Jerry Jensen's ATM idea

[Jerry]

This is baloney. We had mass calculations for Mars way before we ever sent probes. We used these number to do our first flyby.

The Mass of Mars was first estimated from the orbits of the Martian moons, and 'confirmed' by the Ranger fly-bys. I will continue to argue that we have no factual basis for assuming the mass-orbit relationship of Mars and Mars' moons is precisely indentical to the Earth-moon relationship. The same is true of the Jovian and Saturn systems. There is mounting evidence that the moons of Saturn are composed of elements too heavy to meet the the Newtonian predictions of the masses of these moons. This is especially true of Phoebe (there is too much iron on the surface), Titan (sand where there should be water) and Enceladus (too much internal energy).

I've read all of the peer-reviewed Huygens papers and I don't recall a single one that supported these assertions.

Some of it is not, I believe one of the Nature articles mentioned the penetrometer data compared favorably with sand. - they don't tend to put what they do not understand in published journals. These facts are the ones that tend to slip by unnoticed. Many of them are in the various Planetary Society articles and blog entries - I think the bit about finding benzene but not water vapor near the surface was in a 'Huygens one year later press release'. It is easy to see that the albedo and color of Titan is not anything like that of other water-ice coated moons like Enceladus. There has been considerable debate on the structure of the 'cat scratches', the dunes, and whether or not they resemble snow drifts on Unmannedspaceflight.com

I've said my piece and have added the factual information on MRO.

MRO burned longer and used more fuel than expected to achieve the exact orbit desired. Venus Express burned exactly the expected amount of fuel for exactly the expected amount of time, but stayed in occultation 7 seconds longer than expected. 7 seconds means the orbit should be off by about 1%. In both cases, these are almost trivial differences, well within expected margins of errors, but as I have said many times, the orbital calculations should be very close, but not exactly correct - it is the masses of Mars and Venus used in making these calculations that are wrong.

[Hamlet]

MRO burned longer and used more fuel than expected to achieve the exact orbit desired. Venus Express burned exactly the expected amount of fuel for exactly the expected amount of time, but stayed in occultation 7 seconds longer than expected. 7 seconds means the orbit should be off by about 1%. In both cases, these are almost trivial differences, well within expected margins of errors, but as I have said many times, the orbital calculations should be very close, but not exactly correct - it is the masses of Mars and Venus used in making these calculations that are wrong.

???!!! !!!??? No it didn't. Do you even bother to read what people write? The engines on MRO were underperforming. They were delivering less thrust than expected. The additional burn time was needed to compensate for this underperformance.

Where has there been any report that MRO used more fuel than expected? How much more?

This is, at least, the third time it's been brought to your attention and you keep twisting it to mean something else. Quit making stuff up to bolster your pet theory.

[Jerry]

???!!! !!!??? No it didn't. Do you even bother to read what people write? The engines on MRO were underperforming. They were delivering less thrust than expected. The additional burn time was needed to compensate for this underperformance.

The response of the engine, relative to the helium tank pressure at any given temperature and cold soak condition, is well-known and characterized before the flight, and it is not even possible to calculated the expected thrust without knowing all of the relevent temperatures and pressure dynamics.

I know this, because I do this kind of thing: I write the routines that determine the burnrates of various propellants under different conditions of temperature, initial chamber pressure and cold soaking conditions. Likewise, I have calculated the expected Mach numbers of nozzles under varying conditions. These are exact sciences, but the measurements are not: And this is why lower-than-expected temperatures may explain why the expected thrust was not achieved: The sensors do not always paint the full picture.

An impossible culprit would be a greater-than-expected acceleration towards Mars, that would lead to a miscalculation of the braking thrust generated by the motors. But that is what I think is happening, and what must happen if Newtonian physics are do not correctly calculate the effects of gravity outside of the Earth-moon domain.

Where has there been any report that MRO used more fuel than expected? How much more?

A report of 'underperformance' normally implies less specific impulse per gram of propellant, but we all know these press accounts are not always accurate. Suffice to say that with any motor configuration I am aware of, it would take a woefully underpressurized system to allow the motor to burn for another 37 seconds without consuming significantly more fuel. I have looked and ask for better explanations, but I am not aware of any public disclosures. I have more faith in our engineering, than in the theories that constrain the results, and the interpretations of the results.

[Jerry]

The Lorentz transform correctly predicts the results of the Michelson Morley experiment, but it is not the only possible solution. In the classic special relativity case of two trains approaching each other, both trains are moving relative to the center of the mass of the Earth, and also the center of mass of the solar system. If the ‘ether’ Maxwell proposed that electromagnetic waves move through is a function of mass, there is a simpler solution:

Each train moves within in its own weak gravitational field, relative to the ‘fixed’ fields of the Earth and the Sun. Because gravity also moves at the speed of light, this field will be compressed, or Doppler shifted in the direction that the train is moving, relative to the fixed inertial framework of the Earth and Sun. A second train approaching the first train will also have a compressed gravity field. Light will move more slowly through this compressed medium, and the sum of the velocity of light between the two trains will be the speed of light in the Earth/Sun inertial framework. Notice that if the only masses involved were the masses of the trains, the gravitational field would also be compressed, so that the speed of light between the two trains would also be slowed to an absolute maximum. However, in the absence of the gravitational field asserted by other bodies, this maximum would be greater. What is the speed of light in a true vacuum, absent of all matter? I don’t know, but I suspect it is less than 10% faster than the speed of light on Earth (although I have speculated it may be as much as 30% faster. It is not inconceivable though, that it is much faster.)

In any case, this explains how cosmic rays enter our solar system at velocities that are 99+% of the speed of light. Using general relativistic equations, these particles (and gamma rays) should have been slowed in collisions with the cosmic microwave background photons. Increasing the maximum speed of light allows for these collisions without reducing the energy to currently understood limits.

