00:00Why does Blue Origin use hydrogen for the upper stage? Methane or hydrogen? In spaceflight,
00:06that's an almost philosophical question with very real technical and economic consequences.
00:13While SpaceX consistently relies on methane, Blue Origin uses liquid hydrogen, or LH2 for short,
00:20with liquid oxygen, or LOX for short, for New Glenn's second stage. But why? And was that a
00:27clever decision? Here are the advantages of hydrogen as a rocket propellant. On paper,
00:32hydrogen has some impressive properties. LH2 is the most efficient chemical rocket propellant when
00:39it comes to specific impulse. The BE-3U engines on the New Glenn achieve over 450 seconds in vacuum,
00:48while the Raptor 2 sits at 350 seconds. That means an LH2 stage can fly farther with the same amount
00:58of
00:58propellant. Because hydrogen has a low density, the tanks are lighter, which enhances the mass
01:03efficiency advantage. LH2 and LOX were used for decades in the Saturn V, the Space Shuttle, and Ariane 5.
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