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At 2017's International Astronautical Congress, Elon Musk claimed that SpaceX could master propulsive landing without landing legs.

The assertion was that Falcon 9's "next version" could "land back on its launch mount".

Guessing that by "next version" he meant the recently flown Block 5, I wonder if Block 5s will ever fly without landing legs. Same thing with Falcon Heavy.

Obviously, there are no launch mounts on the drone ships (at the moment). However there is quite some percentage of boosters returning to the landing zones, close to their launch pads.

Is that vision even possible? How would a launch mount have to be modified in order to support landing rocket boosters?

I wonder, because the landings' precisions appear to be within a couple of meters only. Here the mentioned Block 5's maiden landing: enter image description here

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SpaceX has never suggested that the Falcon 9 line would be landing back on the launch mount. Only the BFR/ITS are expected to have the accuracy to do that.

Watching the current landings, assuming that the target is the middle of the X, they are pretty close, but not likely close enough to hit a mount to land on.

Additionally, at only 3 meters wide (about 10 feet) a Falcon 9 is much narrower than a BFR (9 meters (27 feet), or the original ITS at 12 meters (36 feet)).

Thus a BFR can be a meter or two off, and it is much less of a miss for a 9 meter wide vehicle, than for a 3 meter wide vehicle.

I.e. More room for error in accuracy on a larger vehicle.

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    $\begingroup$ "Thus a BFR can be a meter or two off, and it is much less of a miss for a 9 meter wide vehicle, than for a 3 meter wide vehicle. I.e. More room for error in accuracy on a larger vehicle. " Care to expand on that? How is missing the launch mount by a meter OK just because the vehicle is bigger? $\endgroup$
    – Organic Marble
    May 16, 2018 at 0:27
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    $\begingroup$ @OrganicMarble Good point. I think this is essentially my second question How would a launch mount have to be modified in order to support landing rocket boosters? $\endgroup$
    – Everyday Astronaut
    May 17, 2018 at 20:46
  • $\begingroup$ I have heard that the Super Heavy landing thust-to-weight will be much closer to 1 - a much longer hover will be allowable, providing more time to get properly aligned. This is all just conjecture, however. $\endgroup$
    – 0xDBFB7
    Dec 10, 2019 at 1:47
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Somebody on reddit did an excellent chart of the Falcon 9's landing accuracy:

enter image description here

[source]

While these landing positions are probably just approximate, I think it is reasonable to assume that the answer to the question is: yes, Falcon 9 and Heavy boosters need landing legs because they cannot land back onto their launch mounts.

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