Returning to the heart of the solar system, now I am going to run my trains toward each other on Mercury instead of on Earth. Since Mercury is much closer to the sun, the gravitational field effect from the sun is much greater, and the speed of light is slower. Since the individual atoms of the trains must also negotiate this gravity field, it takes at least 9% more energy for the trains to get up to speed, and the speed of light between the two approaching trains is even slower. The trains have not become more massive as relativity predicts, but the effective path through space has become longer.

The advantage to this interpretation over the special relativist interpretation is obvious: To account for the greater energy needed to move the trains near Mercury, Einstein had to bend the space near massive objects as well as slow down the clocks. Interpreting the same experiment as a change in the path through space, rather than a shift in both the curvature of space and time is a much more simple solution.

Simple is better, but it also predicts another somewhat startling result. Since the trains require more kinetic energy to approach each other at the same velocity when they are closer to the sun, a probe in orbit about Mercury must also have more kinetic energy at a given velocity than the same probe would have in an orbit about the Earth. If we use the orbital acceleration of the probe to determine the mass of Mercury, we well OVER estimate the mass of the planet. We make the same mistake at the orbit of Venus, but at greater distances than the Earth from the sun, using orbital velocities, we under-estimate the masses of all the planets and all of their moons.

Within a few years, Messenger will, hopefully, be in orbit about Mercury. As we approach this planet, the velocity of the probe will slow due to the solar wind, but if gravity behaves the way I am describing, the probe will slow noticeably more than expected, due to the solar wind and general relativistic effects. If there are features on Mercury – mountains – any gravitational maps will show extremely low densities at the peaks of these mountains – as if they are covered with many feet of snow or other very light elements. The valleys of Mercury will appear to be super dense – virtually molten iron.

When New Horizon’s does its Pluto fly-by, it will not be able to make gravity maps, but will see something just as astounding: Like Phoebe, Pluto will have a surface composed of elements much to heavy to account for Pluto’s low density. (The albedo of Pluto (~0.55) is rather low for a moon that must have a surface of condensed water and gases.)

[R.A.F.]

Within a few years, Messenger will, hopefully, be in orbit about Mercury.

...you mean it's not going to crash into Mercury?

[Celestial Mechanic]

Within a few years, Messenger will, hopefully, be in orbit about Mercury.

...you mean it's not going to crash into Mercury?

I wouldn't worry. Mercury doesn't have an atmosphere.

[Jerry]

I wouldn't worry. Mercury doesn't have an atmosphere.

You guys ARE still around!

If you have not read Micheal Griffins comments about Spirit's landing, you should do so:

Remarks by NASA Administrator Michael Griffin at the National Space Symposium

Two things:

1) At the time of Spirits landing, to the best of my knowledge there was no public acknowledgement of any kind that 'Spirit' was in trouble, and in fact, except for a brief mention in 'Opportunitie's' event log that after reviewing the descent of 'Spirit' they had raised the altitude at which 'Opportunities' parachute would be deployed, there was no public announcement of any kind that 'Spirit' had almost crashed.

Now we read, two years later, that planetary scientist saved the day, even though the hypothesis that a 'layered atmosphere' was responsible for Spirit's near demise is just that: another guess. NASA does sit on data they do not want made public, such as the reason behind the DART failure, and especially data that they do not understand. (I have been told - unofficially - that the EDL engineering data from the Spirit and Opportunity missions will never be made public because of ITAR...What in the hell does the landing of a probe on Mars have to do with international arms trafficking? Don't the Martians already know how to land on their own planet?)

2) If I would have predicted Spirit would fall like a rock, I would have been hooted and hollor'ed at after the landing, because just like Huygens' descent, for two years there has been no public admission that the missions almost failed. It has been 15 months since Huygens landing, and we still do not have a completed descent profile - one that includes time stamped radar and/or sonar data. They have not released the results of the VLA triangulation, either. The VLA triangulation is very important, because it should indicate whether the sudden wind direction shift (~110km) necessary to model the "unexpected wind shear" during Huygen's descent into the expected time frame actually occurred. I think the reason the VLA data has not been released, is because they are having an impossible time reconciliating the data within the the possible framework, given the known laws of physics.

[Hamlet]

The response of the engine, relative to the helium tank pressure at any given temperature and cold soak condition, is well-known and characterized before the flight, and it is not even possible to calculated the expected thrust without knowing all of the relevent temperatures and pressure dynamics.

I know this, because I do this kind of thing: I write the routines that determine the burnrates of various propellants under different conditions of temperature, initial chamber pressure and cold soaking conditions. Likewise, I have calculated the expected Mach numbers of nozzles under varying conditions. These are exact sciences, but the measurements are not: And this is why lower-than-expected temperatures may explain why the expected thrust was not achieved: The sensors do not always paint the full picture.

An impossible culprit would be a greater-than-expected acceleration towards Mars, that would lead to a miscalculation of the braking thrust generated by the motors. But that is what I think is happening, and what must happen if Newtonian physics are do not correctly calculate the effects of gravity outside of the Earth-moon domain.


A report of 'underperformance' normally implies less specific impulse per gram of propellant, but we all know these press accounts are not always accurate. Suffice to say that with any motor configuration I am aware of, it would take a woefully underpressurized system to allow the motor to burn for another 37 seconds without consuming significantly more fuel. I have looked and ask for better explanations, but I am not aware of any public disclosures. I have more faith in our engineering, than in the theories that constrain the results, and the interpretations of the results.

This is just more bloviation that distracts from the core issue. The lower helium tank temperature was a measured value in the telemetry stream. The lower tank pressure was a measured value in the telemetry stream that was also indicated by controllers before the burn. The lower pressure feed slightly reduced the perfomance of the motors. The FSW compensated for this by buring the motors a little longer to reach the programed delta-V target. This was also reported in the telemetry stream and was noted in the post-MOI press conference. You say you have faith in the engineering but continue to ignore what the engineers say.

That you keep trumpeting this as some type of validation of your "theory" is beyond the pale.

