APOD: A Night at Poker Flat (2015 Jan 30)

Comments and questions about the APOD on the main view screen.
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APOD: A Night at Poker Flat (2015 Jan 30)

Post by APOD Robot » Fri Jan 30, 2015 5:05 am

Image A Night at Poker Flat

Explanation: Four NASA suborbital sounding rockets leapt into the night on January 26, from the University of Alaska's Poker Flat Research Range. This time lapse composite image follows all four launches of the small, multi-stage rockets to explore winter's mesmerizing, aurora-filled skies. During the exposures, stars trailed around the North Celestial Pole, high above the horizon at the site 30 miles north of Fairbanks, Alaska. Lidar, beams of pulsed green lasers, also left traces through the scene. Operating successfully, the payloads lofted were two Mesosphere-Lower Thermosphere Turbulence Experiments (M-TeX) and two Mesospheric Inversion-layer Stratified Turbulence (MIST) experiments, creating vapor trails at high altitudes to be tracked by ground-based observations.

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Re: APOD: A Night at Poker Flat (2015 Jan 30)

Post by Boomer12k » Fri Jan 30, 2015 7:42 am

Awesome looking....
Doing the Science with Awesomeness...

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Locutus76

Re: APOD: A Night at Poker Flat (2015 Jan 30)

Post by Locutus76 » Fri Jan 30, 2015 11:34 am

So can anyone describe all the phenomena we see in this picture? What is the curved line at the top? Is that LIDAR? Then what are the small upwards pointing lines at the bottom, near the bushes?
And what about the small streaks at the image center, just above the rocket arcs? And what are the bright bluish flashes?

Weckerling

Re: APOD: A Night at Poker Flat (2015 Jan 30)

Post by Weckerling » Fri Jan 30, 2015 2:26 pm

Is that a bird flying up in the center of the image?

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Re: APOD: A Night at Poker Flat (2015 Jan 30)

Post by Chris Peterson » Fri Jan 30, 2015 3:11 pm

Locutus76 wrote:What is the curved line at the top? Is that LIDAR? Then what are the small upwards pointing lines at the bottom, near the bushes?
All of those are laser beams. Whether they are for lidar or some other type of measurement can't be determined here.
And what about the small streaks at the image center, just above the rocket arcs?
They are clearly aligned with the rocket launches. Presumably upper stages or the payloads.
And what are the bright bluish flashes?
Gaseous or particulate trackers released into the atmosphere by instruments on one or more of the rockets.
Chris

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Leasal

Re: APOD: A Night at Poker Flat (2015 Jan 30)

Post by Leasal » Fri Jan 30, 2015 8:49 pm

It looks like angels from heaven flying around. Two in white and the others within the background.

nigel

Re: APOD: A Night at Poker Flat (2015 Jan 30)

Post by nigel » Sat Jan 31, 2015 4:09 am

Locutus76 wrote:So can anyone describe all the phenomena we see in this picture? What is the curved line at the top? Is that LIDAR? Then what are the small upwards pointing lines at the bottom, near the bushes?
And what about the small streaks at the image center, just above the rocket arcs? And what are the bright bluish flashes?
The curved (green) line is not really curved. It is a very straight laser "beam" (actually here the backscattered light from a laser). It appears curved because a very wide angle lens is being used and it is close to the camera (distortion). Because it is close to the launch site, I'm guessing maybe it is used to help aim the rockets.

The small streaks in the image center are the light from the second stage rocket motors. A bit confusing, but here's what we seem to be looking at: The first stage ("Terrier") motors fire for only 5.2 seconds or so, but produce extremely high accelerations (something like 30g). Where the bright streaks become dimmer is the end of burn, but the motor is still glowing enough to be seen. A little above this is a slight brightening that I am guessing is from explosives that separate the burnt out first stage from the second stage a second or two later. After this the first stage continues to coast upward and is still visible, but the path becomes more sharply curved because it is slowing significantly relative to the second stage. The second stage is more streamlined and coasts upward (invisibly) on a straighter line. At ten seconds into the flight the second stage motor fires, and burns for a further 15 seconds or so. The rockets are many kilometers away at this point, so lines appear short.

There are two different experiments here and two different types of second stage. It looks to me like the two right hand ones--one of which looks like it might be misbehaving a little bit--are the less powerful Terrier/Improved Orions of the MIST experiment. These are supposed to each drop a "bomb" of reflected material once on their way up and once on their way down. I guess the two bluish explosions (and the in the center are the "on the way up" and the bigger birdlike blob to the right is one or both of the "on the way down" ones.

The two left hand rockets presumably are the higher flying Malamutes (which also have a Terrier first stage). It doesn't look like any of the second stages are visible after burnout--momentum carries the rockets much, much higher--to several hundred kilometers altitude. The dashed lines cutting near the celestial pole look like they created by the residual light of the "bombs" that created the dust clouds that are being studied here.

This site has a video and stills that may help visualize the flight paths:

http://sites.wff.nasa.gov/mpl/w_terriermalemute.html

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Re: APOD: A Night at Poker Flat (2015 Jan 30)

Post by RedFishBlueFish » Sat Jan 31, 2015 1:07 pm

nigel wrote:
Locutus76 wrote:... what about the small streaks at the image center, just above the rocket arcs? And what are the bright bluish flashes?
... each drop a "bomb" of reflected material once on their way up and once on their way down. I guess the two bluish explosions (and the in the center are the "on the way up" and the bigger birdlike blob to the right is one or both of the "on the way down" ones.
That makes sense. Thank you.

For myself, and for most people I showed the image to, these pareidolic figures were the most striking portion of the photograph. The birdlike one truly is birdlike, but the other was clearly non-biological, non-natural and so had to be part of the experiment - but *what* part was not clear.

Locutus76

Re: APOD: A Night at Poker Flat (2015 Jan 30)

Post by Locutus76 » Tue Feb 03, 2015 11:17 am

Thanks Nigel and Chris for your explanations!