OK thanks. My only question remaining than is: do they measure an acceration (like the name suggests) or a change (derivative?) in acceleration, like Captain Swoop said?

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To the regular visitor of internet bulletin boards it is clear that it's an excellent idea your parents get to choose your real name.

True, but if you put those measurements on a graph you can see the changes.

Then again, if you want to calculate velocity and position you don't want the changes in acceleration, it's the acceleration itself you need to integrate once for velocity, and twice for position/distance.

Also, as Nicolas pointed out, acceleration (and velocity) are vectors, so you need to keep vertical and horizontal separate.

OK now it is fully clear to me.

I don't know the accelerometer layout of Huygens, but spacecraft that measure perturbations due to the earth's irregularities often have 2 accelerometers per direction, one at each corener of the craft.

The difference in acceleration is casued by the perturbation, the common value by surface forces.

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To the regular visitor of internet bulletin boards it is clear that it's an excellent idea your parents get to choose your real name.

No, it didn't! That is you fantasy which you've failed to provide any corroborating evidence. We know that the parachute sequence happened within seconds of predicted time. We got signal acquistion on Earth at the predicted time. We know how long Huygens was under the chutes and when it landed.

Evidence? The parachute sequence happend within seconds of the predicted time. Quit ignoring these facts.

Evidence? As has been explained to you before, The TAT was NOT used to sequence the parachutes. Signal acquisition and telmetry data show that Huygens was where it was predicted to be. You cannot explain this away with your "quick descent theory".

LOL! That's quite the exercise in seeing what you want to see. How did you expect that the flimsy Mylar thermal blanket would survive re-entry? Why would there be an electrical harness attached to the heat shield and how did it survive re-entry?

Evidence? Signal acquisition and telemetry show that entry detection was within seconds of prediction.

Evidence? Since we know the parachute sequence was initiated within seconds of predicted time, this little fantasy makes no sense.

Trying to use the TAT as some kind of talisman to save your "theory" doesn't cut it. The TAT was updated with RAU data. How many times does this have to be explained to you? You can't claim the RAU's didn't work since we have the return data.

The lamp was activated at 400 meters based on radar altimeter data. Since we know the RAU's worked, there's no reason to suspect that the lamp didn't turn on when expected.

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"A mystic is a person who is puzzled before the obvious but who understands the nonexistent." -- Elbert Hubbard

No Jerry, you're the only one showing cheek.

Huygens knew when it was getting close to the surface based on return data from the acoustic sounder and the radar altimeter. It knew it hit the surface from the penetrometer data. To my knowledge the sun sensor didn't have any input into scheduling events after landing.

Evidence? You wouldn't design a system to to assign a timestamp to an event at some pre-determined time. You'd record the timestamp when the event occurred! That way, regardless of delays in scheduling or buffering, the data would have the correct timestamp. You're relying quite a bit on the TAT. Too bad it doesn't really help you case.

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"A mystic is a person who is puzzled before the obvious but who understands the nonexistent." -- Elbert Hubbard

So, little wind and plenty of turbulence. That's what your quotes were saying. Do you now admit that you were wrong when you attempted to forcibly interpret contradictions into these quotes?

Sorry, the picture isn't very helpful since it's hard to make out what it tries to be saying. The Doppler reconstruction assumed north/south winds to be negligible because that is what was expected and they could only measure east/west motion by using Doppler measurements. They need interferometry results for north/south movement reconstruction, which I don't think has been completed.

From what I read, he changed his conclusion based on his limited Doppler data due to additional data that is not contradictory.

And what about the measured variations they interpret as turbulence? Was Huygens tap dancing after landing?

Actually, it was based upon a ratio between the velocity and the speed of sound - Mach 1.5 - although you mostly right - they measure the velocity to determine this parameter. The most important thing, is that the probe must have been slowed enough by the atmosphere enough not to totally shred the parachutes.


