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Atlas V's Sonic Boom Made Visible By Sundog

timothy posted more than 4 years ago | from the right-time-and-place dept.

NASA 99

Ross-Shire Geek writes "Atlas V lifted off on Feb 11 from Kennedy. As it goes supersonic through a sundog (aka parhelion) you can see (video link) wonderful visible ripples of the shock wave in the sky."

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sundog millionaire (-1, Troll)

Anonymous Coward | more than 4 years ago | (#31217310)

first post

Re:sundog millionaire (0, Offtopic)

bmecoli (963615) | more than 4 years ago | (#31217318)

What do you want, a cookie?

Re:sundog millionaire (0)

Anonymous Coward | more than 4 years ago | (#31217668)

probably has cookies turned off

Re:sundog millionaire (1)

blai (1380673) | more than 4 years ago | (#31221144)

argument follows.

4. In Soviet Russia, cookies turn YOU off!
5. I'm in Korea, you insensitive clod!
6. In Korea, only old people clod cookies
7. ???
8. PROFIT!

Wow (3, Insightful)

cntThnkofAname (1572875) | more than 4 years ago | (#31217316)

There is something incredibly belittling about trying to comprehend the vastness that vehicles like that help us explore.

Re:Wow (4, Informative)

stjobe (78285) | more than 4 years ago | (#31217328)

Indeed, and apart from that, the linked video is really, really cool.

Ripples in the sky FTW.

Re:Wow (4, Funny)

Hadlock (143607) | more than 4 years ago | (#31217502)

A glitch in the matrix, nothing more.

Re:Wow (3, Interesting)

Cryacin (657549) | more than 4 years ago | (#31217552)

Is it just me, or does anyone else think this is CGI? My first thought was Photoshop!

I guess real life looks less real to me than special effects these days.

Re:Wow (0, Flamebait)

MrMista_B (891430) | more than 4 years ago | (#31217604)

It's just you. It's not CGI. Tip - get out of the basement for awhile, there's a whole other world out there.

Re:Wow (1, Funny)

Zawahiri (963352) | more than 4 years ago | (#31217664)

Is it just me, or does anyone else think this is CGI? My first thought was Photoshop!

I guess real life looks less real to me than special effects these days.

I thought it was claymation at first.

Re:Wow (1, Funny)

daveime (1253762) | more than 4 years ago | (#31217710)

Wallace and Grommit are more likely to re-visit the moon than the US !

Nice bit o' cheese Grommit !

Re:Wow (1)

WindBourne (631190) | more than 4 years ago | (#31219276)

And no doubt that intellectuals like yourself are busy watching Wallace and Grommit 24x7. We will be heading back for the moon before the end of the decade.

Re:Wow (0)

Anonymous Coward | more than 4 years ago | (#31226700)

Are you Indian or Chinese?

Re:Wow (1)

daveime (1253762) | more than 4 years ago | (#31227760)

How convenient for you that we've just started a new one. (Decade).

Re:Wow (1)

WindBourne (631190) | more than 4 years ago | (#31230822)

Not really. With the old plan, we would not be heading back to the moon before 2025 (most likely later). With this approach, we are using Private money to get us there.

Re:Wow (0, Troll)

JustOK (667959) | more than 4 years ago | (#31217672)

GIMP is better

Re:Wow (1)

Hadlock (143607) | more than 4 years ago | (#31217854)

Are you serious?? Us artsy type grew up with Photoshop, and Gimp is FINALLY going to introduce a more photoshop-like interface after YEARS. Photoshop has been, and will continue to be the standard upon which all others will be judged.
 
I keed, I keed....

Re:Wow (1)

ZosX (517789) | more than 4 years ago | (#31218354)

Don't feed the troll.... :P

Re:Wow (1)

Hadlock (143607) | more than 4 years ago | (#31218410)

I keed! (Kidding!)

Re:Wow (1)

machine321 (458769) | more than 4 years ago | (#31220828)

Just because it's real doesn't mean it's not computer-generated...

Re:Wow (1)

saisuman (1041662) | more than 4 years ago | (#31217618)

Nope, it's "ripples in the time-space continuum".

Re:Wow (1)

WindBourne (631190) | more than 4 years ago | (#31219262)

Oh cool. I could swear that I have seen that same posting here before.

Re:Wow (5, Informative)

Anonymous Coward | more than 4 years ago | (#31217632)

To skip the first ~2minutes and cut to the... ripples: http://www.youtube.com/watch?v=SsDEfu8s1Lw#t=1m51s [youtube.com] .

