Just been looking at two space stocks that both went public through SPACs back in 2021 and actually survived the crash that killed most of their peers. AST SpaceMobile and Rocket Lab took pretty different paths though, and understanding how rockets work in space is key to seeing why their business models diverge so much.

So here's the thing - AST is betting on satellite constellations for cellular coverage. They're launching bigger, more capable satellites (their Block 2 versions are 3.5 times larger than the originals and process about 10 times more data). They're partnering with AT&T and Verizon to reach rural areas, and they're ramping up fast - targeting 45-60 satellites by end of year with plans to eventually hit over 240. Pretty ambitious.

Rocket Lab is more about being the delivery service. They've already launched their Electron rocket 81 times, getting smaller payloads into orbit. What's interesting is their launch cadence keeps accelerating - 6 launches in 2021, jumped to 21 in 2025. This year they're introducing Neutron, a heavier-lift rocket that can handle payloads up to 13,000 kilograms. Understanding how rockets work in space means appreciating that different payload sizes need different solutions, which is exactly what they're building.

Looking at the growth projections, AST is expected to hit 200% revenue CAGR through 2028, reaching $1.9 billion. Rocket Lab is more modest at 38% CAGR to $1.6 billion. Both are expected to turn profitable in 2027. But here's where valuation gets interesting - AST trades at 16x 2028 sales while Rocket Lab is at 26x. That gap is pretty significant.

Given the stronger growth trajectory and cheaper valuation, AST looks more attractive right now if you're choosing between these two space plays. The satellite constellation model seems to have more runway, and the numbers support it. That said, both companies are building real infrastructure in the space economy, which is why they're worth watching.