Mar 15 2009
Shuttle Launch - What Goes Into It?
It occurred to me, as I watched the Shuttle preparing to launch this evening, that I’ve been watching Shuttle launches for some time. I know, when the countdown restarts after all the “go-calls” at T-9 minutes, that, whether I can hear the commentator or not, that things are getting close when I see the main engines gimballing from null to each of their extreme positions and then back to null, hydrogen escaping in little plumes from the engine bells. (For those that don’t know, the engine bells are cooled by liquid hydrogen that goes through pipes on the bells before being shunted into the bell for combustion.)
Next the vent hood is pulled back from the external tank. The vent hood pulls any escaping oxygen and hydrogen away from the structure during the time the tanks are loaded but prior to lift off. Time is getting short.
We’re only seconds away when the noise suppression deluge begins, a flood of water that pours into a trench beneath the mobile launch platform (that hearken back to the Apollo years). In addition to reducing the noise of our rockets as they go to full power for launch, they also provide the huge clouds of steams that you see during a launch. Gotta love a night launch.
Next, the sparks, an orange wall of fire that lights the main engines with their almost invisible red-blue flames. The main engine bells swivel and it holds there for several seconds, even after engine light as the solid rocket boosters are lit, as the thrust overcomes gravity and slowly pushes the ungainly contraption up into the sky.
For me, this is when I’m most anxious, watching the blurring long range video for plumes that don’t belong, for flashes of foreign object debris, for anything that might presage something bad. Thankfully, tonight, as has happenedover a hundred times before, there was nothing immediately visible. Each step after that, each milestone, is just one less worry. Throttle down, where both the SRBs and the engines are throttled back to keep from putting too much dynamic load on the Orbiter. Throttle back up, where they climb back out of the “bucket” and push the main engines to full power.
As the solid rocket boosters run low of fuel, pyro bolts fire and release them from the stack, to fall back to the ocean where they’ll be retrieved, refurbished, refilled for another flight. The burn their last as they fall away.
All that’s left is a little spot (the smoke you see during launch comes from the hypergolic fuel in the solid rocket boosters, not the clean-burning main engines) with the triangle brightness of the three engines. Time ticks by as the milestones pass us. Two engine TAL, where we could abort to across the ocean even if we lost an engine, then one engine, then we call out being able to make orbit losing one engine. Then two. But, tonight, all the engines burned well and we made it into orbit exactly as planned.
There are literally thousands of people who worked to make sure that flight worked, that the launch was successful, that everything worked as designed. But it isn’t just their launch, it’s yours as well. The Shuttle belongs to all us, here in America and, with the different crews going up of more and more different nationalities, to all mankind, at least to an extent.
Go STS-119.
Excellent post and well said! I love to watch the shuttle launch, and any type of space vehicle. I have always been a fan of the space program and when they were broadcasted on regular TV - I was glued to the TV for the entire session. Too bad these launches and activities are not available to the general public for viewing - unless you happen to have a cable or satellite service that provides the NASA TV network. For those of us living in rural America where there is not service other than broadcast TV - we miss out. Well, soon it will be out on DVD and I can add to my collection. Thanks to an organization - spacecraft films for re-creating the historical footage of America’s space program into nice DVD packages for the space enthusiast to relive the missions.
lvs and david, thank you.
Boris, There have been issues after launch before. On one flight, we aborted to orbit because of an early engine shutdown. We’ve also had auxiliary power units that have failed. However, those failures are very much the exception; usually things go very smoothly.
The Shuttle has several abort options, usually focusing on main engines that might not operate appropriately. The SRBs, once lit, can not be unlit. I suspect they could be jettisoned under the right circumstances, but I really don’t know for certain. The engines are throttle-able, moveable, etc. If we had an abort situation, we could (a) return to landing site, basically dumping the extra components and gliding back for a landing. It’s a challenging activity, but something our commanders and pilots are trained to perform. They’ve all run simulations, but we’ve never had to try them out.
We also have emergency landing sites in Africa so that we could abort and land there if we’d gone too far to make returning to the landing site practical. We can also abort once around which is like making an orbit around the earth once and returning back to the landing site. We can also abort to orbit, where we end up in a different orbit than originally planned. This is the only abort scenario we’ve used and we were able to perform the mission from the different orbit, so no harm done. On a rendezvous mission, however, this would probably negate the mission.
All of these abort scenarios depend on the nature of the failure and how far into the launch they occur.
mpaulin,
I’m sorry you can’t see them. If you’re stuck on dial-up, you can’t even watch it on the net, which is a real shame. floridatoday always has a link for watching NASA TV real time during launch and NASA.gov does as well; however, the same situations that preclude cable make high speed internet more unlikely as well.
I’m glad you’re a supporter. So am I.
Wonderful post! I knew a little of this (it’s the friends I hang out with, heh), but still, it’s so meaningful to hear it all from someone on the inside of the program.
I remember my first thought after the Challenger: “I’d go up tomorrow in the next one, to show how much I believe in our destiny in space.” And I’m not even in the U.S.!
I’m always thrilled to hear that a launch was successful, and that a mission is going well. And then of course, I start fretting about the re-entry and landing, hoping everyone is safe.
Anyway, I loved this post and the wealth of information in it. I’ll be linking to it from a couple of places, for my friends who also feel like I do.
Thank you, bookish. I had no idea it would appeal as well as it has.
Woohoo! I just watched the video of the lift-off on the NASA website. I can watch NASA-TV, but I was off doing other things at the time of lift-off. And it was cool to watch it this time with your article running in my head. When the wall of sparks showered down at ignition, I thought “Aha! So that’s what Steph was talking about!” Heh, heh! You provided commentary for my lift-off viewing. Good job.
Wow–very descriptive. I understand a little more about what’s happening now. I got an email from khou.com about Discovery launching on Sunday at 6:43 p.m. for a construction mission at the international space station. I meant to watch it stream live from their website, but forgot.
Davida
Glad I could help, Roy.
I hope you enjoyed it, Davida.