Tuesday, August 18, 2009

Delta II Launch Spectacular

This was the view of the final Air Force Delta II launch from Jetty Park in Cape Canaveral, FL. I was not there: I was watching from my front porch but did not think of taking a picture, as I had no idea just how spectacular this launch would be.

I awoke just before sunrise and opened my computer for my morning cyber-ritual, when I heard the sound and felt the rattle that means only one thing - a rocket launch. I went outside to see the contrail rising behind sparse clouds, just in time to see the color change. The rocket arced its way into orbit for a successful launch. Many friends in Orlando, however had the impression the rocket exploded. Here's why:

The Delta launched just before dawn, still in darkness. As it rose, it's contrail was illuminated only by the fire from it's engines. But as it climbed, it reached the sunlight spilling over the horizon from the rising sun, filtered into the ruddy glow we see at sunrise and sunset. At the same time, upper level winds at that altitude distorted the shape of the contrail. From the angle and distance of Orlando, this appeared at the height of the arc the rocket took as it followed the curvature of the Earth away from the Cape. The rocket was then flying in direct sunlight, brightly illuminating the contrail into a white streak. Observers who watched further would have seen the rocket reaching higher more rarified altitudes and see the contrail begin to expand in the thinning atmosphere. Here is a launch from Vandenberg on the west coast during sunset that shows the same phenomena:
(Somewhere I have picture I took like this - I'll substitute it if I can find it).

So, really just a typical Delta launch. The timing at sunset gave us a beautiful display, with the thin crescent Moon and Venus hanging in the morning sky. What a way to start a morning!

No comments:

Post a Comment