Huygens set for Titan encounter

[kegetys 2]

Mars, Venus, Titan:

rocks, rocks and rocks. Those all might as well be taken from some corner of earth

[denoir 0]

I am very impressed to see this happen! What's even more astounding in my eyes, is that ESA and NASA worked on this together. Collaborations like these, will be needed in the future aswell, if we want to reach further out into space. Very impressive, indeed!

While I'm personally inclined to the international cooperation approach, the question is what is better. The greatest achievements in space exploration were made during the cold war, by the Soviet Union and America - it was competition, not cooperation that got us so far.

While space exploration is certainly a matter that concerns all man kind, the question is if it is better to work together (joining resources) or compete (incentive for further work).

I'm not entirely sure, but I'm leaning towards the cooperative approach. These things are so bloody expensive, that it's very difficult for any single country to finance large scale operations. Even for the largest economies in the world, it is a bigass cost to carry and unfortunately space exploration is a popular budget cut. Through international cooperation, that cost can be reduced per country, not making it such an economic burden.

Quote[/b] ]rocks, rocks and rocks. Those all might as well be taken from some corner of earth

Yes, we know that when we start colonizing other worlds, we won't run out of rocks.

[der bastler 0]

Yes, we know that when we start colonizing other worlds, we won't run out of rocks.

Rock and Roll!

SCNR

[Apollo 0]

Quote[/b] ]I'm not entirely sure, but I'm leaning towards the cooperative approach. These things are so bloody expensive, that it's very difficult for any single country to finance large scale operations. Even for the largest economies in the world, it is a bigass cost to carry and unfortunately space exploration is a popular budget cut. Through international cooperation, that cost can be reduced per country, not making it such an economic burden.

Lets see what happens when china begins to send stuff all around our solar system.

[denoir 0]

First color image:

[Ex-RoNiN 0]

Dammit, another candidate for a developed, advanced civilisation seeing our probes as a threat and launching an invasion of Earth has now turned out to be no such thing

I want Star Wars!!

[cozza 24]

looks like mars only a little more oranger

[theavonlady 2]

I'm sorry. I'm becoming more and more inclined to join the chorus of people saying we earthlings are not getting our bang for the buck - er - Euro, in this case. This wasn't my opinion a few years ago.

Rocks, rocks, rocks, indeed. All for billions and billions of dollars. Brilliant technologies but little to show for it. And there's so much to do way back down here.

[der bastler 0]

Rocks, rocks, rocks, indeed. All for billions and billions of dollars. Brilliant technologies but little to show for it. And there's so much to do way back down here.

Eh, the mission goal was to explore the atmosphere of Titan. The pics are a nice bonus... And I would be angry if they'd do such an expensive mission just to take some eye-candy pictures! It is a scientific mission! Ask ILM for spectacular images...

I suppose you don't use a diskless terminal to write in these forums? Right, then your computer does have a HDD. Look what deep space probe communications got for us:

http://www.seagate.com/support/kb/disc/tp/prml.html

Just one example...

[theavonlady 2]

Rocks, rocks, rocks, indeed. All for billions and billions of dollars. Brilliant technologies but little to show for it. And there's so much to do way back down here.

Eh, the mission goal was to explore the atmosphere of Titan. The pics are a nice bonus... And I would be angry if they'd do such an expensive mission just to take some eye-candy pictures! It is a scientific mission! Ask ILM for spectacular images...

I suppose you don't use a diskless terminal to write in these forums? Right, then your computer does have a HDD. Look what deep space probe communications got for us:

http://www.seagate.com/support/kb/disc/tp/prml.html

Just one example...

I do not question that there are benefits from space exploration.

I'm not interested in images but they speak a lot for themselves.

As for HDDs, one wonders whether the same technologies would have been developed for down-to-earth applications. Even the example you gave was not discovered in space. It was developed here for use in space.

[denoir 0]

As for HDDs, one wonders whether the same technologies would have been developed for down-to-earth applications. Even the example you gave was not discovered in space. It was developed here for use in space.

Things discovered in space:

Quote[/b] ]

Teflon

Dr. Spock

Several new kinds of rock

No, but seriously, the things we have learned is mostly about is the universe and about Earth. Many theories that we take for granted today were developed (or at least confirmed) through empirical measurements during space missions.

Having said that, I partially agree with the critics. It may be a good scientific mission, but the science has to be taken in context of what humans are interested in. And we like to experience things the way we naturally do. Images are therefor important. They give us an intuitive understanding, a good idea of how things "look" over there.

