Video On Hand for the SpaceX Launch That Almost Was (Video) 100
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This morning's nixed launch of SpaceX's Dragon capsule to the ISS with the company's Falcon booster was an exciting thing to be on hand for, despite the (literally) last-second halt. Shuttle launches used to cause miles of traffic backups extending well outside the gates of NASA's Cape Canaveral launch facilities; for all the buzz around the first private launch to the ISS, today's launch attempt was much more sparsely attended. In a small set of bleachers set up near the massive countdown clock, there were a few dozen enthusiasts and reporters aiming their cameras and binoculars at the launch site on the horizon. They counted down in time with the clock, and — just like NASA's own announcer — reached all the way to "liftoff." There was a brief flash as the engines ignited, but it died as fast as it appeared. It took only a few seconds for the crowd to realize that it was all over for today's shot. While the company's representatives remain upbeat, pointing out that the software worked as intended to stop a launch before anomalies turn into catastrophes, most of those on hand to see what they'd hoped to be a historic launch were a bit glum as they walked back to the parking lot and the press area — especially the ones who can't stay until the next try. I'm sticking around the area until the next scheduled launch window; hopefully next time the fates (and engines) will align.
Re:It was actually pretty exciting to watch (Score:5, Interesting)
I was reading a on this earlier, (not sure if it is in the link) but SpaceX is actually using a new launch system that intentionally holds the rocket on the pad after ignition just so that additional telemetry can be gathered about the operating state of all the engines at power...
Re:It was actually pretty exciting to watch (Score:4, Interesting)
These hold downs are pretty amazing. If you've ever watched recent shuttle launch videos you can see the top of the shuttle lurch a couple of feet laterally when the SSME's light up. It's pretty spectacular. I believe that the SRBS light a couple of seconds before liftoff, so the entire thing is held down for a second or two, even after SRBs lit.
The main difference between the Shuttle and the Falcon 9 as far as launch abort goes is that the SRBs cannot be shut down. As soon as they light, the launch has to happen. The SSMEs of course could shut down after ignition, and in fact did so on an occasion or two. Normally this would happen about T-6 seconds or so, unlike the T-0 shutdown of the falcon 9.
Re:It was actually pretty exciting to watch (Score:4, Interesting)
You are right about the lateral movement, but the shuttle stack doesn't just move laterally one way--it actually reverses (since the stack is still bolted to the pad) and the timing is such that when the SRBs fire, the stack is pointed true vertical again.
The SRBs are not held down once they fire though. Check out this incredible series of slow-motion video [youtube.com] from a lot of cameras you might never have seen footage from--it's like porn for space tech junkies. Jump to 6m28s for the first camera on the SRBs, which record the explosive bolts that hold the SRBs down. You'll actually see the bolts fire and release the SRBs a fraction of a second *before* we see the flames come out from the SRBs.
I posted earlier today about STS-68, which aborted the launch sequence at T-1.9 seconds, the closest to T-0 the shuttle ever got in an on-pad abort. There's a video of that launch attempt on Youtube too, but there's a second video (not on Youtube, unfortunately) showing the engines firing up and then shutting down. They actually flame out one by one, presumably to lessen the magnitude of the lateral motion that now lasts for several back-and-forth swings.