Fake sonic booms

[Lisa Simpson]

My niece is taking an elective class this year at her middle school called "pop culture". Frankly, I'm pissed off over it anyway as they got rid of computer class for learning Marilyn Monroe's real name, but whatever. Thanks to the Governator, California kids are getting a top notch education in useless crap.

Anyway, the woman teaching the class believes in every conspiracy theory. JFK assassination magic bullet theory, bombs in the World Trade Center, moon Landing hoax - she believes them all. Not only does she believe we didn't land on the moon, she believes we've never been to outer space at all. When a student said "but what about the sonic booms" made by the re-entering space shuttles, she said "the government faked them".

So my question is - how difficult would it be to fake the double sonic booms we hear every time the shuttle comes home?

[Nosi]

This woman is teaching? Get out of California yesterday!

[Arus808]

fake a sonic boom? that originates from the sky? Unless there is someone on a mountain top with a very loud cannon, no one can fake that (especially in areas there aren't even mountains, LIKE IN Cape Canaveral florida)


By the way, I would suggest that you get this teacher out of the classroom by filing a formal complain with the California State Board of Education - http://www.cde.ca.gov/BE/ her nonsense belongs in no classroom

[Lisa Simpson]

My husband suggested military airplanes flying overhead, but unless there's a lot of cloud cover, military planes are usually visible.

Her mom is going to speak with the school's principal first. She's especially concerned that the teacher doesn't allow any dissent. When my niece tried to challenge the magic bullet theory, she got in trouble.

[apathoid]

So my question is - how difficult would it be to fake the double sonic booms we hear every time the shuttle comes home?


Easy. Hang loudspeakers from the chemtrail clouds. I wish I had a teacher like that, would have been a blast.

[Arus808]

My husband suggested military airplanes flying overhead, but unless there's a lot of cloud cover, military planes are usually visible.

And if there is cloud cover, most times the Shuttle wont land at that point. The weather needs to be near perfect for the Shuttle at most times, otherwise they divert to another airforce base (ie White Sands)

Her mom is going to speak with the school's principal first. She's especially concerned that the teacher doesn't allow any dissent. When my niece tried to challenge the magic bullet theory, she got in trouble.

the teacher just created a hostile environment to learn, if she wont allow differing opinions or even be asked that she back up her claims with facts. This teacher needs to be put out as soon as possible. The school year just started; no way to let this abuse continue

[Elizabeth I]

My husband suggested military airplanes flying overhead, but unless there's a lot of cloud cover, military planes are usually visible.

Her mom is going to speak with the school's principal first. She's especially concerned that the teacher doesn't allow any dissent. When my niece tried to challenge the magic bullet theory, she got in trouble.

At least it's obvious your niece is well brought up. :D

[Horatius]

My husband suggested military airplanes flying overhead, but unless there's a lot of cloud cover, military planes are usually visible.




You're forgetting that they could mount the same holographic projectors to this plane that they used to fake the planes on 9/11.



Hey, those suckers are expensive, we've got to get some more use out of them!

[Lisa Simpson]

At least it's obvious your niece is well brought up. :D

Both of my nieces have heard a steady stream of critical thinking (at least from me). When my other niece was in third grade she announced loudly that Christopher Columbus did not discover the earth was round, people already knew that and mostly what he did was kill and enslave the native peoples.

Teacher also told my niece that any studies showing organic farming isn't more nutritious are funded by the meat industry. My niece asked why the meat industry would care about organic vegetable farming.

[Elizabeth I]

Both of my nieces have heard a steady stream of critical thinking (at least from me). When my other niece was in third grade she announced loudly that Christopher Columbus did not discover the earth was round, people already knew that and mostly what he did was kill and enslave the native peoples.

Teacher also told my niece that any studies showing organic farming isn't more nutritious are funded by the meat industry. My niece asked why the meat industry would care about organic vegetable farming.

Charming children, simply charming.

[TheDaver]

There isn’t a doubt in my mind that this teacher should be fired for her behavior. This sort of exposure to – no, forced acceptance of – delusional thinking is bordering on criminal.

[R.Mackey]

Serious answer, it would be extremely difficult.

The Shuttle gives off a unique double boom, caused by its rather blunt structure and high speed. The shockwave is known as an oblique shock (http://en.wikipedia.org/wiki/Oblique_shock), and it always starts at the nose of an aircraft, and the shock front takes a conical shape, where the air inside is moving with the aircraft, the air outside moving at ambient speed -- the shock front itself is the discontinuity, and the air moves at totally different speeds on either side. That's what a shock is.