[Tassel]

1) At the time of Spirits landing, to the best of my knowledge there was no public acknowledgement of any kind that 'Spirit' was in trouble, and in fact, except for a brief mention in 'Opportunitie's' event log that after reviewing the descent of 'Spirit' they had raised the altitude at which 'Opportunities' parachute would be deployed, there was no public announcement of any kind that 'Spirit' had almost crashed.

Now we read, two years later, that planetary scientist saved the day, even though the hypothesis that a 'layered atmosphere' was responsible for Spirit's near demise is just that: another guess.

And two years ago, within 48 hours of the first Mars Exploration Rover's landing on Mars, we learned that atmospheric conditions were not as calculated. Based on their knowledge of the layering of Earth's atmosphere, NASA Earth scientists provided the information needed to adjust the landing sequence for the second rover.

Did I miss something in the article you linked or are you seriously saying that you interpret the above comments by Michael Griffin as saying "'Spirit' was in trouble" and "almost crashed"?

[Metricyard]

Did I miss something in the article you linked or are you seriously saying that you interpret the above comments by Michael Griffin as saying "'Spirit' was in trouble" and "almost crashed"?

I'm wondering that myself. I've read the article and even did a search for spirit and didn't find any reference of spirit in the article. Am I missing something here? Very confused.

[Tensor]

Did I miss something in the article you linked or are you seriously saying that you interpret the above comments by Michael Griffin as saying "'Spirit' was in trouble" and "almost crashed"?

I'm wondering that myself. I've read the article and even did a search for spirit and didn't find any reference of spirit in the article. Am I missing something here? Very confused.

Well, Jerry has done this type of thing before. The funniest, I thought, was when he referenced a paper that refuted what he was claiming.

[Jerry]

Have you ever read anything that said Spirit was in trouble before? Anything on NASA's website, or in the declarations of success afterward, where anyone said "we almost lost Spirit?".

That is my point. Why wasn't a near miss reported to the public? Let me give you a hypothetical: A group of engineers is lobbying congress for an increase in funding to provide for better instrumentation in the next Mars landing. The congressman is sitting there wondering why we even need to send another robotic mission - he isn't even aware there is a problem.

Spirit and Opportunity landed with a total vector force of about twice the expected velocity and close to the design limit. In both cases, differential rockets were fired that were supposed to null out the lateral motion, but in both landings, to account for all the landing force, the lateral velocity is calculated as being equal to the vertical velocity.

So how did studying the descent of Spirit protect Opportunity, if they landed at the same velocity? Obviously, the parachute deployed higher, so terminal velocity should have been reached sooner and it probably was. But if we almost lost Spirit, we almost lost Opportunity, as well. We should learn more from near misses than from successes and failures. I shouldn't have to scavage for facts that should be general public knowledge. Griffin knew 'We almost lost Spirit.' Did you?

I didn't.

[Tassel]

Have you ever read anything that said Spirit was in trouble before? Anything on NASA's website, or in the declarations of success afterward, where anyone said "we almost lost Spirit?".

Actually, no. And, even after reading your linked article...I still haven't read anything like that. Where are you getting this "we almost lost Spirit" stuff from?

[Jerry]

http://www.unmannedspaceflight.com/i...pic=1172&st=30

The highest-priority goals achievable by an orbiter include measuring both high-altitude air-density fluctuations at 30-50 km, and lower-altitude winds and turbulence. This, to repeat, is extremely urgent for the immediate future -- both of these phenomena came close to wrecking MER-A (Spirit), and larger and more expensive landers will be even more susceptible to the first one. We badly need to be able to monitor and predict them as much as possible. A somewhat lower-priority but still important goal for an orbiter is monitoring dust storms.

Bruce is on committees that study and recommend objectives for future space missions, and he has made a number of statements like this lately. Either the atmosphere of Mars is layered, volatile and turbulent, or there are unknown physics involved, accelerating and buffetting these probes more than anyone realizes. I am still trying to learn how long the EDL's of the MERs lasted, compared to the projected landing times. I think they both landed much sooner, but I am still looking for data.

[Jerry]

http://www.unmannedspaceflight.com/i...showtopic=2522

While I was scooting around on the Web the other night trying to find something else, I also ran across a brief reference somewhere to the fact that MER-A would unquestionably have crashed due to the low upper air density, had it not been for the fact that (for some as-yet unknown reason) its parachute's braking ability also proved higher than expected! I'll see if I can track down that note again. Clearly we cannot go on just trusting to good luck where Mars landers are concerned...

I've found it -- and it was a lot more than a brief reference. It was, in fact, the "MER Flight Operations Technical Consultation" ( http://nesc.larc.nasa.gov/admin/docu...tion_Paper.pdf ), and the relevant material on the problems during MER-A's landing are spread over pg. 8-9, 25-34, and 40-43. Quoting the summary of the two main problems on pg. 8:

"1. The reconstruction of the atmospheric density profile was based on accelerometer measurements and the assumption that the aerodynamic characteristics of the aeroshell were nominal. The reconstructed density was lower prior to parachute deployment and higher after parachute deployment than had been predicted on the basis of the atmospheric model used.

These are EXACTLY the conditions that MUST exist if Mars is heavier than orbital mechanics predict: The gradient of the atmosphere must be such that it is thicker near the surface, and thinner in the upper atmosphere.

Apparently, as a consequence of the initial low-density encounter, parachute deployment time, triggered at a specified dynamic pressure of 725 Pa, was later in time and at a lower altitude (approximately 2-sigma) than expected. Although this reduced the time margins to complete descent and landing to a low level, as measured by the parachute deployment altitude, margin was regained because the parachute descended more slowly than expected. The cause of this fortuitous 'over-performance' of the parachute was not understood.

The drag coefficient of the parachute is a known constant, and yet this is the forth landing mission where NASA has concluded they do not understand it.