And for even more karma whoring: "A sun dog is a prismatic bright spot in the sky caused by sun shining through ice crystals. The Atlas V rocket exceeded the speed of sound in this layer of ice crystals, making the shock wave visible from the ground."

So I guess the normal compression wave by a sonic boom is not enough to alter the way light goes through it (think flickering air when looking across a heated highway), but these ice crystals do the trick. Right?

Re:Wow (5, Insightful)

Solandri (704621) | more than 4 years ago | (#31220916)

So I guess the normal compression wave by a sonic boom is not enough to alter the way light goes through it (think flickering air when looking across a heated highway), but these ice crystals do the trick. Right?

No, the compression wave always alters the way light travels through it. It's just that normally there's no light going straight through the wave to you, or if there is it's uniform in color and brightness (i.e. blue sky) so altering the direction of the light slightly doesn't produce a visible change.

My guess would be that the sundog by its very nature means sunlight is at the proper angle at that location to be reflected back to you. A compression wave at this location alters the angle of sunlight being reflected off ice crystals . So the large variability in brightness as a function of small changes in angle makes the ripples visible. Kinda like if someone were trying to signal you with a mirror. If you're seeing blue sky reflected in the mirror, shaking the mirror still yields blue sky so you don't notice any change. But if you're seeing the sun reflected in the mirror, shaking the mirror makes it alternately reflect sunlight and blue sky, causing a strobing effect which is easily visible.

Re:Wow (-1, Flamebait)

MrMista_B (891430) | more than 4 years ago | (#31217400)

You don't have much self confidence, huh?

Re:Wow (-1)

Anonymous Coward | more than 4 years ago | (#31217512)

You don't have much self confidence, huh?

You tell him!

I looked at that rocket, look down at my crotch and shook my head and said "that rocket pales in comparison!"

Re:Wow (-1, Troll)

Dan541 (1032000) | more than 4 years ago | (#31217582)

That's nothing compared to the inconvenience of this. http://bit.ly/dkpAoI [bit.ly]

Cool! Must see! (0)

Anonymous Coward | more than 4 years ago | (#31217626)

It's been years since I saw something spectacular like this, thanks for reminding me!

The creative use of technology just boggles the mind...

Re:Cool! Must see! (1)

Dan541 (1032000) | more than 4 years ago | (#31223830)

After logging out 119 people the Troll mod has certainly been worth it.

Why? (1)

Snaller (147050) | more than 4 years ago | (#31221930)

Just a huge area with nothing of human value for lightyears.

Lucky miss (4, Funny)

MichaelSmith (789609) | more than 4 years ago | (#31217332)

I thought that bird was going to get skewered a few seconds into the launch...

Re:Lucky miss (-1, Redundant)

Anonymous Coward | more than 4 years ago | (#31217336)

Unless it was a miniature rocket, that bird was more than a mile away. And it was flying towards the spectators, obviously spooked by the noise.

Re:Lucky miss (1)

MartinSchou (1360093) | more than 4 years ago | (#31217370)

Don't be silly. The bird might have been a roc [wikipedia.org] !

Re:Lucky miss (1)

MichaelSmith (789609) | more than 4 years ago | (#31217420)

Don't be silly. The bird might have been a roc [wikipedia.org] !

Clearly it wanted the launcher for its own purposes.

Yo Slashdot, Imma let you finish, but... (1, Funny)

Anonymous Coward | more than 4 years ago | (#31217348)

Dr. Evil's rocket launch was so much better. http://www.youtube.com/watch?v=vkTv8DGlrok [youtube.com]

Well dag nabbit! (-1, Flamebait)

voodoo cheesecake (1071228) | more than 4 years ago | (#31217374)

I'm surprised Obama didn't have it shot down!

Re:Well dag nabbit! (-1, Flamebait)

Anonymous Coward | more than 4 years ago | (#31218872)

I'm surprised Obama didn't have it shot down!

I'm not.

If it were a threat Obama would have talked to it for a few years while it went on building nukes and making statements about wiping out others, then he would have it read its Miranda rights. Then The Master of Hope and Change would have started a months-long strategy review of the best way to shoot it down.

Finally, Obama would go back, read what Bush/Cheney had done, and do that.

When's Gitmo closing? When are US troops going to leave Iraq?

