http://science.ksc.nasa.gov/shuttle/missions/sts-107/images/high/KSC-02PD-1894.jpg shows a large part of the launch pad suspended off the ground.

What is it for and why is there all that empty space underneath it?

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    $\begingroup$ I'm not sure "floating in air" is quite right for something with enormous towers at each end holding it up. ;) $\endgroup$
    – Graham
    Commented Mar 25, 2019 at 22:01
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    $\begingroup$ @Graham - Yeah I was thinking "Which part are you referring to?" $\endgroup$ Commented Mar 25, 2019 at 22:49

1 Answer 1


That is the Rotating Service Structure.

It can be rotated to fit over the Shuttle while it is on the pad, giving access to the Shuttle cargo bay. The empty space allows the RSS to fit over the launch platform.

It's not floating, the leg on the left side of the photo is part of the RSS. This is a detail of the leg:

enter image description here

You can see the cab and wheels used to move the RSS between its positions.

The rotating service structure provides protected access to the orbiter for installation and servicing of payloads at the pad, as well as servicing access to certain systems on the orbiter. The majority of payloads are installed in the vertical position at the pad, partly because of their design and partly because payload processing can thus take place further along in the launch processing schedule.

This photo shows the RSS in its rotated position:

enter image description here

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    $\begingroup$ The last photograph still leaves me with the question of why the launch pad itself is off the ground. I would have expected a tremendous amount of downward force against it. $\endgroup$ Commented Mar 25, 2019 at 18:48
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    $\begingroup$ It had to be off the ground because it was carried by the crawler. The crawler set it down on a bunch of very sturdy pylons. The downward force went through holes in the launch pad. $\endgroup$
    – Hobbes
    Commented Mar 25, 2019 at 18:52
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    $\begingroup$ I always wondered why they needed a raised platform (the "mound") in the first place? A flame trench could have been dug into the ground. Then I remembered the water - millions of gallons that would have to be pumped out of the trench... $\endgroup$
    – Mitch99
    Commented Mar 25, 2019 at 20:48
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    $\begingroup$ @Mitch99, it's not just the water from the sound-suppression system. The entire state of Florida is basically a swamp, so any time you dig into the ground, you'll have to continuously pump water out. $\endgroup$
    – Mark
    Commented Mar 25, 2019 at 21:45
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    $\begingroup$ On top of that add rain season and you start getting real problems. Did the area acutally ever get flooded? $\endgroup$
    – TomTom
    Commented Mar 26, 2019 at 13:30

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