Had relatively simple pressure and temperature sensors been included on the spacecraft for use during terminal descent and after landing, the physical situation actually encountered in situ during Spirit’s EDL would have been much clearer to the reconstruction team. The relative contributions of errors in the density profile model versus possible errors in drag coefficient could have been accurately assessed. As it was, the reconstruction team had to rely on assumptions and inferences in attempting to diagnose significant deviations from expected performance that had the potential for serious consequences for mission success.

The verbage here, is almost identical to what the Huygens reconstruction team wrote when they tried to complete a model without the results of the Doppler Wind Experiment - they had to make some very odd-ball assumptions about shear winds and layered inversions. Since none of these mission have constrained all of the necessary parameters, it is impossible to prove or disprove whether or not exceptional physics are required.

[Hamlet]

Actually, no. And, even after reading your linked article...I still haven't read anything like that. Where are you getting this "we almost lost Spirit" stuff from?

This is typical Jerry hyperbole. Prior to Spirit's EDL, there was an observed dust storm on Mars. Based on this, they recomputed the density profile for Mars and adjusted the dynamic pressure for triggering parachute deployment. The relevant information can be found here. Here is a quote that is pertinent to the matter at hand:

Note, due to an observed dust storm on Mars just weeks prior to arrival, the targeted parachute deployment dynamic pressure was increased from the 700 N/m2 to 725 N/m2 for the “Spirit” entry and to 750 N/m2 for the “Opportunity” entry to raise the deployment altitude. This modification was made to hedge against the possibility of encountering a lower density profile than predicted which would reduce the parachute deployment altitude, and thus, the descent timeline from parachute deployment to RAD firing.

If you look at Table 3 and 4 of the above document you can see the reconstructed data mapped against the predicted values. Parachute deployment time for Spirt was near the upper end of the predicted range and attitude was outside the predicted range. The bridle cut was lower than expected but within the 6DOF predicted range.

Opportunity's EDL was similar but its parachute trigger was just outside the predicted range and the bridle cut was even lower than Spirit. This quote from later in the paper sums up the data:

As seen, almost all the reconstructed parameters are well within the pre-entry predicted 3-σ variations. However, there are a few parameters that are near or slightly exceed the 3-σ variation bounds (e. g., time of and αT at parachute deployment). For both the “Spirit” and “Opportunity” entries, the time of parachute deployment was later than predicted because a lower density atmosphere was experienced. Based on preliminary atmosphere reconstruction estimates, approximately an 8% lower density profile (correlating to roughly a 1-σ low profile) was encountered in the maximum deceleration region during the “Spirit” descent, while approximately a 12% lower density profile was encountered during the “Opportunity” descent. This greater reduction in the density profile for “Opportunity” (as compared to “Spirit”) is consistent with the observed later time of parachute deployment.

There is nothing in this paper that leads me to believe either Spirit or Opportunity "almost crashed". There were some surprises, but the built in margins, based on the EDL simulations, were able to handle them.

A subsequent report on the MER EDL team had some recommendations for future missions. In particular they recommended the following:

Include pressure and temperature sensors on the spacecraft for use during terminal descent and after landing. This information is necessary to be able to differentiate between atmospheric density and drag coefficient effects.

Seems eminently sensible. The lack of these sensors hampered the EDL team in adjusting Opportunity's EDL based on Spirit's experience. Having this information would also be useful data for planning future missions.

[Jerry]

http://sirius.bu.edu/withers/pppp/or...esentation.ppt

Example: Lessons from MER Landing

...steadily increasing oscillations of both Spirit and Opportunity nearly exceeded safe range (could get tangled in the parachute)

*Oscillations due to either unexpected atomospheric turbulence (some unknown aerodynamic instability) or mechanical instability of vehicle in fluid

*The atomospheric state is not well quantified, with both models and NRT calculations yielding weather predictions with large intrinsic errors...

*There are still large unexpected turbulent layers, and unexpected effects from large atmospheric dust storms.

Nearly exceeding safety margins means nearly crashing, or as they stated in the summary "MER had serious difficults because of errors in current prediction techniques".

This is an interesting document, because they are trying to assess all of the possible dangers involved in a human excursion to Mars. It is clear from this document, the EDLs of the MERs have left a big question marks. Nowhere in this document do they ever even consider the possibility that Newtonian dynamics are not applicable, or rather, that the fundamental rules are different as we explore further away from the Earth.

As Hamlet noted, the MERs were not equipped with enough sensors to differentiate between drag and density effects. As everyone has pointed out, it is impossible to claim new physics are needed unless and until atmospheric effects are well understood. That is why the Bouguer anomalies - the fact that the mountain peaks on Mars appear to be extremely heavy, and the chasms extremely light, while on Venus, an exactly opposite trend has been observed, is my strongest evidence that our Newtonian physics are completely out of wack.

And i will keep ringing the bell.

[Jerry]

http://sci.esa.int/science-e/www/obj...objectid=39112
Venus Express Orbital Insertion

The first orbit determination has confirmed excellent performance of the main engine and the following deviations from nominal parameters:

Period: +3.5 hours (~1.6%)
Inclination error: 0.04°
The impact of these deviations is almost negligible.

MRO fired thrusters ~1.5% longer that expected to acheive the expected orbit, while the Venus Express fired thrusters for exactly the expected amount of time and thrust and overshot the orbital period by 1.6%. A little less braking energy would have put the orbit spot on: A little more braking thrust than predicted to insert a probe into orbit on Mars, a little less braking thrust than predicted to orbit Venus. I can live with that.

[Hamlet]

http://sci.esa.int/science-e/www/obj...objectid=39112
Venus Express Orbital Insertion

MRO fired thrusters ~1.5% longer that expected to acheive the expected orbit,

Where is this number from? The actual burn time was a little over 2% longer than planned. The reason for this has been made clear before and yet you ignore it. MRO was monitored via telemetry and Doppler for the entire insertion, except for the time it was behind Mars. The inbound Doppler did not show an increase in velocity due to a more massive Mars. The telemetry showed measured values for the lower helium tank temperature and the resultant reduction in pressure to the thrusters.

while the Venus Express fired thrusters for exactly the expected amount of time and thrust and overshot the orbital period by 1.6%. A little less braking energy would have put the orbit spot on: A little more braking thrust than predicted to insert a probe into orbit on Mars, a little less braking thrust than predicted to orbit Venus.