Re:Well dag nabbit! (-1, Flamebait)

Yosho-sama (800703) | more than 4 years ago | (#31219068)

You're an idiot. Just wanted to let you know that.

Re:Well dag nabbit! (-1, Offtopic)

WindBourne (631190) | more than 4 years ago | (#31219320)

Funny that you speak about that. I recall W blasting Clinton for the NK agreement as well as for dealing with Iran. And here we now stand with NK having done supposedly 2 nukes and Iran close. And you think that it all occurred in the last year? Really? Neo-cons like you are SOOOO FUCKING STUPID. Sadly, there are far too many indies that will listen to idiots like you. Next you will be blaming Obama for increasing the Debt, while ignoring the fact that 80% of it is from republicans (reagan and W accounted for 60% of it).

Re:Well dag nabbit! (0)

Anonymous Coward | more than 4 years ago | (#31221792)

They are blind to what they dont want to see. They have been spoon fed this shit since they were little by their parents, their teachers, their religious leaders and their politicians, and they buy the entire thing hook line and sinker. The more they fight for it, the more liklely they will never come to their sences. These people cant see what everyone else does, cause that just means that they, their parents, their politicians, and their god is all wrong. THey would have nothing to live for. Their life would mean nothing. I say we stop trying to convince them, and just banish them all to Texas, Louisana, Mississippi, Alabama, and depending on space requirements Oklahoma, Arkasas, Georgia, and Florida. We surround these area with electrified fence, and just put all the republicans down there. They can have their little Neo-Con self governing area, and the rest of us can finally get something done. The Democrats will get all the countrys debt from years with a democrat in the white house, and the republicans will get the debt from the years a republican was a president. YAY

In 3D (2, Interesting)

ivoras (455934) | more than 4 years ago | (#31217406)

More impressively - the sonic boom "waves" effect is actually a three-D object - imagine if we could see it from multiple POVs, a spherical wave instead of 2D one :)

Re:In 3D (4, Informative)

Maddog Batty (112434) | more than 4 years ago | (#31217426)

The shockwave is cone shaped rather than spherical for fast moving objects such as a rocket, I believe.

Very very cool though.

Re:In 3D (1)

daniel_i_l (1655579) | more than 4 years ago | (#31217536)

Because of the angle, it's hard to tell whether the shockwave is spherical or cone shaped. A cone looks like a sphere while viewed from underneath like in the video.

Re:In 3D (2, Informative)

smitty777 (1612557) | more than 4 years ago | (#31217644)

The 2D aspect was a result of the shape of the clouds that formed the sundog, not the shape of the sonic wave. Sonic waves are indeed conical.

Re:In 3D (2, Informative)

Anonymous Coward | more than 4 years ago | (#31217796)

A shock is indeed spherical right at Mach 1 (which certainly is not "stationary" LOL). As the Mach number increases further, it becomes a cone. The cone half-angle decreases with Mach number and starts at 90 degrees at Mach 1.

Re:In 3D (-1, Redundant)

Swampash (1131503) | more than 4 years ago | (#31217490)

a spherical wave

Only if the rocket is stationary.

(hint - it's not)

Second POV (5, Informative)

oneiros27 (46144) | more than 4 years ago | (#31218500)

Closer to the pad, and less shaky:

http://www.youtube.com/watch?v=q9S0z1ofcIc [youtube.com]

(it has the voiceover from NASA TV, but doesn't have the launch clock visible ... it might've been a camera angle that they didn't use live, as I don't remember seeing this on TV)

Re:Second POV (1)

bill_mcgonigle (4333) | more than 4 years ago | (#31221470)

t might've been a camera angle that they didn't use live, as I don't remember seeing this on TV

correct, I was watching NASATV too and waiting for a nice supersonic plume, but we only got a modest waver on the broadcast camera.

One of the recent Shuttle launches had one of those nice condensation clouds around the shockwave.

Not a sonic boom (1, Interesting)

Anonymous Coward | more than 4 years ago | (#31217412)

A sonic boom looks like a single shock wave. Those look like ripples. Engine sound maybe?

Re:Not a sonic boom (4, Informative)

GrahamCox (741991) | more than 4 years ago | (#31217738)

A sonic boom looks like a single shock wave

Not necessarily - different edges on the craft will generate additional shock fronts. There are usually two main ones from nose and tail but also from fin tips and even antennae.