Now, the conical front has an angle determined by the speed. This angle takes some work to compute (http://www.grc.nasa.gov/WWW/K-12/airplane/oblique.html), but generally speaking, the faster the aircraft is moving, the narrower the cone. This is important for design, because you don't want any of the aircraft to lie outside this cone. If it does, it greatly increases the drag and the load on the structure. This is why the faster an airplane gets, the more swept back and narrower its wings, until you have things like the SR-71 that resembles an arrowhead more than a typical planform.

The Shuttle, however, doesn't really care about drag so much because it spends most of its performance outside the atmosphere entirely. As it descends, starting from extremely high speed, a good chunk of structure does in fact lie outside the oblique shock coming off the nose, and this sets up a second shock wave, approximately 30 meters behind the first one. This distance translates to a time delay on the ground, and thus a double shock is clearly audible, occuring about 0.08 seconds apart (or more, depending on temperature at altitude).

Modern fighter aircraft, on the other hand, only produce single shocks -- any additional shocks thrown off by structure are weaker, lying within the primary cone, and will be closer together to the point that they will combine with the main shock at any appreciable distance from the aircraft. To get a double boom, you would have to fly a pair of them in close formation, which could be done, I suppose. However, this would be easily detectable by observers with binoculars, and it would have to fly directly over heavily populated areas (the Los Angeles basin, and Orlando Florida, respectively). Good luck with that.

There is also the magnitude of the boom to consider. The Shuttle dives quite steeply at extreme speed and thus makes a particularly loud boom. This is quite different from the boom from fighters -- much more of a rumbling, earthquake-like shock than the simple *SNAP of a lighter aircraft, one that is trying to avoid drag and compressing the air much less.

So, in closing, to replicate the double boom, you'd need a different vehicle or series of vehicles with similar performance. I never got to hear the XB-70 Valkyrie (http://en.wikipedia.org/wiki/XB-70) at full tilt, nor does the Concorde or SR-71 fly any longer, so I can't imagine what that might be. This mystery vehicle would also have to look like the Shuttle, and follow its same route. In short, if it cracks like a duck, it probably is one.

[Lisa Simpson]

Thank you very much, R. Mackey. That is exactly the kind of information I was looking for.

[deep]

Not only does she believe we didn't land on the moon, she believes we've never been to outer space at all. When a student said "but what about the sonic booms" made by the re-entering space shuttles, she said "the government faked them".


..but what about the ISS? It's visible to the naked eye at certain times of the day.

[R.Mackey]

It sure is. Here (http://www.sbig.com/award/legault/iss_shuttle.jpg) is a particularly unmistakable amateur photograph from a while ago. Zoom in for details.

[Pantaz]

. . .
There is also the magnitude of the boom to consider. The Shuttle dives quite steeply at extreme speed and thus makes a particularly loud boom. This is quite different from the boom from fighters -- much more of a rumbling, earthquake-like shock than the simple *SNAP of a lighter aircraft, one that is trying to avoid drag and compressing the air much less.
. . .

You've got that right! I live fairly close to the Shuttle's flight path to Edwards AFB. I once ran outside expecting to see a tree had fallen on the house!

[R.Mackey]

The last time the Shuttle came in to Edwards I was in my office, late in the day, and didn't know about it. I thought an air conditioning unit had fallen off and then slammed against a wall.

Another time, I was in the open, and my first instinct was that a transformer had exploded down the street.

In contrast, I've been up at Edwards for a few dozen supersonic flights, from quals on F/A-18s to testing the F-15S, and F-22 trials. Those are more like rifle shots. Not remotely comparable.

[Riayn]

Good luck getting this teacher removed from the classroom. It is one thing to believe in conspiracy theories but quite another to teach them as fact to school students.

[Pantaz]

Might be interesting to check up on the teacher informally...
http://www.ratemyteachers.com/

[LashL]

Thank you very much, R. Mackey. That is exactly the kind of information I was looking for.

R.Mackey is awesome. He is not only a fount of useful and detailed information on a plethora of scientific subjects, he is also a selfless educator whose knowledgeable and patient explanations (particularly in the 9/11 CT threads) never cease to amaze me.

[/shameless but well deserved exaltation]

[Dan O.]

The students could probably measure the speed of the shuttle by measuring the sonic booms using cell phones at several locations.

But then, maybe the government is faking the speed of sound too.

[JoeyDonuts]

In contrast, I've been up at Edwards for a few dozen supersonic flights, from quals on F/A-18s to testing the F-15S, and F-22 trials. Those are more like rifle shots. Not remotely comparable.

Concur. I went to "C" and "A" school down at Corry Station, close enough to watch the Blue Angels practicing every day over Pensacola. They never boomed low enough to be too terrifying.

