Though SpaceX founder Elon Musk most often commands headline, the story of the private space startup hinges on a collection of key early figures.
One is Tom Mueller, the famed space propulsion expert who ran development of SpaceX's rocket engines and helped crack the code on reusability, the concept SpaceX has pioneered that has dramatically driven launch costs lower.
As SpaceX develops its unprecedented mega rocket, Starship, Mueller, who left the company in late 2020, is betting that the next chapter of the space economy will focus not on how to get to space but rather on the business opportunities once there.
"I decided where the business is, is in space," Mueller said in an interview with CNBC's "Manifest Space" podcast. "The whole point of SpaceX is to move payloads into space, and with Starship coming online [and] able to take 100 tons at a time, I realized there's going to be huge opportunity for moving things around in space."
Mueller started Impulse Space in 2021 and is building space tugs that can move with cargo to different orbits. So far, Impulse Space has raised $30 million in seed funding from investors such as Peter Thiel's Founders Fund and Lux Capital. The startup is currently embarking on a Series A round.
Its first flight spacecraft, Mira, will launch to orbit on a SpaceX Falcon 9 rocket in October. Perhaps unsurprisingly, Mueller said he gleans inspiration from the "early days" of SpaceX and Tesla.
"We can't make them fast enough," he said of the company's space tugs, adding Impulse has already booked capacity on two more SpaceX launches beyond October's Transporter 9 mission and is looking to lock in more.
While the small launch market was more enticing several years ago, according to Mueller, rideshare missions are far more cost-effective. Once the tugs are in orbit, and factoring in Starship capabilities, Mueller estimates the total addressable market to be roughly $8 billion by the end of the decade.
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Mueller is revered in space and engineering circles. He first teamed up with Musk in 2002, introduced to the PayPal co-founder through an amateur rocket club. At the time he worked for TRW, a corporation focused on tech services across the automotive, aerospace and electronics industries, and had been doing "amateur rocket stuff" out in the desert for more than a decade.
He was in on the ground floor when SpaceX formed.
"I ended up being employee No. 1 in payroll because I signed first," recalled Mueller. "Even before we incorporated as a company we already pretty much had the Falcon One architecture."
He ran propulsion at the SpaceX, spearheading development of the Merlin and the Draco engines that power the Falcon 9 rocket and Dragon spacecraft, respectively. He also worked on the engines that now power Starship.
But that pedigree doesn't mean Impulse is closed off to other startups in the space space – including rocket makers.
Earlier this month Vast Space, which is building a commercial space habitat, selected Impulse to develop the Haven-1 Space Station's propulsion system. Haven-1 is targeting a 2025 launch to low earth orbit.
Impulse has also partnered with 3D rocket launcher Relativity Space to conduct the first-ever commercial landing on Mars as early as 2026. Mueller told CNBC that he believes humanity is within a decade of putting the first people on the red planet.
While Mueller admires Musk and those focused on Mars, he says the real opportunity, is on the moon. Mueller sees the moon as almost a natural resource play.
"The moon has basically all the resources that we have on Earth," he said, adding it's "literally 20 times easier, energy wise, to take [resources] from the surface of the moon" than to transport them up from Earth.
"Manifest Space," hosted by CNBC's Morgan Brennan, focuses on the billionaires and brains behind the ever-expanding opportunities beyond our atmosphere. Brennan holds conversations with the mega moguls, industry leaders and startups in today's satellite, space and defense industries. In "Manifest Space," sit back, relax and prepare for liftoff.