Re:Not a sonic boom (1)

thms (1339227) | more than 4 years ago | (#31217876)

You are mixing up two things here:

The sonic boom is what you hear when any aircraft going faster than mach 1 passes overhead, not just when it breaks the sound barrier.

The shock wave (very nice to see here: http://imgur.com/Cw5nS [imgur.com] (an F-22?)) only happens at around mach 1 when all the sound waves are on top of each other and don't diverge because the source is moving slower or faster than mach 1.

Re:Not a sonic boom (1)

GrahamCox (741991) | more than 4 years ago | (#31217938)

The shockwave is a pressure discontinuity that is always there above Mach 1. When it hits your ears, the discontinuity sounds like a boom.

Re:Not a sonic boom (4, Informative)

Anonymous Coward | more than 4 years ago | (#31218170)

Exactly [wikipedia.org] .

The higher the speed, the more the shock waves become compressed into a series of cones stacked inside each other [google.ca] rather than the spheroids typical at slower speeds. Taken together, the passage of these shock waves through a plane perpendicular to the direction of travel would look a lot like circular ripples.

How incredibly appropriate. (3, Insightful)

Jane Q. Public (1010737) | more than 4 years ago | (#31217442)

Very appropriate, it seems to me, that a rocket carrying the Solar Dynamics Observatory should make pretty with a sundog.

Parhelion (1)

Shin-LaC (1333529) | more than 4 years ago | (#31217518)

I think the word "parhelion" sounds better than "sundog".

Re:Parhelion (3, Interesting)

the3stars (1030420) | more than 4 years ago | (#31217558)

They're bad luck for mariners. I respectfully disagree with you, sundog is a much better name.

Re:Parhelion (1, Funny)

Anonymous Coward | more than 4 years ago | (#31217566)

Depends how hungry you are.

Re:Parhelion (2, Funny)

ZERO1ZERO (948669) | more than 4 years ago | (#31217670)

Isn't that a type of Matrox Video Card?

Re:Parhelion (1)

Opportunist (166417) | more than 4 years ago | (#31217712)

Agree. Sundog sounds like some sort of a weekend snack at the Wienerschitzel.

Re:Parhelion (0)

Anonymous Coward | more than 4 years ago | (#31218366)

sundog sounds too much like a food...

Re:Parhelion (1)

TangoMargarine (1617195) | more than 4 years ago | (#31220976)

Isn't that a Mozilla product? Sunbird, Firefox, Thunderbird...

Any idea what that name is supposed to mean? After looking at the Wikipedia article, it seems to me that it would make about as much sense to call it a Sunhippo or Sunrhino...

Nice, but... (-1, Troll)

Anonymous Coward | more than 4 years ago | (#31217546)

Photoshopped, you can tell by the pixels.

Not surprising really (-1, Offtopic)

Anonymous Coward | more than 4 years ago | (#31217578)

I am with Linus on this one
Linus is right
The man makes sense
He is absolutely correct on this one

moD down (-1, Offtopic)

Anonymous Coward | more than 4 years ago | (#31217688)

not going home prospects afre

Anonymous ME (0)

Anonymous Coward | more than 4 years ago | (#31217784)

I posted this days ago but Timothy gets priority on the homepage? Thanks guys

Awesome (1)

Uranium-238 (1586465) | more than 4 years ago | (#31217908)

Holy fuck Batman, that was awesome!

That's not a Sun Dog... (3, Informative)

MBaldelli (808494) | more than 4 years ago | (#31217922)

What the Saturn V encountered was an Iridescent Cloud [wikipedia.org]

Re:That's not a Sun Dog... (0)

Anonymous Coward | more than 4 years ago | (#31222058)

That's also not a Saturn V.

This could be even more cool... (0)

Anonymous Coward | more than 4 years ago | (#31217982)

...if a ball-lightning did a Hadouken to the rocket afterwards.

new waves below the rocket (1)

multi io (640409) | more than 4 years ago | (#31218064)

At 2:00 it looks like there are new wavefronts being generated far below the craft. Reflections from the ground? Can't think of any really good explanation.

Re:new waves below the rocket (1)

multi io (640409) | more than 4 years ago | (#31218100)

..or maybe those are waves that are much nearer to the camera.

Just "waves?" Motorized cam; music choice (1)

dpbsmith (263124) | more than 4 years ago | (#31218332)

1) I don't think those are "shock waves," just ordinary very-low-frequency sound waves. I think shock waves occur when a pile of sound waves are forced to stack up on top of each other and create an actual pressure discontinuity.