Later on, I was stationed at Norfolk. Used to visit the Oceana commissary right at the tail end of the EA-6B's career. That sucker would shake the roof of the place...not from sonic booms - the bastard was just that loud.

[R.Mackey]

The students could probably measure the speed of the shuttle by measuring the sonic booms using cell phones at several locations.

But then, maybe the government is faking the speed of sound too.

Sure can. My father also used to host school experiments where they'd talk to the Shuttle (and Mir) via 2-meter Ham radio, both voice and packet. In order to get a good signal, they needed a directional antenna, and hence the exercise. They'd work out the orbits, and during the passes a team of students would steer the antenna accordingly. Worked like a charm.

Concur. I went to "C" and "A" school down at Corry Station, close enough to watch the Blue Angels practicing every day over Pensacola. They never boomed low enough to be too terrifying.

Later on, I was stationed at Norfolk. Used to visit the Oceana commissary right at the tail end of the EA-6B's career. That sucker would shake the roof of the place...not from sonic booms - the bastard was just that loud.

Yup, turbojets are noisy beasts. I've always thought the (similarly subsonic) Harrier was a noisy bird, but the Intruder/Prowler might be even worse...

[JoeyDonuts]

Sure can. My father also used to host school experiments where they'd talk to the Shuttle (and Mir) via 2-meter Ham radio, both voice and packet. In order to get a good signal, they needed a directional antenna, and hence the exercise. They'd work out the orbits, and during the passes a team of students would steer the antenna accordingly. Worked like a charm.

Cool! How much dwell time did each pass have? (I can't imagine they could have reliably tracked along the orbit with the directional antenna. ETA - By this I mean constantly adjusting the Azimuth/Elevation to match the path of the shuttle real-time) From my old SATVUL exercises, I'm guessing around 5-10 minutes overhead time? (Depending on your sensitivity/ERP/beamwidth/etc...)

[R.Mackey]

Yup, not long. Low orbit. We'd get six minutes of solid comm on average. I think we once managed 11 minutes on Mir, when it was directly overhead, at home with the big antenna, at altitude, and with the ocean only a few miles away... The cosmonauts seemed to have a lot of time on their hands, and we talked to them fairly often.

But we did track the orbit as it went over. We'd paint lines on the ground and set up little flags, one for every minute, and just march along as close as we could. Worked quite well.

[JoeyDonuts]

But we did track the orbit as it went over. We'd paint lines on the ground and set up little flags, one for every minute, and just march along as close as we could. Worked quite well.

Well, I'll be damned. Hats off. Who needs synchros, right? :D

Besides, it's not like you're pointing a target illuminator. From what I understand of the 144.000 MHz range, you don't really need to be dead on with a directional antenna. Periodic adjustments every so often to keep it in the ballpark, and it looks like that's just what you guys did.

Man - why couldn't I have had cool experiments like that when I was coming up? All I learned about was a bunch of Young Earth Creationism and how to refute evolutionists.

[R.Mackey]

Right. Plus or minus about five degrees is plenty. It isn't like S-band or Ka-band comm where you're focusing through a straw. 2 meter is pretty forgiving, but it is only line-of-sight.

If I remember the apparatus correctly, he had the antenna on a boom made from 2x4's, with the lines on the ground for azimuth, and a plumb bob and a big paper protractor for elevation. Redneck engineering at its finest.

He still has some QSL cards from Mir. I'd have to ask him which ones.

[JoeyDonuts]

Shadetree HAM engineers never cease to amaze me. I've seen some pretty entertaining (and impressive) rigs. Getting my amateur class license has been on my to-do list for a long time now. Maybe after I get my black belt in Judo, run a triathlon, finish my degree, land a better paying job, etc... :D

[R.Mackey]

I haven't thought about this in years, but it's coming back to me...

Talking to the Shuttle was quite popular. We got a lot of contacts on Mir because, first of all, they were on orbit for a long, long time, and second, not too many people seemed to know about it.

Shuttle was different. Lots of competition. We could get a weak signal with no direction-finding at all, but if we wanted them to talk to us in the limited time available, we needed to have a nice, strong, readable signal, and we needed to get on it as soon as the track began. Being on the West Coast helped, but we had to be right on it as soon as they came over the horizon.

Although I also seem to recall my dad had an ace in the hole -- 2 meter simplex is supposed to be limited to 5 watts, if I remember right, but he had a 1500 W amplifier on standby, just in case it didn't work out, so as not to disappoint the kiddies. Never needed it, though. :p

[Hokulele]

Nerds!