The nail misses, if the ending was signaled by a timed or acceleration based event. If the landing accelerometers were not sampled until the the probe was good-and-ready to sample them, the time stamp cannot be used to validate the landing time. It should be easy to determine this with time-stamped radar data - and if you were able to see the radar plot I posted on Wikipedia, it is clear the descent during that minute looked nothing like the expected profile.

Yes, but I am hoping someone who knows more than me and you, and the specific sequence - for example, does the transmitter send a special signal to confirm the landing - would jump in and explain when I threw that out. I know the polling of the devices by the software is somewhat the way I have described it, but the more detail, the better.
I'm sure it has been, and will be, but not necessarily in the context of Newton and Einstein's curves not working.

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jwj

It's a big universe out there...is it really unwinding, really burning out?

Supernova 1987A exploded recently.

Do you have a plausible answer? Nasa had a half dozen different explanations for the behavior of Galileo's wheels, which one is more plausable? Dark Matter, inflation, Dark energy, time dilation - all magic.

Actually, what I am hoping is the other way around: The behavior of the reaction wheels, if I were privy to the details, could better constrain the theory. I don't know if the wheels are using more power or less, or if there is a conflict as to the momentum expected in the wheel. Here are things that could be happening:

1) The wheel tracking roll, is recording more roll than expected - this could be true if the gravitational effects of the moon are tugging with a greater force than calculated, so the wheel gets in a tug-a-war with the other parts of the guidence system.

2) There could be certain resonant velocities in the wheels - any of the wheels - that interacts with one of the nature frequencies of Saturn - this would be the interference wave nodes involving both Saturn and her moons.

3) A true violation of the weak equivalence principle - the electrical force necessary to drive the wheel is greater or less than expected, screwing up the hysterises dampening parameters.

4) Something else.

I have always favored door 1), but this last episode sounds more like door 3), - effecting multiple types of stepper motors.

Don't you think it is odd that when both Galileo and Huygens were close to Jupiter and Saturn, reaction wheels have behaved curiously?

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jwj

It's a big universe out there...is it really unwinding, really burning out?

The evidence is real - I will repost the radar on the Huygens article. I'll pull out the speculative comment, but graphs use real data - unscaled, but even these yield valid scientific information.

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jwj

It's a big universe out there...is it really unwinding, really burning out?

No, you're wrong again. They weren't measuring velocity, they were measuring acceleration. The parachute sequence was initiated by the CASU when it detected it's acceleration limit.

Stating the obvious again.

The nail hits right to the heart of the matter. We know that the parachute sequence was within seconds of the predicted time. We know we got signal acquisition at the predicted time. We know Huygens was on the chutes for 2hrs 27min. There's no getting around these facts.

As I explained before, you wouldn't design a system to timestamp events at arbitrary times. You collect the timestamp when the event occurs. That way the data is valid regardless of whether we telemeter the data in real-time or we send you to Titan to download the information directly.

Quit trying to obfuscate the situation with these silly notions of which you have not a shred of evidence.

Where did you get the raw data to do this plot? Do you have access to telemetry the rest of us don't?

Whether there is a "special signal" or not is irrelevant. The landing can be inferred from the penetrometer data and by the timestamps on the images taken from the surface. We also have the reports from the Earth-based radio telescopes that detected the landing.

Why would they do such an analysis when there's nothing to indicate they should? This is all in your fevered imagination. The scientists and engineers involved in the project have to work in the real world.

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"A mystic is a person who is puzzled before the obvious but who understands the nonexistent." -- Elbert Hubbard

Why not? Planets go into retrograde all the time

Seriously, a Doppler signal that clearly demonstrates Hugyens landed at the correct time (or the moon stopped) absolutely kills my theory. Accelermeters that stored the landing force, then delivered this data to the computer when Huygens ask for it do not.

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jwj

It's a big universe out there...is it really unwinding, really burning out?

Non sequitor. Was this supposed to mean something?