2) I was fascinated to hear the background sounds of someone taking photos with a motorized SLR. That is, film... silver nitrate on polyester film. Is that a pro photojournalist? Do they still use film? Or just someone clinging to a nifty old piece of technology that still does the job?

3) Why would anyone choose the Imperial March from Star Wars, inseparably associated with Bad Guys, as background music?

Why the Imperial March? (1)

maillemaker (924053) | more than 4 years ago | (#31218380)

Because it's bad-ass, just like this was.

Re:Just "waves?" Motorized cam; music choice (2, Informative)

jhesse (138516) | more than 4 years ago | (#31218464)

That sounded like the music from the awards ceremony at the end, I thought.

Re:Just "waves?" Motorized cam; music choice (1)

Yosho-sama (800703) | more than 4 years ago | (#31219086)

3. That wasn't the imperial march. That was the song they played at the end of A New Hope after the Death Star was destroyed during the award ceremony.

Re:Just "waves?" Motorized cam; music choice (1, Informative)

budgenator (254554) | more than 4 years ago | (#31219304)

Film is still used, excellent resolution, expose now process later. it will always beat digital in rapid fire situations.

Re:Just "waves?" Motorized cam; music choice (0)

Anonymous Coward | more than 4 years ago | (#31219674)

Your film is as fast as it can be rolled and exposed, digital is as fast as tiny electrons moving as fast as they can.. you can only roll and expose your film so fast. If your sucking that film into the little roll, and it snags in the least on anything inside the camera, it will rip that film apart, now you have a gummed up camera and a missed shot. It seems pretty stupid to assume that anything that has physical movement can always be faster then digital.. rotational hard drives are faster then all that solid state crap right?... RIGHT?, it seems to me that digital if it hasnt already will be one day much faster then any regular slr. OTOH you might have a perfectly good case saying that some photographers just prefer film. Your just spouting non sensical bull... pls shut up

Remember the more moving parts there are, the more likly your shit is gonna brake.

Re:Just "waves?" Motorized cam; music choice (1)

budgenator (254554) | more than 4 years ago | (#31224048)

You forgot that digital has to charge all of those teeny tiny capacitors in the CCD, auto-focus, expose them to light, then read the voltage on each one, store them in a computer read-able format, then apply the color correction and exposure factors, then store the image on the mass-storage device; for each picture. My favorite camera is a Canon FTbQL [wikipedia.org] , 135 format [wikipedia.org] , forty years old and has never had a film jam and the battery is only used for the exposure meter so it completely optional. I can expose 3 frames a second manually with that one, it's my workhorse camera. My second favorite is a Soviet build Lubitel 2 [wikipedia.org] a 120 format [wikipedia.org] rugged as hell. The Lubitel's sweet-spot is casual portraits and landscapes when you don't want to use the big-guns. Then there is my 4X5 view camera [wikipedia.org] for spectacular photo quality (it's one hundred years old too), that's the big-gun for formal portraits and composed art photographs. Most of the time, the digital camera on my cellphone gets the most use for snapshots. It's really a matter of using the proper tool for the job.

Re:Just "waves?" Motorized cam; music choice (1)

beckett (27524) | more than 4 years ago | (#31226654)

not that i'm disagreeing with your points, but i find it interesting that you respond to digital imaging tech with more tech, albeit film tech. i realise this is slashdot, but i think the mindset of which is technically better based on specs like film size is missing the point of photography. A photographer is someone that can take a great picture with whatever they have on hand, whether homemade pinhole or Mamiya 645 or digital P&S. I find it absurd that people turn their noses up to one format or another, and most of the time photography discussion isn't really about photography at all; it's about what gear people own or what ideological nostalgia they happen to side with. boring.

A camera, whether film or digital, should be good enough to get out of the way of taking a photo. Everything past this is gadget fetishism.

1:54 (1)

maillemaker (924053) | more than 4 years ago | (#31218368)

1:54 is really the sole reason we explore space.

Couldn't see that from my vantage point (1)

sdo1 (213835) | more than 4 years ago | (#31218506)

I drove over to the Canaveral National Seashore [nps.gov] for this launch. The position of the sun made it very hazy from where I was. This shot [flickr.com] is geotagged if you're so inclined to see exactly where it was taken. I didn't see that sonic boom wave and no one I was with made any mention of it either. That's really spectacular.

