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I understood that part of the reason the landing ship can be so small is that the drone ship is actively maneuvering to a spot to catch the booster. It's annou

I understood that part of the reason the landing ship can be so small is that the drone ship is actively maneuvering to a spot to catch the booster. It's announced in the sequence when the drone ship acquires tracking signals from the booster, I'm guessing it's 99% automated other than abort contingencies. Even if it's only moving 50ft that'd require a radial increase for a fixed landing spot. But then they also stuck their land-based landings right on the money so it could just be a purely safety related thing.

mikeash 9y ago
I don't think the ship maneuvers at all. Both the ship and rocket are pre-programmed with the landing coordinates, and independently arrange to be at the right spot at the right time. The ship has fancy thrusters, but their purpose is to hold it perfectly still even when the water is moving around a lot.
- singingboyo 9y ago
  That's my understanding as well. The ship moves really slow by comparison to the rocket, not much useful moving it can do - it just stays in place despite waves and weather.
- Already__Taken 9y ago
  The ship is also painted with a radar reflective X that the booster is targeting on the way down. The ship just has massive engines for solid station keeping in rough seas. Like you say they don't use those to move to the booster. I'm fairly sure it's these things: https://www.thrustmaster.net/out-drive-propulsion-unit/ https://www.thrustmaster.net/out-drive-propulsion-unit/ They were posted about when the ships were first made. And I know spacex had gone a size up from the originals.
  - trapperkeeper74 9y ago
    Totally what that guy on Gold Rush needs to get his barge up the Yukon. ;)
ygra 9y ago
That's just a tracking signal, not guidance. Both the booster and the drone ship navigate to the same GPS coordinates.
- SEJeff 9y ago
  They also have a radar on the ASDS that the rocket locks onto to help it navigate in addition to the GPS. This gives it a much more exact set of coordinates to shoot for so to speak. There was extensive discussion regarding this on r/SpaceX after they managed a virtually perfect bullseye landing several landings ago.
SEJeff 9y ago
The landing ship is the size of a football field, not something I'd call small by any means. The booster that lands on it is approximately 14 stories high (230ft / 70m).

mikeash 9y ago

I don't think the ship maneuvers at all. Both the ship and rocket are pre-programmed with the landing coordinates, and independently arrange to be at the right spot at the right time. The ship has fancy thrusters, but their purpose is to hold it perfectly still even when the water is moving around a lot.

singingboyo 9y ago
That's my understanding as well. The ship moves really slow by comparison to the rocket, not much useful moving it can do - it just stays in place despite waves and weather.
Already__Taken 9y ago
The ship is also painted with a radar reflective X that the booster is targeting on the way down. The ship just has massive engines for solid station keeping in rough seas. Like you say they don't use those to move to the booster. I'm fairly sure it's these things: https://www.thrustmaster.net/out-drive-propulsion-unit/ https://www.thrustmaster.net/out-drive-propulsion-unit/ They were posted about when the ships were first made. And I know spacex had gone a size up from the originals.
- trapperkeeper74 9y ago
  Totally what that guy on Gold Rush needs to get his barge up the Yukon. ;)

ygra 9y ago

That's just a tracking signal, not guidance. Both the booster and the drone ship navigate to the same GPS coordinates.

SEJeff 9y ago
They also have a radar on the ASDS that the rocket locks onto to help it navigate in addition to the GPS. This gives it a much more exact set of coordinates to shoot for so to speak. There was extensive discussion regarding this on r/SpaceX after they managed a virtually perfect bullseye landing several landings ago.

SEJeff 9y ago

The landing ship is the size of a football field, not something I'd call small by any means. The booster that lands on it is approximately 14 stories high (230ft / 70m).