To the OP, I vote for the mess-with-the-teacher's-head option. Tell your niece to tell the teacher that the sounds aren't faked, but that the so-called space shuttle is simply a cover story for the real cause of the sonic booms. The US government is trying to repair a rift in the space-time continuum, sometimes known as the "San Andreas Fault". This repair work involves the demolition of the older, failed repair, also know as the "Los Angeles Rams", and the second boom is the echo off of the area's cell phone towers. Which everyone knows are really mind-control ray emitters. So you only think you hear the second boom.

[uk_dave]

So my question is - how difficult would it be to fake the double sonic booms we hear every time the shuttle comes home?

My question is : WTF is that idiot doing teaching in a school?

[rwguinn]

Serious answer, it would be extremely difficult.

The Shuttle gives off a unique double boom, caused by its rather blunt structure and high speed. The shockwave is known as an oblique shock (http://en.wikipedia.org/wiki/Oblique_shock), and it always starts at the nose of an aircraft, and the shock front takes a conical shape, where the air inside is moving with the aircraft, the air outside moving at ambient speed -- the shock front itself is the discontinuity, and the air moves at totally different speeds on either side. That's what a shock is.

Now, the conical front has an angle determined by the speed. This angle takes some work to compute (http://www.grc.nasa.gov/WWW/K-12/airplane/oblique.html), but generally speaking, the faster the aircraft is moving, the narrower the cone. This is important for design, because you don't want any of the aircraft to lie outside this cone. If it does, it greatly increases the drag and the load on the structure. This is why the faster an airplane gets, the more swept back and narrower its wings, until you have things like the SR-71 that resembles an arrowhead more than a typical planform.

The Shuttle, however, doesn't really care about drag so much because it spends most of its performance outside the atmosphere entirely. As it descends, starting from extremely high speed, a good chunk of structure does in fact lie outside the oblique shock coming off the nose, and this sets up a second shock wave, approximately 30 meters behind the first one. This distance translates to a time delay on the ground, and thus a double shock is clearly audible, occuring about 0.08 seconds apart (or more, depending on temperature at altitude).

Modern fighter aircraft, on the other hand, only produce single shocks -- any additional shocks thrown off by structure are weaker, lying within the primary cone, and will be closer together to the point that they will combine with the main shock at any appreciable distance from the aircraft. To get a double boom, you would have to fly a pair of them in close formation, which could be done, I suppose. However, this would be easily detectable by observers with binoculars, and it would have to fly directly over heavily populated areas (the Los Angeles basin, and Orlando Florida, respectively). Good luck with that.

There is also the magnitude of the boom to consider. The Shuttle dives quite steeply at extreme speed and thus makes a particularly loud boom. This is quite different from the boom from fighters -- much more of a rumbling, earthquake-like shock than the simple *SNAP of a lighter aircraft, one that is trying to avoid drag and compressing the air much less.

So, in closing, to replicate the double boom, you'd need a different vehicle or series of vehicles with similar performance. I never got to hear the XB-70 Valkyrie (http://en.wikipedia.org/wiki/XB-70) at full tilt, nor does the Concorde or SR-71 fly any longer, so I can't imagine what that might be. This mystery vehicle would also have to look like the Shuttle, and follow its same route. In short, if it cracks like a duck, it probably is one.

To fake the STS would be very difficult. Dynamite on a Rocket?
It is my understanding that the shock comes off the front and back of the airplane--every one I've ever heard was a double boom--and I spent 4 years at Edwards doing flight test.
Just FYI, Ryan, et al. The SR-71 sonic boom is a (Fairly) long, drawn-out thing, and not of a particularly high amplitude.
When I was at Edwards in the 1970's we flew the YF-12/SR aircraft with F-104 chase (only for T-O, landing, and refuel, of course). The SR-71 bOOm was a kaaaaa-boooooom.
The F-104 was a very sharp, rifle-like CRACK-crack! of a very, very short duration--and BTW-I've actually SEEN the shocks from a 104 on the lakebed!
The Flight Sciences guys told me that that was due to the fact the aerodynamic length of the SR is around 1000 feet, and the F-104 is more like 10 feet. Not being a fluids guy, I dunno.

[Lisa Simpson]

The students could probably measure the speed of the shuttle by measuring the sonic booms using cell phones at several locations.

But then, maybe the government is faking the speed of sound too.

The last time the shuttle landed, here in California, I was in the chatroom and it was about three minutes between the time I heard the booms and someone else in chat living in Los Angeles heard the booms.