Why are you trying to compare percentages of burn time to orbital period? This doesn't make any sense.

I can live with that.

It easy to live with numbers when they don't have to conform to reality.

[Jerry]

Where is this number from? The actual burn time was a little over 2% longer than planned. The reason for this has been made clear before and yet you ignore it. MRO was monitored via telemetry and Doppler for the entire insertion, except for the time it was behind Mars. The inbound Doppler did not show an increase in velocity due to a more massive Mars. The telemetry showed measured values for the lower helium tank temperature and the resultant reduction in pressure to the thrusters.

...and I have been trying to tell you for a half dozen posts I have the specs for helium pressurized motors sitting in my hot little hands, and that it would take a much more significant drop in pressure of the replacement helium due to temperature changes than was indicated to change the volume of gas burned by 2%. These are not the specs for MRO, but we have been using similiar systems for forty years and it is extremely unlikely that the specs on MRO are tighter than what I am looking at. Lower temperatures cannot explain why it took more energy than expected to place MRO in the expected orbit. Perhaps in another two years, NASA will admit that.

You say it is perfectly nominal for NASA to explain why Spirit almost crashed in terms of a funky atmosphere at the end of a dust storm - OK - why is it perfectly normal to withhold this information at the time of the landing - Why, when i mention this two years later, doesn't anyone know about it?

Spirit and Opportunity both entered the atmosphere at steeper attitudes than predicted, and landed more than 10km down range - that is close to three sigma off of expectations. The reality is, they came in 'hotter' than expected - and it is pretty hard to blame the attitude on the atmosphere. (Viking I&II and Pathfinder also had steeper attitudes than expected.)

Likewise, MRO would have gone into a hotter orbit, if more braking force than expected to been needed had not been applied.

Why are you trying to compare percentages of burn time to orbital period? This doesn't make any sense.

Of course it does. The orbit is a function of velocity, acceleration, and the acceleration of gravity. If the acceleration due to gravity near Mars is greater, orbiters and landers are going to come in hotter than expected - and every one has.

On Venus, if the native gravity is slightly less than expected, an orbital insertion burn will lead to a slight overshot and the slower orbit, and that is what happened on Venus Express - The acceleration due to Venus was overestimated, and the probe ended up in a slighly higher orbit - 1.5%.

It easy to live with numbers when they don't have to conform to reality.

The reality is, none of the numbers returning from Cassini are making a great deal of sense. Titan's albeto is too low, Enceladus' too high. Nobody can explain where the energy is coming from to lauch water from the surface of Enceladus, and Cassini experiences an unexpected wobble every time it gets close to Titan.

We have no justification for the assumption that beyond the Earth-Moon orbit Sir Isaac Newton is still in the driver's seat. His formula cannot explain the orbit of Mercury, nor the orbits of stars in galaxies. Close to us - Our missions to Venus and Mars have told us the same thing if we look at the data closely and carefully. This July, Cassini is scheduled to pass within 950km of Titan. Cassini will experience an unexpected jerk towards the planet that may send it into safe mode and should trigger a corrective, automated firing, just like one of the Voyagers (I?) did when it passed too close to Saturn. In any case, the anomally already observed at higher altitudes will be much more pronounced. Watch and See.

[Hamlet]

...and I have been trying to tell you for a half dozen posts I have the specs for helium pressurized motors sitting in my hot little hands, and that it would take a much more significant drop in pressure of the replacement helium due to temperature changes than was indicated to change the volume of gas burned by 2%.

Why don't you post the specs then? For now, I'll take the word of the people who actually flew the mission, who called out these measurements, reported from telemetry. in realtime during MOI.

As usual you make vague assertions like "much more significant drop in pressure" without any number or calculations to back it up.

Why should I believe your handwaving over the real data from the people who actually know what they're talking about?

These are not the specs for MRO, but we have been using similiar systems for forty years and it is extremely unlikely that the specs on MRO are tighter than what I am looking at. Lower temperatures cannot explain why it took more energy than expected to place MRO in the expected orbit.

It didn't take more energy than expected. The engines were underperfoming. How many times are you going to ignore this. This "more energy" red herring is your own invention and is not supported by the facts.

Perhaps in another two years, NASA will admit that.

Classic. Raise the conspiracy and incompetancy bogeyman. There's nothing to admit. The measurements and explanation are in the public record already. You don't wish to acknowledge them because the don't support your pet ideas.

You say it is perfectly nominal for NASA to explain why Spirit almost crashed in terms of a funky atmosphere at the end of a dust storm

You description of MER landings is hyperbole and is not supported by the reconstruction data. The truth is the missions succeeded because new observations of the Martian atmosphere indicated a change to the EDL parameters. The reconstruction of Spirits EDL told the team they should make additional changes to Opportunity's parameter.

If the MER EDL team had not been vigilent in monitoring conditions, the MER's would have been in trouble.

- OK - why is it perfectly normal to withhold this information at the time of the landing - Why, when i mention this two years later, doesn't anyone know about it?

This is totally bogus! No one withheld any information. The MER EDL reconstruction paper was published in 2004 about 8 months after the landings. Any one interested could find it.

You also have a short memory. This has all been discussed before in other threads. That you try to pretend this hasn't been discussed before is disingenuous.

Likewise, MRO would have gone into a hotter orbit, if more braking force than expected to been needed had not been applied.

Quit making stuff up! This is not what happened as has been pointed out to you ad nauseum.

Of course it does.