After hearing about the successful landing, not many people asked "What's the pressure at 1,000 meters altitude on Titan?". People asked "When are the pictures coming?".

And since these things are financed through taxes by the people, I really think that it should carry some weight. Now I'm not saying that it should all be turned from science to entertainment, but impressive images should be high on the list. If nothing else, it will spark some interest for space exploration and thus provide funding in the future.

Fortunately they seem to have understood this, at least for the last five years or so. Cassini-Huygens is quite an old mission, that was in development for almost 20 years, so it's pretty outdated.

If we instead look at the much newer ESA Mars Express, there's a significant difference. Take a look at this picture:

http://www.esa.int/export/externals/images/015-090204_1-0037_01-6v.jpg

Quite impressive quality, isn't it? Well, that's a scaled-down version. The Mars Express, has two of the highest resolution cameras ever built. Not only does it give hstunning pictures, but it can do it in stereo for creating 3d models. While it has an impressive array of remote sensing scientific instrumentation, it's the natural color pictures that you'll remember it by.

[theavonlady 2]

If we instead look at the much newer ESA Mars Express, there's a significant difference. Take a look at this picture:

http://www.esa.int/export/externals/images/015-090204_1-0037_01-6v.jpg

If anyone's interested, rotate this image right 90 degrees and try it out as your Windows wallpaper (set POSITION to STRETCH).

[shinRaiden 0]

Link to IEEE Spectrum article about the Doppler Shift problem here.

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WHEN THE CASSINI-HUYGENS MISSION BLASTED off from Cape Canaveral in October 1997, no one suspected that a critical design flaw was lurking deep within the telemetry system onboard Cassini that was dedicated to harvesting Huygens's broadcast. Uncorrected, the flaw meant the data flowing from the hardy lander was in danger of being hopelessly scrambled, its seven-year odyssey across the solar system in vain.

"We have a technical term for what went wrong here," one of Huygens's principal investigators, John Zarnecki of Britain's Open University, would later explain to reporters: "It's called a cock-up."

But back in 1998, as Cassini was swinging past Venus and the Earth to build up speed for its run out to Saturn, Zarnecki and the other scientists and engineers at ESA and NASA were still blissfully unaware of any problem.

In fact, everything was working fine. The mission builders felt confident in their work: both the Cassini orbiter and the Huygens lander had been extensively tested on the ground, both separately and together. However, a proposal for a so-called full-up high-fidelity test of the radio link between the probes (where every system is subjected to a simulation of the exact signals and conditions it will experience during flight) had been rejected because it would have required disassembly of some of the communications components.

"Budget was a key part" of this decision, explained Robert Mitchell, program manager for the Cassini-Huygens Mission at NASA's Jet Propulsion Laboratory (JPL) in Pasadena, Calif. The reassembled spacecraft would then have had to undergo exhaustive and expensive recertification. In hindsight, these testing failures were embarrassing. "We had three safety nets set up to catch things like Cassini-Huygens's communications problem," said John Credland, head of ESA's scientific projects, "and it now appears that we fell through all three."

Fortunately, Claudio Sollazzo, Huygens's ground operations manager at ESA's European Space Operation Centre (ESOC) in Darmstadt, Germany, had a nagging worry about the lack of a full-up communications systems test. Sollazzo knew there was time to run some tests during Cassini's long, uneventful stretches between the planets. So he approached (Boris) Smeds in January 1998 with an unusual request: design a test to send a signal from Earth toward Cassini that would mimic a radio transmission from Huygens during its landing.

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The Cassini-Huygens mission plan had Cassini jettisoning Huygens toward Titan before Cassini began a low-altitude, high-velocity fly-by of the mysterious moon. Huygens would reach Titan well in advance of Cassini, and as Cassini streaked along at some 21 000 km/h relative to Titan, Huygens would be descending on parachutes through the moon's soupy atmosphere at a comparatively leisurely 18 to 22 km/h. The relative velocity of Huygens to Cassini was expected to be about 5.5 kilometers per second, increasing the frequency of Huygens's transmitter by about 38 kilohertz as seen by Cassini because of Doppler shift.

If you've ever heard a screaming ambulance or whistling train pass by, you're familiar with Doppler shift. When an acoustic or radio wave is emitted by a moving object, an observer in front of the object will notice an increase in the wave's frequency as the wave's peaks and troughs are compressed by the object's motion, and an observer behind it will notice a decrease in the wave's frequency as the wave is stretched—hence the familiar rise and fall in the pitch of an ambulance's siren as the vehicle speeds by.

