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My thinking is that:

  1. The primary reason to try to land on a barge instead of land appears to be safety (Answers to this question). Ultimately, it looks like they want to return it to land.
  2. SpaceX have shown in the past 3/4 attempts that it can guide the booster to a precise location for landing.
  3. At least the second last attempt, they could not attempt recovery due to ocean swells that were too high.
  4. The ocean weather / salt can damage the booster on return to land.

Based on the above, why not just clear the immediate area of the landing pad and test landing on land from now on?

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  • $\begingroup$ To my untrained eye the landing issues have nothing to do with movement of the boat but that the rocket doesn't maintain it's stability when it gets close to the ground. I don't see how that will be any better on land? $\endgroup$
    – JamesRyan
    Commented Apr 17, 2015 at 11:16

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According to Defense News, SpaceX plans to make the next attempt on land:

While not providing details of when or where that attempt would occur, Gwynne Shotwell, SpaceX President and COO, told Defense News on Wednesday that the company hopes its next attempted landing will take place on land, not at sea.

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SpaceX has leased LC-13 on the Florida coast, and renamed it Landing Complex 1. Then renamed to Landing Zone 1.

They are building 5 landing pads there, but the Environmental assessment (the document you have to get to be able to start building and construction) says they will only land one at a time. (So Heavy's three cores not quite yet).

Gwynne Shotwell in interviews post landing is suggesting that they should try for land on the next one. As noted, they have proven they can hit the target. Land is most stable so should be easier.

It is all about assuaging the FAA's concerns for safety. Whatever the FAA says, goes in this instance.

Then December 21, 2015, on the Orbcomm OG2 mission, the first stage (F9-21) was landed successfully at LZ-1 in Florida.

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  • $\begingroup$ The FAA? Are they concerned about the rockets interfering with aircraft, or with the rockets hitting the ground in the wrong place? $\endgroup$
    – raptortech97
    Commented Apr 18, 2015 at 2:12
  • $\begingroup$ @raptortech97 The FAA is concerned that something 'flying' might hurt humans. So yes to everything they are concerned about. However, mostly hitting the ground in the wrong place. $\endgroup$
    – geoffc
    Commented May 20, 2015 at 22:03
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There are two reasons to attempt a landing on the sea vs on land:

  1. There are no safety requirements to land on sea, at least not beyond the obvious ones of clearing the immediate area. On land, one has to be subject to the laws of the country in which they are attempting the landing, so in other words, the United States FAA.
  2. Less fuel is required to land at sea. By the time the first stage is dropped, it has considerable horizontal velocity. Landing it at sea will allow one to take advantage of that velocity, while returning it back to where it came from requires one to fight the velocity.

Of course, landing on the sea has plenty of challenges as well, as have been mentioned. Still, no doubt the ability of SpaceX to hit the barge twice in a row is a good indicator that the system is safe enough to attempt and land on land, so long as all of the standard precautions are in effect (Range safety). The latest launch is the first time where it seems it would have been successful on land if that is where it had been attempted. I think they still need to prove out the system a bit more before they are willing to try on land. Remember, the previous attempt hit the mark, but the rocket immediately flew off after hitting the barge, at considerable speed. That would be potentially dangerous on land. I suspect a few more similar level of successes at sea would be sufficient for them to be able to try on land, but I believe it is not yet safe enough to try.

In addition, it seems like it could take quite a bit more fuel. Granted, most of the horizontal velocity will take place in the first part of the flight, but there is a substantial velocity that will have to be negated. I'm sure, however, that they would prefer to land on land given the chance.

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  • $\begingroup$ "Remember, the previous attempt hit the mark" - It did not hit the mark. It missed the barge. The attempt two days ago hit the mark but the rocket fell over after not stabilizing. $\endgroup$
    – Engineer2021
    Commented Apr 16, 2015 at 19:23
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    $\begingroup$ @staticx: no, the January attempt crashed on the barge. $\endgroup$
    – Harry Johnston
    Commented Apr 16, 2015 at 22:13
  • $\begingroup$ Even if the first attempt had only scratched the edge of the barge and then sank in the ocean, I would still call it incredibly accurate. $\endgroup$
    – Mike Nakis
    Commented Apr 17, 2015 at 11:18
  • $\begingroup$ @HarryJohnston: It did not hit the mark, it crashed. I am a fan of SpaceX but it did not hit the mark. $\endgroup$
    – Engineer2021
    Commented Apr 17, 2015 at 11:31
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    $\begingroup$ To staticx: The phrase can be used metaphorically, but it also has a literal meaning, and that is clearly the intent here. You are being pedantic. Furthermore, your last post contradicts your first post here, where you say 'the attempt two days ago hit the mark'. One can also say the previous attempt succeeded in the sub-goal of navigating to the landing zone, which is obviously the point here. $\endgroup$
    – sdenham
    Commented Apr 17, 2015 at 16:29

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