No it doesn't. You're trying to compare a percentage of one quantity (burn time) with the percentage of another totally different quantity (orbital period). That the two values are similar is coincidence. The comparision is meaningless. You still haven't explained why you used the 1.5% figure when the actual data for the burn time is available and can easily be calculated.

[Metricyard]

Snip..and Cassini experiences an unexpected wobble every time it gets close to Titan.

Cassini has made 12 passes of Titan, I haven't read anything about any 'unexpected wobbles'. Care to site some of this info for us please?

We have no justification for the assumption that beyond the Earth-Moon orbit Sir Isaac Newton is still in the driver's seat.

I don't know, Newton seems to have worked pretty well for the last 300+ years.

His formula cannot explain the orbit of Mercury, nor the orbits of stars in galaxies.

Hmm, maybe a quick read on Einsteins General relativity theory is in order?
Oh, that's right, Einsteins theories are wrong too.

[Tassel]

Spirit and Opportunity both entered the atmosphere at steeper attitudes than predicted, and landed more than 10km down range - that is close to three sigma off of expectations.

And this claim is just a joke. Here's a map of that show's Spirit's landing ellipse: Spirit's Landing Ellipse

It's plain to see that Spirit was well inside the ellipse and much closer to the center of the ellipse than to any edge. There's no other way to interpret this other than to say Spirit's landing was right on the money.

[Jerry]

Cassini has made 12 passes of Titan, I haven't read anything about any 'unexpected wobbles'. Care to site some of this info for us please?

It is mentioned briefly in the event logs:
http://saturn1.jpl.nasa.gov/news/sig...cfm?newsID=587
http://saturn1.jpl.nasa.gov/news/sig...cfm?newsID=588
What is not mentioned in the event logs, is that the INMS recorded an atmospheric thickness that is a factor of three less than what would be necessary to cause this motion toward Titan, and these differences remains unreconciled.

I don't know, Newton seems to have worked pretty well for the last 300+ years.

Newton has never correctly predicted Mercury's orbit, or galactic orbits. Most of the last three hundred years we did not know that. Einstein plugged in some fudge factors that almost agree with Mercury's orbit, but without undetectable dark matter, neither Einstein nor Newton is close. I don't believe in the Easter Bunny or any other dark stuff that consistently avoids all attempts to detect it. One explanation is that neither theory correctly models gravity.

Hmm, maybe a quick read on Einsteins General relativity theory is in order?
Oh, that's right, Einsteins theories are wrong too.

Everyone knows GR and QED cannot be reconciliated. Since GR doesn't correctly predict the orbits of galaxies, it is a reasonable assumption that GR isn't correct.

[Hamlet]

It is mentioned briefly in the event logs:
http://saturn1.jpl.nasa.gov/news/sig...cfm?newsID=587
http://saturn1.jpl.nasa.gov/news/sig...cfm?newsID=588

Where's the mysterious "wobble"? The event logs are clearly talking planning and execution of a low altitude pass over Titan. The concern was that the original projected altitude may cause too much torque on Cassini causing it to lose attitude control and go into safe mode. The relevant information is contained in this quote:

Last week at the Titan Atmosphere Model Working Group (TAMWG) telecon, the key topic of discussion was the appropriate altitude for the upcoming T7 flyby in September. Because of variations in atmospheric density observed to date, there is no consensus model to predict the atmospheric density to be encountered at T7. Use of worst-case density values indicate that the T5 altitude of 1025 km may not be safe for T7 with its far southern hemisphere latitude of closest approach, and might lead to spacecraft loss of attitude control and safing.The closer the spacecraft (S/C) gets to Titan, the greater the atmospheric torque applied to the spacecraft. At some point the atmosphere becomes dense enough that the S/C cannot maintain its orientation while flying through it. Then it executes safing and has to find the sun in order to regain its proper orientation so that it can communicate with Earth again. Safing terminates the executing sequence, so all science observations planned between the safing activity and when the sequence is resumed are lost. By raising the flyby altitude we essentially eliminate any chance of this happening because the atmosphere will be thinner.

Please note the bolded portion. There is no mystery wobble here.

Your second event log makes no mention of "wobble" either. The relevant text is here:

As was mentioned in the report last week, the Program approved raising the T7 flyby altitude from 1025 to 1075 km to avoid the risk of atmosphere-induced torques that could possibly result in spacecraft loss of attitude control and safing. Today the Navigation team released a new reference trajectory 050207 to accommodate these changes.

Again note the bolded portion. These are totally normal responses to uncertainties in the atmospheric models.

What is not mentioned in the event logs, is that the INMS recorded an atmospheric thickness that is a factor of three less than what would be necessary to cause this motion toward Titan, and these differences remains unreconciled.

What motion? The logs are talking about atmospheric affects on Cassini. The no mention of any unusual motion toward Titan.

Newton has never correctly predicted Mercury's orbit, or galactic orbits. Most of the last three hundred years we did not know that. Einstein plugged in some fudge factors that almost agree with Mercury's orbit, but without undetectable dark matter, neither Einstein nor Newton is close. I don't believe in the Easter Bunny or any other dark stuff that consistently avoids all attempts to detect it. One explanation is that neither theory correctly models gravity.

Everyone knows GR and QED cannot be reconciliated. Since GR doesn't correctly predict the orbits of galaxies, it is a reasonable assumption that GR isn't correct.

I'll let others comment on the rest of your screed. I'm laughing too hard to type.

[Jerry]

Why don't you post the specs then?

Sorry, this type of detail is ITAR sensitive, (although it shouldn’t be!).

No it doesn't. You're trying to compare a percentage of one quantity (burn time) with the percentage of another totally different quantity (orbital period). That the two values are similar is coincidence. The comparision is meaningless.

???How can you say this??? - the orbital insertion burn determines the orbital periond.

You still haven't explained why you used the 1.5% figure when the actual data for the burn time is available and can easily be calculated.

Careless mistake: 2% is correct. It is a moot point anyway: We both agree a 2% difference between expected an actual performance is not necessarily significant.