[Brattus]

I wonder if this is how most California teachers are?
My niece had a teacher a few years ago who told her that the human body was not designed to sit in chairs.
He had removed all the chairs in the classroom and they kinda hunkered down on the floor.
My niece really believed this and for about a year would not sit in chairs.

[Lisa Simpson]

I wonder if this is how most California teachers are?
My niece had a teacher a few years ago who told her that the human body was not designed to sit in chairs.
He had removed all the chairs in the classroom and they kinda hunkered down on the floor.
My niece really believed this and for about a year would not sit in chairs.

Nah...every place has bad teachers and the bad ones are the ones that get bitched about publicly. I think the biggest problem is the teacher's union, which makes it difficult to get rid of bad teachers. There used to be a kindergarten teacher at the school where I work and it took years to get rid of her, even though she was physically abusive to the children.

[Especially]

Everybody knows Neil Armstrong walked on the film studio in 1969. That was how he and his friends resisted the solar radiation beyond the Van Allen Belt.

Simple, right ?

[Brattus]

Nah...every place has bad teachers and the bad ones are the ones that get bitched about publicly. I think the biggest problem is the teacher's union, which makes it difficult to get rid of bad teachers. There used to be a kindergarten teacher at the school where I work and it took years to get rid of her, even though she was physically abusive to the children.

Wow! Abusive! I'm not sure which is worse. Filling their young minds with garbage they carry around forever or slapping them around.
I of course think both are horrible and unacceptable but the sting of a slap will eventually fade away.

[Brattus]

Everybody knows Neil Armstrong walked on the film studio in 1969. That was how he and his friends resisted the solar radiation beyond the Van Allen Belt.

Simple, right ?

You mean fellow highly trained astronauts or was Neil having a barbecue up there?

[Nosi]

Forgive my nieve question:

But can the sonic boom harm the Earth's ozone layer? It currently has a hole. (http://en.wikipedia.org/wiki/Ozone_depletion)

[Lisa Simpson]

You mean fellow highly trained astronauts or was Neil having a barbecue up there?

A kegger.

[R.Mackey]

It is my understanding that the shock comes off the front and back of the airplane--every one I've ever heard was a double boom--and I spent 4 years at Edwards doing flight test.

If you want to get really, really technical about it, most supersonic aircraft throw off a whole series of oblique shocks, as you can see in a Schlieren image of a test article. Here's one for a T-38: NASA Image (http://www.dfrc.nasa.gov/gallery/photo/Schlieren/Small/EC94-42528-1.jpg)

Now every one of those shocks is a pressure discontinuity. Air hits the shock at one speed and angle, and leaves it at a different speed and angle. It's kind of like light waves "bending" when they hit glass or water at an angle -- think of the shocks defining the edges of the glass, not describing the fluid flow. What's happening is the supersonic freestreem is coming straight at the aircraft, and it's being forced to turn, first by the aircraft's nose, then the inlets or wing roots, the canopy, the structure, tail surfaces, etc. Each turn sets up its own shock.

The air also has to turn back to the direction of the freestream after the aircraft has passed. That's the "tail" shock. This and the nose shock are the strongest ones, because they correspond to the greatest amount of turning. The other shocks, all the little ones inside the cone of the nose shock, are much weaker -- they only turn the fluid a little bit, and the fluid is already mostly going the direction it needs to after encountering the nose. Correspondingly, the pressure discontinuities here are much smaller.

Now, again, with the Shuttle, because the Shuttle is the only aircraft that doesn't fit entirely within the cone of its own nose shock, it actually gives off two of them. So its "double boom" is two booms of extremely high amplitude. The Shuttle, like all other aircraft, has all of these other little shocks and also a tail shock as well, so it's not really a "double boom" and with sensitive equipment you can see all of these. But it is much more likely to sound like a double boom than any other vehicle.

Just FYI, Ryan, et al. The SR-71 sonic boom is a (Fairly) long, drawn-out thing, and not of a particularly high amplitude.
When I was at Edwards in the 1970's we flew the YF-12/SR aircraft with F-104 chase (only for T-O, landing, and refuel, of course). The SR-71 bOOm was a kaaaaa-boooooom.
The F-104 was a very sharp, rifle-like CRACK-crack! of a very, very short duration--and BTW-I've actually SEEN the shocks from a 104 on the lakebed!
The Flight Sciences guys told me that that was due to the fact the aerodynamic length of the SR is around 1000 feet, and the F-104 is more like 10 feet. Not being a fluids guy, I dunno.

Cool. I believe the long SR-71 boom, it was a very long aircraft and highly optimized for low drag, so the nose shock would have been relatively weak, perhaps comparable to the secondary shocks. It also would have entrained the air for some distance so the tail shock would be delayed quite a bit, I don't know about 1000 feet but it's possible. The Shuttle, in contrast, is trying to be as draggy as possible, so its wake is almost certainly turbulent and the tail shock would follow it closely...