We're not talking about Galileo, were talking about Cassini. Why are you bringing up any of this? These other theories have no bearing on Cassini other than you don't like them. The difference between these theories and your musings is that they actually have some evidence to back them up.

Lots of flailing, but you've yet to show how any of this could effect one wheel and not the rest.

No. Balky reaction wheels are part of the space game. Take a look at the problems Hubble and the ISS have had. Your reading too much into this.

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"A mystic is a person who is puzzled before the obvious but who understands the nonexistent." -- Elbert Hubbard

Quit making stuff up. Do you have any evidence for this? You've conveniently ignored the last two times I explained this. Timestamps would be totally useless if you didn't record them at the time of the event. Why is this so hard to understand? Your only saying this to shoehorn the telemetry into your "quick descent" scenario. It doesn't work.

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"A mystic is a person who is puzzled before the obvious but who understands the nonexistent." -- Elbert Hubbard

That is my key point: The Doppler wind teams said the turbence ended at 60km, but the imaging team says no, the probe was rocking and tap dancing just before landflall. I think they are describing the same event, twenty minutes into the descent, seconds away from landing.

The balance of the Doppler day, recorded from the earth, showed a smooth descent, with a wind in the same direction that Titan was turning, at virtually no wind in the landing zone: All of it, on the ground.

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jwj

It's a big universe out there...is it really unwinding, really burning out?

Parkes Tracking of the Huygens Probe:

What the DWE's principle investigator said about the Doppler data collected by the ground based telescopes:

Things that would have to be true for Jerry to be right:

1. Even though Titan pulled on Huygens much harder than predicted by Newtonian physics, Huygens magically hits the atmosphere on time anyway.

2. A "large glitch" in the Doppler data occurred, completely coincidentally, within 13 minutes of the predicted landing time.

3. Doppler data received before the landing "glitch" is inconsistent with a probe falling through the atmosphere while dangling from a parachute...and no one ever noticed this.

4. Doppler data received after the landing "glitch" is inconsistent with a probe sitting on the surface of Titan and instead looks a lot like the data received before the landing "glitch"...and no one ever noticed this.

5. We ignore every other excellent point that has been raised in this thread

The referenced article is not a "technical" article at all. It's more an informal recount of the work done tracking Huygens from the Parkes telescope in Australia. I think most reasonable people would agree that even just this article is evidence enough that we have a fairly good idea of the timeline of Huygens' descent (ie: the landing time isn't off by an hour).

I haven't religiously followed the Jerry portion of this thread but I believe, up until now, it's periodically been implied that various agencies are confused, dishonest or just plain stupid. But now it's real, published, accomplished scientists with names (and email addresses, and phone numbers, if you do a little searching) that Jerry has to say can't tell the difference between a probe falling through the atmosphere of Titan and a probe sitting motionless on the surface, using the equipment they are responsible for operating, at the Parkes radio telescope.

Tassel wrote:

Ah! But you've forgotten about Jerry's variable speed of light :roll:

Jerry, you have waffled your way through 61 pages (on this theread alone) but you will just have to get used to the idea that Huygens was a success by any measure of Newtonian and Einstien mechanics you care to name.

Time to give this a rest. At best your ideas were pure speculation based on pure bunk.

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If the speed of light varied with distance from the Sun then this would lead to refraction effects that would distort the relative positions of stars. You might be able to measure this.

Jerry, how large an effect are you predicting, based on your assessment of the "anomalies"?

Just to make a couple of comments for the altitude look-up table:

1) It is not used for the descent reconstruction

2) Its purpose is to provide rough position data to the experimenters. For exampe, the HASI scientists would get lots of different data for the HASI sensors. On top of their experiment data, they also get an attachment, called Descent Data Broadcast file (DDB). This contains some useful data to support the instument teams to do their analyis, such as time that each data point was selected, orientation of the probe (coming from the directly from the accelerometers), altitude (from a look-up table, when radar is not functioning, and from the radar when it is working) etc.

