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A Raptor engine firing on the test stand in McGregor, Texas
Knowledge base · 17 explainers

Learn the engineering, not the hype.

In-depth, sourced explainers on the history, physics, and human impact of making life multiplanetary and understanding the universe.

Photo: Elon Musk · CC0
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Falcon 9 climbing away from Vandenberg Air Force Base
SynthesisSeptember 27, 20267 minIn timeline
The Retrograde Burn That Drops Perigee into the Atmosphere

From a 275 km circle, about 58 m/s of retrograde velocity lowers perigee to 80 km. Flight 14 confirmed that burn after about three hours in orbit, then a Pacific splashdown.

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Super Heavy booster descending onto the launch tower arms at Starbase, seen from a surveillance aerostat, October 13 2024
SynthesisJune 24, 20268 min
Aerodynamic Control Laws and Relative Kinematics for Super Heavy Booster Tower Catch

Precision control of the Super Heavy booster during high-angle-of-attack reentry and flip uses grid-fin aerodynamics and thrust vectoring; relative position/velocity kinematics enable mechanical catch by the launch tower for full reusability.

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A Starship upper stage standing inside the Megabay at Starbase, Texas
SynthesisJune 24, 20267 min
Microgravity Cryogenic Propellant Transfer and Ullage Control for Starship In-Orbit Refueling

In zero-g, cryogenic liquids are managed by surface tension, settling burns, and ullage motors; conservation principles enable efficient transfer between Starships to achieve the propellant mass for deep-space missions.

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A Raptor engine firing on the test stand in McGregor, Texas
SynthesisJune 24, 20268 min
Full-Flow Staged Combustion Thermodynamics in Raptor for Starship Reusability

The full-flow staged combustion cycle in Raptor engines maximizes specific impulse and thrust through complete propellant pre-burning, enabling the high performance margins required for Starship's rapid full reusability at scale.

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SpaceX workers looking up at the engine section of a Super Heavy booster
SynthesisJune 24, 20267 min
Tsiolkovsky Rocket Equation Mass Ratio and Recovery Δv Overhead at Starship Scale

At Starship masses, the exponential nature of the rocket equation means small improvements in structural fraction or Isp provide large gains; recovery Δv for catch is an overhead that must be minimized to preserve payload for full reusability.

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Starship glowing with plasma during atmospheric re-entry
SynthesisJune 24, 20267 min
Stagnation Heat Flux and Convective Heat Transfer on Starship Reentry Heat Shield

Convective and radiative heat flux during atmospheric reentry scales with the cube of velocity and density; Starship's tiled heat shield manages this to enable full reusability after orbital and interplanetary returns.

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The first recovered Falcon 9 booster standing on Landing Zone 1 the morning after landing
SynthesisJune 24, 20267 min
The Tsiolkovsky Rocket Equation and Falcon 9 Booster Reuse Economics

The Tsiolkovsky rocket equation reveals why recovering and reusing the Falcon 9 first stage produces order-of-magnitude gains in delivered payload per unit of propellant and cost.

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Nine Merlin engines arranged in the octaweb pattern at SpaceX headquarters
SynthesisJune 6, 202610 minIn timeline
First Principles in Action Across Frontiers

How the discipline of reasoning from fundamental truths — rather than analogy or tradition — powers the engineering culture at both SpaceX and xAI.

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A Falcon 9 lifting off from Space Launch Complex 40 against a peach sunset sky on a Starlink mission
SpaceXJune 6, 20269 minIn timeline
Starlink: Connecting the World

How the largest commercial satellite constellation in history is delivering global broadband, enabling new economies, and supporting the infrastructure of exploration itself.

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xAISeptember 30, 202510 minIn timeline
Colossus and the Infrastructure of Discovery

xAI's Memphis Supercluster represents one of the largest concentrations of AI training compute ever assembled. Scale is not the goal — it is the necessary precondition for the mission.

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Falcon 1 lifting off from Omelek Island on its fourth flight, September 28 2008
SpaceXSeptember 30, 202511 minIn timeline
From Falcon to Starship: A Continuous Thread

The through-line from the first Falcon 1 success to today's Starship program is not different vehicles — it is the same engineering culture applied at increasing scale.

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A Falcon 9 first stage descending on its landing burn and touching down beside the Pacific at Vandenberg, November 21 2020
SpaceXSeptember 30, 202513 minIn timeline
The Reusability Revolution

How Falcon 9's first-stage landings transformed the economics of access to space and made everything that followed — Starlink, Starship, Artemis — possible.

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