The space investment landscape extends far beyond a single, dominant player.

While SpaceX's upcoming IPO presents a major opportunity for investors to access the high-growth space economy, it also shines a spotlight on other publicly traded aerospace firms. These companies may lack the brand recognition of Elon Musk's ventures, but several boast compelling business models and significant growth potential.

Rocket Lab (RKLB) stands as a prime example. This Nasdaq-listed company is one of the few globally with proven orbital launch capability, albeit at a smaller scale than SpaceX. Achieving orbital insertion is an exceptionally high barrier to entry, a feat that alone distinguishes it from most competitors. Other public companies like Virgin Orbit and Astra have faced repeated setbacks in their launch endeavors, and even Jeff Bezos's private Blue Origin has recently encountered major project hurdles.

Founded two decades ago in New Zealand and now headquartered in California, Rocket Lab has successfully conducted 88 small-payload launches to low-Earth orbit, with only four failures, the most recent occurring in 2023.

The company aims to be more than just a supporting actor to SpaceX's massive rocket projects, which launch Starlink satellites and other cargo every few days. Under the leadership of self-taught engineer Peter Beck, Rocket Lab plans the inaugural flight of its medium-lift Neutron rocket this year, with a maximum payload capacity of 13 tons.

This represents a critical turning point, potentially narrowing the cost gap with SpaceX. While SpaceX's Falcon Heavy can deliver nearly 60 tons to orbit at a cost of around $1,500 per kilogram, Neutron's projected cost is approximately $4,000 per kilogram. Although not the industry's lowest price, this is competitive with some variants of the Falcon 9. Demand remains robust even at this premium.

Leveraging the reliable track record of its small Electron rocket, Rocket Lab has secured significant defense contracts. Many military clients prefer dedicated, flexible launch schedules for reconnaissance satellites over sharing rides with commercial payloads like Starlink, aligning with needs for rapid, responsive deployment.

In March, the company won a $190 million contract with the U.S. Department of Defense to support hypersonic vehicle environmental testing using the Electron rocket. It is also collaborating with defense giant Raytheon Technologies (RTX) on the U.S. "Golden Dome" space-based missile defense project.

Beck revealed on last month's earnings call that the company has a backlog of over 70 launch missions. Last year's revenue surged 38% year-over-year, surpassing $600 million. The total backlog at the end of the first quarter stood at $2.2 billion and is expected to grow further with accelerating space militarization and the emergence of new sectors like space-based AI computing centers.

Chief Financial Officer Adam Spice indicated that if the space AI industry booms and demand for large-payload launches surges, Rocket Lab would develop even larger rockets to compete more directly with SpaceX.

With a comprehensive vertical integration strategy, the company is even building and operating its own space data center. "We prefer to own and operate the computing infrastructure in orbit, leasing capacity to customers, rather than just being a manufacturing contractor," the company stated.

Rocket Lab's current stock is not cheap, having risen over 50% this year. Based on SpaceX's proposed IPO valuation, Rocket Lab's price-to-sales ratio is roughly on par with SpaceX. However, compared to SpaceX, which has an extremely high valuation ceiling, Rocket Lab's smaller base makes its elevated valuation potentially easier to justify through earnings growth.

The investment thesis for other public space companies varies significantly.

The prospects for lunar services provider Intuitive Machines remain uncertain. Communication satellite operators like AST SpaceMobile, Viasat, and Iridium have more solid growth fundamentals, but their markets are becoming increasingly crowded and competitive. Industry demand stems from space-based mobile communications and satellite IoT connectivity, a core business for Iridium. Data shows the global satellite operations industry generated $24 billion in revenue last year, with steady future growth expected, though unlikely to reach the $1.6 trillion potential market cited in SpaceX's IPO filings.

Nevertheless, smaller operators may struggle to capture a large revenue share. SpaceX's Starlink already holds a dominant position, estimated to account for nearly half of the industry's revenue last year. Amazon is also entering the fray with its substantial resources, deploying satellites for its Project Kuiper to build a space-based internet network.

This landscape is not entirely negative for established players like AST, Viasat, and Iridium. Even if scaling their own operations proves difficult, these companies hold valuable and scarce satellite spectrum licenses (rights to transmit voice and data on specific frequencies), making them attractive acquisition targets for larger players and providing potential exit opportunities for investors. Amazon's acquisition of Globalstar in April was driven precisely by its satellite network and spectrum assets.

While many investors equate the space sector solely with SpaceX, this vast frontier is not the domain of a single company.