3) This DDB data is for practical analysis reasons: for example, when they measure certain temperatures at some point, they also want to know at what altitude this measurment occured. But they dont really care if this altitude is defined with an accuracy of 10 cm. They just need their approximate location: to say HASI measured this between 20-60 km and ACP acquired atmoshpere samples at altitude of 20 and 100 km. If the actual number is 18.78 km and 101.25 km it doesn't matter, because sizes of structures in an atmosphere are in the scale of tens of kilometers and not meters. That is why there is an altitude table there. To support fast experiment analysis and data interpetation. Not for altitude reconstruction.

4) The experiment teams are going to use more accurate altitude data as the descent reconstruction progresses, if it is really needed. The descent reconstruction will mainly use accelerometer and radar data for recreating an accurate descent profile, plus it will also use doppler. temperature, pressure, imaging data to improve if possible the accelerometer data (edit: or derive "descent profiles" of different scientific importance).

5) Until the descent reconstruction progresses a lot to give supportive results to the experiment teams, what they have to say to them is whether the data indicates that the precomputed altitude table is actually sufficient for initial data interpetations. If it is off by 20-30 or more km, then they will say: "don't use the altitude table, wait for some reconstruction from the accelrometers". If the altitude table is off by 3-4 km, then it is no problem for reasons that I explained.

So, that's all with the altitude table. It was proven that it is sufficient, since, as I posted before, the descent profile from the accelerometers and radar matches the expected one.

I like how every new bandaid he tries to put on works against him!

And don't yell BB bandaid Jerr, those ones actually help the theory. Those would actually be called something like "revisions based on evidence."

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Feynman
>~~~~<
Science is a way of trying not to fool yourself. The first principle is that you must not fool yourself, and you are the easiest person to fool.

Religion is a culture of faith; science is a culture of doubt.

A gravity meter is a type accelerometer: One designed specifically to measure the minute difference in the acceleration caused by changes in the densities and vectors of gravimetric forces.

Good descriptive, but this part is not quite correct. My head is not a flag pole. The muscles in my neck and back are constantly performing work to hold it up – I both sense and act against gravity continuously – no matter whose physics we are describing.

Shifting gears into Jerry’s physics, this is an important concept, and it is helpful in explaining why a moon or planet further from the sun appears to be less massive than it really is. I am hypothesizing that in the space near matter, there is an extended standing wave of energy proportional to the mass, that must be negotiated while moving through space - this "up and down" movement consumes only trivial ammouts of energy, but slows progress, just like driving through rolling hills, as opposed to speeding across the salt flats.

Near the Earth, which is close to the massive sun, the amplitude of this wave function is very strong, so a satellite in orbit about the earth moves more slowly than the same satellite would if it had the same amount of kinetic energy and was in motion around Mars, Jupiter, or Saturn – this slower movement near the Earth is somewhat analogous to a slower response to the effect of gravity on my head when I'm tired. The further from the sun, the shorter the effective path through space, because the standing wave field slowly diminishes in magnitude (as a 1/r function).

If I didn't know I was tired, I could assume the force of gravity is stronger. Since we do not account for the smaller wave nodes with increasing distance from the sun, we underestimate the masses of the more distant planets. (And over estimate the masses of Mercury and Venus.)

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jwj

It's a big universe out there...is it really unwinding, really burning out?

I am arguing that the entire descent only took twenty minutes, more than fifteen of which were with the shield on, and only the HASI devices taking data. Then, when Huygens was less than 100 meters from the ground, the shield was popped off more-or-less on schedule. One large panaramic series of photographs was planned ~30 seconds after the heat shield was released, while the Large parachute was still deployed. Most of the arial images we have were taken during this minute.

This is in conflict with Elias's statement that the radar altimeter data is 'in agreement with' the time-at-altitude tables. I have no way to reconciliate his statement with my interpretation, other than that the 1st radar lock was ambiguous, meaning the probe ASSUMED the Doppler image from the radar was more than 540 degrees out-of-phase, when it was barely over 180 degrees out-of-phase.

