Jerry wrote:

Hmmm... I did read it all, including the second half of the last para:

Sounds like a sensible precaution to me while they sort out the data and get to the bottom of the mystery. I dont see any panic or, "Gosh we have a problem, let's ask Jerry what the answer is" It's just another in-flight issue to resolve and even then the higher flyby isn't mission critical.

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That a thermal blanket could survive entry is not predicted by any theory. Your "theory" makes it even worse for the thermal blanket. A thinner upper atmosphere means less slowing and greater speed when it hits the much thicker lower atmosphere. Hitting the thicker atmosphere at hight speeds mean more heat and aerodynamic forces not less. You still need to dump the 5700m/s of kinetic energy in order for the parachute sequence to initiate. You've yet to explain how you "gently" do this.

Please show some numbers on how thin this atmosphere was and how it could so gently slow Huygens down so that a flimsy MLI blanket could survive.

Nice word salad, but it doesn't answer the question. We don't need "decades of experiments" to know what happens to heat shields during entry. We've already done that. The point about Mars was that it has a much less dense atmosphere than Titan and yet produced about 1500 degrees C when the MER probes entered.

BTW, no one mentioned the speed of light in this scenario. Stop throwing in extraneous bits of data. It doesn't help your credibility.

No one said it was an explanation, they said that's where they were going to investigate next. They had already ruled out that the vanes were installed improperly. This was the next step in their investigation.

Page 15 of what? You may be thinking of the 10 - 20 degree swing under the parachute.

Are you saying that this was in the earlier recording but has now been taken out? Conspiracy again!

It is bizarre that anyone could hold such a plethora of mutually contradictory ideas.

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

Hamlet wrote:

Actually I think bazaar was the right word to use. You know, a place where you can pick up any old junk that's passed off as real 8)

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Naturally, march out the usual suspects. Never even suspect one of the Gods: Newton, Einstein, or Bogurt.

There is a two-ton Gorilla on Titan, and his name is Gravity. He is screwing with the optical density and scattering, cranking up the temperature of the probe, bouncing the Reynolds numbers, unscrewing the rotation, tilting Huygens on its end, mooning the cameras, and as I intimated before, causing orbital eccentricity of Cassini when it gets too close to Titan.

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jwj

It's ok not to know.

Cassini is in orbit about Saturn, not Titan. If you look at the ratio of the mass of Saturn to the mass of Titan, the effect of Titan on Cassini's orbit is trivial unless the the probe passes very close to Titan. Then the numbers rise dramatically:

So they have a bug counter counting bugs on the windscreen, they even know what kind of bugs, but the vehicle is still slowing down at three times the known bug rate. Bad gas?

What were the thrusters fighting if not gravity? More Dark energy?

Wrong! Everybody and their dog assumes there is no gravity issue, even though the strong equivalence principle has only been tested outside of the Earth - Moon orbit twice, and it failed both tests.

Once again, 99% of the trajectory of Huygens was based upon the path of Huygens relative to Saturn, not Titan. Huygens was not monitored during the closing moments of the descent, at distances in which we now know Cassini experienced an unexpected and as yet unexplained tugging towards Titan. This discrepancy has not been deemed serious enough to dedicate more than one line to in the significant event log, but serious enough to reroute the rest of the mission. This is nuts.

Wanna see a really good demonstration of new physics? Sometime, near the end of Cassini's mission, we should put it on a spiraling free-orbit into one of Saturn's moons, preferably the largest moon without a complicating atmosphere, then watch what happens. We would FINALLY have an extra-Earth orbit demonstration of unexpected gravity forces that could not be written of as bugs on the windscreen, high drag, low drag, updrafts, down drafts, solar wind, gas leaks, late parachute deployment, paint chips...

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jwj

It's ok not to know.

Jerry wrote:

I don't think two tons imperial, two tonnes metric or even two Jerry tuns Titan of anything (including banana chucking gorrilas) would make much difference to the atmosphere of Titan or the Newtonian tragetory of Cassini.

(Though come to think of it, a tribe of banana eating gorrilas might provide the answer to where Titan got its methane from. Makes as much sense as any of the other marsh gas we've had)

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By asking questions we sometimes get the wrong answers, from wrong answers we learn to ask the right questions.

Jerry wrote:Banana skins? ...

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By asking questions we sometimes get the wrong answers, from wrong answers we learn to ask the right questions.

[quote="frogesque"]

This is an interesting search. After finding a magnetic field on Europa, researchers concluded that there must be a salt water ocean under the skin of the moon, because Europa is 'too light' to have enough iron as magna to cause the observed magnetic moment.

The last time I went looking for a submerged saltwater ocean was when I was looking for the lost ten tribes of Isreal and Atlantis.

Bettcha Europa is magnetic because it has an Iron, possibly molten core.

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jwj

It's ok not to know.