In the case of Huygens, its signal will vary not only in frequency but also in strength as the probe is buffeted by the atmosphere, changing the orientation of its transmitter. When Smeds was brought into the picture, the plan to test Cassini's receivers was to transmit a signal from Earth that would duplicate Huygens's carrier signal without modulating it with any simulated telemetry from the lander's instruments. If the Cassini receiver could pick up a fluctuating, Doppler-shifted carrier wave, all should be well. But Smeds wanted to do better. "If I do a test like this, I want to do it properly and simulate everything, not just a part of it," he told IEEE Spectrum.

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w00t! That's engineers for you. Even if he is a swede.

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Huygens is designed to generate telemetry at a rate of 8192 bits per second. Using a common modulation technique known as binary phase-shift keying, Huygens's transmission system represents 1s and 0s by varying the phase of the outgoing carrier wave. Recovering these bits requires precise timing: in simple terms, Cassini's receiver is designed to break the incoming signal into 8192 chunks every second. It determines the phase of each chunk compared with an unmodulated wave and outputs a 0 or a 1 accordingly.

Smeds's scheme required that his test signal pattern be broadcast from Earth in a sequence of varying power levels to simulate the effect of Huygens and its transmitter's being swung around in Titan's atmosphere. The test signal's frequency would also be adjusted at broadcast so that when it arrived at Cassini, it would match the Doppler-shifted signal expected from Huygens. The echoed signal could then be decoded and verified by matching it against the original telemetry used to create the test signal.

In proposing this more complex test with simulated telemetry, Smeds "had to argue with those who didn't think it was necessary," recalled JPL's Mitchell. Smeds was persistent and continued championing the test even after it was initially rejected. In the end, with the backing of Sollazzo and Huygens's project scientist, Jean-Pierre Lebreton, Smeds's plan was accepted because it was easy to do, even though hardly anybody seemed to think it was worth doing. On such seeming trivia US $300 million missions can turn: the simpler carrier-signal-only test, Mitchell noted, would never have uncovered any problems.

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When Cassini appeared over the horizon, the test sequence began. Smeds's test signal was transmitted to Cassini at a given power level for 5 minutes at a time before moving on to another power level. Cassini was now so far from Earth—430 million km away, somewhere in the asteroid belt—that it took 48 minutes for the signal to reach the probe and be relayed back to Goldstone. The signal from Cassini was then sent to ESOC in Darmstadt for decoding and verification; the center kept in touch with Smeds during the test by fax and phone.

Soon, it became obvious that something was very wrong. Darmstadt reported that it was picking up the carrier signal, but none of the simulated telemetry was coming through. The data in the decoded signal was a mess. As Smeds worked through his test sequence, the situation grew even more puzzling, as Darmstadt would occasionally get short bursts of good data. "Specific things were very confusing. When you increase the power, you expect the signal to get better. Initially it did, but then when I increased the power even more, the data was corrupted again," Smeds told Spectrum.

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Quote[/b] ]

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Even with the test results in hand, Smeds was greeted with some skepticism on his return to Darmstadt. "Some people didn't believe me," he chuckles. They thought that "something was wrong with the test setup. But I had the engineering model, and I continued doing tests on the ground and doing more investigations. I could demonstrate the effect of the Doppler shift and the effect it had on the data reception."

By September 2000, Smeds and his allies had managed to convince ESA that the problem was real and that it was time to tell NASA. "Without Smeds, we wouldn't have known we had a problem," says JPL's Mitchell. Adds Zarnecki, "The guys who pushed the original test through are heroes."

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Over half a year with substantiated data to prove that there is a class-A screw-up going to nuke all the data? Amen to Denoir's comment on competition, if you're private sector that's how to get bankrupted or worse real fast.

Quote[/b] ]

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The board discovered that Alenia Spazio SpA, the Rome-based company that built the radio link, had properly anticipated the need to make the receiver sensitive over a wide enough range of frequencies to detect Huygens's carrier signal even when Doppler shifted. But it had overlooked another subtle consequence: Doppler shift would affect not just the frequency of the carrier wave that the probe's vital observations would be transmitted on but also the digitally encoded signal itself. In effect, the shift would push the signal out of synch with the timing scheme used to recover data from the phase-modulated carrier.

Because of Doppler shift, the frequency at which bits would be arriving from Huygens would be significantly different from the nominal data rate of 8192 bits per second. As the radio wave from the lander was compressed by Doppler shift, the data rate would increase as the length of each bit was reduced.

