Saturday, April 18, 2009

Video Del Fuego, Part XX

Today on Video Del Fuego, the launch and recovery of STS-119, the most recent Space Shuttle mission.

It's rather interesting for me to listen to the radio chatter during the Shuttle's ascent. The commander and pilot are busy managing the vehicle as they ride a controlled explosion into orbit, so the only thing Mission Control bothers them with are updates to their abort modes. They start out with basically no abort mode at all. If something comes unglued while the SRBs are still burning, they're screwed. But after the SRBs burn out, there's the theoretical possibility of a Return To Launch Site abort, or RTLS. Nobody really likes that option. You're basically doing a bootlegger's reverse with a 100-ton glider. They're pretty sure the vehicle would hold together during the maneuver, but not 100% certain. They like the Trans-Atlantic Abort (TAL) option better. Once they have enough energy to clear the Atlantic, they can make an emergency landing downrange at one of several designated sites. This doesn't require any risky mid-air turns, so they're confident they can pull this off if they have to. Their favorite abort option of all, and the only one that's actually been done so far, is Abort To Orbit (ATO). Getting into space is their safest option. Space is mostly harmless. It's going and coming that can kill you.

The landings also fascinate me, from an aviator's point of view. This is probably the riskiest thing they do. Dead-sticking any glider can be challenging. Dead-sticking a 100-ton glider that isn't even all that great a glider to begin with is one of the hardest jobs in aviation. The Shuttle's glide slope angle is insane. No other vehicle approaches the runway so steeply. Then, right before landing, the commander has to "flare" -- pull the nose up to arrest the sink rate -- at just the right moment. Too high and you overshoot the runway, too low and you hit too hard. And with no engines, you have one chance to get it right. These guys are champs. They float it in and kiss the runway, as gentle as you please.

They say any landing you can walk away from is a good one. They also say a great landing is one after which they get to use the airplane again. This was a great landing.

1 comment:

Burr Deming said...

The conversation is startling because it is so routine. Thanks for the insight.