Why Rockets Don't Need (and Often Can't Use) Vision
When Elon Musk noted "Rockets don’t need vision", it highlighted a fundamental difference in physics and control theory between ground autonomy (such as self-driving cars) and rocketry. Ground vehicles navigate dynamic, crowded environments filled with pedestrians, lane lines, and unpredictable drivers. Rockets operate in physical dynamic state space governed by strict Newtonian mechanics and aerospace guidance, navigation, and control (GNC).
1. The Physics Environment is Completely Hostile to Cameras
During liftoff and propulsive landing, rocket engines generate massive fireballs, high-temperature soot, and hypersonic vibration.
- Plume Obscuration: Multi-engine kerosene (RP-1) or methane burns deposit thick soot and optical distortion around the base.
- Dynamic Range: Sunlight in upper atmosphere or dark ocean barge landings create extreme exposure contrast where optical sensors wash out or under-expose.
- Shockwaves & Fog: Transonic vapor cones and re-entry atmospheric ionization blind optical lenses.
2. Mathematical State Estimation (INS + Kalman) is Exact
In rocketry, the primary questions are: What is our exact position vector $\vec{r}$, velocity vector $\vec{v}$, and attitude quaternion $\vec{q}$?
- High-Rate IMUs: Ring Laser Gyroscopes (RLGs) and quartz flexure accelerometers sample acceleration and angular rates at 500 Hz to 2,000 Hz with zero latency.
- Sensor Fusion: Extended Kalman Filters (EKF) fuse inertial data with radar altimeters, GPS/GNSS, and star trackers for absolute calibration.
- G-FOLD & Convex Guidance: The flight computer solves a real-time convex optimization problem every 20ms to gimbal the engine bell directly to the target coordinates without ever "seeing" the landing pad with eyes.