FWIW, I really love this photo [flickr.com] of the launch which was taken by a guy in the same spot where I was. It captures the Atlas V flying past the sun which I thought was perfect given the nature of this mission.

-S

Cool - but probably not shockwaves (5, Interesting)

njord (548740) | more than 4 years ago | (#31218804)

Those look like regular acoustic waves to me.

I don't doubt the the rocket can go faster than the speed of sound (which gets lower as you get further from the surface), but those waves distinctly lead the rocket's motion, which means that they are the product of acoustic perturbations moving at the speed of sound in the medium.

If the rocket were moving faster than the speed of sound in that medium, then we would see the usual 'shock cone', where those waves would appear an a fairly narrow cone around the rocket as it passed though - certainly not before.

I qualify 'medium' since it is possible that the rocket is moving faster than the speed of sound (in the air) but not faster than the medium that the sundog constitutes. Liquids, for example, have much higher speed-of-sounds and it is (conceptually, not physically) fairly simple for something to be moving faster than the speed of sound in air at sea level but not be anywhere close to the speed of sound in a liquid that it is travelling - and thus producing the regular u-c, u+c acoustic waves.

However, as I understand them, sundogs are collections of ice crystals and probably don't have a higher speed of sound than the air around them. But anyway, waves preceding the motion of a body in a medium are certainly not shockwaves - if we could visualize the waves any object makes in the air, you would see acoustic waves arising from the object's motion before and after it.

Still neat-looking, though.

Re:Cool - but probably not shockwaves (1)

Zak3056 (69287) | more than 4 years ago | (#31220936)

At 2:01 you can hear the mission controller (or at least the same voice who was calling the countdown, ignition, etc) in the background saying, "Vehicle is now supersonic."

Just acoustic pressure waves (2, Informative)

slyborg (524607) | more than 4 years ago | (#31221092)

Another video of the launch with clean audio. Rocket isn't supersonic until roughly 2 minutes after launch.

http://www.youtube.com/watch?v=TRFWq7gcj2E&feature=fvw [youtube.com]

It didn't look like a shockwave to me from the start, as the name implies, it would be visible as a very sharp, immediate disturbance, not a bunch of ripples. Actually, would have been really cool if it *had* gone supersonic in that cloud layer.

Re:Just acoustic pressure waves (1)

goodmanj (234846) | more than 4 years ago | (#31221678)

Not quite 2 minutes.

According to the ground loop audio, rocket goes supersonic at 1:38 in that video; launch is at 0:12. So mach 1 is at T+84 seconds or so. This matches my calculations in another thread, which I did using published Atlas rocket launch profiles.

The amateur video in the summary shows the phenomenon 75 seconds after launch. So while the rocket isn't yet supersonic, it's close. And that makes sense: in the transsonic region just shy of Mach 1, you get violent and irregular pressure-wave phenomena.

If the vehicle was far above Mach 1, you're right, you'd see a series of perfectly elliptical shock fronts. But if the vehicle was far short of Mach 1, you'd see nothing at all.

Shows how remarkable this video is: not just perfect weather and perfect observer location, but perfect timing too.

Worst Camera Work Ever (0, Troll)

bangzilla (534214) | more than 4 years ago | (#31218810)

You know, after getting up in the wee small hours of the morning, driving miles to find a spot to observe the launch and having paid good cash for a video camera (and PC and editing software), you'd think that the joker that took the video would learn **how to pan with the moving object**!. That's "pan with the object" not wait until the object has left the frame and then jerk the camera up until it's at the bottom. And you know, you can buy cameras these days with image stabilization (or even stabilize in post). *very* frustrating video.

Re:Worst Camera Work Ever (2, Interesting)

Yosho-sama (800703) | more than 4 years ago | (#31219116)

Not going into the subject of "if you're going to whine about it, do it yourself" but if he hadn't been stationary, he might have missed recording the shockwave event, or recorded it so seeing it wasn't as impressive as we saw.

Re:Worst Camera Work Ever (1)

mano.m (1587187) | more than 4 years ago | (#31241758)

Mod parent 'unappreciative', 'glass quarter-empty', and 'nitpicking boss from Hell'.

