SpaceX vs. Rocket Lab vs. AST SpaceMobile: 3 Space Stocks Compared on the Only Numbers That Matter

Space Exploration Technologies (NASDAQ: SPCX), also called SpaceX, reported revenue of about $14.6 billion in the third quarter. However, more than half came from its Super Intelligence (SI) business, formerly known as the artificial intelligence (AI) business, rather than from its traditional space operations. SpaceX's other two businesses include Space, which manufactures and launches reusable rockets, and Connectivity, which provides satellite internet services through Starlink.

Rocket Lab (NASDAQ: RKLB) generated $234 million in its fiscal second quarter (ended June 30), mainly from its Space Systems segment. Rocket Lab manufactures spacecraft and satellite components through Space Systems, while its Launch Services business sends satellites and other payloads into space.

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AST SpaceMobile (NASDAQ: ASTS) reported just $31.5 million in its fiscal second quarter (ended June 30), with no recognized revenue from its planned satellite-cellular service. AST SpaceMobile is developing a satellite-based cellular broadband network that aims to connect ordinary smartphones directly to satellites through existing mobile operators.

However, revenue alone cannot determine which stock offers better returns. The more important numbers are the companies' ability to generate future cash flows relative to their current valuations.

Revenue may not translate into cash

SpaceX's Connectivity segment earned $2.37 billion in operating profit, while the SI segment earned $431 million in the third quarter. However, SI is also accounted for about $40 billion of the company's $48.1 billion in capital expenditures during the first nine months of 2026. SpaceX also reported $13.1 billion of operating cash flow and nearly $35 billion of negative free cash flow in the first nine months of 2026.

SpaceX's profitable Connectivity business is not yet generating enough cash to offset the company's enormous AI infrastructure spending. Additionally, a single unidentified SI customer accounted for 34.5% of the company's third-quarter revenue, equivalent to roughly two-thirds of SI revenue. The high customer concentration risk makes future cash generation particularly sensitive to that customer's spending decisions.

Rocket Lab and AST SpaceMobile are also free cash flow negative. In the first six months of 2026, Rocket Lab reported about $188 million in negative free cash flow, compared with roughly $1 billion for AST SpaceMobile.

AST SpaceMobile is burning cash at a high rate mainly due to investment in its satellite components and supporting infrastructure. While Rocket Lab needs to improve cash generation from its existing businesses and future launches, AST SpaceMobile must still convert its network investments into recurring commercial service revenue.

Growth has a cost for existing shareholders

Rocket Lab exited the second quarter with an order backlog of $2.36 billion, of which 45.5% is expected to convert into revenue by June 2027. This provides visibility into future sales, although revenue still depends on the fulfillment of launch and spacecraft contracts. The inaugural launch of the company's next-generation Neutron rocket has been pushed to 2027, potentially delaying revenue from the new rocket while development costs continue.

Rocket Lab's planned acquisition of Iridium Communications could add an established satellite-services business. Iridium Communications reported $245.7 million of revenue in the third quarter, with services accounting for 76% of the total.

However, certain risks can't be ignored. In September, Rocket Lab raised $1.94 billion by issuing 29.3 million shares, primarily to finance the acquisition. Iridium Communications' existing term loans, totaling about $1.78 billion as of June 30, are also expected to remain outstanding after the deal closes, with a guarantee from Rocket Lab's operating subsidiary.

Hence, the acquisition will create value for existing shareholders only if the additional cash flow justifies the equity dilution and increasing financial obligations.

AST SpaceMobile faces a different challenge. Management estimates that the company needs 45 to 60 operating BlueBird satellites to provide continuous service across key markets, including the U.S., Europe, and Japan. Although the company has partnerships with mobile operators serving more than 3 billion subscribers, it remains unclear how many will eventually use its satellite service and how much revenue they will generate.

AST SpaceMobile believes it has sufficient funding to manufacture and launch about 90 satellites. However, deploying the network is only part of the challenge. The company must also generate enough recurring revenue to cover operating costs and earn attractive returns on its investment.

What are investors paying for future growth?

SpaceX, Rocket Lab, and AST SpaceMobile traded at 57 times, 40.8 times, and 101.8 times trailing-12-month sales (as of Oct. 30), respectively. These premium valuations already assume significant ramp-up in revenue and profit in the coming quarters.

AST SpaceMobile's valuation is particularly steep. The company expects $150 million to $200 million in revenue for 2026, supported partly by U.S. government contracts. Hence, even if AST SpaceMobile achieves the upper end of this forecasts, its $13 billion market capitalization would still represent more than 61 times projected 2026 revenue.

AST SpaceMobile also expects to recognize only 6.6% of its $1.2 billion in remaining contractual performance obligations as revenue by June 2027. This highlights that a significant amount of time is required to convert contracted business into recognized revenue. With its commercial SpaceMobile service yet to generate recognized revenue, AST SpaceMobile's valuation depends heavily on future network monetization.

Rocket Lab needs to become free cash flow positive, while SpaceX must demonstrate that its substantial AI investments can deliver attractive returns.

Which stock offers the strongest case?

Of the three, Rocket Lab appears to be the best pick on a risk-reward basis, although its valuation is rich. The company's established launch and spacecraft businesses provide a foundation for growth, while the Iridium acquisition could add recurring service revenue. However, the company must demonstrate that its expansion can improve per-share cash flow after accounting for dilution and financing obligations.

SpaceX ranks second. Starlink's profitability is a significant advantage, but the company's huge AI investments can't be ignored.

AST SpaceMobile ranks third for now. The company's satellite-cellular network offers substantial growth potential, but commercial service revenue and long-term profitability remain unproven.

Manali Pradhan, CFA has no position in any of the stocks mentioned. The Motley Fool has positions in and recommends AST SpaceMobile and Rocket Lab. The Motley Fool recommends Space Exploration Technologies. The Motley Fool has a disclosure policy.