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Horttor never got an explanation of why Alenia Spazio's telemetry system was built with a timing system that couldn't accommodate the Doppler shift in Huygens's telemetry. "It is a design feature of another application in Earth orbit, and they just reused it," he told Spectrum, adding, "I don't know why anyone would ever want to build it that way." (An Alenia Spazio spokeswoman said that none of the company's officials were available to comment because of a company-wide summer vacation period.)

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Over here, pagers go off and they come find you. So much for vacations, you broke it - you fix it, and now.

Quote ]

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Frustratingly, engineers discovered that the timing scheme was implemented by firmware loaded in Cassini's receiver; a trivial change to some operating parameters would have fixed Cassini's comprehension problem. But the firmware could not be altered after launch.

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That what saved the Mars rovers. They found out they had a buffer overrun, designed their code, and flashed the memory live. Arm-chair quarterback me says nothing flys in the future without that capability.

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As for Smeds, ESA's staff association awarded him and some of his colleagues a plaque and a small cash prize for their role in saving the $300 million mission, though Smeds told Spectrum that he is still looking forward to his real reward: "I hope to sit in Darmstadt and see the data coming in on the screen in January."

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Joy. A friggin plaque. The bane of all "I-nearly-got-myself-fired-for-complaining-that-it-wasnt-going-to-work-but-I-was-righ

t-all-along-so-they-sing-my-praises" awards.

[iNeo 0]

lol they call pictures sized 305x261 from Titan "high-res."

[der bastler 0]

As for HDDs, one wonders whether the same technologies would have been developed for down-to-earth applications. Even the example you gave was not discovered in space. It was developed here for use in space.

See? Space exploration was the trigger to develop an error-proof coding algorithm for long distance communications...

Nowadays it is not only applied to fight radio noise of long distance communications but also to fight signal noise of narrow magnetic flux changes on HDD platters.

[der bastler 0]

lol they call pictures sized 305x261 from Titan "high-res."

Well, regarding a Huygens-to-Cassini communication bandwidth of 8192 Bits/s they are "high-res". Especially because they aren't the important part of the measurement data...

[sanctuary 19]

Mars, Venus, Titan:

[im g] comparison picture[/img]

rocks, rocks and rocks. Those all might as well be taken from some corner of earth

Actually, what is interesting is that Titan rocks are more round

So we can say in a scientific conclusion that when we will run out of round rocks on Earth, we will be able to find some more on Titan

[denoir 0]

Titan: A glimpse into the unknown [bBC]

Quote[/b] ]

The Huygens mission to Saturn's moon Titan is already being hailed as one of the most successful missions in the history of space exploration.

A few days ago, Titan was a cosmic enigma. Shrouded in a pumpkin-coloured smog, the moon was notoriously reluctant to shed its secrets.

But on Friday 14 January, Huygens penetrated the murky haze to expose the moon's true face.

"As the first landing on Titan, this is going to be in the history books for centuries," Dr Andrew Ball of the Open University, a scientist on Huygens' surface science package (SSP) told the BBC News website. It is a world unlike anything human eyes have seen.

Titan's surface is a frigid, misty landscape where dark rivulets run off icy plains into a sea of unknown constitution.

But although it is tempting to see the scenes this way, scientists say it will take extensive analysis to truly interpret what the images show.

"We link some of the features in the pictures with things we see on Earth or other planets in the Solar System because that's what our brains latch on to," said Dr Ball.

"But we may be seeing things that aren't there because we're just not used to looking at the surface of Titan."

Key to life

Much of the appeal of space exploration can be summed up simply as the thrill of the unknown.

But for many scientists, the allure of Titan also lies in its apparent resemblance to the Earth around 4.5 billion years ago.

The moon is one huge complex chemistry experiment, dominated by organic (carbon-containing) compounds such as methane, ethane and acetylene.

This could provide the key to solving one of the greatest mysteries in the Universe: how life arises. The complex chemistry going on Titan could be similar to that which set the stage for the appearance of biology on Earth.

There is one difference, however. With temperatures as low as -179C, the Saturn moon is locked in a deep freeze. As such, it is considered too cold to host life forms itself.

Giant step

In more general terms, Huygens is a landmark mission for the European Space Agency (Esa). This was a mission its US counterpart, Nasa, would surely be proud to have called its own.

Of course, there was a glitch (as there are with all big space missions), which is now the subject of an Esa inquiry. But it was impossible to ignore the sense of being caught up in an historic event.

Landing on another planetary body is one of the riskiest ventures it is possible to undertake. So a successful touch down on a world so far away - especially one about which very little is known - was a tremendous achievement.