The radar pattern I had extracted from the ESA audio agrees with this interpretation. It shows a sudden drop in altitude that is over two orders of magnitude in less than two seconds. This is consistent with the software suddenly determining the lock was not ambigous, and adjusting the altitude accordingly. So until the ESA releases the complete radar data package, this remains an ambiguous puzzle.

You would have to know both the latitude an longitude at which Huygens landed. I don't have this data. Remember also that Cassini may be in a slightly different place as well - accelerating and decelerating a little more than anticipated using Newtonian physics near the planet, and causing the roll stabilizing wheel to have a hickey fit.

[quote]In this case, there was a slightly negative velocity as well - With the 8 meter parachute deployed, and Huygens only meters above the surface, the descent rate was extremely slow - the probe was virtually hoovering just before it released the heat shield. When the heat shield was released 12 seconds into the audio radar, the probe elevated slightly.

The slight increases in velocity were at 12 and 24 seconds - these are not on the velocity plot, that is only from 25 second to the ending. During the first 25 seconds, the radar was only 'pinging' about once ever two seconds, so there was not enough resolution in the data to plot meaningful 1st &amp; 2d derivatives.

This is also one of the reason for concluding Huygens thought the probe was at a much higher altitude - only sampling the ground at very broad intervals. Twenty-five seconds into the audio radar release, the sampling rate became much greater - and increased each second.

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jwj

It's a big universe out there...is it really unwinding, really burning out?

Ah, a key point. Very good. I trust you can provide a source for the claim that turbulence ended at 60 km, according to Doppler measurements?


And for that part from another post...
If you bring in muscles in connection with gravity and then continue to discuss something energy related (which I won't touch), then your grasp of physics is much worse than I assumed. We all know - should know - that while there is a certain amount of physical work required for something mechanical, muscles run at variable efficiencies depending on the kind of work.

In the worst case down to zero efficiency. That's what makes them useless in any kind of analogy regarding physics and energy balances.

Here is the approximate longitude and latitude of where Huygens landed.
(latitude 10.6 S, longitude 191 W

The latitude and longitude information was retrieved from this web site

I'm sure you can find the rest of the data you need.

Have at it

You are taking for granted that the graph that you produced from the sound files is correct. It is not, and it doesn't look anything like the real altitude data coming from the radar.

You don't have it because you didn't search for it. Like a lot of other things that you wait for someone to "release".

Thanks Metricyard for "releasing" the information to the public. :wink:
Say, how do you managed to break into NASA's mainframe computer where they store top secret information like this one? 8)


That means a medium velocity above 1km/s during the descent, more than 10 times faster than predicted (and measured) velocity. Do you think that such a difference wouldn't be visible in Doppler shift?

Someone has already pointed (Elias ?) that the radar doesn't work at low altitudes (few hundred meters). So you cannot make any reconstruction below 100 meters. And the radar will not be able to lock at 100 meters, so a positive lock means a higher altitude.

ESA's audio contains 2 hours data compressed into a 2 minutes stream.
Those 12 and 24 seconds that you mention are not real time.
Although I think the PR releases (like photos and sounds) are a good and desirable thing it seems that some people (Jerry included) are unable to make the difference between non-scientific data (presented in order to give the uninformed and unscientific public a basic idea about what's up out there) and what is published in scientific papers.


Actually only HASI devices inside Huygens; the rest of HASI has been deployed after heatshield ejection. That's leave us with no data, except accelerometers.


Actually what is your descent profile for Huygens? Maximum velocity? Maximum deceleration? At which altitude? At what moment?

Can you state with a certainty that these accelerometers had a time stamping capacity that was independent of the time that they were polled? Can you state that the time of landing was based upon the this time stamp?

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jwj

It's a big universe out there...is it really unwinding, really burning out?