As for the F-104, I wonder if you weren't hearing only the nose shock, but instead hearing it directly and then reflected off the lakebed? All of these effects will echo off of hard surfaces.

[rwguinn]

If you want to get really, really technical about it, most supersonic aircraft throw off a whole series of oblique shocks, as you can see in a Schlieren image of a test article. Here's one for a T-38: NASA Image (http://www.dfrc.nasa.gov/gallery/photo/Schlieren/Small/EC94-42528-1.jpg)

Now every one of those shocks is a pressure discontinuity. Air hits the shock at one speed and angle, and leaves it at a different speed and angle. It's kind of like light waves "bending" when they hit glass or water at an angle -- think of the shocks defining the edges of the glass, not describing the fluid flow. What's happening is the supersonic freestreem is coming straight at the aircraft, and it's being forced to turn, first by the aircraft's nose, then the inlets or wing roots, the canopy, the structure, tail surfaces, etc. Each turn sets up its own shock.

The air also has to turn back to the direction of the freestream after the aircraft has passed. That's the "tail" shock. This and the nose shock are the strongest ones, because they correspond to the greatest amount of turning. The other shocks, all the little ones inside the cone of the nose shock, are much weaker -- they only turn the fluid a little bit, and the fluid is already mostly going the direction it needs to after encountering the nose. Correspondingly, the pressure discontinuities here are much smaller.

Now, again, with the Shuttle, because the Shuttle is the only aircraft that doesn't fit entirely within the cone of its own nose shock, it actually gives off two of them. So its "double boom" is two booms of extremely high amplitude. The Shuttle, like all other aircraft, has all of these other little shocks and also a tail shock as well, so it's not really a "double boom" and with sensitive equipment you can see all of these. But it is much more likely to sound like a double boom than any other vehicle.



Cool. I believe the long SR-71 boom, it was a very long aircraft and highly optimized for low drag, so the nose shock would have been relatively weak, perhaps comparable to the secondary shocks. It also would have entrained the air for some distance so the tail shock would be delayed quite a bit, I don't know about 1000 feet but it's possible. The Shuttle, in contrast, is trying to be as draggy as possible, so its wake is almost certainly turbulent and the tail shock would follow it closely...

As for the F-104, I wonder if you weren't hearing only the nose shock, but instead hearing it directly and then reflected off the lakebed? All of these effects will echo off of hard surfaces.
Well-there were 2 lines of dust that went past us at a high speed coincident with the "cracks". And they were reeeeal close together.
(He was pretty low, however)

[fuelair]

This woman is teaching? Get out of California yesterday!

Pay attention - it's California. Almost all the nuttiness seems to start there!!!:D:(

[Hamradioguy]

Talking to the Shuttle was quite popular. We got a lot of contacts on Mir because, first of all, they were on orbit for a long, long time, and second, not too many people seemed to know about it.

Shuttle was different. Lots of competition. We could get a weak signal with no direction-finding at all, but if we wanted them to talk to us in the limited time available, we needed to have a nice, strong, readable signal, and we needed to get on it as soon as the track began. Being on the West Coast helped, but we had to be right on it as soon as they came over the horizon.

Although I also seem to recall my dad had an ace in the hole -- 2 meter simplex is supposed to be limited to 5 watts, if I remember right, but he had a 1500 W amplifier on standby, just in case it didn't work out, so as not to disappoint the kiddies. Never needed it, though. :p

I remember talking to MIR a few times- it helped running around 500 watts (In FM mode the loudest signal overrides all the others.) But to me the most amazing ham communications coup was when my friend K2RIW was able to copy the astronauts in the Apollo Command Module while in lunar orbit using a homemade dish antenna. The "we never went to the Moon" wackos always seemed to have a hard time explaining how that worked if the astronauts really were just in Earth orbit.

This woman needs to be removed from her teaching position post haste.

[R.Mackey]

But to me the most amazing ham communications coup was when my friend K2RIW was able to copy the astronauts in the Apollo Command Module while in lunar orbit using a homemade dish antenna. The "we never went to the Moon" wackos always seemed to have a hard time explaining how that worked if the astronauts really were just in Earth orbit.

That's pretty impressive.

Of course, here at NASA, we did the same thing, except our "homemade dish antenna" was 64 meters wide (http://deepspace.jpl.nasa.gov/dsn/history/1950s.html)... Before my time, alas.

