[Animats]

It's been on the launch pad for weeks, and had a successful static test. Space-X has to launch it soon or tilt it back down and take it away.

Although the Falcon Heavy is almost as big as the Saturn V, the launch setup is far simpler. It's lifted into vertical position at the pad. No vertical assembly building, no crawler-transporter. That's a big improvement. Takes some extra structural strength, which costs some payload, of course.

[JshWright]

It's been up and down several times over the past few weeks. It only takes a couple hours to move it in or out.

The fact that Falcon 9/Heavy only support horizontal integration is a bot of an issue for some payloads (particularly those with people, or big optics). SpaceX will be adding vertical integration (the ability to mount the payload after the rocket is vertical) to its pad at LC-39A.

[ygra]

Are they? I was under the impression that crew can be loaded via the Crew Access Arm with the rocket vertical, but Dragon would still be integrated horizontally.

[RX14]

Dragon likely will be integrated horizontally but some national security payloads need vertical integration.

[tuxxy]

Why do some national security payloads need vertical integration?

[jccooper]

They won't say, because they're secret. But it's probably optics or just some legacy designs that they don't want to qualify for horizontal.

[Rebelgecko]

It also prevents them from launching payloads that require vertical integration (can make the design of satellites a bit more complicated if they have sensitive bits)