This is totally bogus! No one withheld any information. The MER EDL reconstruction paper was published in 2004 about 8 months after the landings. Any one interested could find it.

The title may say “reconstruction”, but if you look at the tables, almost all of the ‘reconstructed’ values are left blank, and it says at the end of the report the table will be filled in when “what happened during the descent of Spirit and Opportunity is understood.”

I am still trying to find such simple 'reconstructed' values as the exact landing time.

To make a reconstructed Monty Carlos SIMULATION, they assumed that the upper atmosphere is at the thinnest edges of expectations, and they also assumed that the parachute drag coefficient ‘somehow increased at the end of the descent’. Parachutes can’t do that: They don’t have claws that they can reach out and grab more air with. A more realistic assumption would be that the air is thicker near the surface, but that would imply that the acceleration due to gravity is greater. We do not know, because the MER’s were not equipped with density sensors.

The only conspiracy is what amounts to a pathological expectation of the observational results to agree with prior expectations. Did you happen to catch NOVA’s presentation on Cassini, Huygens and Titan last Tuesday? They should footage of photographic NEGATIVES of basaltic lava flows while they were talking about cryogenic volcanism on Titan. What is wrong with that? If they had even bothered to look at Larry Soderblom’s presentation, they would know that Cassini’s sensors have not found anything that looks anything like they were presenting: From the IR and radar images, we know the color is wrong and the emissivity is wrong for water-ice flows. If cryogenic ice flows exist on Titan, we have not seen them. What we have seen is inconsistent with the NOVA presentation: That is the reality of Titan: A surface no one understands.

http://www.usatoday.com/news/science...urprises_x.htm

Where's the mysterious "wobble"? The event logs are clearly talking planning and execution of a low altitude pass over Titan. The concern was that the original projected altitude may cause too much torque on Cassini causing it to lose attitude control and go into safe mode. The relevant information is contained in this quote:

Please note the bolded portion. There is no mystery wobble here.

Sorry, it took me a while to find this:

http://www.planetary.org/news/2005/0..._of_Titan.html

"If you ask the thrusters, 'what’s the density that you see?' you don’t get the same information as you do if you ask INMS," Ray explains. "There's a difference of a factor of two or three. So what’s happening physically with the thrusters is a little bit of a mystery, and can’t be matched with the density of the atmosphere [as measured by INMS]. But the Huygens probe went through and saw the same density as INMS." If the density is as low as INMS and Huygens data agree that it is, Cassini should not have to work so hard to maintain proper orientation during close flybys, and the 950-kilometer altitude should be safe.

So the measured and predicted thickness of the atmosphere at altitude is less than Cassini experienced, or the INMS calibration is off by a factor of 'two or three'...or, the force of gravity is greater than expected.

This is similar to our argument about Mars, but in this case, we know the density, there is actual instrumentation that says the effect cannot be atmospheric, unless the instrument is completely out-of-wack.

You description of MER landings is hyperbole and is not supported by the reconstruction data. The truth is the missions succeeded because new observations of the Martian atmosphere indicated a change to the EDL parameters. The reconstruction of Spirits EDL told the team they should make additional changes to Opportunity's parameter.

If the MER EDL team had not been vigilent in monitoring conditions, the MER's would have been in trouble.

The MERs were in trouble, especially Spirit, and every landing attempt on Mars will continue to be iffy until the all of the variables are well understood, including gravity.

[Demigrog]

???How can you say this??? - the orbital insertion burn determines the orbital periond.

Err, the burn time alone is not enough to determine the orbit; the thrust and mass of the spacecraft obviously come into play. So, it is rather unlikely that there would be a 1:1 correlation between burn time and orbital period, even when expressed as a percentage. So, as Hamlet said, the similarity is purely coincidence.

[Hamlet]

Sorry, this type of detail is ITAR sensitive, (although it shouldn’t be!).

Baloney! I just searched up the specs on the MRO thrusters. Why are yours different?

???How can you say this??? - the orbital insertion burn determines the orbital periond.

Quit trying to recast what you said. Your original comparison was between the burn time of MRO, which you erroneously reported as being 1.5% longer, and the orbital period of Venus Express. Your trying to compare percentages from two separate quantities that aren't related. You were trying to make something up because you thought it suited your idea. It doesn't.

Careless mistake: 2% is correct. It is a moot point anyway: We both agree a 2% difference between expected an actual performance is not necessarily significant.

This is funny. You get called on sloppy math and erroneous comparisons and now the point becomes moot and not necessarily significant. BTW, when did I agree to this stipulation? My contention has been and still is that the MRO MOI burn duration was a result of underperformance in the thrusters as was reported in realtime during MOI and in the post-MOI publications. My objection has been and still is to you trying to twist this to mean something that it clearly doesn't. Since the point is moot, can I take it then that you are withdrawing your claim?

The title may say “reconstruction”, but if you look at the tables, almost all of the ‘reconstructed’ values are left blank, and it says at the end of the report the table will be filled in when “what happened during the descent of Spirit and Opportunity is understood.”

Is this a direct quote? I didn't think so. Here's the actual quote from here:

The reconstruction work is ongoing in order to gain a better understanding of what transpired during the “Spirit” and “Opportunity” landings.

Nice twist of the sentence to change the meaning.

The reconstructed values in the tables are all that is available. It says so right in the document on page 7:

Accelerometer and gyro flight data were recorded during both descents and the parameters that can be reconstructed from this data set are listed.

There were no other sensors on board to measure other values. I've been in contact with one of the authors of the reconstruction paper and he has corroborated the above. They are continuing work on reconstruction, but there aren't any other values forthcoming for those tables.

Sorry, it took me a while to find this:

http://www.planetary.org/news/2005/0..._of_Titan.html

So the links from your last post were just a diversion? Now you've switched to something else.