This is a very important point, and it explains why Huygens - and the ESA would have assumed Huygens was still falling long after the probe reached the surface: Which accelerometers detect gravimetric acceleration, and which detect wind acceleration, depend upon the tilt angle of the probe. Since the ESA is assuming the G force is well known, if it is greater than expected, this additional gravimetric force, will be interpreted as wind acceleration.

The signature attribute of this 'faux wind acceleration' is that the wind velocity would have to appear to decrease very constantly from the time the small parachute deployed, until Huygens' time-out sequence told it it was time to start polling the penetrometers. This is consistent with the Doppler Wind Teams characterization of the wind profile below 60 km.

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jwj

It's a big universe out there...is it really unwinding, really burning out?

Except all evidence shows that the descent, from entry detection to landing, took 2hrs 27min. No one is claiming 20 minutes except you.

More or less on schedule? The transition from the entry phase to the descent phase was predicated on the CASU detecting the desired acceleration. This acceleration comes from the aerodynamic drag on the probe as it plunges through the atmosphere and slows the probe down.

Your intepretation makes the atmosphere much less dense than expected. What evidence do you have of this?

Let's examine this a little further. The heat shield is timed to be released about 30 seconds after main chute deployment. The probe is still traveling at about 0.6 Mach. So according to you, the probe is only 100 meters above the surface travelling at 0.6 Mach. How did the probe not slam into the surface and disintegrate?

You're going to have to invoke some powerful mojo to explain this.

Based on your above scenario, the probe would not have had time to do anything but crash.

No way to reconcile? It seems quite obvious that your interpretation doesn't bear any resemblence to what actually happened.

Making stuff up again? Do you have any evidence that radar lock was ambiguous or out-of-phase? This doesn't help your case in any event. Entry detection and parachute deployment was based on the CASU, not the RAU's. If the heat shield didn't come off until a 100 meters above the surface, then how did we get any radar data at all? The RAU's weren't turned on until about 32 minutes after main parachute deployment.

Why should we trust your interpretation? The ESA audio was a compressed version of the entire descent. It wasn't realtime.


Please give details on how you did your "analysis" so that we can replicate it. What assumptions did you make? What techniques did you use?

This makes no sense. The audio we heard was simply the return signals from the ground. There is nothing in this audio to infer anything about the software determining or adjusting anything. You're extrapolating beyond the data.

No the probe would not have been hovering. We've already seen that according to your scenario the probe would be travelling very fast. Your whole scenario is bunk since you continue to base the timing of events on a table. It has been explained to you multiple times that this is not the case. Re-read the lastest post from Elias.

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"A mystic is a person who is puzzled before the obvious but who understands the nonexistent." -- Elbert Hubbard

You're being obtuse. You can infer it from basic design rules. A timestamp is useless unless it can be correlated with the event. If I send someone out in the field to record an event and I later ask them when that event occurred and they give me the current time, it is useless. For events that need to be timed, you need to record the time when the event occurs. This can't be that hard to understand.

Your timestamp obfuscation is just another diversionary tactic trying to move focus off the fact that your "theory" is bunk.

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"A mystic is a person who is puzzled before the obvious but who understands the nonexistent." -- Elbert Hubbard

I missed this post, and this is an important point. I think you are right, that jitter would not likely be related to gravity. If it is related to anything other than a normal failure mode, it would more likely be a violation of Newton's weak equivalence principle (which assumes the ratio of inertial energy to mass is constant) rather than Einsteins strong equivalence principle.

The weak equivalence principle is strongly constrained in the earth-moon environment, although this limit is lifted somewhat if the speed of light varies in the same magnitude and proportion as the 'path through space'. At Saturn's distance from the sun, there is no overwelming effect of the sun's standing wave, and the gravimetric gradiant between Saturn and her moons may measurable effect the weak equivalence principle.

I think you can see why it is very difficult to apply firm constraints on a new cosmology - when you start by throwing out the whole rulebook.

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jwj

It's a big universe out there...is it really unwinding, really burning out?