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Comment by asdfman123 | Hacker News Reader

Right? They land fighter jets on carriers with a light signal that projects out from the ship at a particular angle. It seems very easy to do something like this with some form of electromagnetic radiation. Or have some way for the tower to detect the exact position and communicate with the rocket.

I understand engineering is complicated but this honestly seems like the easiest part of the problem to solve.

It's more likely that SpaceX determined they didn't need super tight tolerances and called it a day.

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Carrier landings are accomplished using a combination of indications, and the meatball is only one of three primary tools. If you are not flying an on-speed angle of attack AND lined up on the centerline of the landing area, the meatball position is invalid to a degree proportional to the degree to which those other inputs are off.

The meatball Fresnel lens is canted slightly side-to-side, and only places the hook in the right spot at a given angle of attack. Which is a design compromise necessitated by having to allow multiple types of aircraft with multiple hook-to-eye distances to land on the same aircraft carrier while using a visual input in one location (the cockpit) to properly place a device in another location (the hook point) with high precision.

Source: I've done it.

So just as it is not "very easy" to trap on board the boat with "just" a light signal, I would assume landing a building-sized booster has a similar if not bigger list of potential "gotchas."

Very easy compared to all the other hard problems SpaceX has to solve, yes.

> SpaceX determined they didn't need super tight tolerances and called it a day

Yup! This is my conclusion in the article - the landing box for the Super Heavy booster is 5x13x18 meters on each side, with 5-15 degrees of angular tolerance in each of the vehicle axes. So the margins are big enough that you don't need millimeter level precision for the rocket position.

> Could you use other real-time distance measurements like laser rangefinding or visual processing? I don’t think so

This is the part I question though. Seems like an org as well motivated as SpaceX could easily solve that if it was necessary.

My take is that it would probably be possible with enough effort, but there isn't an easy solution. And if you don't need it then the best part is no part. :)

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