More importantly, the Soviets also tracked the flight. With the Doppler shifts for orbits, differential between the command module and lander, occlusion behind the Moon, etc., etc. Absolutely no way in the world one could fake all that.

[JoeyDonuts]

Absolutely no way in the world one could fake all that.

Just wait til Dan Brown gets around to it.

Wait...He sorta already did in Deception Point. Okay, not a moon landing plot, but preposterous all the same.

[Nosi]

CT's get hammed...:D

[Bad_Doggie]

That's pretty impressive.

Of course, here at NASA, we did the same thing, except our "homemade dish antenna" was 64 meters wide (http://deepspace.jpl.nasa.gov/dsn/history/1950s.html)... Before my time, alas.

More importantly, the Soviets also tracked the flight. With the Doppler shifts for orbits, differential between the command module and lander, occlusion behind the Moon, etc., etc. Absolutely no way in the world one could fake all that.

The brits were also watching.

http://wapedia.mobi/en/Goonhilly_Satellite_Earth_Station

But, I guess we were in on it so that doesn't count.

Woof!

[Lupie]

This "teacher" probably cannot even remotely grasp the technical aspects of the unique sonic boom the Shuttle creates. And, I doubt she could grasp the technical near impossibility of faking a unique sonic boom such as this.

I have watched the shuttle docked with the ISS through my telescope using a satellite tracking program. You can't see fine detail, but you can easily recognize the general shapes of the various ISS components as well at the shuttle itself. I wonder how this so called "teacher" would explain away this fact.

L.

[Horatius]

I have watched the shuttle docked with the ISS through my telescope using a satellite tracking program. You can't see fine detail, but you can easily recognize the general shapes of the various ISS components as well at the shuttle itself. I wonder how this so called "teacher" would explain away this fact.

L.



That's easy. Every telescope has a mini CGI projector built in, just to create fake images of the shuttle.


And before you ask, yes, even the telescope you made yourself, Mr. NASA Shilly Person!

[R.Mackey]

The brits were also watching.

The Aussies, too. Wow, this conspiracy just gets bigger and bigger..!

[dropzone]

Everybody knows Neil Armstrong walked on the film studio in 1969. That was how he and his friends resisted the solar radiation beyond the Van Allen Belt.Even Van Allen rejected that hypothesis. And the radiation is IN the belts, not beyond them.

Loads of info here: http://www.clavius.org/envrad.html

[dropzone]

I saw, with my naked eyes, the Shuttle and Mir during one of their link-ups. That same night my wife and I laid in the park across the street watching satellites go by.

[twinstead]

That same night my wife and I laid in the park across the street watching satellites go by.

Wow. Is that what you kids are calling it now days? ;)

[Foolmewunz]

My niece is taking an elective class this year at her middle school called "pop culture". Frankly, I'm pissed off over it anyway as they got rid of computer class for learning Marilyn Monroe's real name, but whatever. Thanks to the Governator, California kids are getting a top notch education in useless crap.

Anyway, the woman teaching the class believes in every conspiracy theory. JFK assassination magic bullet theory, bombs in the World Trade Center, moon Landing hoax - she believes them all. Not only does she believe we didn't land on the moon, she believes we've never been to outer space at all. When a student said "but what about the sonic booms" made by the re-entering space shuttles, she said "the government faked them".

So my question is - how difficult would it be to fake the double sonic booms we hear every time the shuttle comes home?


Ya know, as soon as I think I'm getting staid in my life, I see something like this and realize I'm going to be an activist up to drawing my very last breath.

This person is allowed to be teaching??!! I'd create a sonic boom just by the speed with which I'd be heading to the principal's office of the school. I really don't give a damn if she's a human and has feelings. She is dangerous! And given enough rope - she'll probably be anti-fluoride, anti-vax, etc... This person shouldn't be allowed to teach any class.

And just what are the educational/training requirements for a teacher of "pop culture"?

Well, I've ready every issue of People Magazine,... ever!
You're hired!

[Lisa Simpson]

She teaches other classes besides the pop culture class. English, I think. Not sure. None of my sons ever had her as a teacher.

[ElMondoHummus]

While I'm not quite as vociferous about it as Foolmewunz here, I agree: The principal needs to be talked to. It's one thing to hold a weird belief, but if she's starting to propogandize to students, that's a whole other level right there. It's a real problem at that point. School is for learning, not agitprop. And preaching trutherism and other pseudoscientific conspiracy fantasy is the epitome of that.