Why stop at iron? Why not nickle, chrome or any of the other ferromagnetics or rare earth elements?. Sure, there probably is a rudimentary core of magnetic material comprised of meteoric debris. The best theory we have at the moment though is that an electrically conducting sublayer of salt water is reponsible for a dynamo effect that is analogous to the fluid magma beneath the Earth's mantle. Determining the internal stucture of Saturn's moons and defining the changing magnetic field is a part of Cassini's mission. We really don't know for sure at the moment - investigation is part of what most folk recognise as S-C-I-E-N-C-E. Cassini isn't just there for a joyride to take pretty pictures however enthralling they are.

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By asking questions we sometimes get the wrong answers, from wrong answers we learn to ask the right questions.

No, the scientists concluded that there MAY be a salt water ocean. Nowhere in all the articles I searched through on Europa mentions that it is too small for an iron core. Their observations of the changing magnetic field shows evidence of water, not that water is causing a magnetic field.

Nice try though.

Here is an article on Europa that even has a diagram that shows a metalic core.

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"The universe is driven by the complex interaction between three ingredients: matter, energy, and enlightened self-interest." - G'Kar

Size matters. So does density. Nobody knows what lies under the surface of Europa, except superman. The only reason it is assumed that the iron core of Europa must be small (if it exists at all), and that a saltwater ocean lies hidden under the skin of Europa, is that the density is predicted to be too low to support as massive core of iron and yes, nickle, relative to the size of the moon. A compositional profile similar to the Earth would yield a density that is too great. And yet Europa has a magnetic field. So like a James Bond movie, a hidden lake lies just underneath each crater.

Notice how much the Ice fields of Europa, in your reference, resemble the Ice fields on the poles of the Earth, and the ice fields covering Enceladus? Why is are the -water-ice rocks of Titan so different? Could it be that they are rocks, not ice-water rocks? Rocks too dense to reside on a moon with a density of less then two, so they must be made out of water-ice? Bad logic. Bad conclusion - it is not supported by the evidence. Bad Astronomy.

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jwj

It's ok not to know.

Thanks for the link Metricyard, it explains it all a lot better than I could and clears up some of my own misconceptions. What they are researching is the secondary magnetic field on Europa and the tidal effects on the proposed circulating subsurface salt water layer caused by the primary magnetic source on Jupiter.

Not wanting to hijack this thread - since it's so tightly constrained to the threat to Huygens - but is there any further news on that model for Europa?

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Jerry, I don't want to quote your whole post, but why is Cassini so in trouble by Titan and not in trouble at all by Saturn? Wouldn't the miscalculated effect of gravity be much much greater with regards to Saturn? Why does only Titan have such an effect in your mind?

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Personally I blame it all on this chappy

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By asking questions we sometimes get the wrong answers, from wrong answers we learn to ask the right questions.

Yes, but with some qualifications. Remember the basic idea is that the Strong Equivalance Principle is false: We cannot use Newtonian estimates of gravity to predict the mass of anything outside of a lunar-earth orbit. The difference is small, but by the time we arrive at the orbit of Saturn, the predicted mass, using Newtonian physics, is off by a factor of more than two.

As you know, to the first order, orbits are not a function of the mass of the orbiter, so using Newton's mechanics to plunk Cassini into an orbit does not test this concept. But changing the orbit, moving closer to Saturn, or moving close to one of the moons reveals perturbations that should be interpreted as greater mass in the system, not bugs on the windscreen or the other usual suspects.

Posters on this board have been dogging me for months now, pointing out these perturbations should exist, and all I have been able to do is kind of half heartedly suggest that NASA is not reporting these minor deviations from nominal trajectories. Now look what we find out: The IR mirrors are vibrating, the thrusters are thrusting and these potentially mission compromising events are not even making it into the significant event log.

(Although you can read, about troops of girl scouts visiting the mission control center.)

Could this be one of the reasons NASA is having so many mission failures? Could the servo problem with Cassini's mirrors have something in common with Dart's navigational problem? I don't know. Does anybody?

The weakness in detail in reporting the navigational trials of Cassini demonstrates that NASA still does not get it: Missions fail when everyone puts on a smilely face and pretends everything is according to Hoyle. Chunks of foam and ice were falling off the Shuttle fuel tank on every flight, some of them seriously damaging flight hardware. Did the wingmen even know it? The public? The astronauts?

If a software problem is causing Cassini to panic and fire thrusters, shouldn't the Dart engineers have known that as soon as it happened? If the Descent, entry and landing phase of Spirit and Opportunity produced data streams that can't be modeled, shouldn't ESA and Japanese engineers planning missions to Mars know that? Shouldn't you and I know that?

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jwj

It's ok not to know.

We are not talking about the orbiter's mass. We are talking about Saturn's and Titan's mass. And if we would have miscalculated them by a factor of two, Cassini and Huygens would be anywhere, but not in orbit around Saturn or sitting on Titan's surface. Compared with planetary masses, our spacecrafts masses are neglectible - which saves us a lot of complicated maths.

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"Flying in space is risky business, but just staying on this planet is risky business too." - John Young, astronaut

You and I know that...would someone please tell NASA?

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jwj

It's ok not to know.