I cannot find references, but prior to the Pad Abort test, for years, it was stated or implied that the test would take place from a platform at LC-40 that would simulate the height of the first stage for realism.

But looking at pictures SpaceX sent out, of the Pad Abort unit at LC-40, it is clearly at ground level. You can see the nozzles from the Niagara water deluge system right next to it, which are usually seen in images of the engines igniting.

Dragon Pad Abort article at LC-40

You can see the pipe of the Niagara water deluge system, blocking our view of the engine in this photo to make the point of how close to ground level the Dragon is sitting.

enter image description here Hans Koenigsmann in the pre-test briefing suggested that there would be a truss structure to attach too, which I interpreted as something larger, and is most likely the upper right part of the image, with the umbilical connectors.

So what changed between the plans for using a platform high up, to a test down low. (A consequence noted in the press conference is that the lightning towers needed to be disassembled or maybe just the wiring removed to avoid a collision).


1 Answer 1


There is relatively no advantage to constructing a truss system and there is actually a small advantage to launching from pad level.

The Pad Abort Test took place on LC-40 which is an active launch pad and the only pad SpaceX currently can use to launch Geostationary Satellites from. Building a 100+ foot steel truss on the pad and tearing it down would have taken time, time in which LC-40 couldn't be used for launching rockets with paying payloads.

The goal of the Pad Abort Test is to validate that the Launch Escape system activates quickly enough to pull the capsule away from the launch vehicle before it is destroyed and get it to an altitude in which the parachutes can safely deploy. The Falcon 9 is 68.4m tall. The capsule will reach a max altitude of >1500 meters. The extra height doesn't significantly impact the test and achieving the desired height with a ~70m deficit actually proves the LES more capable than required.

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    $\begingroup$ I was a bit more interested in the change. I knew the reasons you suggest for doing it at ground level. But for many years it was going to be on a truss, but they changed the plan. I was wondering why the change. $\endgroup$
    – geoffc
    Commented Jun 9, 2015 at 17:42

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