So the measured and predicted thickness of the atmosphere at altitude is less than Cassini experienced, or the INMS calibration is off by a factor of 'two or three'...or, the force of gravity is greater than expected.

There is nothing in that link about a different force for gravity.

The MERs were in trouble, especially Spirit, and every landing attempt on Mars will continue to be iffy until the all of the variables are well understood, including gravity.

Why do you keep picking on Spirit? Opportunitiy's values were much closer to limits. The MER's survived due to well-engineered limits even though the input to the atmospheric models was imperfect. Vigilant monitoring of the atmosphere allowed the MER team to adjust parameters to the best of their knowledge. Spirit's EDL experience provided input to Opportunity's.

The lessons learned from MER (like including temperature and pressure sensors) will undoubtably be carried forth into future missions.

[Celestial Mechanic]

[Snip!]Einstein plugged in some fudge factors that almost agree with Mercury's orbit, but without undetectable dark matter, neither Einstein nor Newton is close.

There are no "fudge factors" in the original general relativity of Einstein. The cosmological constant came later and it had to be chosen so as not to disturb Solar System mechanics, which was already predicted with fantastic accuracy. Newton is quite close, thank you, and Einstein closer still. What ephemerides have you calculated with your "theory"? I didn't think so.

I don't believe in the Easter Bunny or any other dark stuff that consistently avoids all attempts to detect it. One explanation is that neither theory correctly models gravity.

Once again, show us your ephemerides!!

Everyone knows GR and QED cannot be reconciled. Since GR doesn't correctly predict the orbits of galaxies, it is a reasonable assumption that GR isn't correct.

How does the failure to reconcile at the quantum level affect orbits at the galactic level? Is it even relevant? (I think not.) The conclusion that GR is incorrect is not the only conclusion that can be reached; it is still possible that there is something that we forgot somewhere.

[Jerry]

There are no "fudge factors" in the original general relativity of Einstein. The cosmological constant came later and it had to be chosen so as not to disturb Solar System mechanics, which was already predicted with fantastic accuracy. Newton is quite close, thank you, and Einstein closer still.

Only if you accept the Newtonian densities of the planets and moons as being accurate AND accept the dark matter explanation for where current theories fail so miserably. I don't - that is a philosophical choice - there is no scientific (that is measurable) justification for dark stuff.

What ephemerides have you calculated with your "theory"? I didn't think so. ...Once again, show us your ephemerides!!

I don’t have to: A. Einstein already did it for me. In his 1911 rendition of GR, Einstein proposed a 1/r attenuation of space-time curvature, and whether you call it curvature or path length, the effect on the orbit of a planet is about the same. The difference is in how the energy is distributed: Einstein increases the mass of objects as they are accelerated or enter a stronger gravimetric field, I argue the energy increases the strength of the field and increases the length of the path through it. (Likewise when we accelerate a particle near the Earth, the increasing amounts of energy needed to accelerate the particle are piled up in the Earth’s gravitational field, not in the mass of the particle, although the effect on the particle is the same.)

This does make a big difference when we try to interpret phenomenon near the sun: I have the solar wind literally surfing on the waves of the gravimetric field and accelerating away from the sun, Einstein has no explanation for why the solar wind increases in energy as it moves away from the solar boundary.

The problem Einstein ran into with a 1/r attenuation, is that he could not account for both the procession of Mercury and gravitational lensing with attenuation factor, so he created a relativistic factor that could address both lensing and procession – albeit with wide error bars that have not been resolved. Einstein was curve fitting, adjusting the variables within his theory until they matched reality. There is nothing wrong with this, but it is not true that his predictions predated gravitational lensing observations: The procession in Mercury’s orbit was well-known, and the degree of gravitational lensing was highly suspected from non-photographic observations during eclipses, but not certain, prior to 1919.

So how do I get the right procession of Mercury? I get to use parameter or fudge factor here, but I can see phenomenon that support it: Since I am arguing the gravity field is a chaotic electromagnetic field that is above the Planck cutoff, there are nodal events within this field that transfer gravitational energy into lower energy spectra. When a planet is in an elliptical orbit such as Mercury, the gravimetric field strength increases as the planet swings closer to the Sun. The nodal harmonics increase, and more energy is transferred to the iron core of the planet. This braking energy is akin to aerobraking, it causes the procession of Mercury’s orbit, while at the same time explains why the planetary orbits are so nearly circular: Over time, this ‘electrogravimetric braking’ circularizes all orbits, including the Earth's.

This explains how the planets and moons can have completely different histories: They did not evolve from the same primal planetary gravel, but were captured by the sun independently, and their orbits became naturally circular through this braking process. It also explains why most planets (including the Earth) are known to radiate more energy than they absorb: There is heat being generated in the Earth’s core at it orbits and reacts electromagnetically with the gravitational field even today. It is gravitational energy syphoned from Saturn that heats Enceladus and creates the spectacular water jets, although why this energy is released from near the southern pole is a good mystery.

There was an article in the Universe Today forum, discussion the ‘wake’ behind the earth in the solar wind with no assignable cause. When the Earth disturbs the suns gravitational field, the rebalancing of the energy distribution in the vacuum space is not instantaneous, and this is the reason for the disturbed pattern in the solar wind in the wake of the Earth. Returning to our particle accelerators, we see very similar effects, in the massive triboelectric discharges that plague these facilities.

How does the failure to reconcile at the quantum level affect orbits at the galactic level? Is it even relevant? (I think not.)

I think it is relevant because of the renormalization process. To get around the time constraints imposed by GR, Feinman's 'black box' approach allows paths 'backward through time', and pair production anywhere. Since I have a nodal field everywhere, pair production has an energy source that is a function of the local mass, and therefore much more likely to occur close to large masses.

The conclusion that GR is incorrect is not the only conclusion that can be reached; it is still possible that there is something that we forgot somewhere.

Absolutely. This is just another theory that will only exist until it is proven wrong: It should not be allowed to sprout new parameters every time it fails.