It is also a personal triumph for many of the scientists who have spent years and in many cases decades working on the mission.

"This is not only a mission of exploration, it's a way of life," said Dr Carolyn Porco, who leads the imaging team on the Cassini space probe.

"It's taken a lot of work on the part of the scientists and an extraordinary amount of time... to make this happen. This is the life of an explorer."

Professor David Southwood, Esa's director of science, added: "We've had a hell of a lot of fun and many minor triumphs on the way there. The future's just beginning for [the scientists]."

Researchers are still analysing science data from the Voyager 2 probe, which explored the Solar System in the 1980s. There is enough data from Huygens to occupy scientists for just as long, and perhaps longer.

Also, a thing regarding the images, what should be noted is that they're not taken by a regular camera. It's actually a 2D spectrometer that captures a very wide range of the spectrum. The images shown so far are just a slice of the data that cover the visible frequencies. The rest are among other things used for deciding exactly of what material everything we see on the images is made of. It allows for some very detailed chemical analysis of all compounds in the atmosphere and on the ground.

[Bernadotte 0]

Rocks, rocks, rocks, indeed. All for billions and billions of dollars. Brilliant technologies but little to show for it. And there's so much to do way back down here.

Specifically, like what?

I would gladly haven given up the capture of Saddam Hussein for another 50 Huygens missions or, better still, around 12 more ITER projects.

[Bernadotte 0]

I'm trying to work out what a space suit for Titan would have to deal with, besides the cold.

If the atmospere is actually 94% Nitrogen and 6% Methane then you would only need to raise the Oxygen content of what the astronaut breathes to 15%, given that Titan's atmospheric pressure is ~60% greater than the Earth's.  The additional atmospheric pressure would be like undersea diving on Earth at a depth of about 6 meters.  Methane gas, like Nitrogen, is non-toxic and biologically inactive.

Now I'm trying to find out what would happen if you lit a match in a breathable mixture of Titan's atmosphere + 15% Oxygen (i.e. 80% Nitrogen, 15% Oxygen, 5% Methane).

So far, it seems to me that Titan could offer the most hospitable environment for humans away from the earth.

Btw, the gravity would only be about 1/7th of that on Earth.

edit: Damn. The lower explosive limit for Methane in air is 5% at normal atmospheric pressure and probably even less at Titan's higher pressure. Maybe Huygens' new measurements will correct the Methane levels downward.

[denoir 0]

Methane gas, like Nitrogen, is non-toxic and biologically inactive.

Are you sure about that? Now, I'm truly no chemist, but Methane is CH4 right? So if you add some oxyen to it, you'd easily get an OH group i.e CH3OH which is Methanol.

And Methanol, I know for sure is nasty. Low quality home-made booze can contain it. If you are unfortunate to drink it, best case scenario is blindness, worst death.

On the other hand, these CH based gases are highy reactive to just about anything you can think of - so it shouldn't be too difficult to create a filter to get them out of the system, before you add oxygen.

[Donnervogel 0]

Well consider the teperature there. It's fucking cold. And that means every acohol would freeze anyway.

[Bernadotte 0]

Methane gas, like Nitrogen, is non-toxic and biologically inactive.

Are you sure about that? Now, I'm truly no chemist, but Methane is CH4 right? So if you add some oxyen to it, you'd easily get an OH group i.e CH3OH which is Methanol.

Coal miners have been breathing small concentrations of Methane for millenia, so it's effects have been quite deeply studied (pun intended).  Seriously, Methane is quite stable and will not go to methanol under normal conditions.  It would much rather burn with Oxygen to produce simple CO2 and water.

Btw, don't forget that our bodies are safely producing and venting Methane gas all the time.  /cue fart noise...

However, if Oxygen existed on Titan the upper atmospheric Methane could theoretically evolve to more complex hydrocarbons like methanol by exposure to the sun's UV and solar winds (Titan has no protective magnetic field).  But instead of Oxygen, Titan has Nitrogen resulting in Carbon-Nitrogen chemicals.  Btw, Carbon-Nitrogen anions are quite stable and better known as Cyanides.

[Schoeler 0]

I would just like to proudly announce that my University is the major contributor to this project. It's big news here in the desert.

Go Cats!

[Commander-598 0]

As cool as seeing images from Titan is, I think the money that goes into some of these things could be better spent nearer to this mudball we call Earth.

Exactly what did we get out of this? Pictures of rocks, and proof that our theory of Titan being a frozen, primordial chunk of rock being proved.