New York CNN Business  — 

Rocket startup Relativity Space has yet to fire anything into space. But customers are already writing big checks.

Relativity, which is building rockets to launch small satellites, said Monday that a company called Spaceflight is purchasing up to six launches. It marked the company’s third major contract announcement in just five weeks.

Tim Ellis, Relativity’s CEO who co-founded the company just over three years ago, said Relativity is attracting more attention because people are excited about its novel approach to manufacturing. Its rockets will be 3D-printed top to bottom.

“People are really starting to rally around that as the future of rocket technology,” Ellis told CNN Business. “3D printing allows us to evolve extremely quickly.”

Relativity says it will be able to reconfigure its 3D printers to change the design of its rockets and nimbly respond to satellite companies’ needs.

It’s an approach that has excited some high-profile investors.

Relavity has backing from Y Combinator, Silicon Valley’s famed startup incubator, and Mark Cuban, the billionaire of “Shark Tank” fame.

“I’m excited,” Cuban said about Relativity in an email Saturday. “They have the contracts in place. Once the launches begin their momentum will only accelerate.”

Cuban initially invested $500,000 in Relativity and he has put more money in at each opportunity, he said.

Over the past year, Relativity has grown from just 14 people to about 85, and it’s attracted top brass from leading rocket companies like Elon Musk’s SpaceX and Jeff Bezos’ Blue Origin. (Ellis, the co-founder and CEO, previously worked at Blue Origin as an engineer.)

The big business of small satellites

Relativity is gunning to tackle a tough industry. Like more than 100 other young companies around the world, Relativity wants to build rockets that cater specifically to the small satellite, or smallsat, industry, which has ballooned as new technologies have made devices cheaper and more capable.

Relativity Space plans to 3D print its rockets, which wil be smaller than a SpaceX Falcon 9 but bigger than Rocket Lab's Electron.

Not all of those startups will survive. And only one, Rocket Lab, has ever actually sent a rocket to orbit.

But Relativity is among a small list that have already landed launch contracts, noted Laura Forczyk, founder of industry analysis firm Astralytical, who believes Relativity has a promising future. Arizona-based Vector and Richard Branson’s Virgin Orbit have also secured contracts.

“When you’re talking to outside investors, people who aren’t very familiar with rocket companies, it’s very impressive,” Forczyk said. “If you make [3D printing] part of your branding, you stand out.”

And Relativity’s approach really is unique. Although companies from SpaceX to legacy engine maker Aeroject Rocketdyne build some parts with additive manufacturing, Relativity plans to use in-house technology to 3D print every single component.

That could allow the company to significantly lower production costs and churn out rockets faster than competitors, Forczyk said.

Relativity has signed deals to test and launch rockets at prestigious facilities — including NASA’s Stennis Space Center and the Cape Canaveral Air Force Station — which could help the company land lucrative military and government launch contracts.

Its first rocket design, the Terran 1, hits a sweet spot in the launch market: It’s nowhere near as big as SpaceX’s Falcon 9 rocket, but it’s still much larger than what Rocket Lab is offering. The largest satellite it will be able to send to low-Earth orbit would be about as heavy as a Mini Cooper, which is plenty of room for a big bundle of smallsats.

Still, Forczyk said the ultimate test will come when Relativity finally puts a Terran 1 rocket on a launch pad.

“Anybody can write a PowerPoint. Anybody can raise money,” she added. “I look for actual hardware testing and operations. So far, Relativity is on a good path, but we haven’t seen those last tests.”