Saturday, February 15, 2014
Rocket Science, Part 1
Well I mentioned in the last post that I would be on a rocket campaign. I've been waiting until we launched the rocket to make an update, but turns out we made it through the whole launch window without favorable conditions to launch. We actually had pretty good science conditions on several nights but the rocket was grounded due to high winds which left a significant probability of blowing out of our intended landing zone. So we're waiting for the Moon to not be so bright then we'll open another window.
The image above is one I took during a night waiting to launch, the three red streaks are weather balloons released to measure the winds. It's a composite of about 40 two minute exposures. I've been thinking about a better way to process star trails for a while, that would preserve the single image 'background' so that the aurora would be detailed and pretty (and, in other situations, would give you stationary foreground foliage even if it's windy) while still allowing the stars to trail over many hours. So you're looking at something like 1.5 hours (~40 exposures) of stars but only 2 minutes (1 exposure) of aurora. What I did was loaded all the images into IDL and calculated the standard deviation on each pixel. I picked a single image to use as a background, then I went through and picked the pixels with a large positive standard deviation, meaning something temporary and bright happened in that pixel (e.g. a star moved through), and replaced that pixel from the background image with the pixel from the brightest single image. The tricky part is I can do the statistics on a single color channel, so if I ignore the green channel the process is blind to the aurora movement. I used the red channel for this example to get the red flares on the weather balloons, but normally I'd probably use the blue channel since there can be significant auroral emissions in red. It still needs some work but I think it's a good start. Eventually I plan to make it into a simple GUI where people can use it without needing to know how to script.
Other than that, we did actually launch a rocket, a small experimental prototype designed by some of the folks here at UAF. Since it was a test it didn't need to launch into an aurora like our typical rockets, so it actually launched in daytime. Here's a shot I got of it going up with the 150mm Sigma lens and the D7000:
And here's a video I took with the new NEX F3 and a 50mm Nikon lens:
I don't know why Flickr isn't offering me the video embed code that it offers for every other video.
Here's a shot of it leaving the launch pad from a camera that was very close, taken by Jeff Rothman:
And click here for an album of it taking off then descending under parachute in the sunset, taken by Mark Conde.
Our next launch window opens on the 24th of this month, so hopefully we'll get the big rocket off the ground without too much trouble this time.
In other news, I got rear-ended by a big truck while waiting for the car in front of me to turn, sandwiched between the two, and my car is probably totaled. So I'm shopping around and I think I'll get a 2014 Subaru Forester. I am disappointed with Subaru for not offering the ridiculously oversized moonroof on manual transmission models.