[Lupie]

If you want to get really, really technical about it, most supersonic aircraft throw off a whole series of oblique shocks, as you can see in a Schlieren image of a test article. Here's one for a T-38: NASA Image (http://www.dfrc.nasa.gov/gallery/photo/Schlieren/Small/EC94-42528-1.jpg)

Now every one of those shocks is a pressure discontinuity. Air hits the shock at one speed and angle, and leaves it at a different speed and angle. It's kind of like light waves "bending" when they hit glass or water at an angle -- think of the shocks defining the edges of the glass, not describing the fluid flow. What's happening is the supersonic freestreem is coming straight at the aircraft, and it's being forced to turn, first by the aircraft's nose, then the inlets or wing roots, the canopy, the structure, tail surfaces, etc. Each turn sets up its own shock.

The air also has to turn back to the direction of the freestream after the aircraft has passed. That's the "tail" shock. This and the nose shock are the strongest ones, because they correspond to the greatest amount of turning. The other shocks, all the little ones inside the cone of the nose shock, are much weaker -- they only turn the fluid a little bit, and the fluid is already mostly going the direction it needs to after encountering the nose. Correspondingly, the pressure discontinuities here are much smaller.

Now, again, with the Shuttle, because the Shuttle is the only aircraft that doesn't fit entirely within the cone of its own nose shock, it actually gives off two of them. So its "double boom" is two booms of extremely high amplitude. The Shuttle, like all other aircraft, has all of these other little shocks and also a tail shock as well, so it's not really a "double boom" and with sensitive equipment you can see all of these. But it is much more likely to sound like a double boom than any other vehicle.



Cool. I believe the long SR-71 boom, it was a very long aircraft and highly optimized for low drag, so the nose shock would have been relatively weak, perhaps comparable to the secondary shocks. It also would have entrained the air for some distance so the tail shock would be delayed quite a bit, I don't know about 1000 feet but it's possible. The Shuttle, in contrast, is trying to be as draggy as possible, so its wake is almost certainly turbulent and the tail shock would follow it closely...

As for the F-104, I wonder if you weren't hearing only the nose shock, but instead hearing it directly and then reflected off the lakebed? All of these effects will echo off of hard surfaces.

I just wanted to say, this is really some fascinating stuff. Thanks for taking the time to put this info into easily understandable terms.

L.

[Longfellow]

I just wanted to say, this is really some fascinating stuff. Thanks for taking the time to put this info into easily understandable terms.

L.

+2

That's what I like so much about this place: most of the scary smart people can explain esoteric concepts in such a way that even I, the world's preeminent layperson, can understand.

[Macgyver1968]

Yup, turbojets are noisy beasts. I've always thought the (similarly subsonic) Harrier was a noisy bird, but the Intruder/Prowler might be even worse...

Probably the loudest sound I've ever heard. My father worked for McDonald Douglas as a stress engineer on the AV-8B. I dropped him off at work one day, and one was hovering around. It eventually hovered over near my car. At the time, I was a car stereo nut, and had 1500 watts of amplifiers pushing 8 12-inch woofers. I cranked the stereo to full blast, and the jet noise still drowned everything out. It was incredible.

[jakesteele]

My niece is taking an elective class this year at her middle school called "pop culture". Frankly, I'm pissed off over it anyway as they got rid of computer class for learning Marilyn Monroe's real name, but whatever. Thanks to the Governator, California kids are getting a top notch education in useless crap.

Anyway, the woman teaching the class believes in every conspiracy theory. JFK assassination magic bullet theory, bombs in the World Trade Center, moon Landing hoax - she believes them all. Not only does she believe we didn't land on the moon, she believes we've never been to outer space at all. When a student said "but what about the sonic booms" made by the re-entering space shuttles, she said "the government faked them".

So my question is - how difficult would it be to fake the double sonic booms we hear every time the shuttle comes home?

As a teacher, she should not be allowed to express her views on something like that the same was as trying to foist religion, atheism or any other kind of belief system. The kids are the to learn 'readin', ritin' and 'rithmetic.

[Cuddles]

learning Marilyn Monroe's real name

I think everyone's getting a bit distracted by this science nonsense and missing out the really important issue here - Marilyn Monroe wasn't her real name? Why the hell did no-one teach me that when I was in school?

[Elizabeth I]

I think everyone's getting a bit distracted by this science nonsense and missing out the really important issue here - Marilyn Monroe wasn't her real name? Why the hell did no-one teach me that when I was in school?

Oh, everybody knows, we just didn't tell you.

She was christened Norma Jean Baker.

[ElMondoHummus]

I think everyone's getting a bit distracted by this science nonsense and missing out the really important issue here - Marilyn Monroe wasn't her real name? Why the hell did no-one teach me that when I was in school?

That's what'cha get for napping in class. :p