rocket is designed to place more than 20,000 kilograms into LEO, a capacity comparable to the Falcon 9.

Terran R, while similar in performance to the Falcon 9, looks more like SpaceX’s Starship vehicle, from its metallic finish to the aerodynamic design of the upper stage. And, like Starship, both stages of Terran R are intended to be reusable.

“That architecture really opens up a lot of long-term possibilities for Terran R,” Tim Ellis, co-founder and chief executive of Relativity, said in an interview. “It serves where we see the commercial market demand is today and over the next decade.”

Terran R will be powered by Aeon R engines, upgraded versions of the Aeon 1 engine it developed for Terran 1 that use liquid oxygen and methane propellants. The first stage of Terran R will have seven Aeon R engines, each producing 302,000 pounds-force of thrust, while the upper stage will have a single vacuum-optimized version of that engine. The company expects to begin testing a prototype version of that engine as soon as the end of this year, a schedule that supports a first launch of Terran R as early as 2024.

Both Terran R and its Aeon R engines will make extensive use of 3D printing, which has become a hallmark of Relativity. “3D printing actually will help us make a far better reusable rocket that couldn’t really exist with traditional manufacturing,” Ellis said. That technology can allow the company to produce “algorithmically generated and optimized structures” that can’t be made with traditional techniques, along with the use of exotic alloys that have a higher temperature resistance but are lightweight.

Ellis said he sees NASA and the Defense Department as major customers for Terran R, positioning Relativity as a disrupter of the status quo, much like SpaceX. “There’s overall interest there in having a second truly disruptive, fast-paced and innovative launch company.”


Other small launch vehicle companies are looking at developing medium-class and larger rockets. Firefly Aerospace, whose Alpha small launch vehicle is nearing its first launch, has plans for a larger vehicle called Beta, but the company is only now starting design work on the vehicle.

“The long pole will be the engines,” Tom Markusic, chief executive of Firefly, said after the company raised $75 million in May. “Propulsion will be the big focus in the next few months, which is great, because I love rocket engines.”

The experience of another company, though, offers a cautionary note. Fifteen years ago, Orbital Sciences Corp. started work on a medium-class rocket originally called Taurus 2 that it envisioned as a successor to ULA’s Delta 2. It found an anchor customer in NASA through its commercial cargo program, allowing it to proceed with development of the rocket, now called Antares.

While Antares now regularly launches Cygnus cargo spacecraft to the space station, the rocket has not found any customers beyond NASA’s Commercial Resupply Services (CRS) program.

“We are continuing to pursue sales of Antares for non-CRS missions,” said Kurt Eberly, director of space launch programs at Northrop Grumman, at a press conference the day before the most recent Antares launch Aug. 10. Antares is on the NASA Launch Services 2 contract vehicle, allowing it to compete for other agency launches. “We’re talking to some other customers as well.”

That sales job, already difficult given current competition like SpaceX, will presumably become even harder with the introduction of Neutron and Terran R around the middle of the decade that will offer similar or higher performance for lower prices. But Eberly noted there’s often a difference between what a company plans to do and what it actually delivers.

“Everything looks very rosy on paper,” he said. “By the time the new entrants get to launch, we’ll see where they end up. It’s a difficult business.”

This article originally appeared in the August 2021 issue of SpaceNews magazine.

Jeff Foust writes about space policy, commercial space, and related topics for SpaceNews. He earned a Ph.D. in planetary sciences from the Massachusetts Institute of Technology and a bachelor’s degree with honors in geophysics and planetary science...