Can SpaceX land a rocket with 1/2 cm accuracy?

Claimed 0.5 cm Accuracy: Absolute vs Relative

• Several commenters argue the key distinction is absolute vs relative error.
• Consensus: the booster likely cannot know its global (lat/long) position to 0.5 cm, but could know its position relative to a buoy or tower much more precisely.
• Some think the “0.5 cm” statement was almost certainly a slip and should have been ~0.5 m; others suggest it might refer to a narrowly defined metric (e.g., rotation or final pin alignment).

GNSS/RTK and Other Positioning Methods

• RTK GNSS is widely cited as achieving multi‑centimeter accuracy; sub‑centimeter is considered difficult but not impossible in ideal, slow, or averaged scenarios.
• Disagreement on how often commercial systems truly deliver 0.5 cm in real time with high confidence.
• Multiple commenters suggest hybrid schemes: RTK + IMU for most of the trajectory, switching near the tower to optical, radar, lasers, or other short‑range relative tracking.
• Some argue the article underestimates the feasibility of tower‑mounted sensing; others think high dynamics, exhaust, smoke, and multipath make “lab‑grade” methods hard to apply.

Control Error vs Measurement Error

• Several stress the difference between what the rocket thinks its error is (control error) and the true miss distance.
• The 0.5 cm figure might refer to controller cross‑track error rather than physical landing accuracy.
• For reliability, error budgets must consider 95–99.9% confidence regions, not just RMS or best‑case numbers.

Physical Tolerances and Catch Mechanics

• The actual landing “box” for the booster on the chopsticks is large (meters and degrees of angular tolerance), so millimeter‑level knowledge is not strictly required.
• Catch arms visibly adjust during capture; they likely handle much of the fine alignment.
• Some speculate the quoted precision could describe the final resting position of the catch pins after the arms close and the booster settles.

Environment, Structure, and Dynamics

• Commenters question whether vibration, slosh, wind gusts, and structural flex make sub‑centimeter accuracy meaningful.
• The booster’s size and moment of inertia aid stability but also mean flex and alignment over tens of meters.
• Crosswinds and gusts are seen as major practical constraints, mitigated by weather limits and control authority but not eliminated.

Broader Reflections

• Many highlight that centimeter‑class landing control on an orbital‑class booster is extraordinary regardless of the exact 0.5 cm claim.
• Some see this as emblematic of a “new” space age enabled by modern control, simulation, and manufacturing; others remain skeptical of the broader value and economics of such programs.