Here's what I don't get (2, Insightful)

fat_mike (71855) | more than 4 years ago | (#31219274)

Once upon a time, men would have been sitting on top of that rocket. Men with no fear, who couldn't give a shit about politics. They just wanted the ultimate ride.
Every politician thinking about cancelling Ares needs to think about that. They wouldn't have cell phones and 3G internet and GPS if it weren't for the brave men and women who are, as Steve Buscemei so perfectly put it (minus the nuke):

"You know we're sitting on four million pounds of fuel, one nuclear weapon and a thing that has 270,000 moving parts built by the lowest bidder. Makes you feel good, doesn't it? "

Re:Here's what I don't get (1)

mano.m (1587187) | more than 4 years ago | (#31241774)

Once upon a time, men would have been sitting on top of that rocket.

I doubt it. It's only putting a satellite in orbit. Why'd anyone put men on that rocket?

My explanation (2, Interesting)

Thagg (9904) | more than 4 years ago | (#31219580)

I've looked at this a few dozen times. It's truly an amazing effect.

Being in the CGI effects business myself (and actually right in the middle of bidding some interesting atmospheric effects for a movie dogfight) I thought it was fake at first, mostly because I've never seen anything like this before. A spectacular display like this, I would have thought, would have been photographed many times if it was a normal occurrence. Some commenters have said that something similar happened on the Apollo XI launch, I haven't seen film that confirms that.

But no, it's clearly real. Many people saw it, several people filmed it.

What it is, is the shockwave moving through a thin layer of clouds and atmosphere. The shockwave disturbs that layer of clouds in some way (in the case of the sun dog, apparently disturbing the crystals orientation -- shockingly these sun dogs require the hexagonal crystals to be hanging more-or-less flat in the air) There are any number of films of airplanes flying above the speed of sound causing clouds to pop into existence and then disappear as the shockwave passes. Every nuclear bomb sequence has these kind of shock-induced clouds as well.

I suppose that clouds with exactly the characteristics to make this happen for rocket launches are rare, because I've watched film of hundreds of launches and never seen this. It always pays to look up!

Re:My explanation (0)

Anonymous Coward | more than 4 years ago | (#31220016)

The shockwave disturbs that layer of clouds in some way (in the case of the sun dog, apparently disturbing the crystals orientation -- shockingly these sun dogs require the hexagonal crystals to be hanging more-or-less flat in the air)

Eh, no. You can only see them if they are oriented correctly toward you. Think "tiny clear plastic mirrors".

Statistics. Learn them.

Re:My explanation (1)

mano.m (1587187) | more than 4 years ago | (#31241570)

I love Mondays. On a Monday, anything is possible.

That is a genuinely novel and interesting sig. Is it a quotation from someone, or is it you?

yuo 74il it (-1, Redundant)

Anonymous Coward | more than 4 years ago | (#31219900)

troubled OS. NoW it just 0wnz.', and Michael Smith in any way related

Sonic boom or not? Math (5, Informative)

goodmanj (234846) | more than 4 years ago | (#31220944)

Some debate here as to whether what we're seeing is a sonic boom, or just loud low-frequency sound waves. Let's do the math...

Basic question: is the rocket going at Mach 1 or greater when the phenomenon happens?

In the video, the launch happens at 0:38, and the ripples are seen at 1:53, 75 seconds later.

Here's a handy document [umd.edu] showing the launch profile of an Atlas V. It doesn't show velocity vs time, but on page 19 there's an acceleration vs time graph for the Atlas V 401, the specific vehicle [nasa.gov] used in this launch. It shows the average thrust during the first 75 seconds is 1.4 +/- .05 g's (uncertain because I can't read the graph that accurately.)

Subtract out 1 g for gravity pulling the rocket down, to get a vehicle acceleration of 0.4 +/- 0.05 g, which over 75 seconds will lead to a final velocity of 294 +/- 36 m/s.

The speed of sound is 330 m/s. So at the time we see the ripples, the rocket is riiiiight about at the speed of sound, maybe a little over, maybe a little under, impossible to tell.

This transition to supersonic flow is often chaotic and irregular, which would explain the intense but complicated ripples seen. If the rocket was going at mach 2 or 3, we'd see a perfectly shaped set of concentric rings; if it was going at far less than mach 1, we'd see nothing at all.

Re:Sonic boom or not? Math (2, Informative)

mano.m (1587187) | more than 4 years ago | (#31241654)

It's at about 11 km above the ground after 75 s. At that height, the speed of sound is 295 m/s (WolframAlpha). So it is a sonic boom.

Re:Sonic boom or not? Math (1)

mano.m (1587187) | more than 4 years ago | (#31241716)

PS. Really impressed at how deeply you looked into this. Respect.
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